Lesser Grain Borer

Ten biscuit types namely Tea, Digestive, Butter Scotch, Cream Cracker, Coaster, Fibre Plus, Shapes, Gin-Gin, Cabin and Crunchy were examined for their proximate composition and susceptibility to Tribolium castaneum Herbst. The biscuit samples had proximate composition ranging from 4.9-5.5% moisture content, 8.6-12.0% crude protein, 3.4-4.8% ash, 15.4-24.0% fat, and 55.4-64.0% carbohydrate and 2.09-2.81% crude fibre. Assessment of the biscuit types for susceptibility test was based on percentage adult mortality, mean number of adult emergence and percentage weight loss. Results showed that there were significant differences (P<0.05) in the parameters studied. Fibre Plus biscuit had significantly (p<0.05) lower mortality of T. castaneum adults, higher level of adult emergence and the most weight loss of 53.0% as a result of insect infestation within 120 days after infestation. Results showed that the biscuits were susceptible to T. castaneum infestation particularly if not properly packaged or preserved. Apart from proper preservation, biscuits should be supplemented with protein-rich diets to meet the nutritional needs of consumers.

Phosphine is the only economically viable fumigant for routine control of insect pests of stored food products, but its continued use is now threatened by the worldwide emergence of high-level resistance in key pest species. Phosphine has a unique mode of action relative to well-characterised contact pesticides. Similarly, the selective pressures that lead to resistance against field sprays differ dramatically from those encountered during fumigation. The consequences of these differences have not been investigated adequately. We determine the genetic basis of phosphine resistance in Rhyzopertha dominica strains collected from New South Wales and South Australia and compare this with resistance in a previously characterised strain from Queensland. The resistance levels range from 225 and 100 times the baseline response of a sensitive reference strain. Moreover, molecular and phenotypic data indicate that high-level resistance was derived independently in each of the three widely separated geographical regions. Despite the independent origins, resistance was due to two interacting genes in each instance. Furthermore, complementation analysis reveals that all three strains contain an incompletely recessive resistance allele of the autosomal rph1 resistance gene. This is particularly noteworthy as a resistance allele at rph1 was previously proposed to be a necessary first step in the evolution of high-level resistance. Despite the capacity of phosphine to disrupt a wide range of enzymes and biological processes, it is remarkable that the initial step in the selection of resistance is so similar in isolated outbreaks.

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functions and faster mortality. The findings of this study revealed that it is important to select graphene materials with optimal structural and interfacial properties to achieve the highest insecticidal performance in potential development of a new generation of sustainable insecticides.

Laboratory bioassays were carried out to evaluate the insecticidal efficacy of SilicoSec ® against 7-14 day old adults, old and young larvae of Tribolium castaneum (Herbst) with the mean ± SE (n = 30) weight of 3.4 ± 0.1 and 0.6 ± 0.1 mg, respectively at 27˚C and 55 ± 5% RH. Wheat treated with four dose rates of SilicoSec ® and untreated wheat served as a control with three replications. Adult's mortality was measured after 2, 7 and 14 days of exposure. After 14 day mortality counts, all adults were removed and samples retained under the same conditions for a further 60 days to assess progeny production. In the case of larvae, mortality was counted after 1, 2 and 7 day. After 2 day no concentration achieved 11% mortality for adults, however; adult's mortality exceeds 89.65% when exposed for 7 day to SilicoSec ®. Mortality of old and young larvae at 600 ppm after 2 day were 28.88 and 22.22%, respectively and exceed to 60.71 and 69.04% at longer exposure of 7 day. Due to results mortality of T. castaneum was influenced by interval exposed to wheat treated with SilicoSec ® and over this exposure, the increases in application rate of SilicoSec ® had significant effect on the mortality. Young larvae of red flour beetle were more sensitive to SilicoSec ® than old larvae and adults were more tolerant. The mean number ± SE of progeny in the control was 1.66 ± 0.101 individuals per vial and there was a significant difference between treated and untreated wheat, so reproductive potential of adults in treated wheat was suppressed when compared with untreated wheat.

Phosphine, a widely used fumigant for the protection of stored grain from insect pests, kills organisms indirectly by inducing oxidative stress. High levels of heritable resistance to phosphine in the insect pest of stored grain, Rhyzopertha dominica have been detected in Asia, Australia and South America. In order to understand the evolution of phosphine resistance and to isolate the responsible genes, we have undertaken genetic linkage analysis of fully sensitive (QRD14), moderately resistant (QRD369) and highly resistant (QRD569) strains of R. dominica collected in Australia. We previously determined that two loci, rph1 and rph2, confer high-level resistance on strain QRD569, which was collected in 1997. We have now confirmed that rph1 is responsible for the moderate resistance of strain QRD369, which was collected in 1990, and is shared with a highly resistant strain from the same geographical region, QRD569. In contrast, rph2 by itself confers only very weak resistance, either as a heterozygote or as a homozygote and was not discovered in the field until weak resistance (probably due to rph1) had become ubiquitous. Thus, high-level resistance against phosphine has evolved via stepwise acquisition of resistance alleles, first at rph1 and thereafter at rph2. The semi-dominance of rph2 together with the synergistic interaction between rph1 and rph2 would have led to rapid selection for homozygosity. A lack of visible fitness cost associated with alleles at either locus suggests that the resistance phenotype will persist in the field.

Most stored-grain pest insects increase their population within a relatively short time, causing serious damage to stored products. (L.) is one of the world&#39;s major stored-grain pest insects and was chosen as the model insect for our studies. This study compared the efficacy of three different dusts under laboratory conditions: aluminum dust (nanostructured alumina), DiatomiD, and Protect-It (commercial diatomaceous earth). Parental survival, grain damage, and progeny production were measured at 250 and 500 ppm in treated wheat. The tests were conducted in 400 mL galvanized steel jars, an experimental model used for the first time to measure the effectiveness of nanostructured alumina, since most studies have been typically performed in small petri dishes. Parental survival obtained was highest in the untreated controls, followed in decreasing order by DiatomiD, Protect-It, and nanostructured alumina (NSA). NSA caused the greatest mortality. All treatments significantly reduced ...

Stegobium paniceum (L.) is a major pest for several stored products worldwide. Monitoring methods for this species, based on pheromone traps, are affected by the complexity and expensiveness of the chemical synthesis of the pheromone isomer [(2S,3R,1’R)-Stegobinone] and/or by its lost of efficacy after two weeks at room temperature. So other semiochemicals that can be exploited for monitoring this species are highly desirable. In this study was tested the behavioral response in two-choice olfactometer of S. paniceum adults to Volatile Organic Compounds (VOCs) collected from colonized substrate. The elution of the headspace collection from S. paniceum colony elicited attraction of both sexes. The GC-MS chemical analysis of the extract indicated the presence of several alkanes, alcohols, aldehydes and fatty acids, some of them already reported to attract other stored product coleopteran pests and promising candidates for further studies to test their attractiveness on S. paniceum.

A white low polyphenol sorghum, a red-waxy starch sorghum, a red-tannin sorghum with moderate polyphenol levels, and a red non-tannin sorghum were evaluated for susceptibility to Rhyzopertha dominica (Fab.) (Coleopter: Bostrychidae), the lesser grain borer. Density levels of 0 (untreated controls), 10, 20, or 30 mixed-sex adults were exposed on 100 g replicates of each of the varieties and removed after two weeks. Progeny production and physical damage were evaluated on each variety, along with quality characteristics such as moisture content, protein, starch, phenolic content, and kernel vitreousity. Progeny production and physical damage varied with density level and variety, but was generally lowest on the red-waxy sorghum. At the density level of 30 parental adults more progeny were found in the redtannin sorghum compared to the other varieties. Starch content, kernel vitreousity and hardness was lower in the red-tannin sorghum. Total phenolic content was 2e3x greater in the red-tannin sorghum compared to the other varieties, but the high phenolic content did not seem to affect R. dominica progeny production. Results suggest the insects bypassed the bran layer of the sorghum varieties to feed on the germ and endosperm. Results of this study could be used to further explore the relationships between kernel hardness, chemical composition, and susceptibility to stored product insects, and incorporate results into management programs for maintaining quality of stored sorghum and processed sorghum food by-products.

DESCRIPTION Grain weevils in the genus Sitophilus are worldwide in distribution, but the granary weevil is more temperate in distribution. All three species attack grain and grain products, but they are primarily pests of whole grain in storage. Like all weevils, these have a distinct snout. When disturbed, it will draw its legs up to its body and remain motionless. Rice Weevil: This weevil has small round pits on the surface of the thorax (although miline is usually free of pits), four red to yellow markings on the forewings, and is able to fl y. It is approximately 1/8 inch long (3 mm). Granary Weevil: This weevil is slightly larger (3/16 inch (4.8 mm)) than the other two weevils. It is black-brown in coloring although it can be red-brown shortly after adult emergence. If you examine the thorax closely you can see longitudinal punctures. Adults cannot fl y.

Post‐harvest management constraints are economically significant in Africa for a broad range of commodities, resulting in a substantial negative impact on food security and livelihoods. Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) coexists with Sitophilus oryzae (L.) (Coleoptera: Dryophthoridae) – they infest stored cereal grains, especially in sub‐Saharan Africa, and cause significant losses in storage. Laboratory studies were carried out to determine the efficacy of Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) and Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae), alone or in combination, in suppressing populations of R. dominica and S. oryzae in stored rice and wheat grains. The weight loss and moisture of the infested grains were assessed, for the various combinations of the two pest insects and the two natural enemies. In rice there was a synergistic effect of the combined release of T. elegans and X. flavipes against both R. dominica and S. oryza...

Lethal effects of a diatomaceous earth (DE) formulation (Protect-It) against rice weevil (Sitophilus oryzae L.) and red flour beetle (Tribolium castaneum Herbst) were investigated in wheat bioassay. Lethal effects of DE were examined indoors, at 45 % r.h. and 26 °C, after exposing adults of both insect species to treated wheat over periods of 2, 7, 14 and 21 days, and 7 days recovery on untreated wheat. DE effects on progeny reduction in both species were also investigated after each exposure period. The mortality produced in groups with different numbers of exposed S. oryzae adults (25, 50 and 100 individuals per 100 g of treated wheat per replicate) after 2, 7, 14 and 21 days was 52.0-61.0 %, 73.5-88.0 %, 98.8-100 % and 100 %, while the respective mortality of T. castaneum adults was 8.0-20.3 %, 77.0-87.0, 100 % and 100 %. Reduction in the F 1 generation of S. oryzae adults exposed for 2, 7, 14 and 21 days, depending on the initial number of exposed individuals, ranged 7.14-47.06 %, 2.77-13.11 %, 2.46-5.00 % and 1.45-4.00 % for. A corresponding reduction in T. castaneum fecundity over the same exposure periods ranged 0.00-25.00 %,

Progeny numbers and life parameters of Tribolium castaneum reared on a range of different animal feeds which varied in their protein-carbohydrate ratios (corn starch; corn feed flour; wheat bran; soybean meal; corn gluten; soy protein concentrate and soy protein isolate), four initial (population) densities (1, 2, 5 and 10 insect pairs) were evaluated. Adult insects were kept for seven days on a range of different diets to feed and oviposit before they were removed. After removing the adults, the emerging progeny were examined. The study found T. castaneum offspring could not develop on a carbohydrate-rich diet (corn starch) and on protein-rich diets (corn gluten, soy protein concentrate and soy protein isolate). Soy isolate showed a high, possibly insecticidal effect on parents. The fastest total development (egg to adult) (23.25-23.88 days, depending on the initial density), the highest offspring number (111.63-324.13) and the highest offspring body mass (1.38-1.73 mg) were recorded in wheat bran, while the slowest egg to adult development (35.13-37.88 days), the lowest offspring number (25-29) and the lowest offspring mass (1.04-1.48 mg) were recorded in soybean meal. The higher initial densities caused the eclosion period to be prolonged, reductions in female productivity and in offspring body mass on all diets. Initial density interacted differently with diet type in terms of offspring number, so as the density rose, the number of offspring in wheat bran and corn feed flour increased, while in soybean meal it remained low at all initial densities. This research gives us a better insight into the development of T. castaneum in animal feed that can help us to improve existing pest management in a way of finding a better solution to store products based on their susceptibility to this storage pest.

Any biocontrol agent used against stored grain insects will have to interact with insecticides used as grain protectants due to their heavy use especially in tropical areas. Therefore, the interaction between the pyrethroid insecticides bifenthrin and deltamethrin and Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae), an egg parasite of the stored cereal pest Rhyzopertha dominica(F.) (Coleoptera: Bostrichidae), was assessed in

Rhyzopertha dominica is a primary pest which causes damages to stored cereals such as corn, grain, rice, wheat, sorghum, tubers, and starch-containing substrates and packaging made from wood.  They not only cause losses in terms of quantity but also affect quality during storage period through their feeding activities.  The aimed of this research to investigate the level of susceptibility and damage to cereals during the storage period by pest R. dominica. The cereals used in the study were sorghum, wheat, corn, rice grain, white rice, black glutinous rice, and white glutinous rice. The method used in this research was no-choice bioassay with variables observed: number of F1 progeny, median development time and damage cereals. The results revealed that that different kind of cereals had a different level of susceptibility to infestation by R. dominica from moderate to susceptible. Sorghum, corn, rice, white rice, and white glutinous rice were classified as moderate, while wheat was ...

he time necessary to larvae of Rhyzopertha dominica to drill kernels with or without dusts (semolina or debris from adults), and the possibility of development on semolina were evaluated. T ests were carried out on durum wheat kernels (Triticum durum Desfontaines), debris deriving from rearing, and semolina. Development was observed also on 0.5 and 6 mm of semolina and of debris. T hirty replicates were carried out for each test. The number of first instar larvae, that successfully drill sound kernels within 10 days, was higher by adding semolina or debris. When only kernels were provided, the time needed to larvae to drill increased. Development and the number of emerging adults were not significantly influenced by the addition of semolina to the kernels. Larvae couldn’t develop on 0.5 mm, while an equal number of individuals completed the development to adult in 6 mm of semolina as in the tests with kernels. When development was on debris, a lower number of emerged adults was obse...

Rice is the most important durable food product for more than half of the world’s population, as it is very nutritious food in terms of carbohydrate containment and can meet a large part of human caloric needs on a daily basis. The sensitivity of a rice product fortified with spearmint or basil was evaluated for three stored product insect species: Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Five different containments of fortified rice were used (0, 25, 50, 75 and 100% of the total rice quantity), and the population growth of the above species was examined after 65 days. We found that fortification generally reduced the infestation level of the species tested and reduced their population growth, as compared with the control rice. In some of the treatments, there were some differences between the application of spearmint and basil. There was higher frass producti...

Field experiments in metal bins were conducted over a 96-week period to compare the efficacy of spinosad, chlorpyrifos-methyl, and a combination of spinosad and chlorpyrifos-methyl as grain protectants. Each bin contained 4.6 metric tons of hard red winter wheat that was treated as each bin was loaded with grain. Insect populations were monitored and grain samples

Although high concentrations of zinc and manganese were found in mandibles of insect larvae that bore into seeds, these metals were not detected in mandibles of insect larvae that attack previously damaged seeds. Metals were present in the larval mandibles of a lepidopteran, the Angoumois grain moth (Sitotroga cerealella), and eight coleopterans, the lesser grain borer (Rhyzopertha dominica), cigarette beetle (Lasioderma serricorne), drugstore beetle (Stegobium paniceum), spider beetle (Gibbium aequinoctiale), warehouse beetle (Trogoderma variabile), cadelle (Tenebroides mauritanicus), larger black flour beetle (Cynaeus angustus), and cowpea weevil (Callosobruchus maculatus). Larvae of these species can chew into seeds. Larvae of six other coleopterans, the varied carpet beetle (Anthrenus verbasci), sawtoothed grain beetle (Oryzaephilus surinamensis), rusty grain beetle (Cryptolestes ferrugineus), red flour beetle (Tribolium castaneum), longheaded flour beetle (Latheticus oryzae), and granary weevil (Sitophilus granarius) have little if any ability to chew into seeds, and did not have metal in their mandibles. Larvae of the granary weevil hatch and feed within seeds that were penetrated previously during egg deposition by adults. However, newly hatched larvae of the cowpea weevil and the Angoumois grain moth have to bore through the seed coat before they begin feeding, and they have mandibles with high concentrations of zinc. These data support the hypothesis that deposition of zinc and/or manganese in larval mandibles enhances the larva's ability to penetrate seeds. Published by Elsevier Science Ltd.

DESCRIPTION Grain weevils in the genus Sitophilus are worldwide in distribution, but the granary weevil is more temperate in distribution. All three species attack grain and grain products, but they are primarily pests of whole grain in storage. Like all weevils, these have a distinct snout. When disturbed, it will draw its legs up to its body and remain motionless. Rice Weevil: This weevil has small round pits on the surface of the thorax (although miline is usually free of pits), four red to yellow markings on the forewings, and is able to fl y. It is approximately 1/8 inch long (3 mm). Granary Weevil: This weevil is slightly larger (3/16 inch (4.8 mm)) than the other two weevils. It is black-brown in coloring although it can be red-brown shortly after adult emergence. If you examine the thorax closely you can see longitudinal punctures. Adults cannot fl y.

The majority of overwintering insects avoid lethal freezing by lowering the temperature at which ice spontaneously nucleates within their body fluids. We examined the effect of ice-nucleating-active bacteria on the cold-hardiness of the lady beetle, Hippodamia convergens , a freeze-intolerant species that overwinters by supercooling to ca. −16°C. Topical application of the ice-nucleating-active bacteria Pseudomonas syringae increased the supercooling point to temperatures as high as −3°C. This decrease in cold tolerance was maintained for at least 3 days after treatment. Various treatment doses (10 8 , 10 6 , and 10 4 bacteria per ml) and modes of action (bacterial ingestion and topical application) were also compared. At the highest concentration of topically applied P. syringae , 50% of the beetles froze between −2 and −4°C. After topical application at the lowest concentration, 50% of the individuals froze by −11°C. In contrast, beetles fed bacteria at this concentration did not ...

Post-harvest management constraints are economically significant in Africa for a broad range of commodities, resulting in a substantial negative impact on food security and livelihoods. Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) coexists with Sitophilus oryzae (L.) (Coleoptera: Dryophthoridae)they infest stored cereal grains, especially in sub-Saharan Africa, and cause significant losses in storage. Laboratory studies were carried out to determine the efficacy of Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) and Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae), alone or in combination, in suppressing populations of R. dominica and S. oryzae in stored rice and wheat grains. The weight loss and moisture of the infested grains were assessed, for the various combinations of the two pest insects and the two natural enemies. In rice there was a synergistic effect of the combined release of T. elegans and X. flavipes against both R. dominica and S. oryzae compared to the effect of one natural enemy alone. With the combined release, only 2% F 1 progeny of the pest beetles emerged compared to the untreated control (100%), whereas 3.5 and 6% emerged when X. flavipes and T. elegans, respectively, were released alone. When the two natural enemies were released in combination, 0.4% R. dominica F 1 progeny emerged, compared to 1.6% with X. flavipes or T. elegans alone. In the combined release only 0.3% S. oryzae F 1 progeny emerged, whereas 65% emerged with X. flavipes alone and 41% with T. elegans alone. No synergistic effect of the combined release of the two natural enemies was detected in wheat. In stored rice, the lowest percentage of weight loss (44%) was found when both natural enemies and both beetle species were present. We conclude that the combination of the predator and the parasitoid should be recommended when R. domininca and S. oryzae coexist and feed on stored cereals, especially rice.

Phosphine gas, or hydrogen phosphide (PH 3), is the most common insecticide applied to durable stored products worldwide and is routinely used in the United States for treatment of bulk-stored cereal grains and other durable stored products. Research from the late 1980s revealed low frequencies of resistance to various residual grain protectant insecticides and to phosphine in grain insect species collected in Oklahoma. The present work, which used the same previously established discriminating dose bioassays for phosphine toxicity as in the earlier study, evaluated adults of nine different populations of red ßour beetle, Tribolium castaneum (Herbst), and Þve populations of lesser grain borer, Rhyzopertha dominica (F.) collected from different geographic locations in Oklahoma. One additional population for each species was a laboratory susceptible strain. Discriminating dose assays determined eight out of the nine T. castaneum populations, and all Þve populations of R. dominica, contained phosphine-resistant individuals, and highest resistance frequencies were 94 and 98%, respectively. DoseÐresponse bioassays and logit analyses determined that LC 99 values were Ϸ3 ppm for susceptible and 377 ppm for resistant T. castaneum, and Ϸ2 ppm for susceptible and 3,430 ppm for resistant R. dominica. The most resistant T. castaneum population was 119-fold more resistant than the susceptible strain and the most resistant R. dominica population was over 1,500-fold more resistant. Results suggest a substantial increase in phosphine resistance in these major stored-wheat pests in the past 21 yr, and these levels of resistance to phosphine approach those reported for other stored-grain pest species in other countries. KEY WORDS fumigation, stored-product, red ßour beetle, lesser grain borer, phosphine resistance The United States is among the worldÕs leading producers of wheat. Oklahoma is a major producer of winter wheat in the United States and in 2010 was ranked the third largest producer of this type of wheat among U.S. states with production of 3.3 million tonnes (121 million bushels) (National Agricultural Statistics Service [NASS] 2012). Production levels this high are associated with grain pest management practices to protect the enormous wheat investment in storage from losses caused by stored-wheat insect pests. Moreover, Oklahoma is a high-risk state for grain storage because of the longer storage period for grain and the relatively high ambient temperatures (Cuperus et al. 1990, Hagstrum and Flinn 1992). The main method used for controlling insect infestations in stored wheat in Oklahoma is fumigation using phosphine gas, hydrogen phosphide (PH 3), and all wheat stored in Oklahoma is fumigated at least once a year (Cuperus et al. 1986, Flinn et al. 2003). Commercial storage facilities in Oklahoma use fumigation as the primary management tool and on average fumigate 2.6 times per year (Cuperus et al. 1990). In many grain elevators in the United States, phosphine is currently the only economically viable product for stored-wheat insect pest management (Hagstrum et al. 1999). This scenario has resulted in the frequent use of phosphine, especially in the southern Unite States. The common use of phosphine globally is because of government regulation of pesticides that led to the loss of older fumigants (carbon tetrachloride, carbon disulÞde, ethylene dichloride, and ethylene dibromide), the phasing out of methyl bromide, the declining use of residual contact insecticides stemming from harmful residues they leave in food, and the lack of alternative fumigants that are as convenient to use and cost-effective as phosphine (e.g., Collins et al. 2001, Fields and White 2002, Nayak et al. 2003, Phillips and Throne 2010). Attributes that contribute to widespread use of phosphine are that it is relatively inexpensive, easy to apply, leaves minimal residues, and can be used in a wide range of storage types and commodities (Nayak and Collins 2008). These attributes plus the fact that wheat storage in southern United States is risky have made phosphine the Mention of trade names or commercial products in this publication is solely for the purpose of providing speciÞc information and does not imply recommendation or endorsement by Oklahoma State University or Kansas State University.

The lesser grain borer, Rhyzopertha dominica, and red flour beetle, Tribolium castaneum, are two notorious primary and secondary pests of stored products. Extensive research has been done to prevent the establishment and subsequent infestation of the insects in stored product facilities. Long-lasting insecticide netting (LLIN) on mosquitoes has proved effective in controlling the spread of malaria, but little research has been conducted on the LLIN’s behavioral effects of stored product insects. In this study, a movement and dispersal assay were performed. In the movement assay, the video-tracking software, Ethovision, recorded the movement of R. dominica and T. castaneum after 1-10 min exposures to LLIN or control netting and a waiting period of 1 min, 24 hr, 72 hr, or 7 days after netting exposure. In the dispersal assay, R. dominica and T. castaneum were observed after 5 minutes of exposure to LLIN or control netting to measure the insects’ ability to reach new food patches at th...

Diatomaceous earths (DE) are fossil diatoms (phytoplankton) that contain silicon dioxide (SiO 2), the particles absorb the waterproof lipids from the arthropod cuticle resulting in death through desiccation. The DE SilicoSec ® is registered in Germany. The field trials presented here were performed in order to determine (1) the efficacy of SilicoSec ® under temperate Central European climatic conditions, (2) the distribution in empty rooms and (3) the possible effect of different surface materials. For empty room treatment, a 41 m² storage room was treated with 20 g/m², the total surface treated including walls was 145 m². At 19 sampling points the amount of DE on the floor was determined. Distinctly less DE attached to the walls compared to the floor, and an uneven distribution on the floor ranging from 2.6 to 49.5 g/m² with a mean±SD of 15.4±14 g/m² per sampling point was measured. Additionally, test pieces with 5 different surface types were placed in the treatment room prior to the treatment. Adult Tribolium confusum and Cryptolestes ferrugineus were placed on all surfaces at 15 to 19°C and 65-81% r.h.. Mean corrected mortality after 14 d in T. confusum and C. ferrugineus was 94% and 65%, respectively. No significantly different mortality was recorded for T. confusum depending on surface type, but in C. ferrugineus significantly less beetles (20%) died on concrete flagstone compared to natural flagstone, glazed ceramic flagging, plywood and porcelain stoneware. For bulk grain, 10 t of wheat were treated with either 0.7 kg/t or 2 kg/t DE. Sitophilus granarius, Oryzaephilus surinamensis and C. ferrugineus adults were placed in vials with treated wheat together with data loggers and placed deep within the bulk for 19 d. Corrected mortality was around 90% for all treatments except for S. granarius at the lower dose where 60% mortality was achieved only.

Insects can cause damage to stored grain, especially on smallholder farms in the tropics. Sitophilus zeamais (maize weevil, MW) and Rhyzopertha dominica (lesser grain borer, LGB) are often involved. Our objective was to determine, by four experiments, if physical disturbance of grain can control these pests. In Experiment 1, 2.6-L unsealed recycled coffee cans were each loaded with 1 kg of maize and 25 live adult MW/kg. Every 12 h, disturbed treatment cans were manually rolled through one circumference. After 160 d, live MW numbers had been reduced by 93% compared to undisturbed cans. In Experiment 2, MW-infested maize was placed in 20-L plastic cans and stored by farmers in Tanzania. Each farmer had three cans. Two were disturbed by shaking morning and evening and the third was left undisturbed. After 90 d, MW populations had increased in the undisturbed containers, but had decreased to zero in every disturbed container. In Experiments 3 (and 4), maize (wheat) infested with 25 adul...

MThe lesser grain borer, Rhyzopertha dominica is one of the serious cosmopolitan stored grain pests worldwide. High phosphine resistant R. dominica has been reported in several countries. The evolution of strong phosphine resistance is a major challenge for continuous application of the fumigant. Rapid detection of phosphine resistance level is a prime key to implement an appropriate strategy for control the stored-product pests. Dihydrolipoamide dehydrogenase (DLD) is a key metabolic enzyme mediating the phosphine resistance in population of R. dominica, Tribolium castaneum and Caenorhabditis elegans. Analysis of the DLD sequences deposited in GenBank revealed that the P45/49S mutation was the most common one in many PH3-resistant stored-product pest insects. This information now enables direct detection of resistance using molecular diagnosis in field populations. We herein propose a method for rapid detection of phosphine resistance in R. dominica according to P49S point mutation...

Most overwintering insects do not survive internal freezing and must avoid low temperatures or enhance the capacity of their body fluids to supercool to survive low temperature exposure. Recent reports have demonstrated that the application of ice-nucleating active microorganisms markedly diminishes supercooling. Topical application of as little as 20 ppm of a suspension of a freeze-dried preparation of the ice-nucleating active bacterium Pseudomonas syringae van Hall was sufficient to elevate the mean supercooling point of thc overwintering adults of the Colorado potato beetle, Leptinotarsa decemlineata (Say), from-8.7 to-4.7"C. Previous reports have demonstrated that topical application of these biological icc nucleators to insects whose mouths have been sealed still reduces supercooling capacity; however, the anatomic,J route by which these agents make contact with body water is unclear. Application of the P. syringae suspension to the ventral abdomen did not significantly increase the supercooling point (-5.5°C) compared with beetles treated with the non-ice-nucleating active (eontrol) bacterium Escherichia coli (Migula). However, application of the icc-nucleating agent to the thoracic spiracle, ventral cervix, or abdominal spiracle elevated supercooling point values above those of beetles treated on the ventral abdomen. These data are instructive in the development of methods for the use of ice-nucleating active microorganisms for the biological control of overwintering pests.

Topical application of ice nucleating active (INA) bacteria or fungi decreases the cold tolerance of freeze-intolerant insects by raising their supercooling points (SCPs). However, the route by which INA agents come in contact with insect body water is unknown. To determine their effect on the SCP, we topically applied a suspension of INA Pseudomonas syringae to four anatomic sites of the freeze-intolerant lady beetle, Hippodamia convergens. Aqueous suspensions of either cultured or lyophilized, ultraviolet irradiated (UVI) P. syriugae produced significantly higher mean SCPs than control treatments when applied to the thoracic spiracle of the insect,-7.7 and-5.6'C, respectively, compared with the control treatment's mean SCP of-14.9'C. Application of an aqueous suspension of UVI P. syringae to three other anatomic sites on the beetle produced less dramatic and more varied increases in mean SCP. Application of the INA fungus Fusarium avenaceum to the thoracic spiracle significantly elevated the mean SCP to approx.-10°C. Application of powdered UVI P. syringae to the thoracic spiracle resulted in a SCP increase from-14.9 to-4.6'C, the most dramatic increase in this study. These results indicate that the efficacy of INA microorganisms in elevating the SCP varies with the microorganism and its site of application. Supercooling capacity Pseudomonas syringae Fusarium avenaceum Ice nucleating active Hippodamia convergens Microbial. 54, 16788168 1. Knight C. A. and Duman J. G. (1986) Inhibition of recrystalization of ice by insect thermal hysteresis proteins: a possible cryoprotective Acknowledgements-We thank Jon Costanzo and the anonymous role. Cryobiology 23, 256262. reviewers for critically reviewing an earlier draft of this manuscript. We

Using fumigation toxicity data of 11 natural and synthetic cyanohydrins to house fly (Musca domestica) and a stored-product pest, the lesser grain borer (Rhyzopertha dominica), the quantitative structure−activity relationships (QSAR) of cyanohydrins were examined by Oxford Molecular CAChe 3.2 and Microsoft Excel. This analysis used eight physicochemical parameters. Correlation between the LC50 values for house fly and lesser grain borers was also evaluated. The results showed that log P, polarizability, and molar refractivity are the best descriptors to explain the relationship between the structure of cyanohydrins and biological effects in house flies, and to a lesser degree in lesser grain borers. A significant relationship was also found between the toxicity to house flies and lesser grain borers.

A laboratory experiment was carried out to test the larval development of lesser grain borer. Rhyzopertha dominica Fabrecios on different varieties of wheat Triticum aestvum Linn was evaluated at Department of Zoology, D.B.S. College, Kanpur, India during 2004 to 2005 in protected and unprotected condition. The data revealed significant differences among six wheat varieties namely TL 174, K 65, HI 774, UPT 72294, Kalyan Sona and HD 1982 for larval development of R. dominica. The data revealed significant differences among various wheat varieties for larval development of R. dominica. The lowest larval period 27.50 days was found in HI 7747 followed by HD 1982 and Kalyan Sona having the larval period 27.76 and 29.20 days respectively. These do not differ significantly to each other. In HI 7747 one larva could not complete its development even up to 48 days and it was dead before population. The highest larval period (33.44 days) was observed in UPT-72294 followed by K 65 and TL 174 having the larval period 32.42 and 31.54 days respectively. These three varieties do not differ significantly each other but differ significantly from the others.

The lesser grain borer, Rhyzopertha dominica Fabricius (Coleoptera: Bostrichidae) is a primary pest of stored wheat. Many authors studied its development on this cereal like (e.g. wheat, rice, sorghum, oats, pearl, millet, malt, barley chickpeas, peanuts and beans etc. The aim of performed laboratory experiments was to assess the feeding preferences for the different varieties of wheat viz; HI 7747, HD 1982, K 65, Kalyan Sona, TL 174 and UPT 72294 and to evaluate their susceptibility/resistance to progeny production of R. dominica particularly larvae. The experiments were conducted at 28°C and 60 ± 5% of relative humidity. The mean survival rate of R. dominica larval and dockage in various wheat were determined. The influence of the wheat genotypes on the larval development of R. dominica was significant. The highest number of Rhizopertha dominica larvae 23.00 were present in UPT 72294 which is observed the most preferred variety. This variety differs significantly from the others. The next variety in order to preference for food is TL 174 having 10 larvae followed by H.D. 1982 having 5.66 larvae, which do not differ significantly to each other but differ significantly from the rest of the varieties. The least preferred varieties are HI 7747 and K65 having only 1.33 larvae and these do not differ from Kalyan Sona and HD 1982.

Inert dusts are increasingly becoming an integral part of programs for protection of cereal grains from stored-product insects. The intention in this study was therefore to conduct preliminary tests of insecticidal potentials of the natural zeolite formulation Minazel SP (66% SiO 2 , particle size ≤ 50 μm) originating from Serbia in controlling S. oryzae, R. dominica and T. castaneum . Dust effectiveness was tested in the laboratory (24±1oC and 50-55% r.h. for parents and 24±1oC and 60±5% r.h. for F 1 progeny) by exposing insects to wheat treated with 0.50, 0.75 and 1.00 g/kg of Minazel SP. Mortality was determined after 7, 14 and 21 days of insect contact with threated wheat, and total mortality after an additional 7 days of recovery on untreated broken wheat. Progeny production in F 1 generation was also determined for each insect species after 8-12 weeks. After seven days of exposure and 7 days of recovery of all tested species, the highest efficacy of 62% was observed after the ...

The insecticidal efficacy of the diatomaceous earth formulation DiatoSec® (Ediafilt Diatomite Mining and Processing Ltd., Hungary) against the granary weevil, Sitophilus granarius (Coleoptera: Curculionidae), was evaluated on maize and barley grain in laboratory tests. The diatomaceous earth formulation was applied at three doses of 1, 2 and 4 g kg-1 of both grain types. Mortality of S. granarius adults was estimated after 24 and 48 h and 7, 14 and 21 d of exposure on treated grain. After the 21 d counts, all the exposed adults were removed and progeny production on treated grains was assessed 45 days later. The insecticidal efficacy of the examined diatomaceous earth against the granary weevil was highly influenced by grain type, exposure time and dose. The longer exposure times increased weevil mortality in the case of both grains. The efficacy on maize was unsatisfactory. On the other hand, 85% of the weevils were died after a 21 d exposure on barley treated with the highest dose. In addition, progeny production on treated barley was completely suppressed. In all, a satisfactory level of protection was only achieved with barley at a rate of 4 g kg-1. Differences in efficacy between grain types could be traced back to differences in grain surface. The lower efficacy-than some examined silica products-of DiatoSec as compared to similar products can be explained by the lower SiO 2 content.

Phosphine is the only economically viable fumigant for routine control of insect pests of stored food products, but its continued use is now threatened by the worldwide emergence of high-level resistance in key pest species. Phosphine has a unique mode of action relative to well-characterised contact pesticides. Similarly, the selective pressures that lead to resistance against field sprays differ dramatically from those encountered during fumigation. The consequences of these differences have not been investigated adequately. We determine the genetic basis of phosphine resistance in Rhyzopertha dominica strains collected from New South Wales and South Australia and compare this with resistance in a previously characterised strain from Queensland. The resistance levels range from 225 and 100 times the baseline response of a sensitive reference strain. Moreover, molecular and phenotypic data indicate that high-level resistance was derived independently in each of the three widely separated geographical regions. Despite the independent origins, resistance was due to two interacting genes in each instance. Furthermore, complementation analysis reveals that all three strains contain an incompletely recessive resistance allele of the autosomal rph1 resistance gene. This is particularly noteworthy as a resistance allele at rph1 was previously proposed to be a necessary first step in the evolution of high-level resistance. Despite the capacity of phosphine to disrupt a wide range of enzymes and biological processes, it is remarkable that the initial step in the selection of resistance is so similar in isolated outbreaks.

The morphology and ultrastructure of ovarioles in Rhizopertha dominica (Coleoptera : Bostrichidae) are described. Ovarioles are of telotrophic type and are composed of an apical terminal filament, trophic chamber, and vitellarium. The trophic chamber consists of numerous individual trophocytes that remain connected by intercellular bridges. The vitellarium is composed of 3 oocytes, 2 of them are in the previtellogenic young phase, the 3rd (terminal one) is in the vitellogenic or chorionic phase. Individual oocytes are joined with trophocytes by long trophic cords. Special attention is paid to the morphogenesis of follicular cells and oocyte nucleus (germinal vesicle).

Diatomaceous Earth (DE) is a dust composed of fossilized bodies of unicellular algae used as an insecticide. In this study, the insecticidal potential of four Iranian DE deposits was assessed in adults of Oryzaephilus surinamensis (L.) . Three of DE deposits were collected from Maragheh, Mamaghan, and Khorasan Jonoobi mines and Sayan ® formulation was obtained from Kimia Sabz Avar Company. The insect adults were exposed on wheat, peeled barley, and rice treated with 300, 600, 1,000, 1,500, and 2,000 ppm of the DE deposits. Experiments were conducted at 27 ±1°C and 55 ±5% RH in continuous darkness. Mortality of the exposed individuals was counted after 2, 5, 10, and 14 days of exposure on the treated substrate. Mortality increased with increasing exposure intervals and concentration level. Satisfactory level of protection was observed on wheat grain; as 100% mortality was recorded on wheat treated with 600 ppm of all tested DE deposits after a 10-day exposure. However, for rice, even...

Inert dusts are increasingly becoming an integral part of programs for protection of cereal grains from stored-product insects. The intention in this study was therefore to conduct preliminary tests of insecticidal potentials of the natural zeolite formulation Minazel SP (66% SiO 2 , particle size ≤ 50 μm) originating from Serbia in controlling S. oryzae, R. dominica and T. castaneum . Dust effectiveness was tested in the laboratory (24±1oC and 50-55% r.h. for parents and 24±1oC and 60±5% r.h. for F 1 progeny) by exposing insects to wheat treated with 0.50, 0.75 and 1.00 g/kg of Minazel SP. Mortality was determined after 7, 14 and 21 days of insect contact with threated wheat, and total mortality after an additional 7 days of recovery on untreated broken wheat. Progeny production in F 1 generation was also determined for each insect species after 8-12 weeks. After seven days of exposure and 7 days of recovery of all tested species, the highest efficacy of 62% was observed after the ...

The sensitivity of the main external and internal stored product insect pests to the commercial formulation of Detia Degesch Diatomaceous Earth – DDDE - Inerto (DE) was studied in laboratory experiments. The tested insects were adults of internal feeders Sitophilus oryzae Rhyzopertha dominica and external feeders Oryzaephilus surinamensis, Tribolium castaneum , and larvae (third instar) of T.castaneum . The DE was applied to wheat grain of 12% moisture content at concentrations of 0.5, 1.0, 2.0 and 4.0 g/kg of grain. The treated and untreated (control) grain were kept at 28°C and 65 ± 5% r.h. The numbers of dead and survived insects were counted two, three and four weeks after treatment. The number of adult progeny was counted nine weeks after treatment. At a concentration of 0.5 g/kg, mortality of S. oryzae and O. surinamensis after three weeks of exposure to DE were 92 and 86%, respectively. In contrast, mortality of T. castaneum and R. dominica adults was 3 and 37%, respectively....

The aim of this study was to investigate the efficacy of some plant dusts i.e. black pepper seeds dust (Piper nigrum L.); Cloves flowering buds (Syzegium aromaticum); Chili fruits dust (Capsicum frutescens); Cinnamon dust (Cinnamonum zeylanicum); Diatomaceous earth (DE) dust in comparison with katel-sous dust against Rhizopertha dominica (F.) at 30+1C and 65+5% RH, also the efficacy of two organophosphorus insecticides namely malathion and piromiphos –methyl (Actellic) and one botanical insecticide (Neemazal T/S 1% Azadirachtin) was evaluated. The results indicated that adult mortality was concentration and exposure period dependent. Adult mortality was increased with increasing the dust concentration and exposure period. The results of the various dusts against Rhizopertha dominica adults indicated that DE was the most effective followed by black pepper dust, cloves flowering dust, katel-sous dust and chili dust which was the least effective one. On the other hand the highest teste...

The aim of this study was to investigate the efficacy of some plant dusts i.e. black pepper seeds dust (Piper nigrum L.); Cloves flowering buds (Syzegium aromaticum); Chili fruits dust (Capsicum frutescens); Cinnamon dust (Cinnamonum zeylanicum); Diatomaceous earth (DE) dust in comparison with katel-sous dust against Rhizopertha dominica (F.) at 30+1 o C and 65+5% RH, also the efficacy of two organophosphorus insecticides namely malathion and piromiphos-methyl (Actellic) and one botanical insecticide (Neemazal T/S 1% Azadirachtin) was evaluated. The results indicated that adult mortality was concentration and exposure period dependent. Adult mortality was increased with increasing the dust concentration and exposure period. The results of the various dusts against Rhizopertha dominica adults indicated that DE was the most effective followed by black pepper dust, cloves flowering dust, katel-sous dust and chili dust which was the least effective one. On the other hand the highest tested cinnamon dust concentration (6% w/w) resulted a lower mortality (less than 40%) even after two weeks from treatment. Results of the toxicity index of the various tested insecticides against Rhizopertha dominica (F.), revealed that Actellic was the most effective followed by Malathion and Neemazal which was the least effective one. EFFECTIVENESS OF SOME PLANT DUSTS AND INSECTICIDES AGAINST LESSER GRAIN BORER-RHIZOPERTHA DOMINICA (F) (COLEOPTERA: BOSTRYCHIDAE) 864 but its antifeedant and other efficacies may also be important in controlling these legume pests (Ketkar, 1987). Thus the aim of this work was to study:-1-Investigate the efficacy of some plant dusts namely:-Black pepper (piper nigrum) (L.), cloves flowering buds (syzygium aromaticum), chili dust (capsicum frutescens), cinnamon (cinnamonum zeylanicum), Diatomaceous earth and katel sous against Rhizopertha dominica (F.). 2-Investigate the efficacy of some insecticides namely:-Neemazal T/S 1% azadirachtin, Actellic EC 50% (pirimiphos methyl) and malathion EC 57% against Rhizopertha dominica (F.). MATERIALS AND METHODS * Insects: Laboratory strain of the Rhizopertha dominica(F.) the lesser grain borer, (Bostrychidae, Coleoptera) was used during this work. Insects were collected from the stores during 2006 and maintained at the stored product pests' laboratory of the plant protection Dept. Faculty of Agric., Moshtohor Benha University. * Insect cultures Adults were reared in glass jars of approx. 250 ml., each jar contained about 450 g. of wheat kernels for R. dominica and covered with muslin cloth and fixed with rubber band. Insect cultures were kept under controlled conditions of 30 ± 1ºC and 65+ 5% R.H. at the rearing room of the laboratory. Wheat grains were treated well by freezing at-18ºC for 2 weeks before application to eliminate any possible infestation by any insect species. The moisture content of the grains was about 14%. Adults samples were exposed to the various treatments for varying length of time. After the desired exposure period mortality assessment was performed. Mortality percentages were corrected by Abbott's formula (1925). Grain protectants tested :-Katel-sous (KS): A dust powder formulation (contains 84% calcium triphosphate plus 16% sulpher, produced by Kafr El-Zayat Company for Pesticides, Egypt), was mixed with wheat grains and tested at 6, 4, 2, 1 and 0.5 % (w/w) concentrations. Diatomaceous earth (DE): Algae Diatomes in the form of rigid, rocky mountains and it was grounded into fine powder.

The stored insect pest can cause a reduction in weight, quality of the grain, seed viability, and commercial value (Akhter, Sultana, Akter, & Begum, 2017). The loss of total post-harvest maize caused by insect attacks is estimated at ca. 20% (Acheampong, Ayertey, Eziah, & Ifie, 2019). Kumar & Kalita (2017) also reported cause huge losses in the grains (30%-40%) due to the pests and up to 50% of losses also has been known in tropical countries on the untreated kernel and due to improper storage facilities (Demissie, Swaminathan, Ameta, Jain, & Saharan, 2015). Atwal (2002) and Edde (2012) reported that Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), the lesser grain borer, is known as one of the most destructive stored cereal pests on maize, rice, and wheat. In addition, Astuti, Mudjiono, Rasminah Ch, & Rahardjo (2013) also stated that R. dominica is more dominant than other insects that attack rice in storage. Rhyzoperta dominica can cause high economic losses to agricultural commodities by damaging grains, producing frass, and fecal matter, releasing unpleasant odor, depleting grain nutrients, converting product that is unsuitable for humans, and reducing the digestibility of product (

The insecticidal potential of two natural zeolite formulations, Zeocem and Mycostop, was tested against the rice weevil Sitophilus oryzae (L.) and the sawtoothed grain beetle Oryzaephilus surinamensis (L.) on wheat, at the dose rates of 0.25, 0.50, 0.75, and 1 g/kg. The bioassays were carried out under laboratory conditions at three temperature levels (20, 25, and 30 ο C) and two relative humidity (r.h.) levels (55, 75%). Mortality was recorded after 7, 14, and 21 d of exposure and progeny production was recorded 65 d later. Complete (100%) mortality was achieved only for O. surinamensis adults with Zeocem for most temperature and r.h. combinations tested. Progeny production for this species was extremely low. In contrast, mortality for S. oryzae was much lower and did not exceed 87% after 21 days at any of the combinations tested, while progeny production was high. For O. surinamensis exposed to Mycostop, mortality after 21 days did not exceed 97% for all temperature and r.h combinations, while overall progeny production was low. Moreover, S. oryzae mortality was generally low and did not exceed 56%, while progeny production for this species was high for most temperature and r.h. combinations. Despite the fact that some general trends were evident, the effect of temperarature and r.h. in zeolite efficacy was often found inconclusive. The results of the present study illustrated the insecticidal potential of zeolites for the contol of certain stored product insect species, which requires additional investigation.

Phosphine gas, or hydrogen phosphide (PH 3), is the most common insecticide applied to durable stored products worldwide and is routinely used in the United States for treatment of bulk-stored cereal grains and other durable stored products. Research from the late 1980s revealed low frequencies of resistance to various residual grain protectant insecticides and to phosphine in grain insect species collected in Oklahoma. The present work, which used the same previously established discriminating dose bioassays for phosphine toxicity as in the earlier study, evaluated adults of nine different populations of red ßour beetle, Tribolium castaneum (Herbst), and Þve populations of lesser grain borer, Rhyzopertha dominica (F.) collected from different geographic locations in Oklahoma. One additional population for each species was a laboratory susceptible strain. Discriminating dose assays determined eight out of the nine T. castaneum populations, and all Þve populations of R. dominica, contained phosphine-resistant individuals, and highest resistance frequencies were 94 and 98%, respectively. DoseÐresponse bioassays and logit analyses determined that LC 99 values were Ϸ3 ppm for susceptible and 377 ppm for resistant T. castaneum, and Ϸ2 ppm for susceptible and 3,430 ppm for resistant R. dominica. The most resistant T. castaneum population was 119-fold more resistant than the susceptible strain and the most resistant R. dominica population was over 1,500-fold more resistant. Results suggest a substantial increase in phosphine resistance in these major stored-wheat pests in the past 21 yr, and these levels of resistance to phosphine approach those reported for other stored-grain pest species in other countries. KEY WORDS fumigation, stored-product, red ßour beetle, lesser grain borer, phosphine resistance The United States is among the worldÕs leading producers of wheat. Oklahoma is a major producer of winter wheat in the United States and in 2010 was ranked the third largest producer of this type of wheat among U.S. states with production of 3.3 million tonnes (121 million bushels) (National Agricultural Statistics Service [NASS] 2012). Production levels this high are associated with grain pest management practices to protect the enormous wheat investment in storage from losses caused by stored-wheat insect pests. Moreover, Oklahoma is a high-risk state for grain storage because of the longer storage period for grain and the relatively high ambient temperatures (Cuperus et al. 1990, Hagstrum and Flinn 1992). The main method used for controlling insect infestations in stored wheat in Oklahoma is fumigation using phosphine gas, hydrogen phosphide (PH 3), and all wheat stored in Oklahoma is fumigated at least once a year (Cuperus et al. 1986, Flinn et al. 2003). Commercial storage facilities in Oklahoma use fumigation as the primary management tool and on average fumigate 2.6 times per year (Cuperus et al. 1990). In many grain elevators in the United States, phosphine is currently the only economically viable product for stored-wheat insect pest management (Hagstrum et al. 1999). This scenario has resulted in the frequent use of phosphine, especially in the southern Unite States. The common use of phosphine globally is because of government regulation of pesticides that led to the loss of older fumigants (carbon tetrachloride, carbon disulÞde, ethylene dichloride, and ethylene dibromide), the phasing out of methyl bromide, the declining use of residual contact insecticides stemming from harmful residues they leave in food, and the lack of alternative fumigants that are as convenient to use and cost-effective as phosphine (e.g., Collins et al. 2001, Fields and White 2002, Nayak et al. 2003, Phillips and Throne 2010). Attributes that contribute to widespread use of phosphine are that it is relatively inexpensive, easy to apply, leaves minimal residues, and can be used in a wide range of storage types and commodities (Nayak and Collins 2008). These attributes plus the fact that wheat storage in southern United States is risky have made phosphine the Mention of trade names or commercial products in this publication is solely for the purpose of providing speciÞc information and does not imply recommendation or endorsement by Oklahoma State University or Kansas State University.

Phosphine is the only economically viable fumigant for routine control of insect pests of stored food products, but its continued use is now threatened by the worldwide emergence of high-level resistance in key pest species. Phosphine has a unique mode of action relative to well-characterised contact pesticides. Similarly, the selective pressures that lead to resistance against field sprays differ dramatically from those encountered during fumigation. The consequences of these differences have not been investigated adequately. We determine the genetic basis of phosphine resistance in Rhyzopertha dominica strains collected from New South Wales and South Australia and compare this with resistance in a previously characterised strain from Queensland. The resistance levels range from 225 and 100 times the baseline response of a sensitive reference strain. Moreover, molecular and phenotypic data indicate that high-level resistance was derived independently in each of the three widely separated geographical regions. Despite the independent origins, resistance was due to two interacting genes in each instance. Furthermore, complementation analysis reveals that all three strains contain an incompletely recessive resistance allele of the autosomal rph1 resistance gene. This is particularly noteworthy as a resistance allele at rph1 was previously proposed to be a necessary first step in the evolution of high-level resistance. Despite the capacity of phosphine to disrupt a wide range of enzymes and biological processes, it is remarkable that the initial step in the selection of resistance is so similar in isolated outbreaks.

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is a widespread pest of stored products. While the direct effects of several pesticides have been evaluated on this notorious species, little is known on their indirect effects in terms of progeny fitness. In this study, we investigated the cost of different exposure intervals of T. castaneum females to spinosad by calculating the life table parameters of its progeny. For this purpose, females of T. castaneum were exposed for 5, 10 and 20 min to spinosad and birth or death rates of progeny were estimated. Water was used as a control treatment. The mean values of the net reproductive rate, the intrinsic rate of increase, the finite rate of increase, the mean generation time and the doubling time of the control treatment were 6.3 females/female, 0.029 females/female/day, 1.029, 63.6 days and 24.1 days, respectively, which are indicative of the potential population increase of T. castaneum. When female parental time exposure to spinosad was 5, 10 and 20 min, the corresponding values were 0.073, 0.135 and 0.097 females/female;-0.045,-0.031 and-0.048 females/female/day; 0.956, 0.970 and 0.953; 60.6, 67.7; and 50.3 days;-15.9,-23.3 and-14.8 days, respectively, which indicate a population decrease. However, based on the 95% confidence intervals criterion, the different exposure intervals of T. castaneum females to spinosad did not affect the fitness of their progeny. These results may have bearing on the management of T. castaneum in storage facilities.

The effects of different population levels of Rhyzopertha dominica (F.), the lesser grain borer, on physiochemical properties of sorghum kernels and flour, were investigated through a laboratory study at 27 and 32 1C, and 57% relative humidity. Initial population level and temperature, and their interaction, were significant for the number of F 1 progeny and feeding damage (Po0.01). A strong positive correlation was also found between initial population size, number of F 1 progeny, percentage of insect-damaged kernels (IDKs) and feeding damage. The impact of R. dominica on the milling quality of sorghum was seen through a reduction in abrasive hardness, milling yield, and kafirin content. Initial population and temperature affected most pasting properties, and overall pasting viscosity increased with initial population, number of F 1 progeny, and percentage of IDK at 32 1C. Results show that R. dominica can potentially impact the milling quality of sorghum and also alter the physicochemical properties of sorghum flour.

Losses of grain quality and quantity as a result of insect activity during storage impose the need for proper pest control. One of the major pests of stored wheat is the lesser grain borer (LGB), Rhyzopertha dominica. This pest is usually controlled with insecticides. However, there is recently a growing interest in the use of plant-based products in pest management. Plants are a rich source of active compounds and for centuries have been used for the control of harmful insects. This study was carried out in order to evaluate the effects of Satureja montana aqueous extract on LGB adults in contact and contact-digestive tests. The mortality of LGB adults during contact exposure to S. montana extract was low, regardless of the concentration (16.7-33.3% after 24 h and 30.0-33.3% after 48 h). After 24 h of contact-digestive exposure, the highest mortality was caused by 2% S. montana extract (23.3%), while after 48 h the level of mortality increased in all treatments with S. montana extract (0.5, 1, and 2%) and was 28.4, 28.4, and 41.7%, respectively. After 72 h of contact-digestive exposure, it ranged from 57.5 to 63.5%, while in the control it remained the same (2.7%). After 7 days of such exposure, it was 91.6-98.4%, depending on the concentration. Based on the obtained results, we conclude that S. montana aqueous extract caused mortality of LGB adults, the level of this mortality depending on concentration of the applied extract and duration of the experiment.