ZOOLOGY

Riparian systems are threatened globally, but contribute disproportionately to biodiversity and ecosystem function. Restoration to reverse their loss is costly, and requires careful monitoring and evaluation. Odonates are amongst the most reliable arthropod bio-indicators for monitoring riparian ecosystems. Despite functional diversity (FD) reflecting ecosystem pattern and processes better than taxonomic diversity, Odonate FD has yet to be used in evaluating riparian conservation and restoration outcomes. We surveyed 45 sites across six riversystems in northeastern South Africa, to compare Odonate FD and standardised effect size of Odonate FD (sesFD) in riparian systems that had been invaded by alien plants, cleared of alien invasives, and sites that had never been invaded (15 sites each). Although species richness did not differ between treatments, Odonate sesFD was lower in invaded sites than those that had been cleared of alien riparian vegetation and those that had never been invaded. Clearance of 40% of alien riparian vegetation was associated with sesFD greater than that of invaded sites by almost two standard deviations. Representation of traits varied between treatments but was similar between cleared and natural sites, suggesting that invasion by alien plants directly impacts food webs, and that clearance can restore ecosystem processes and ecological services. This study confirms that Odonate FD can respond to restoration efforts. Secondary impacts of restoration to complete suites of functional groups can be anticipated to enhance ecological services and impact food webs at a range of scales.

This case study of a fish market near the border of Namibia and Zambia examines how economic and environmental changes have affected the marketing channels associated with fishery in southern Africa. We monitored the volume and origin of fish entering the market in Katima Mulilo, Namibia, between 2007 and 2012, and conducted semi-structured interviews with fish committee members and market vendors. Prior to 2010, the market for fish had a simple commodity chain, involving local producers and consumers. Since then, a nearby lake has refilled, providing a new source of fish. The market has expanded and diversified, with large volumes of fish now being sent to consumers in urban centres in Zambia and even to the Democratic Republic of Congo. We consider the sustainability of the fishery in relation to expansion and re-alignment of the marketing channel and the degree to which intra-regional trade in fish promotes or hampers food security and sustainable use of the resource. 45 Hapke, 'Petty Traders'.

... BCW van der Waal Department of Biological Sciences, University of Venda, PO Bag X 5050, Thohoyandou 0950, South Africa FAM Volckaert Laboratory of Aquatic Ecology, Katholieke Universiteit Leuven, Ch. Deberiotstraat 32, B-3000 Leuven, Belgium ...

A field investigation was conducted in the Sesheke District of Zambia along the Zambezi River to determine the fish species susceptible to epizootic ulcerative syndrome (EUS), a newly confirmed disease in Southern Africa. A total of 2,132 fishes were inspected for gross EUS-like lesions, of which 188 (8.82%; 95% CI= 7.67-10.1%) were found with typical characteristic lesions of EUS. Of these 188 samples, 156 were found to have mycotic granulomas on histopathological analysis, representing 83.0% (95% CI=76.7-87.9%) of the initially identified in the laboratory through gross examination. The following 16 species of fish were examined and found with EUS lesions; Clarias ngamensis, Clarias gariepinus, Barbus poechii, Tilapia sparrmanii, Serranochromis angusticeps, Brycinus lateralis, Micralestes acutidens, Sargo-chromis carlottae, Hydrocynus vittatus, Phryngochromis acuticeps, Schilbe intermedius, Hepsetus odoe, Labeo lunatus, Oreochromis andersonii, Barbus unitaeniatus, and Barbus paludinosus. T. sparrmanii did not show any lesions, while the Clarias species were found to be the most afflicted with EUS. These results could be useful to fish farmers and organizations interested in improving aquaculture in the area.

Mountains are biodiversity hotspots and provide
spatially compressed versions of regional and continental
variation. They might be the most cost effective way
to measure the environmental associations of regional
biotic communities and their response to global climate
change. We investigated spatial variation in epigeal ant
diversity along a north–south elevational transect over the
Soutpansberg Mountain in South Africa, to see to what
extent these patterns can be related to spatial (regional) and
environmental (local) variables and how restricted taxa are
to altitudinal zones and vegetation types. A total of 40,294
ants, comprising 78 species were caught. Ant richness
peaked at the lowest elevation of the southern aspect but
had a hump-shaped pattern along the northern slope. Species
richness, abundance and assemblage structure were
associated with temperature and the proportion of bare
ground. Local environment and spatially structured environmental
variables comprised more than two-thirds of the
variation explained in species richness, abundance and
assemblage structure, while space alone (regional processes)
was responsible for\10%. Species on the northern
aspect were more specific to particular vegetation types,
whereas the southern aspect’s species were more generalist.
Lower elevation species’ distributions were more
restricted. The significance of temperature as an explanatory
variable of ant diversity across the mountain could
provide a predictive surrogate for future changes. The
effect of CO2-induced bush encroachment on the southern
aspect could have indirect impacts complicating prediction,
but ant species on the northern aspect should move uphill at
a rate proportional to their thermal tolerance and the
regional increases in temperature. Two species are identified
that might be at risk of local extinction.

Factors that drive species richness over space and time are still poorly understood and are
often context specific. Identifying these drivers for ant diversity has become particularly relevant
within the context of contemporary global change events. We report on a long-term biannual
(wet and dry seasons), standardized sampling of epigeal ants over a five year period
on the mesic and arid aspects of an inselberg (Soutpansberg Mountain Range) in the tropics
of Africa. We detail seasonal, annual and long-term trends of species density, test the
relative contribution of geometric constraints, energy, available area, climate, local environmental
variables, time, and space in explaining ant species density patterns through Generalized
Linear Mixed Models (GLMM) where replicates were included as random factors to
account for temporal pseudo-replication. Seasonal patterns were very variable and we
found evidence of decreased seasonal variation in species density with increased elevation.
The extent and significance of a decrease in species density with increased elevation
varied with season. Annual patterns point to an increase in ant diversity over time. Ant density
patterns were positively correlated with mean monthly temperature but geometric constraints
dominated model performance while soil characteristics were minor correlates.
These drivers and correlates accounted for all the spatio-temporal variability in the database.
Ant diversity was therefore mainly determined by geometric constraints and temperature
while soil characteristics (clay and carbon content) accounted for smaller but significant
amounts of variation. This study documents the role of season, elevation and their interaction
in affecting ant species densities while highlighting the importance of neutral processes
and temperature in driving these patterns.
Introduction

The distribution, abundance and sensitivity of invertebrates to habitat change are largely unknown. Long-term monitoring of ecological gradients with standardised and comparable protocols can form the basis of a better understanding. Altitudinal gradients are particularly relevant within this context. Here we provide a check list and baseline data for ant species collected over a 5-year period across the Soutpansberg Mountain Range, South Africa. Standardised pitfall surveys across 11 sites yielded a total of 133 species in 38 genera and 6 subfamilies. Sample coverage of epigeal ants was 0.98 for the transect as a whole. Of these species, 21% were restricted to the southern slope of the mountain and 14% to the northern slope. Extrapolated richness estimates reached an asymptote for all, except for three sites. These were the only sites impacted by bush encroachment. Observed richness was the highest at a low-altitude mesic site that is exposed to considerable disturbance by megaherbivores and mechanical clearing of woody vegetation. Structural classification of vegetation was predictive of a broad-scale ant assemblage structure. On a smaller scale, however, structure was a function of elevation, space and temperature.

Predators play a disproportionately positive role in ensuring integrity of food webs, influencing ecological processes and services upon which humans rely. Predators tend to be amongst the first species to be affected by anthropogenic disturbance, however. Spiders impact invertebrate population dynamics and stabilise food webs in natural and agricultural systems (potentially mitigating against crop pests and reduced yields). Africa's savannas are undergoing continent-wide conversion from low-density rangelands to villages and croplands, as human populations burgeon. Despite limited research , and evidence of deleterious impacts to biodiversity, African savannas are earmarked by prominent international organisations for conversion to cropland. Given the key role of spiders in food webs, they can have beneficial impacts in agroecosystems. Furthermore, functional diversity (FD) reflects ecosystem pattern and processes better than species diversity, so we evaluated impacts of large-scale landuse change on both species richness and FD. We surveyed spiders using pitfall traps at 42 sites (14 replicates each in rangeland, cropland, and villages) in South African savannas, investigating effects of landuse, season, and habitat variables on spider species diversity and FD. Species richness was lowest in villages. FD was lowest in cropland, however, with reduced representation of traits associated with hunting of larger invertebrates. Furthermore, there were fewer specialists in croplands. These findings suggest that even when cropland does not impact species diversity, loss of FD can still occur. As savanna systems transform,

Africa's savannas are undergoing rapid conversion from rangelands into villages and croplands. Despite limited research, and evidence of deleterious effects to biodiversity, international organisations have earmarked this system for cropland. Invertebrates, and ants in particular, are sensitive indicators of habitat fragmentation, and contribute to ecosystem services at a range of scales. We investigated how rangelands, villages and croplands differ in ant species and functional diversity, and assemblage composition. We sampled ants using pitfall traps at 42 sites (14 replicates each in rangeland, cropland, and village) in northern South African savannas. We investigated the impact of landuse, season , and multiple soil and vegetation habitat variables on ant species diversity, assemblages and functional diversity. Rangelands had the greatest ant species richness, particularly in the wet season. Richness declined with increasing soil clay content. Ant assemblages were distinctly different between landuse types. Rangeland harboured the

Cabbage aphid (Brevicoryne brassicae L.) is one of the most problematic pests in smallholder vegetable production, causing significant yield losses in heavy infestations. Current control strategy focuses on use of synthetic pesticides that consequently lead to decimation of natural enemies, development of insect resistance and resurgence and upset biodiversity. Botanical pesticides have been used widely in smallholder farmers but not much documented literature exists on efficacy of these products. A field trial was done to assess the efficacy of crude aqueous extracts of Tephrosia vogelii, Allium sativum and Solanum incanum in controlling Brevicoryne brassicae in Brassica napus production. The trial was laid in a randomized complete block design (RCBD) with five treatments replicated four times. The five treatments used in the experiment were T. vogelii, A. sativum, S. incanum, dimethoate and control. Wingless adult female aphids were inoculated three weeks after transplanting of seedlings. Spraying and data collection were done weekly for four weeks. Data was collected on aphid nymph and adult counts on the third leaf from the aerial plant part of randomly selected plants from each treatment for 24 hours after the application of treatments and total plant fresh weight per each treatment. There were significant differences (p<0.05) in the efficacy of botanicals and synthetics in controlling aphids, with dimethoate being the most effective followed by T. vogelii, A. sativum, S. incanum and lastly the control. The treatments applied had a significant effect (p<0.05) on the yield of rape. It was concluded that T. vogelii, S. incanum and A. sativum aqueous crude extracts have some pesticidal effects on aphid in rape production. Article Citation: Shepherd Mudzingwa, Simbarashe Muzemu and James Chitamba. Pesticidal efficacy of crude aqueous extracts of Tephrosia vogelii L., Allium sativum L. and Solanum incanum L. in controlling aphids (Brevicoryne brassicae L.) in rape (Brassica napus L.) Journal of Research in Agriculture An International Scientific Research Journal amylovora and Curobacterium flaccumfaciensis subsp. poinsettiae. Turk. J. Agric, 28: 57-61. Roy B, Amin R, Uddin MN, Islam ATMS, Islam MJ and Halder BC. 2005. Leaf extracts of selected wild plants as botanical pesticides against aphid species.