Papers by Candice Stafford
Frankliniella occidentalis (Pergande) feeding behavior is altered by Tomato spotted wilt virus (Bunyaviridae, Tospovirus) infection
Communicative & Integrative Biology, 2012
Proceedings of the National Academy of Sciences, 2011
Vector infection by some animal-infecting parasites results in altered feeding that enhances tran... more Vector infection by some animal-infecting parasites results in altered feeding that enhances transmission. Modification of vector behavior is of broad adaptive significance, as parasite fitness relies on passage to a new host, and vector feeding is nearly always essential for transmission. Although several plant viruses infect their insect vectors, we have shown that vector infection by a plant virus alters feeding behavior. Here we show that infection withTomato spotted wilt virus(TSWV), type member of the only plant-infecting genus in theBunyaviridae, alters the feeding behavior of its thrips vector,Frankliniella occidentalis(Pergande). Male thrips infected with TSWV fed more than uninfected males, with the frequency of all feeding behaviors increasing by up to threefold, thus increasing the probability of virus inoculation. Importantly, infected males made almost three times more noningestion probes (probes in which they salivate, but leave cells largely undamaged) compared with ...
The last decade has seen a huge interest in classification of time series. Most of this work assu... more The last decade has seen a huge interest in classification of time series. Most of this work assumes that the data resides in main memory and is processed offline. However, recent advances in sensor technologies require resource-efficient algorithms that can be implemented directly on the sensors as real-time algorithms. We show how a recently introduced framework for time series classification, time series bitmaps, can be implemented as efficient classifiers which can be updated in constant time and space in the face of very high data arrival rates. We describe results from a case study of an important entomological problem, and further demonstrate the generality of our ideas with an example from robotics.
Phenology and descriptions of two sympatric native whiteflies (Hemiptera: Aleyrodidae) with a high degree of niche overlap
Pan-pacific Entomologist, 2008
Stylet penetration behavior resulting in inoculation of beet severe curly top virus by beet leafhopper, Circulifer tenellus
Entomologia Experimentalis Et Applicata, 2009
Beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), is the only known North A... more Beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), is the only known North American vector of beet curly top virus (Geminiviridae), which causes major economic losses in a number of crops including sugar beet, tomato, beans, and peppers. Beet curly top virus is a phloem-limited, persistently transmitted, circulative geminivirus. The strain/species of curly top virus used in this study is the CFH strain, also referred to as beet severe curly top virus (BSCTV). The direct current (DC) electrical penetration graph technique was used to determine the specific stylet penetration behavior associated with inoculation of BSCTV. Viruliferous leafhoppers were allowed to feed on healthy 3–4-week-old sugar beet plants until specific electrical penetration graph waveforms were produced, at which point feeding was artificially terminated. A series of comparisons between leafhoppers that produced different combinations of waveforms clearly implicated waveform D1 as the only waveform correlated with inoculation of BSCTV. All successful inoculations contained waveform D1, and 56 out of 64 leafhoppers that produced waveform D1 successfully inoculated test plants. Eighty-five leafhoppers did not produce waveform D1 and none of these inoculated BSCTV. While the occurrence of waveform D1 appears to be necessary for BSCTV inoculation, there was no correlation between duration of waveform D1 and inoculation success rate. The correlation of waveform D1 and BSCTV inoculation found in this study implies that waveform D1 is associated with phloem salivation.
Entomologia Experimentalis Et Applicata, 2009
Feeding behavior of beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), was s... more Feeding behavior of beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), was studied with a DC electrical penetration graph. Nine different electrical penetration graph waveforms associated with feeding were identified and characterized. Waveforms were correlated with specific feeding behaviors using a number of techniques, including high magnification video recording, honeydew analysis, stylectomy, and histological processing. Waveforms were grouped into three phases based on feeding behavior: pathway phase (waveforms A, B1, B2, and C), non-phloem ingestion phase (waveform G), and phloem phase (waveforms D1, D2, D3, and D4). No ingestion was found to occur during waveforms A, B1, B2, and C. Waveform G was associated primarily with ingestion of xylem sap and occasionally with ingestion of mesophyll sap. Stylet tips were located in phloem during waveforms D1, D2, and D3, and waveforms D2 and D3 were correlated with ingestion of phloem sap. Waveform D4 probably also plays a role in phloem ingestion, because D4 is very brief and always occurs embedded in either waveform D2 or D3. In contrast to most other homopteran insects, rate of honeydew production (and hence rate of ingestion) was much lower on phloem than on xylem. More rapid rates of ingestion are expected on phloem, because its high turgor pressure drives sap into the feeding insect whereas the negative pressure of xylem sap is expected to cause a slow rate of ingestion. The very slow ingestion rate of beet leafhopper feeding on phloem suggests that it is not able to exploit the high turgor pressure of phloem to achieve the high rate of ingestion that is typical of phloem ingestion by other insects.
Biological Control, 2007
The egg parasitoid Avetianella longoi Siscaro attacks two species of eucalyptus longhorned borers... more The egg parasitoid Avetianella longoi Siscaro attacks two species of eucalyptus longhorned borers (Phoracantha semipunctata F. and P. recurva Newman) in southern California. During the past decade, P. recurva has replaced P. semipunctata as the dominant borer species, apparently due to diVerential rates of parasitism. The present study reveals that this replacement is due in part to a physiological defensive response mounted by one species (P. recurva) against parasitoid eggs and larvae, similar to the encapsulation/melanization immune response observed in larval host/parasitoid systems. Fluorescence microscopy and vital dyes conWrmed that the defensive response was cellular in nature. Both Phoracantha species exhibited a cellular wound-healing response around the wasp egg pedicel, but the encapsulation of the wasp eggs/larvae was elicited only in eggs of P. recurva. This is the Wrst conclusive evidence that hosts in the egg stage can mount a cellular immune response against a metazoan parasitoid, and may provide insight into the mechanisms underlying the host speciWcity of many egg parasitoids.
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Papers by Candice Stafford