A landscape-scale study from 2004 to 2006 investigated the spatial and temporal dynamics of a new pest to the Columbia Basin of the Pacific Northwest, the potato tuberworm, Phthorimaea operculella (Zeller). Male P. operculella were monitored in spring, summer, and fall each year with a pheromone-baited trapping network in Oregon and Washington. The objectives of the study were to (1) describe the temporal and spatial dynamics of the recent outbreak of P. operculella in the region and (2) examine the relationship of the spatial and temporal distribution of the outbreak and weather (air temperature, precipitation, and dew point) and geographic variables (elevation and latitude). Weather data during the P. operculella outbreak were compared with a reference period (1993–1999) that occurred before the outbreak. The outbreak in 2004, which caused the first widespread tuber damage in the region, was positively associated with warmer temperatures in the preceding fall and in the spring, summer, and fall of the growing season. October and November 2003 and March 2004 were also drier than the reference period. However, the winter of 2003/2004 was colder than the reference period and thus mild winter conditions did not explain the outbreak. The importance of environmental variables on the seasonal spatial distribution of the pest each year was examined using nonparametric multiplicative regression. Locations with higher spring, summer, or fall temperatures were associated with increased trapping rates in most seasons. Elevation and latitude seemed to play a constraining role, because low trapping rates of P. operculella were associated with higher elevations and latitudes.

A detailed study of the distribution of egg masses of Homalodisca vitripennis (Germar) and H. liturata Ball was done across a 2-yr period (2001–2003) on six host plants in southern California (Marsh grapefruit, Lisbon lemon, Washington navel, Dancy tangerine, rough lemon, and jojoba in Riverside; jojoba in Desert Center). The majority of egg masses in Riverside belonged to H. vitripennis (84–100%), whereas in Desert Center, all Homalodisca egg masses were H. liturata. Oviposition in Riverside occurred in two discrete periods, a late winter and spring period (mid-February to late May), followed by a short interval of very low oviposition during most of June, and then a summer period (late June to late September) followed by a relatively long period of very low oviposition in fall and early winter (October to mid-February). Levels of oviposition during the late winter-spring period were similar to those during the summer despite an observed larger population of adults during the latter period. Moreover, egg clutch size for H. vitripennis was generally greater in spring than during summer and was generally higher than that for H. liturata, especially on Riverside jojoba. Larger egg clutch size was seen on grapefruit than on lemon, navel, and tangerine during summer. There appeared to be temporal host shifts in oviposition; most evident was the shift from relatively high rates of oviposition on lemon and tangerine in late winter-early spring to relatively higher rates of oviposition on grapefruit and navel during summer.

In the north central United States, populations of the exotic soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), are highly variable across space, complicating effective aphid management. In this study we examined relationships of plant nutrients, landscape structure, and natural enemies with soybean aphid abundance across Iowa, Michigan, Minnesota, and Wisconsin, representing the range of conditions where soybean aphid outbreaks have occurred since its introduction. We sampled soybean aphid and its natural enemies, quantified vegetation land cover and measured soybean nutrients (potassium [K] and nitrogen [N]) in 26 soybean sites in 2005 and 2006. Multiple regression models found that aphid abundance was negatively associated with leaf K content in 2005, whereas it was negatively associated with habitat diversity (Simpson's index) and positively associated with leaf N content in 2006. These variables accounted for 25 and 27% of aphid variability in 2005 and 2006, respectively, suggesting that other sources of variability are also important. In addition, K content of soybean plants decreased with increasing prevalence of corn-soybean cropland in 2005, suggesting that landscapes that have a high intensification of agriculture (as indexed by increasing corn and soybean) are more likely to have higher aphid numbers. Soybean aphid natural enemies, 26 species of predators and parasitoids, was positively related to aphid abundance; however, enemy-to-aphid abundance ratios were inversely related to aphid density, suggesting that soybean aphids are able to escape control by resident natural enemies. Overall, soybean aphid abundance was most associated with soybean leaf chemistry and landscape heterogeneity. Agronomic options that can ameliorate K deficiency and maintaining heterogeneity in the landscape may reduce aphid risk.

Predictions from individual distribution models for Mexican Geotrupinae species were overlaid to obtain a total species richness map for this group. A database (GEOMEX) that compiles available information from the literature and from several entomological collections was used. A Maximum Entropy method (MaxEnt) was applied to estimate the distribution of each species, taking into account 19 climatic variables as predictors. For each species, suitability values ranging from 0 to 100 were calculated for each grid cell on the map, and 21 different thresholds were used to convert these continuous suitability values into binary ones (presence-absence). By summing all of the individual binary maps, we generated a species richness prediction for each of the considered thresholds. The number of species and faunal composition thus predicted for each Mexican state were subsequently compared with those observed in a preselected set of well-surveyed states. Our results indicate that the sum of individual predictions tends to overestimate species richness but that the selection of an appropriate threshold can reduce this bias. Even under the most optimistic prediction threshold, the mean species richness error is 61% of the observed species richness, with commission errors being significantly more common than omission errors (71 ± 29 versus 18 ± 10%). The estimated distribution of Geotrupinae species richness in Mexico in discussed, although our conclusions are preliminary and contingent on the scarce and probably biased available data.

Soybean aphid (Aphis glycines Matsumura) is a severe pest of soybean in central North America. Outbreaks of the aphid in Ontario are often spotty in distribution, with some geographical areas affected severely and others with few or no aphid populations occurring in soybean for the duration of the season. A. glycines spend summers on soybean and overwinter on buckthorn, a shrub that is widespread in southern Ontario and is commonly found in agricultural hedgerows and at the margins of woodlots. A. glycines likely use both short distance migratory flights from buckthorn and longer distance dispersal flights in the search for acceptable summer hosts. This study aims to model colonization of soybean fields by A. glycines engaged in early-season migration from overwintering hosts. Akaike's information criterion (AIC) was used to rank numerous competing linear and probit models using field parameters to predict aphid presence, colonization, and density. The variable that best modeled aphid density in soybean fields in the early season was the ratio of buckthorn density to field area, although dramatic differences in relationships between the parameters were observed between study years. This study has important applications in predicting areas that are at elevated risk of developing economically damaging populations of soybean aphid and which may act as sources for further infestation.

The effects of biotic and abiotic factors on stem borer parasitoid diversity, abundance, and parasitism were studied in cultivated and natural habitats in four agroecological zones in Kenya. Comparing habitat types, we found partial support for the “natural enemy” hypothesis, whereby, across all localities, parasitoid diversity was higher in more diverse host plant communities in natural habitats, whereas parasitoid abundance was higher in cultivated habitats. For both habitats, parasitoid richness was mainly influenced by stem borer density and/or its interaction with stem borer richness, whereas parasitoid abundance was mainly affected by stem borer abundance. Parasitoid richness was higher in localities (with bimodal rainfall distribution) with increased spatial and temporal availability of host plants that harbored the borers. Across seasons, parasitoid richness was lower in both cultivated and natural habitats in the driest locality, Mtito Andei. Overall, parasitoid diversity was low in Suam and Mtito Andei, where maize cultivation was practiced on a commercial scale and intense grazing activities persist across seasons, respectively. Across localities, habitats, and seasons, stem borer parasitism was positively correlated with parasitoid richness and abundance. Furthermore, the interaction of rainfall and altitude influenced the presence and absence of parasitoids, and consequently, stem borer parasitism. Parasitism was positively and negatively correlated with temperature in cultivated and natural habitats, respectively. Overall, natural habitats seem to serve as important refugia for sustaining parasitoid diversity, which in turn can affect stem borer parasitism in the cereal cropping system.

Pale swallow-wort (Vincetoxicum rossicum [Kleopow] Barbar.) and black swallow-wort (V. nigrum [L.] Moench), European species of herbaceous, perennial viny milkweeds, have become increasingly invasive in various natural and managed habitats in the northeastern United States and southeastern Canada, including low- and high-light habitats. A classical biological control program is being developed, but almost no information was available on the current arthropod fauna for either species in the invaded range. I conducted quantitative surveys on pale and black swallow-wort at several locations in New York State over 3 yr to identify and compare the seasonal assemblage of phytophagous arthropods that are feeding and developing on the plants in sunny and shaded habitats. Of the ≈84 nonpredatory species collected, 10 polyphagous, ectophagous species of native and exotic arthropods were identified, exclusively from the leaves or stems, which could develop to the adult stage and in most cases complete at least one generation on one or both species of swallow-wort. However, their densities were low throughout the season and generally did not differ between the sunny and shaded habitats. Very little to no damage was observed on the plants. Exotic swallow-worts seem to have been released from specialized natural enemies and have not accrued a damaging suite of generalist herbivores. This may be a contributing factor in the increasing invasiveness of these weeds, and biological control appears promising for these plants.

The aim of this survey is to faunistically describe ladybeetle assemblages from the canopies of olive orchards in southern Spain (Cordoba and Granada) and determine the indicator ladybeetle species that are representative of each region, taking into account (1) the ecological importance of predatory ladybeetle species in olive orchards and (2) the variability of ladybeetle community composition in relation to landscape configuration and different farming systems (organic, integrated, and conventional), using ordination and classification methods. The total number of coccinellids collected was 481; they belonged to 9 genera and 13 species. Canonical correspondence analysis (CCA) showed a clear separation between orchards from Granada and orchards from Córdoba, taking into account ladybeetle species, environmental variables, and sampled orchards. The land use types and geographical locations showed that Scymnus mediterraneus Iablokoff-Khnzorian 1972 and Platynaspis luteorubra (Goeze, 1777) captured at higher latitudes benefited more from a larger organic olive area and from the presence of holm oak forests in the surrounding area. Coccinella septempunctata L., 1758 and Hippodamia variegata (Goeze, 1777) were found at lower latitudes and at higher longitudes. Ladybeetle assemblages can vary in response to the type of farming system, especially with regard to pesticide use and landscape configuration. Nevertheless, evaluation of species composition might help identify the state of conservation of these agroecosystems. This knowledge could be used to improve the sustainability of agricultural landscapes to increase the presence of coccinellids and their ecological function in olive pest control.

This study examined the distribution of major mosquito species and their roles in the transmission of Ross River virus (RRV) infection for coastline and inland areas in Brisbane, Australia (27°28′ S, 153°2′ E). We obtained data on the monthly counts of RRV cases in Brisbane between November 1998 and December 2001 by statistical local areas from the Queensland Department of Health and the monthly mosquito abundance from the Brisbane City Council. Correlation analysis was used to assess the pairwise relationships between mosquito density and the incidence of RRV disease. This study showed that the mosquito abundance of Aedes vigilax (Skuse), Culex annulirostris (Skuse), and Aedes vittiger (Skuse) were significantly associated with the monthly incidence of RRV in the coastline area, whereas Aedes vigilax, Culex annulirostris, and Aedes notoscriptus (Skuse) were significantly associated with the monthly incidence of RRV in the inland area. The results of the classification and regression tree (CART) analysis show that both occurrence and incidence of RRV were influenced by interactions between species in both coastal and inland regions. We found that there was an 89% chance for an occurrence of RRV if the abundance of Ae. vigifax was between 64 and 90 in the coastline region. There was an 80% chance for an occurrence of RRV if the density of Cx. annulirostris was between 53 and 74 in the inland area. The results of this study may have applications as a decision support tool in planning disease control of RRV and other mosquito-borne diseases.

Eastern subterranean termite, Reticulitermes flavipes (Kollar), workers were continuously exposed to one of five chitin synthesis inhibiting (CSI) active ingredients and the protist community from the hindgut quantified biweekly for 21 d. The CSIs tested included commercially available formulations of diflubenzuron, hexaflumuron, lufenuron, noviflumuron, and novaluron. Results showed termites exposed to CSIs had a significant decrease (≥30%) in the estimated total protist population after 3 d, regardless of treatment. Protist species impacted were Dinenympha fimbriata, D. gracilis, Microjoenia fallax, Pyrsonympha vertens, and Trichonympha agilis and could be indicative of weakened digestive homeostasis, but further studies are needed. We also provide evidence that lufenuron is highly toxic and discuss some of the implications this might have on termite management practices.

Host—parasite dynamics can be altered when a host is infected by multiple parasite genotypes. The different strains of parasite are expected to compete for the limited host resources, potentially affecting the survival and reproduction of the host as well as the infecting parasites. Fungus-growing ants, including the well-known leaf-cutters, are an emerging model system for studying the evolution and ecology of symbiosis and host-parasite dynamics. We examine whether the fungus gardens of leaf-cutter ants can be simultaneously infected by multiple strains of the fungal pathogen Escovopsis. Intensive sampling of Escovopsis was conducted from individual gardens, as well as between different garden chambers within individual colonies of leaf-cutting ants. Isolates obtained were genotyped by DNA sequencing. We found that, minimally, 67% of the individual colonies of the leaf-cutter ant genera Atta and Acromyrmex and 50% of the At. colombica garden chambers studied were simultaneously infected by multiple distinct Escovopsis strains. Experimental challenges showed that different Escovopsis strains do not exhibit obvious antagonism toward each other, suggesting that coinfecting strains of the parasite do not engage in interference competition, although interactions were not studied at the cellular level. Further research is needed to understand interparasite interactions between coinfecting Escovopsis strains and to understand the impact of multiparasite infections on the survival of leaf-cutter ant gardens.

Cape-ivy, Delairea odorata Lamaire, is an ornamental vine, native to the eastern part of South Africa, which has escaped into natural areas in many countries and become a serious pest. Exploratory surveys in South Africa located several potential biological control agents. One of these is Parafreutreta regalis Munro, a tephritid fly that causes large (14 by 20 mm) galls to form on the stems of Cape-ivy. Female P. regalis oviposit 1-20 eggs into stem nodes or growing tips of Cape-ivy. During her lifetime, a female may oviposit up to 138 eggs (mean = 61.5 eggs). After 2 wk, the first swellings, indicating gall formation, become visible. There are three larval stages, and, 1 mo after oviposition, the gall is fully formed, and the larvae within scrape a small circular hole through the gall wall, leaving a “window” covered by intact plant cuticle. After another month, adult flies break the window and emerge from the gall. The life cycle from oviposition to adult emergence is ∼2 mo, and we observed up to seven generations in a year in our quarantine laboratory. Females begin ovipositing within a day or two of emergence, and adults live for ≈2 wk. We compare the life history of P. regalis to the published information about other Parafreutreta species.

The elm spanworm, Ennomos subsignarius Hübner (Lepidoptera: Geometridae), is an eruptive herbivore that feeds on numerous tree species in forests throughout its range. An unprecedented outbreak in an urban environment in St. John's, Newfoundland, Canada, caused severe levels of defoliation to a number of native and exotic hardwood tree species, some of which represent novel hosts for this insect. Increased insect performance on these novels hosts was hypothesized as having contributed to the outbreak. To assess this, percentage larval survival and pupal weight were measured for larvae reared on foliage from six different tree species in a no-choice laboratory bioassay. Adult longevity and fecundity (no. eggs laid per female) were assessed for laboratory-reared individuals, as well as for pupae collected from eight different host tree species from the field. A survey to assess feeding occurrence measured defoliation on eight tree species. During this urban outbreak, sycamore maple, Acer pseudoplatanus, a tree species not native to North America, experienced the highest levels of defoliation. Performance of E. subsignarius (pupal weight, female longevity, and fecundity) on this host was comparable with the known host of elm (Ulmus spp.). Despite the fact that E. subsignaria performed well on several introduced hosts, fecundity levels were much lower than previously published reports, suggesting that the current outbreak is not caused by increased fecundity on these novel hosts in contrast to the hypothesis.

Extended drought on the Edwards Plateau, TX, causes high mortality in grass species' populations and their replacement by recruitment from the seeds of survivors. Harvester ant nests may act as refugia for perennial plants during drought, as evidenced by a high survivorship of plants directly adjacent to nests. Because grasses tend to disperse seeds short distances and drought eliminated seed banks, we hypothesized that the spatial pattern of grass seedlings and adults would be clumped at small scales around these refugia. In contrast, nests would be regular at small to moderate scales. We studied the spatial patterns of seedlings, adults, and ant nest locations using a modified Ripley's K-function technique for transect data. Point data were collected along a 1-km transect. Spatially regular patterns were found for nests from 1.0- to 22.0-m scales. We found that two species' seedlings and adults were significantly clumped with ant nests, and two species had significantly regular spatial patterns with nests. Surprisingly, patterns of clumped seedlings occurred up to 30-m scales with nests. Nests appear to affect seedling establishment at multiple scales. These results suggest that nests may facilitate colonization for some grass populations, but regular spatial patterns in other species imply that forager seed harvest may inhibit establishment.

Three main types of stink bug injury have been reported on the surface of apple fruit: (1) discolored dots, (2) discolored dots with depressions, and (3) discolored dots with discolored depressions. From 2005 to 2008, studies were performed to determine the factors linked to the variations in the appearance of adult stink bug injury on apple fruit observed at harvest. The main factors tested were type of feeding injury (i.e., mechanical versus breakdown and removal of tissues), time between injury and evaluation, cultivar, fruit maturity, and relative exposure to sunlight and UV radiation. No differences were observed that were caused by type of feeding. Studies of the time between injury and evaluation showed that there is a progression in the development of injury appearance. This progression of injury is influenced by cultivar and relative maturity of the fruit. Concomitantly, sites of injury on fruit exposed to no or limited sunlight and UV radiation were less likely to progress to discolored depressions.

Cucumber beetles, Acalymma vittatum (F.) and Diabrotica undecipunctata howardi (Barber), are specialist herbivores of cucurbits and the vector of Erwinia tracheiphila (E.F. Smith) Holland, the causative agent of wilt disease. Cucumber beetles transmit E. tracheiphila when infected frass falls onto leaf wounds at the site of beetle feeding. We show that E. tracheiphila also can be transmitted via the floral nectaries of Cucurbita pepo ssp. texana L. Andres (Texas gourd). Under field conditions, we found that beetles aggregate in flowers in the late morning, that these beetles chew the anther filaments that cover the nectaries in male flowers thereby exposing the nectary, and that beetle frass accumulates on the nectary. We use real-time polymerase chain reaction to show that most of the flowers produced during the late summer possess beetle frass containing E. tracheiphila. Greenhouse experiments, in which cultures of E. tracheiphila are deposited onto floral nectaries, show that Texas gourds can contract wilt disease through the floral nectaries. Finally, we use green fluorescent protein-transformed E. tracheiphila to document the movement of E. tracheiphila through the nectary into the xylem of the pedicel before the abscission of the flower. Together, these data show that E. tracheiphila can be transmitted through infected frass that falls on or near the floral nectaries. We hypothesize that the concentration of frass from many beetles in the flowers increases both exposure to and the concentration of E. tracheiphila and plays a major role in the dynamics of wilt disease in both wild populations and cultivated squash fields.

The alfalfa leafcutting bee, Megachile rotundata (Fabricius), is used to pollinate alfalfa, Medicago sativa L., for seed production in the United States and Canada. It is difficult to reliably sustain commercial M. rotundata populations in the United States because of problems with disease, parasites, predators, and unexplained mortality. One possible explanation for early immature mortality is that, relative to floral availability, superfluous numbers of bees are released in alfalfa fields where resources quickly become limited. Our objective was to determine how M. rotundata density affects bee nesting, pollination efficiency, and reproductive success. Various numbers of bees were released into enclosures on an alfalfa field, but only 10–90% of released female bees established nests. Therefore, a “bee density index” was derived for each enclosure from the number of established females and number of open flowers over time. As the density index increased, significant reductions occurred in the number of pollinated flowers, number of nests, and number of cells produced per bee, as well as the percentage of cells that produced viable prepupae by summer's end and the percentage that produced adult bees. The percentage of cells resulting in early brood mortality (i.e., pollen balls) significantly increased as the density index increased. We conclude that bee nest establishment, pollination efficiency, and reproductive success are compromised when bee densities are high relative to floral resource availability. Open field studies are needed to determine commercial bee densities that result in sustainable bee populations and adequate pollination for profitable alfalfa seed production.

Although larvae and adults of the herbivorous beetle Trirhabda geminata Horn (Coleoptera: Chrysomelidae) are primarily considered to be specialists on Encelia farinosa (Compositae: Asteraceae), some reports exist of these beetles feeding on related Encelia species. Within the genus Encelia, many species are thought to have evolved relatively recently. In addition, some Encelia species have very similar secondary chemistries and overlapping geographic distributions. In the laboratory, individual T. geminata were reared on E. farinosa or the sympatrically occurring species E. actoni or E. californica. Survival, growth, and development were analyzed for larvae feeding on each host plant species. Overall, herbivore performance was better on E. farinosa, with significantly greater survival, faster development, and greater mass gain. Beetle development on E. californica was intermediate, with some measure, indicating better performance than on E. actoni and other measure, indicating no difference between these potential hosts. Importantly, although performance was decreased on E. actoni and E. californica, some individuals were able to develop successfully, suggesting that populations of T. geminata may be able to adapt to use these host plants.

Field studies were conducted at two sites in western Montana during 2006 and 2008 to assess the compatibility of mowing with five seed head insect species introduced for biological control of spotted knapweed, Centaurea stoebe Lamarck subsp. micranthos. In 2006, mowing of spotted knapweed plants at the bolting and flower bud stages resulted in the development of new seed heads that contained significantly more seeds and significantly fewer larvae of each insect species than in seed heads in unmowed controls. No seed heads were produced in the plots mowed at the flowering stage. Seed numbers per seed head in 2008 were also significantly higher in plots mowed at the bolting stage than in unmowed controls, but between-treatment differences in insect numbers were more variable. The seed head insects Larinus spp. and Urophora affinis Frauenfeld were the primary cause of the reduced knapweed seed numbers per seed head in 2006. Spotted knapweed should not be mowed at the bolting and flower bud stages if large populations of seed head insects are present because mowing can result in the formation of new seed heads that are free from the insects' attack, thus allowing greater seed production. Mowing of spotted knapweed at the flowering stage and later can be conducted without a subsequent increase in seed production, but the mowing may cause mortality of the insect larvae.

Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), commonly known as the Asian longhorned beetle, is a wood-boring invasive species introduced from Asia to North America and Europe in solid wood packing material. Efficient monitoring traps are needed to assess population density and dispersal in the field and to detect new introductions at ports of entry. For this purpose, we conducted field trapping experiments in China in the summers of 2007 and 2008. In 2007, we tested Intercept panel traps hung on poplar trees. In 2008, we used Intercept panel traps hung on poplar trees, screen sleeve traps wrapped around poplar trunks, and Intercept panel traps hung on bamboo poles 20 m away from host trees. Traps were baited with A. glabripennis male-produced pheromone alone or in different combinations with plant volatiles. Traps baited with the male-produced pheromone alone caught significantly more females than control traps in both years. The addition of a mixture of (-)-linalool, (Z)-3-hexen-1-ol, linalool oxide, trans-caryophyllene, and trans-pinocarveol to the pheromone significantly increased trap catches of females, 85% of which were virgin. Screen sleeve traps baited with a combination of (-)-linalool and the pheromone caught the highest number of beetles overall in 2008, whereas traps placed on bamboo polls caught the lowest number. Although the logistics for the most effective implementation of a trapping program using a mixture of the pheromone and plant volatiles require additional studies, these results indicate that this pheromone has considerable promise as a monitoring tool for A. glabripennis in the field.

Immature survival and development of alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), were examined at 15 constant temperatures ranging from 9 to 37°C. At 9 and 37°C, eggs did not develop. Embryos developed to adulthood between 11.5 and 36°C, although survival was low at both ends of the temperature range. Distribution of development times for all stages of alfalfa weevil were skewed toward longer times mainly at moderate temperatures. Constant proportion of time spent in egg, larva, and pupa indicated rate isomorphy within the range 14–31.5°C. No significant difference was shown between development time of males and females at any of the temperatures tested. Two linear and 23 nonlinear models were fitted to describe development rate of immature stages of H. postica as a function of temperature, as well as estimating the thermal constant and critical temperatures (i.e., T_min, T_opt, and T_max). There was no statistical difference between the estimated parameters, using Ikemoto and ordinary linear methods. Of the nonlinear models fitted, the Logan-6/Lactin-2, Analytis-3/Briere-2, and Analytis-3/Briere-2 models were found to be the best for modeling development rate of egg, larva, and entire immature stages of H. postica, respectively. Our findings will be incorporated in more efficient phenological models of this pest and its population dynamics.

Environmental factors that impact the biology of mosquito vectors can have epidemiological implications. Lack of oviposition sites facilitated by environmental factors such as temperature and drought can often force Culex spp. mosquitoes to retain their eggs. Culex pipiens quinquefasciatus Say were fed blood meals containing West Nile virus (WNV; family Flaviviridae, genus Flavivirus) and either allowed to oviposit or forced to retain their eggs through different time points postinfection (9, 13, 20, 27 d) at 28°C. Oviposition status did not significantly affect rates of WNV infection (% with virus-positive bodies), dissemination (% with virus-positive legs), or transmission (% with virus-positive saliva) for any of the tested time points. As expected, WNV titers in bodies and legs were significantly (P < 0.05) higher at late time points compared with early time points. No significant differences were observed in WNV titers in saliva between time points. There were no significant effects of oviposition status on virus titers of bodies, legs, or saliva. However, we found that egg retention may increase vector competence at early and late time points after infection and that a single oviposition event may decrease vector competence, possibly by activating an immune response against the virus. Environmental changes that influence mosquito biology are important determinants of virus transmission, and further studies are needed to assess the effects of drought on virus transmission risk and how these interactions affect our interpretation of field data.

We studied a population of Liriomyza sativae Blanchard (Diptera: Agromyzidae) identified by morphological and molecular techniques from the semiarid region of the Brazilian northeast. The influence of temperature and relative humidity on the survival and reproductive parameters of L. sativae in cowpeas (Vigna unguiculata L. WaLp.) (Fabales: Fabaceae) was evaluated. We used temperatures of 18, 20, 22, 25, 28, 30, and 32 ± 1°C (50 ±10% RH) and relative humidity values of 30, 50, 70, and 90 ± 10% (25 ± 1°C) under a 14 L:10 D photoperiod. Adult longevity decreased as temperature and relative humidity increased and was greater, in general, for females. The preoviposition and oviposition periods also decreased as temperature increased, whereas relative humidity only caused reductions in the oviposition period at higher levels. Fecundity was similar in the range from 18 to 30°C but decreased at 32°C with respect to relative humidity; the best performances of L. sativae occurred at lower levels. The pattern of oviposition rate changed with temperature and relative humidity. Regardless of temperature and relative humidity, L. sativae laid between 75 and 92% of its eggs on the adaxial surface of the cowpea leaves. This information will be highly useful to design a leafminer production system aimed at the multiplication of natural enemies, as well as for pest management in the field.

The alfalfa weevil, Hypera postica (Gyllenhal), is a serious, yet sporadic defoliator of alfalfa, Medicago sativa L., in Nebraska. A 2-yr study was conducted in 2005 and 2006 to test for variation in degree-day requirements by location in eastern Nebraska. Sampling took place along a latitudinal gradient in three regions of eastern Nebraska. Three fields were sampled in each region during the 2 yr of the study. Alfalfa weevil larval degree-day requirements were found to vary by latitude in eastern Nebraska. Alfalfa weevil larvae were discovered in southern regions after fewer developmental degree-days had accumulated than in fields in the northern regions. Alfalfa weevils may be more damaging to alfalfa in southern regions than in northern regions of eastern Nebraska because they emerge earlier relative to alfalfa growth. Management implications of this shift in alfalfa weevil phenology are discussed.

Morphological deformities in parts of the head capsule of Chironomus spp. larvae inhabiting three polluted rivers (Permatang Rawa [PRR], Pasir [PR], and Kilang Ubi [KUR]) in the Juru River Basin, northeastern peninsular Malaysia, were studied. Samples of the fourth-instar larvae at one location in each river were collected monthly from November 2007 to March 2008 and examined for deformities of the mentum, antenna, mandible, and epipharyngis. At each sample location, in situ measurements of water depth, river width, water pH, dissolved oxygen, and water temperature were made. Samples of river water and benthic sediments were also collected monthly from each larval sample location in each river and taken to the laboratory for appropriate analysis. Total suspended solids (TSSs), ammonium-N, nitrate-N, phosphate-P, chloride, sulfate, and aluminum content in water were analyzed. Total organic matter and nonresidual metals in the sediment samples were also analyzed. Among the three rivers, the highest mean deformity (47.17%) was recorded in larvae collected from KUR that received industrial discharges from surrounding garment and rubber factories, followed by PRR (33.71%) receiving primarily residues of fertilizers and pesticides from adjacent rice fields, and PR (30.34%) contaminated primarily by anthropogenic wastes from the surrounding residential areas. Among the various head capsule structures, deformity of the mentum was strongly reflective of environmental stress and amounted to 27.9, 20.87, and 30.19% in the PRR, PR, and KUR, respectively. Calculated Lenat's toxic score index satisfactorily explained the influence of prevailing environmental variables on the severity of mentum deformities. Redundancy analysis and forward selection selected TSSs, sediment Zn, Mn, Cu, and Ni, and water pH, dissolved oxygen, water temperature, total organic matter, nitrate-N, chloride, phosphate-P, ammonium-N, sulfate, and aluminum as parameters that significantly affected some proportion of deformities. The total deformities correlated closely with deformities of mentum but only weakly with deformities in other parts of head. The total deformity incidence was strongly correlated with high contents of sediment Mn and Ni. The mentum and epipharyngis deformities incidence was highly correlated with an increase of TSSs, total aluminum, and ammonium-N and a decrease in pH and dissolved oxygen.

Salivary secretions play critical roles in aphid- host plant interactions and are responsible for damage associated with aphid feeding. The objectives of this study were to evaluate aspects of salivation and the salivary constituents of Diuraphis noxia (Hemiptera: Aphididae). Salivary proteins were isolated and compared from three aphid probed diets: pure water, 15% sucrose, or amino acids (100 mM serine, 100 mM methionine, 100 mM aspartic acid, and 15% sucrose). After 6 h, more aphids settled on sucrose diet compared with other diets, but there were no significant differences in the number of stylet sheaths produced per aphid after 24 h. There were differences in the amount of soluble salivary protein (watery saliva), with the greatest amount secreted in sucrose diet, followed by amino acid diet and pure water, respectively. Protein constituents secreted into sucrose and amino acid diets were compared using gel electrophoresis using standardized amounts of protein. More protein bands and bands of greater intensity were visualized from probed sucrose diet compared with probed amino acid diet, indicating qualitative differences. Phosphatase was putatively identified from D. noxia saliva from a major protein band using gel electrophoresis and mass spectrophotometry. Alkaline phosphatase activity was confirmed in sucrose diet using enzymatic assays but was not detected in aphid probed water or amino acid diets. Other peptides in sucrose diet weakly but significantly showed similarities to putative dehydrogenase and RNA helicase expressed sequence tags identified from other aphids. The implications of these findings in aphid salivation and plant-insect interactions are discussed.

Genetic diversity within and among 11 geographic populations of the beet webworm Loxostege sticticalis across five provinces in the northern part of China were evaluated using amplified fragment length polymorphism (AFLP) analysis. Five AFLP primer combinations were used on 88 L. sticticalis samples from different locations, detecting a total of 384 polymorphic and 27 monomorphic fragments. Although extensive genetic diversity occurs among individuals from different geographic populations (P = 93.4%, h = 0.398, I = 0.572), the majority of the genetic diversity is within populations and not between populations (G_ST = 0.196), which agrees well with the results of analysis of molecular variance (84% of the total genetic variation is within populations), indicating high gene flow (N_M = 2.046) among natural populations, which are not genetically differentiated. L. sticticalis in northeastern China, northern China, and northwestern China are part of a single large metapopulation. Cluster analyses based on AFLP data were preformed to graphically show groupings between individuals and between populations. Individuals from the same region were not grouped together very well. Eleven subpopulations were clustered into six broad groups, and there was no significant correlation between geographic distance and genetic dissimilarity (r = 0.1236, P = 0.8512). Principle component analysis also indicated a lack of genetic differentiation between the 11 populations. These results indicated that, although high genetic variability existed among individuals, there was little genetic differentiation among geographic populations, which can be explained by the effects of long distance migration of the beet webworm in China and consequent gene flow.

During 2005–2008, field studies were conducted at two locations in Chongqing, China, to assess the potential effects of transgenic rice expressing Bacillus thuringiensis (Bt) Cry1Ab protein on the nontarget ground-dwelling collembolan community in three postharvest seasons. Collembolans in non-Bt and Bt rice fields were sampled with pitfall traps during each of two postharvest seasons of 2005/2006 and 2006/2007 and litterbag traps during each of three postharvest seasons of 2005/2006, 2006/2007, and 2007/2008. Ground-dwelling collembolans in rice fields during the postharvest seasons were abundant, whereas community densities varied considerably between the two locations and among the three seasons. A total of 67,310 collembolans, representing three species, Entomobrya griseoolivata, Hypogastrura matura, and Bourletiella christianseni, were captured during the three postharvest seasons. E. griseoolivata was the predominant species, accounting for 87.7% of the total captures, followed by H. matura (10.7%) and B. christianseni (1.6%). In general, there were no significant differences in species compositions and abundances of each species between Bt and non-Bt paddy fields, suggesting no significantly impact of plant residues of Cry1Ab rice on collembolan communities during postharvest seasons.