Halyomorpha halys (Hemiptera: Pentatomidae) trap captures at orchard and nonorchard sites and the influence of uncultivated woody host plants in adjoining woodlots.

The invasive Halyomorpha halys (Hemiptera: Pentatomidae) has threatened Mid-Atlantic tree fruit since 2010. To identify factors underlying observed differences in H. halys pest pressure among individual orchards within a geographically proximate area, a 3-yr study was conducted across 10 apple orchard and 8 nonorchard sites bordered by unmanaged woodlots. At each site, 3 pheromone traps were monitored weekly for H. halys captures from late April to mid-October. Apple injury was assessed at harvest at orchard sites annually, and a survey of woody plants found in woodlots adjacent to all sites was conducted. There were no significant differences in captures between orchard and nonorchard site types, but captures were significantly different among individual orchard sites and among individual nonorchard sites. A significant positive relationship between the amount of stink bug injury on apple at harvest and late season captures was detected at orchard sites in 2018 and 2019. Among woodlots adjacent to all sites, a significant positive relationship between the proportion of Lonicera spp. and mid- and late-season nymphal captures was identified. Season-long nymphal captures were positively related to the proportion of Lonicera and Elaeagnus and negatively with Sassafras. For adults, captures were negatively related to the proportion of Ailanthus and positively related to the proportion of Fraxinus in the early and mid-season, respectively. Our results indicate that orchard presence was not driving the relative abundance of localized H. halys populations and that differences in relative densities among sites point to other factors, such as abundance of specific uncultivated woody hosts in unmanaged areas.

Temperature-dependent Development, Survival, and Oviposition of Laricobius osakensis (Coleoptera: Derodontidae): A Specialist Predator of Adelges tsugae (Hemiptera: Adelgidae).

A predator, Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae), is being mass-produced and released for the biological control of the invasive hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae). To better understand and predict the seasonality of this predator in North America, the development and reproduction of L. osakensis were evaluated at constant temperatures ranging from 5 to 22°C. The predicted seasonal biology was compared with data from field collections. L. osakensis did not complete development from egg to adult at the two lowest temperatures tested, 5 and 8°C, but did so at the highest temperature of 22°C. The minimum development thresholds were estimated for eggs (4.2°C), first (1.8°C), second (5.5°C), third (4.6°C), and fourth instar (4.1°C), prepupa (3.6°C), and pupa (7.5°C). Oviposition rates were significantly greater at 5 and 10°C than at 20 and 25°C. Head capsule width significantly increased for each of the four larval instars with a mean of 0.19, 0.26, 0.35, and 0.44 mm, respectively. Laboratory and field data were used to develop a phenology forecasting model to predict the occurrence of all developmental stages of L. osakensis. This model will allow land managers to more accurately predict the optimal timing for L. osakensis larval sampling throughout its established range.

Effects of Plant Substrate, Insecticide, and Blood Meal Status on the Efficacy of Barrier Treatments Against Aedes albopictus.

The effects of 3 plant species (Cornus florida [dogwood], rhododendron X 'Chionoides' [rhododendron], and Ilex opaca [American holly]), 4 insecticide treatments (Demand® CS [lambda-cyhalothrin] at 6.25 ml[AI]/liter; Talstar® Professional [bifenthrin] at 7.81 ml[AI]/liter, and Suspend® Polyzone® [deltamethrin] at 11.72 ml[AI]/liter, and water), and 2 physiological states (blood-fed and unfed) were evaluated for knockdown (1 h) and mortality (24 h) against female Aedes albopictus over an 8-wk sampling period. Analyses determined that there was a significant interaction between the tested plant species and the insecticides evaluated. Significant differences were likewise observed between the insecticide treatments for unfed Ae. albopictus females, with Demand CS demonstrating the highest knockdown and mortality rates (from >90% to >10% at wk 8 and >95% to ∼50% at wk 8, respectively), followed by Talstar Professional (from >75% to <10% at wk 2 and >90% to <10% at wk 2, respectively) and Suspend Polyzone (from >20% to <10% at wk 8 and >25% to >50% at wk 8, respectively). All treatments were no longer significant for knockdown or mortality at the end of the 8-wk timeframe. Significant differences were also observed between insecticide treatments for blood-fed Ae. albopictus females; Demand CS showed high knockdown and mortality rates (from 100% to ∼50% at wk 8 and 100% to >60% at wk 8, respectively), Suspend Polyzone rates were similar to Demand CS (from >80% to ∼50% at wk 8 and ∼90% to >65% at wk 8, respectively), and both were followed by Talstar Professional (from 100% to <10% at wk 4 and 100% to <20% at wk 4, respectively). All tested pyrethroid sprays showed a significant increase in effectiveness against recently blood-fed Ae. albopictus females, as compared to the unfed females. These results suggest that Demand CS can be used as an effective barrier spray against Ae. albopictus adults due to the limited impact of target foliage, its long-term efficacy under environmental conditions, and its continued effectiveness regardless of the blood meal status of the target mosquito.

Vector competence of Virginia mosquitoes for Zika and Cache Valley viruses.

BACKGROUND: Vector-borne diseases are a major public health concern and cause significant morbidity and mortality. Zika virus (ZIKV) is the etiologic agent of a massive outbreak in the Americas that originated in Brazil in 2015 and shows a strong association with congenital ZIKV syndrome in newborns. Cache Valley virus (CVV) is a bunyavirus that causes mild to severe illness in humans and ruminants. In this study, we investigated the vector competence of Virginia mosquitoes for ZIKV and CVV to explore their abilities to contribute to potential outbreaks. METHODS: To determine vector competence, mosquitoes were fed a blood meal comprised of defibrinated sheep blood and virus. The presence of midgut or salivary gland barriers to ZIKV infection were determined by intrathoracic inoculation vs oral infection. After 14-days post-exposure, individual mosquitoes were separated into bodies, legs and wings, and saliva expectorant. Virus presence was detected by plaque assay to determine midgut infection, dissemination, and transmission rates. RESULTS: Transmission rates for Ae. albopictus orally infected (24%) and intrathoracically inoculated (63%) with ZIKV was similar to Ae. aegypti (48% and 71%, respectively). Transmission rates of ZIKV in Ae. japonicus were low, and showed evidence of a midgut infection barrier demonstrated by low midgut infection and dissemination rates from oral infection (3%), but increased transmission rates after intrathoracic inoculation (19%). Aedes triseriatus was unable to transmit ZIKV following oral infection or intrathoracic inoculation. CVV transmission was dose-dependent where mosquitoes fed high titer (ht) virus blood meals developed higher rates of midgut infection, dissemination, and transmission compared to low titer (lt) virus blood meals. CVV was detected in the saliva of Ae. albopictus (ht: 68%, lt: 24%), Ae. triseriatus (ht: 52%, lt: 7%), Ae. japonicus (ht: 22%, lt: 0%) and Ae. aegypti (ht: 10%; lt: 7%). Culex pipiens and Cx. restuans were not competent for ZIKV or CVV. CONCLUSIONS: This laboratory transmission study provided further understanding of potential ZIKV and CVV transmission cycles with Aedes mosquitoes from Virginia. The ability for these mosquitoes to transmit ZIKV and CVV make them a public health concern and suggest targeted control programs by mosquito and vector abatement districts.

Effects of La Crosse virus infection on the host-seeking behavior and levels of two neurotransmitters in Aedes triseriatus.

BACKGROUND: La Crosse virus (LACV) infection has been shown to manipulate the blood-feeding behaviors of its main vector, Aedes triseriatus. Here, we investigated the effects of virus infection on serotonin and dopamine and their potential roles in host-seeking. In mosquitoes, serotonin depletion has been shown to interfere with blood-feeding but not host-seeking. Dopamine depletion does not affect either blood-feeding or host-seeking; elevations of dopamine, however, has been shown to inhibit host-seeking. The purpose of this study was to determine the effects of LACV infection on the host-seeking behavior of and neurotransmitter levels in Ae. triseriatus. METHODS: Host-seeking behavior was evaluated using a uni-port olfactometer and a membrane feeder assay. Levels of serotonin and dopamine in infected and control mosquito heads were measured using HPLC-ED. RESULTS: Infection with LACV significantly inhibited the activation and attraction of Ae. triseriatus females to a host. A higher proportion of uninfected Ae. triseriatus females were activated by the presence of a host compared to infected mosquitoes and more uninfected mosquitoes were full responders (95.7%) compared to infected ones (91.1%). However, infection with LACV did not significantly affect the landing, probing, or blood-feeding rates of female mosquitoes. LACV-infected mosquitoes had lower serotonin levels than controls (104.5 vs 138.3 pg/head) while the dopamine levels were not affected by infection status (282.3 vs 237 pg/head). CONCLUSIONS: Our work suggests that virus-induced reduction of serotonin is related to previously reported blood-feeding alterations in LACV-infected mosquitoes and could lead to enhanced transmission and increased vectorial capacity. In addition, some aspects of host-seeking were inhibited by virus infection.

Chlorothalonil Exposure Alters Virus Susceptibility and Markers of Immunity, Nutrition, and Development in Honey Bees.

Chlorothalonil is a broad spectrum chloronitrile fungicide that has been identified as one of the most common pesticide contaminants found in managed honey bees (Hymenoptera: Apidae: Apis mellifera L.), their food stores, and the hive environment. While not acutely toxic to honey bees, several studies have identified potential sublethal effects, especially in larvae, but comprehensive information regarding the impact of chlorothalonil on adults is lacking. The goal of this study was to investigate the effects of exposure to a field relevant level of chlorothalonil on honey bee antiviral immunity and biochemical markers of general and social immunity, as well as macronutrient markers of nutrition and morphological markers of growth and development. Chlorothalonil exposure was found to have an effect on 1) honey bee resistance and/or tolerance to viral infection by decreasing the survival of bees following a viral challenge, 2) social immunity, by increasing the level of glucose oxidase activity, 3) nutrition, by decreasing levels of total carbohydrate and protein, and 4) development, by decreasing the total body weight, head width, and wing length of adult nurse and forager bees. Although more research is required to better understand how chlorothalonil interacts with bee physiology to increase mortality associated with viral infections, this study clearly illustrates the sublethal effects of chlorothalonil exposure on bee immunity, nutrition, and development.

An assessment of pesticide exposures and land use of honey bees in Virginia.

Large-scale honey bee colony loss threatens pollination services throughout the United States. An increase in anthropogenic pressure may influence the exposure of hives to household and agricultural pesticides. The objective of this survey was to provide an assessment of the risk of exposure to commonly used pesticides to honey bee colonies in Virginia in relation to land use. Adult honey bee, pollen, and wax samples from colonies throughout Virginia were evaluated for pyrethroid, organophosphate, organochlorine, and triazine pesticides using gas chromatography-mass spectrometry analysis. Of the 11 pesticides analyzed, nine were detected in one or more hive matrices. The probability of detecting a pesticide in pollen was less in forests than in pasture, agriculture, or urban landscapes. Coumaphos and fluvalinate were significantly more likely to be detected across all matrices with concentrations in wax as high as 15500 and 6970 ng/g (dry weight), respectively, indicating the need for further research on the potential effects of miticide accumulation in wax to larval and adult bees.

In-Hive Acaricides Alter Biochemical and Morphological Indicators of Honey Bee Nutrition, Immunity, and Development.

The honey bee is a widely managed crop pollinator that provides the agricultural industry with the sustainability and economic viability needed to satisfy the food and fiber needs of our society. Excessive exposure to apicultural pesticides is one of many factors that has been implicated in the reduced number of managed bee colonies available for crop pollination services. The goal of this study was to assess the impact of exposure to commonly used, beekeeper-applied apicultural acaricides on established biochemical indicators of bee nutrition and immunity, as well as morphological indicators of growth and development. The results described here demonstrate that exposure to tau-fluvalinate and coumaphos has an impact on 1) macronutrient indicators of bee nutrition by reducing protein and carbohydrate levels, 2) a marker of social immunity, by increasing glucose oxidase activity, and 3) morphological indicators of growth and development, by altering body weight, head width, and wing length. While more work is necessary to fully understand the broader implications of these findings, the results suggest that reduced parasite stress due to chemical interventions may be offset by nutritional and immune stress.

Seasonal Effects and the Impact of In-Hive Pesticide Treatments on Parasite, Pathogens, and Health of Honey Bees.

Honey bee, Apis mellifera (L.; Hymenoptera: Apidae), populations are in decline and their losses pose a serious threat for crop pollination and food production. The specific causes of these losses are believed to be multifactorial. Pesticides, parasites and pathogens, and nutritional deficiencies have been implicated in the losses due to their ability to exert energetic stress on bees. While our understanding of the role of these factors in honey bee colony losses has improved, there is still a lack of knowledge of how they impact the immune system of the honey bee. In this study, honey bee colonies were exposed to Fumagilin-B, Apistan (tau-fluvalinate), and chlorothalonil at field realistic levels. No significant effects of the antibiotic and two pesticides were observed on the levels of varroa mite, Nosema ceranae (Fries; Microsporidia: Nosematidae), black queen cell virus, deformed wing virus, or immunity as measured by phenoloxidase and glucose oxidase activity. Any effects on the parasites, pathogens, and immunity we observed appear to be due mainly to seasonal changes within the honey bee colonies. The results suggest that Fumagilin-B, Apistan, and chlorothalonil do not significantly impact the health of honey bee colonies, based on the factors analyzed and the concentration of chemicals tested.

Effects of Plant Species, Insecticide, and Exposure Time On the Efficacy Of Barrier Treatments Against Aedes albopictus.

The effect of 5 plant species (arborvitae [Thuja occidentalis], boxwood [Buxus sp., Japanese honeysuckle [Lonicera japonica], rhododendron [Rhododendron sp.], and zebra grass [Miscanthus sinensis]) and 2 rates of lambda-cyhalothrin (3.13 ml and 6.25 ml active ingredient [AI]/liter) on knockdown (1 h) and mortality (24 h) of adult female Aedes albopictus was evaluated over an 8-wk period. A significant difference in knockdown was observed between the 2 rates of lambda-cyhalothrin on the 5 plant species, with the highest proportion of knockdown observed on zebra grass and rhododendron treated at the higher rate. Although mortality was ≥60% and 85% on the 5 plant species at the low and high rates of lambda-cyhalothrin, respectively, a significant difference between the 2 rates was only observed on boxwood and Japanese honeysuckle (P < 0.0001). We also tested the residual toxicity of 3 barrier sprays (lambda-cyhalothrin, bifenthrin, and deltamethrin) and evaluated the efficacy of a short (5-min) exposure to the insecticides on knockdown and mortality of adults over time. Significantly higher knockdown was observed with lambda-cyhalothrin compared with bifenthrin and deltamethrin (P < 0.0001). Mean knockdown was ∼98%, 92%, and 20% for lambda-cyhalothrin, bifenthrin, and deltamethrin, respectively, at week 2, and ∼98%, 0%, and 44%, respectively, 8 wk after treatments were applied. Adult mortality from the 3 chemical treatments, however, remained above 90% throughout the study. Lastly, the trends in mean proportion of knockdown were similar for mosquitoes exposed for either 5 min or 24 h to the 3 chemicals. An overall decline in mean mortality over time, however, was observed for mosquitoes exposed for 5 min to the chemicals compared with mortality from the 24-h exposure. The results suggest that lambda-cyhalothrin can be an effective barrier spray treatment against Ae. albopictus adults because its efficacy is limited little by plant species, it has long residual toxicity, and it is effective following only 5 min of exposure.

Amitraz and its metabolite modulate honey bee cardiac function and tolerance to viral infection.

The health and survival of managed honey bee (Apis mellifera) colonies are affected by multiple factors, one of the most important being the interaction between viral pathogens and infestations of the ectoparasitic mite Varroa destructor. Currently, the only effective strategy available for mitigating the impact of viral infections is the chemical control of mite populations. Unfortunately, the use of in-hive acaricides comes at a price, as they can produce sublethal effects that are difficult to quantify, but may ultimately be as damaging as the mites they are used to treat. The goal of this study was to investigate the physiological and immunological effects of the formamidine acaricide amitraz and its primary metabolite in honey bees. Using flock house virus as a model for viral infection, this study found that exposure to a formamidine acaricide may have a negative impact on the ability of honey bees to tolerate viral infection. Furthermore, this work has demonstrated that amitraz and its metabolite significantly alter honey bee cardiac function, most likely through interaction with octopamine receptors. The results suggest a potential drawback to the in-hive use of amitraz and raise intriguing questions about the relationship between insect cardiac function and disease tolerance.

Effects of Pesticide Treatments on Nutrient Levels in Worker Honey Bees (Apis mellifera).

Honey bee colony loss continues to be an issue and no factor has been singled out as to the cause. In this study, we sought to determine whether two beekeeper-applied pesticide products, tau-fluvalinate and Fumagilin-B(®), and one agrochemical, chlorothalonil, impact the nutrient levels in honey bee workers in a natural colony environment. Treatments were performed in-hive and at three different periods (fall, spring, and summer) over the course of one year. Bees were sampled both at pre-treatment and two and four weeks post-treatment, weighed, and their protein and carbohydrate levels were determined using BCA and anthrone based biochemical assays, respectively. We report that, based on the pesticide concentrations tested, no significant negative impact of the pesticide products was observed on wet weight, protein levels, or carbohydrate levels of bees from treated colonies compared with bees from untreated control colonies.

Fitness and physiology of Adelges tsugae (Hemiptera: Adelgidae) in relation to the health of the eastern hemlock.

The hemlock woolly adelgid, Adelges tsugae Annand is an invasive insect that frequently causes hemlock (Tsuga spp.) mortality in the eastern United States. Studies have shown that once healthy hemlocks become infested by the adelgid, nutrients are depleted from the tree, leading to both tree decline and a reduction of the adelgid population. Since A. tsugae is dependent on hemlock for nutrients, feeding on trees in poor health may affect the ability of the insect to obtain necessary nutrients and may consequently affect their physiological and population health. Trees were categorized as lightly or moderately impacted by A. tsugae based on quantitative and qualitative tree health measurements. Population health of A. tsugae on each tree was determined by measuring insect density and peak mean fecundity; A. tsugae physiological health was determined by measuring insect biomass, total carbon, carbohydrate, total nitrogen, and amino nitrogen levels. Adelges tsugae from moderately impacted trees exhibited significantly greater fecundity than from lightly impacted trees. However, A. tsugae from lightly impacted hemlocks contained significantly greater levels of carbohydrates, total nitrogen, and amino nitrogen. While the results of the physiological analysis generally support our hypothesis that A. tsugae on lightly impacted trees are healthier than those on moderately impacted trees, this was not reflected in the population health measurements. Adelges tsugae egg health in response to tree health should be verified. This study provides the first examination of A. tsugae physiological health in relation to standard A. tsugae population health measures on hemlocks of different health levels.

La Crosse virus infection alters blood feeding behavior in Aedes triseriatus and Aedes albopictus (Diptera: Culicidae).

The effects of La Crosse virus (LACV) infection on blood feeding behavior in Aedes triseriatus (Say) and Aedes albopictus (Skuse) were investigated in the laboratory by measuring the size of the bloodmeal imbibed and the extent of refeeding by virus-infected and uninfected mosquitoes. LACV-infected Ae. triseriatus and Ae. albopictus took significantly less blood compared with uninfected mosquitoes. Twice as many virus-infected Ae. triseriatus mosquitoes refed compared with uninfected individuals (18 vs. 9%; P < 0.05); however, virus infection had no significant effect on the refeeding rate of Ae. albopictus. Reduction in bloodmeal size followed by an increased avidity for refeeding may lead to enhanced horizontal transmission of the LACV by its principal vector, Ae. triseriatus.

Population Growth Potential of the Bed Bug, Cimex lectularius L.: A Life Table Analysis.

Experimental life tables were constructed and analyzed for three strains of the common bed bug: a pyrethroid-susceptible laboratory strain (HS), a highly resistant field strain (RR), and a field strain with a declining level of resistance (KR). Egg to adult survival in the RR strain was 94% compared with 79% and 69% in the HS and KR strains, respectively. The RR strain also developed significantly faster from egg to adult (~35 days) than the other two strains (~40 days). Analysis of a survivorship and fecundity life table for the RR strain produced the following results. The average life expectancy for a newly laid egg was ~143 days, and that of a newly molted adult was ~127 days. Females produced an average of 0.64 daughter eggs/day with the highest weekly production during the fifth week of adult life. Analysis of daily reproductive parity showed that females produced 1-3 and 4-6 eggs on 79 and 21% of the days, respectively, when egg laying occurred. The net reproductive rate (R0) of the RR strain was ~35, which represents a 35-fold increase in the population per generation (~92 days). The intrinsic rate of increase, r, was 0.054 indicating that the population multiplies 1.1 times/female/day (λ) and doubles in size every 13 days. The stable age distribution (cx) was dominated by nymphs (54%), followed by eggs (34%) and adults (12%). Reproductive values (vx) for the strain increased from egg to the adult stage.

Survivorship During Starvation for Cimex lectularius L.

Four bed bug strains (Cimex lectularius) with different levels of pyrethroid resistance were evaluated to determine their ability to survive extended periods of starvation. First instar bed bugs of all strains were the most vulnerable to starvation (13.8-36.3 days mean survival time). Fifth instars and adults survived the longest during starvation (41.5-142.6 days). Significant differences in survivorship during starvation were observed between resistant and susceptible strains of bed bugs. Overall, all immature and adult stages of the resistant bed bug strains had significantly shorter survival times than those of the susceptible strains (P < 0.05).

Reproductive Potential of Field-collected Populations of Cimex lectularius L. and the Cost of Traumatic Insemination.

Egg production was compared among three field-collected bed bug strains over the course of 13 feeding/oviposition cycles, each of which lasted ~10 days. No significant differences were found among bed bug strains in the mean number of eggs/female/day (~1.0 egg). However, significant differences were found among strains in their patterns of egg production throughout the study period. Specifically, differences were observed in the timing of peak egg production and the rapidity of egg production decline among the three strains. Egg production was also quantified for female bed bugs that were subjected to single or multiple traumatic insemination events over a period of six feeding/oviposition cycles. Significant differences were found in egg production between females exposed to single and multiple inseminations. Females mated only once produced 83.8 ± 4.5 (mean ± SE) eggs over six feeding cycles. Females exposed to multiple inseminations produced 61.0 ± 3.1 eggs, indicating that multiple traumatic inseminations may reduce female fecundity by as much as 27%. This study is the first to suggest that, in a new infestation (first ~6 weeks), a solitary, singly-mated female with access to regular blood meals is capable of producing greater numbers of offspring than the same female in the presence of a male.

Predicting black light trap catch and flight activity of Acrosternum hilare (Hemiptera: Pentatomidae) adults.

A regression model was developed to predict the flight activity of Acrosternum hilare (Say) using data on the number of adults collected in a single black light trap located in Painter, VA, in the 18-yr period from 1990 to 2007. Eighteen initial weather variables, including cumulative precipitation over different time periods, mean monthly precipitation (PJA) and days below freezing (DFJA) from January to April, and mean monthly temperatures from December to April were tested in developing the regression model. Mixed (backward and forward) stepwise regression analysis showed that a two-variable model using PJA and DFJA was adequate for predicting the seasonal mean weekly number of A. hilare adults in the trap. Validation of the model using five independent black light trap data sets resulted in a strong correlation (r = 0.98) between observed and predicted mean weekly number of A. hilare adults caught in traps. Three peaks in flights of A. hilare adults were observed when mean trap catch was plotted over time for the 18-yr period. Peaks occurred at 319, 892, and 1,331 degree days (DD) from 1 January. Based on known developmental rates, the first peak was attributed to overwintered adults, the second to first-generation adults, and the third to a second generation of adults. This research suggests that A. hilare undergoes two complete generations in Virginia. Cumulative trap catch estimated from the 18-yr mean trap catch showed that 10, 50, and 90% of the total seasonal catch should occur by 153, 501, and 1,066 DD.

Dispersal of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) in potato fields.

The dispersal ability of Trichogramma ostriniae Pang and Chen, a biological control agent of Ostrinia nubilalis Hübner, was studied in commercial potato fields on the Eastern Shore of Virginia. The purpose was to quantify dispersal of T. ostriniae after an inundative release to aid in determining the number of release points needed per unit area for effective biological control of O. nubilalis in solanaceous crops. A single release of approximately 0.5 million wasps was made in two spatially separate potato fields in summer 2005 and 2006. Each release area contained 25 monitoring points at distances from 5 to 45 m from the release point bearing a yellow sticky card and O. nubilalis egg sentinels to observe for adult parasitoids and parasitism, respectively. Results showed that movement of T. ostriniae adults from the release point was rapid with individuals captured at 45 m within 1 d of emergence. High rates of parasitization (20-50%) also were observed at this distance, but the levels decreased with increasing distance from the release point. The distances that encompassed 98% recaptured T. ostriniae adults (x(98)) were 27.5 and 12.9 m from the release point in 2005 and 2006, respectively. The (x(98)) distances for parasitization of O. nubilalis were 21-26 m in 2005 and 8-10 m in 2006. However, the highest levels of parasitization in both years occurred nearest the release point. T. ostriniae showed uniform dispersal within an area of approximately 0.1 ha, indicating that multiple release points should be used for effective dispersal of T. ostriniae and control of O. nubilalis in solanaceous crops. Based on the assumption that a distance of 16 m represents the radius around a release point in which T. ostriniae activity was at its maximum, we estimate that approximately 12 release points/ha would be required in potato fields.

The potential for emergence of Chagas disease in the United States.

To determine the risk for Chagas disease (American trypanosomiasis) in the United States, the characteristics that make the triatomine vector effective and the areas most at risk for transmission were delineated. In addition, the status of Chagas disease awareness among physicians in areas with a potential risk for the disease was determined. A geographical information system (GIS) was used to analyze three triatomine species within the United States known to harbor Trypanosoma cruzi and that exhibit qualities of domesticity. An analysis of the minimum temperature threshold for increased triatomine activity delineates the current population at increased risk, and by incorporating temperature predictions for 2030, the population at risk under a future climate scenario was also delineated. Considering both environmental and social factors, a vignette-based physician survey, based on the results of the GIS analysis, was used to gauge the level of awareness of Chagas disease within the delineated higher risk range. The current area at increased risk for Chagas disease includes much of the southern United States, and the higher risk range is expected to expand into the central United States based upon the 1 degrees C (1.8 degrees F) increase in temperature predicted by the Intergovernmental Panel on Climate Change (IPCC) by the year 2030. Survey results indicate a limited consideration of Chagas disease during differential diagnosis, illustrating that the low number of Chagas disease cases discovered in the United States may be attributable to a lack of disease awareness as opposed to a lack of disease threat. This study combines GIS and survey analyses to evaluate the role that temperature variability and disease awareness among physicians play in the potential emergence of Chagas disease in the United States. This approach indicates that there is a potential for Chagas disease to emerge in the United States.