BackgroundMass drug administration (MDA) programs have dramatically reduced lymphatic filariasis (LF) incidence in many areas around the globe, including American Samoa. As infection rates decline and MDA programs end, efficient and sensitive methods for detecting infections are needed to monitor for recrudescence. Molecular methods, collectively termed ‘molecular xenomonitoring,’ can identify parasite DNA or RNA in human blood-feeding mosquitoes. We tested mosquitoes trapped throughout the inhabited islands of American Samoa to identify areas of possible continuing LF transmission after completion of MDA.Methodology/Principle FindingsMosquitoes were collected using BG Sentinel traps from most of the villages on American Samoa's largest island, Tutuila, and all major villages on the smaller islands of Aunu'u, Ofu, Olosega, and Ta'u. Real-time PCR was used to detect Wuchereria bancrofti DNA in pools of ≤20 mosquitoes, and PoolScreen software was used to infer territory-wide prevalences of W. bancrofti DNA in the mosquitoes. Wuchereria bancrofti DNA was found in mosquitoes from 16 out of the 27 village areas sampled on Tutuila and Aunu'u islands but none of the five villages on the Manu'a islands of Ofu, Olosega, and Ta'u. The overall 95% confidence interval estimate for W. bancrofti DNA prevalence in the LF vector Ae. polynesiensis was 0.20–0.39%, and parasite DNA was also detected in pools of Culex quinquefasciatus, Aedes aegypti, and Aedes (Finlaya) spp.Conclusions/SignificanceOur results suggest low but widespread prevalence of LF on Tutuila and Aunu'u where 98% of the population resides, but not Ofu, Olosega, and Ta'u islands. Molecular xenomonitoring can help identify areas of possible LF transmission, but its use in the LF elimination program in American Samoa is limited by the need for more efficient mosquito collection methods and a better understanding of the relationship between prevalence of W. bancrofti DNA in mosquitoes and infection and transmission rates in humans.

Stink bugs (Hemiptera: Pentatomidae) cause significant damage to many different crops and horticultural commodities in Virginia. However, little is known about the species diversity or impact of stink bug egg parasitoids in the state. A survey was conducted in 2005 and 2006 (May through September) in wheat (Triticum aestivum L.), soybean (Glycine max L.), and several vegetable crops by collecting natural egg masses of various stink bug species and by monitoring sentinel egg masses. A total of 570 Euschistus servus (Say) eggs in 26 egg masses, 11,197 Murgantia histrionica (Hahn) eggs in 939 egg masses, 15 Podisus maculiventris (Say) eggs in 2 egg masses, and 546 Acrosternum hilare (Say) eggs in 18 egg masses were field collected and returned to the laboratory, where emerging parasitoids were identified to species. In addition, 2,512 laboratory-reared E. servus eggs and 230 P. maculiventris eggs were placed as sentinels into crop fields and collected after 7 d, and parasitoid or stink bug emergence was recorded. Four species of hymenopteran parasitoids in the family Scelionidae were recovered from stink bug eggs: Telenomus podisi Ashmead, Trissolcus basalis Wollaston, Trissolcus edessae Fouts, and Trissolcus euschisti Ashmead. In addition, one parasitoid in the family Mymaridae (Hymenoptera) was recovered. Parasitism rates were highest in E. servus with 89.7 and 49.2% of egg masses and individual eggs parasitized, respectively. The predominant parasitoid species was T. podisi.

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Brown stink bug, Euschistus servus (Say), and green stink bug, Acrosternum hilare (Say) (Hemiptera: Pentatomidae), are major agricultural pests. Although various insecticides are used to control nymphs and adults, little is known about how they affect eggs. Laboratory bioassays and field trials were conducted to determine the efficacy of common field rates of acephate, lamda-cyhalothrin, spinosad, and thiamethoxam on developing E. servus and A. hilare eggs, as well as Telenomus podisi Ashmead (Hymenoptera: Scelionidae) parasitoids developing in E. servus eggs. In laboratory bioassays, egg masses were dipped into insecticide and water solutions and assessed for mortality after 2 wk. In the field trials, egg masses on a cloth section were pinned to leaves in each plot ofa randomized complete block and returned to the laboratory 24 h after exposure to insecticide sprays. Mortality was assessed after 2 wk. In dip bioassays, there was a significant effect of insecticide treatment on A. hilare eggs with all insecticides resulting in greater mortality than the water control. However, no effect of treatment occurred in the field with A. hilare or for E. serous eggs in both the laboratory bioassays and the field trials. In contrast, developing T. podisi parasitoids showed significant mortality when exposed to all insecticide treatments, when dipped or field-treated. Spinosad and lamda-cyhalothrin treatments resulted in 100% mortality of T. podisi, and acephate resulted in greater mortality than thiamethoxam. Our results suggest that there is relatively little efficacy from insecticide sprays on stink bugs developing in eggs but that mortality of egg parasitoids may be significant.

Laboratory bioassays and field trials were conducted to evaluate the efficacy of selected organophosphate, pyrethroid, and neonicotinoid insecticides, as well as a chitin inhibitor, novaluron, against 2 common stink bug pests in Virginia, the green stink bug, Acrosternum hilare (Say), and the brown stink bug, Euschistus servus (Say). Green bean dip bioassays revealed differences in insecticide susceptibility between the 2 species. Acrosternum hilare adults were highly susceptible to all pyrethroids tested, the organophosphates except acephate, and the neonicotinoids except acetamiprid. Acrosternum hilare nymphs were also susceptible to all pyrethroids tested. In general, the neonicotinoids, dinotefuran and clothianidin, were toxic to A. hilare, whereas thiamethoxam and acetamiprid were toxic to E. servus. In field trials in soybean, the neonicotinoids, dinotefuran, imidacloprid, and thiamethoxam were efficacious at controlling stink bugs and, in general, performed comparably to the organophosphates and pyrethroids. These results indicate that neonicotinoid insecticides offer an alternative to growers for managing stink bugs that may fit with integrated pest management programs where conservation of natural enemies is a consideration.