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The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an invasive phytophagous species native to eastern Asia. Due to its wide host plant range, it is considered among the most harmful agricultural pests in the invaded areas, including Europe, North and South America. In addition to its impact on crops, this insect causes a nuisance in urban areas, by invading buildings for overwintering using their aggregation pheromones and emitting an unpleasant smell when disturbed. The current management of this species is mainly based on the use of chemical insecticides, which show efficacy when applied frequently, with consequent negative impact on beneficial insects in the agroecosystems. As a result, there is a desire for more environmentally friendly solutions for the management of BMSB. A valid alternative is the use of exotic and coevolved biocontrol agents, for instance, the Samurai wasp, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), which is already showing promising medium and long-term results against BMSB in classical biocontrol projects. Within the frame of the least-toxic alternatives, the use of the Sterile Insect Technique (SIT) in an Area-Wide management approach is potentially a valid strategy to be included in integrated control and eradication programs. The main objective of this research, therefore, was to develop a SIT for potential use in the eradication of BMSB in newly introduced areas and/or as an additional tool to reduce its impact in areas where invasive populations have been already established. However, the effective use of SIT requires producing a high number of insects, and mass rearing for such a species is considered too complicated and expensive. To overcome this limitation, we evaluated a harvest, irradiation, and release strategy using wild overwintering adults. New live traps baited with high-load pheromones have been developed for mass trapping, exploiting the natural phenomenon ruled behaviour of aggregation of BMSB in preparation for overwintering. The captures of the new pheromone traps were compared with those of identically baited sticky panels through daily services lasting 2 weeks. Following winter diapause, the collected males were irradiated with high-energy photons at four different dosages: 16, 24, 32 and 40 Gy. The effects of irradiation on the biology i.e., fertility, longevity, and mating behaviour of overwintering BMSB males were evaluated with respect to unirradiated males. To encourage the use of SIT, a linear accelerator from a hospital facility was used for irradiation instead of the classical method involving radioactive materials. A second control 0 Gy was adopted to evaluate the possible negative effects on the biology (longevity, fertility, and fecundity) of insects due to the preparation for the irradiation. Moreover, as part of an integrated pest management (IPM) strategy, the combined use of the egg parasitoid T. japonicus and SIT was considered. The suitability of sterile eggs as oviposition substrate for T. japonicus was evaluated by comparing irradiated BMSB eggs at 40 Gy, eggs obtained by fertile female mated with sterile males irradiated at 50 Gy, and refrigerated sterile eggs currently used for laboratory rearing and field monitoring. The results of the research are encouraging for SIT applications in IPM approach. 1) The new traps caught up to 15-times more adult BMSB than the sticky panels in the two weeks of collections. 2) The developed irradiation protocol that involved a 6 MV medical linear accelerator has allowed the achievement of a high level of sterility of overwintering males (over 95%) already at 32 Gy without compromising males’ longevity and mating behaviour (in no-choice conditions). No adverse effects due to the irradiation preparation protocol were observed. 3) Sterile eggs obtained by mating sterile irradiated males and fertile females (SIT eggs), showed a higher parasitoid emergence rate (%) than both those directly irradiated and refrigerated. The difference in the emergence rate is even more evident when the eggs are 20 days old, with a parasitoid emergence rate of (75.56 %) for SIT eggs compared to those irradiated (44.68 %) and refrigerated (37.57%). In conclusion: 1) the new live traps are effective in mass trapping, 2) wild harvested males of BMSB can be used in SIT, 3) the use of linear accelerators for irradiation of BMSB is a feasible alternative to classical radioactive sources and 4) sterile eggs obtained by mating sterile males and fertile females are a valid substrate for T. japonicus oviposition, supporting the potential use of SIT on BMSB.

Brown marmorated stink bug, Halyomorpha halys (Stål), is a crossover pest impacting agriculture and invading urban environments. Studies were conducted to better understand the management of the bug through its physiology, behavior and susceptibility to insecticidal intervention. Halyomopha halys exhibit great variability in overwintering site selection with choices including manmade structures and tree bark. Because of these diverse sites, the bug must have the ability to withstand varying conditions throughout the overwintering cycle. We were able to determine that H. halys is chill intolerant and capable of adapting its tolerance to temperatures by season, sex, and location of acclimation. The mean supercooling point (± SEM) in the winter in Minnesota was -17.06°C ± 0.13° and in Virginia was -13.90°C ± 0.09°. Laboratory experiments conducted in Blacksburg, VA were able to determine baseline lethal high temperatures over time against H. halys adults. To achieve 100% mortality, temperatures fell between 45°C and 50°C, 40°C and 45°C, and 42°C and 45°C, over 15-min, 1-h, and 4-h, respectively. Moving forward, we were able to utilize this information to develop heat treatment guidelines for export shipping cargo infested with overwintering H. halys. In a controlled field experiment, we determined that exposing the coldest areas of an infested vehicle to temperatures greater than 50°C for a minimum of 15 minutes resulted in 100% mortality of overwintering BMSB adults. In 2012 and 2013, citizen scientists were recruited through Virginia Cooperative Extension to assist in evaluating several in home light traps designed to help eradicate overwintering H. halys adults in homes. Over the course of the two year study, fourteen houses participated in the study with 72% of those houses having stink bug activity. It was found that the most effective trap was an aluminum foil pan trap. In 2013, the trap was 19 times more effective at catching stink bug adults than any other trap tested. In September of 2014, a near-field experiment was conducted to determine the residual efficacy of several recommended and labeled insecticides for treatment of homes against invading H. halys adults. This study used constructed window screen bags that were dipped in insecticide solution. After the initial treatment, bugs were exposed to the bags for 24h weekly, up to 54 days after treatment (DAT). It was determined that 2 DAT all insecticides had activity except for indoxacarb. All insecticides lost efficacy after 29 DAT except for lambda-cyhalothrin, beta-cyfluthrin, beta-cyfluthrin + imidacloprid, lambda-cyhalothrin + thiamethoxam, and dinotefuran, which had some measureable activity even after 40 DAT. Each of these insecticides contained a pyrethroid alone or in combination with a neonicotinoid. Laboratory bioassays were conducted to determine the LC50 values of clothianidin, dinotefuran, imidacloprid, and thiamethoxam against H. halys nymphs using a systemic application method. Those LC50 values were found to be 0.077, 0.013, 0.068, and 0.018 ppm, respectively. Field experiments conducted in Virginia in 2012 and 2013 showed a significant reduction of stink bug damage using two soil applications of neonicotinoid insecticides in pepper and tomato. In North Carolina, a single drip irrigation application significantly reduced stink bug damage in 2012 and 2014 using dinotefuran or imidacloprid. / Ph. D.

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