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.

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A regional IPM project was initiated with four rounds of sampling for white grubs on the fairways of nine golf courses located on the Lower Peninsula of eastern Virginia, from 2000 through 2002. Fifteen regressor variables were collected and measured that included local-scale variables, golf course management practices and spatial pattern metrics derived from satellite images that underwent two methods of a supervised classification of six land-cover types (turf, woods, wetland, urban, bare soil and water) on four landscape scales derived from 10 km x 10 km buffer zones surrounding each golf course. Pearson's correlation coefficients were calculated to reduce the number of variables to a few that were highly correlated with white grub densities. Mallow's C(p) calculations were performed on the reduced variable sets to extract those that would be highly predictive. A multiple linear regression was performed using the Mallow's variables to develop eight regression equations (two classification methods x four landscape scales) that were used to predict regional white grub presence and abundance in 2003 on six additional golf courses located on the Lower Peninsula. The best model was the 6 km x 6 km buffer zones model from the second classification method, which included one local-scale variable (golf course age) and three spatial pattern metrics (total turf area, total turf area-to-total urban area ratio, and a woods interspersion-juxtaposition index). The mean difference between actual and predicted values was -0.15, standard deviation = 0.79, R2 = 81.38%. Additionally, a study was conducted to determine whether the number of white grubs collected from transects of sampled golf course fairways was significantly different from those found in the roughs. White grub counts from the roughs were significantly higher (mean = 0.283 grubs/transect, standard error = 0.0135) than those from fairways (mean = 0.146 grubs/transect, standard error = 0.0188); t = -4.31, df = 735, P = 0.0001. / Ph. D.

This study evaluates the cost-effectiveness of alternative Integrated Pest Management (IPM) training methods and programs aimed at diffusing IPM innovations to farmers in Bangladesh. Various IPM innovations are categorized as being simple, intermediate or complex, while dissemination methods used to extend these innovations are classified as being less intense, moderately intense, or more intense. Examples of less intense diffusion methods include mass media and field day demonstrations, and moderately intense methods include visits from agents. A "farmer field school" (FFS) is considered a more intense type of training method. The study evaluates the effectiveness of these IPM diffusion methods based on a number of criteria such as a methods ability to reach the greatest number of farmers with a given budget, their capability of reaching farmers quickly, and their ability to influence adoption of IPM. Additional components of effectiveness include influencing appropriate use of IPM, influencing retention of IPM, providing a level knowledge that participants can adapt to other areas on the farm, and providing accessibility to limited resource farmers. Data used in the analysis come from a field survey conducted on 350 rice and vegetable farmers in Bangladesh during July and August of 2004. Three ordered probit models are used to measure adoption of simple, intermediate and complex technologies. Results from these models indicate that FFS participants are more likely than non-participants to adopt simple, intermediate and complex practices, while farmers visited by agents are more likely than non-participants to adopt simple and intermediate practices. Field day attendees are more likely to adopt intermediate and complex practices than non-participants. These results may be influenced by endogeneity of unobserved factors that influence participation in FFS but also affect adoption. The study uses a binary probit model to measure appropriate use, but it does not detect any significant differences among farmers trained through different methods, nor does it find any significant differences in retention rates among farmers who have been to different training programs. Another probit model identifies farmers who have been visited by an agent as being more likely to discover an IPM practice through their own experimentation, indicating that farmers who have been visited by an agent have received enough knowledge to adapt IPM to different problems on their farm. Results of the study indicate that limited resource farms are well represented by their participation in the various training methods, but that a higher percentage of large farmers than small farmers in the sample have been visited by an agent or been to FFS. Informal diffusion of IPM information is found to be occurring among people in FFS villages for simple practices. However, for intermediate and complex practices, farmers who participated in FFS are no more likely to spread information to other people in their villages than are less intense formal training methods such as field days and agent visits. This result indicates that while FFS graduates may be likely to share simple practices with others, they should not be relied upon as the primary means of informally diffusing more complex practices to other farmers. The cost-effectiveness estimation incorporates components of the effectiveness evaluation along with the cost of administering the methods. The study calculates that agent visits are the most cost-effective method for diffusing simple and complex technologies and practices, while field days are the most cost-effective methods for extending intermediate technologies and practices. / Master of Science

Farmers around the world rely on IPM practices in order to increase their yields and reduce their losses due to pests. Assessing the impacts of previous IPM CRSP studies is crucial for successful continuance of the program and to provide meaningful recommendations to farmers. This thesis summarizes previous IPM CRSP impact studies, and provides additional impact assessments of IPM practices developed on the program. Scientist-questionnaires were sent to scientists in each IPM CRSP site around the world. Using the data from the questionnaire responses in combination with additional secondary information on elasticities, prices and quantities, economic surplus analyses were conducted. The tomato IPM program in Albania, the plantain IPM program in Ecuador, and the tomato IPM program in Uganda resulted in net present values of approximately $8 million, $7 million and $1 million, respectively. Sensitivity analyses for each case were also conducted, and net benefits ranged from $5 to 23 million in Albania, from $4 to 7 million in Ecuador, and from $0.03 to 3 million in Uganda. Additionally, an ordered probit analysis was conducted to determine the factors affecting adoption of IPM technologies in Bangladesh. The level of education, being a female, IPM training and awareness of pesticide alternatives were found to have positive and statistically significant impact on the adoption of IPM technologies in Bangladesh. / Master of Science

An instructional guide for high school science and agricultural education courses was designed around the topic of integrated pest management (IPM) and the gypsy moth (Lymantria dispar [L.]) problem in Virginia. Construction of the guide followed three phases—design, development, and evaluation—of the Instructional Development Institute (IDI) model of instructional design. Lessons were developed using information from Virginia agricultural education course competencies, national science standards, a conceptual model of IPM, and gypsy moth management references and contacts. A validation panel consisting of two educators and two gypsy moth managers provided a review of the guide. / Master of Science

The insecticide imidacloprid, has been found to be highly effective in suppressing hemlock woolly adelgid, Adelges tsugae. Laricobius nigrinus is a predatory beetle released as a biological control of adelgids in the eastern U.S. This project was designed to develop a pest management strategy that utilizes both tactics concurrently within the same site. It will assess the efficiency of this strategy in reducing HWA populations and improving the health of hemlock forests. The project was started in 2010 and data were collected annually through 2016. The project spanned three sites in three different states (KY, WV, and TN). Results show that tree health has generally declined across all sites for each year. HWA population index values are highly variable and are more strongly influenced by the occurrence of low winter temperatures than by treatment effect. Cross-correlation analysis of tree health and HWA population, revealed characteristics of their temporal relationship. In two of the three sites, tree health lagged up to three years behind changes in HWA population, and HWA populations lagged approximately one year behind changes in tree health. L. nigrinus did not establish at any site as of 2016. The lack of sustained recovery of the beetle may be attributable to the occurrence of extremely cold temperatures during the winters of 2014 and 2015 which produced subsequent crashes in the HWA population at two of the three sites. In TN, the L. nigrinus population may have never established due to a decline in the HWA population shortly after release. / Master of Science in Life Sciences

Thrips are pests in a variety of crops and are responsible for millions of dollars in damage worldwide. In Virginia there are a few key thrips species that cause a large portion of damage to both vegetable and floricultural crops. Three prominent pests include Frankliniella tritici (Fitch), Frankliniella fusca (Hinds), and Frankliniella occidentalis (Pergande). Significant yield losses in row crops such as cotton, peanuts and vegetables have been attributed to feeding and oviposition of these insects in high densities. In addition, both F. fusca and F. occidentalis can transmit plant pathogenic tospoviruses, such as tomato spotted wilt virus (TSWV), in certain susceptible crops. While all of these thrips species are difficult to detect due to their cryptic lifestyles, F. occidentalis is a particularly challenging pest to manage due to its resistance to many insecticides commonly used for thrips treatment. Early spring weeds were sampled for the presence of F. occidentalis in 2008 and 2009 in eastern Virginia. Weed samples consisted of mustard, henbit and wild radish and were collected from several different sites on the Eastern Shore of Virginia. During the summer of 2008, 2009 and 2010 various agroecosystems were sampled for the relative incidence of F. occidentalis. Overall, thrips numbers were very low in weed samples. F. occidentalis was detected in early spring weed samples in 2009 at a few of the sites sampled. In nearly every habitat, the species composition was dominated by F. fusca and F. tritici, with F. occidentalis occurring in very low numbers. Two different lures were evaluated in their ability to attract Frankliniella spp. thrips. The lures included Chemtica P-178 floral kairomone (AgBio Inc., Westminster, CO), a floral iii kairomone lure composed of a proprietary floral compound mixture, and ThriplineAMS (Syngenta Bioline Ltd., Oxnard, CA) pheromone lure, containing the aggregation pheromone of F. occidentalis. In spring 2009 and 2010 lure experiments were conducted in several different agroecosystems including: a tomato and potato field in Painter, VA, a cotton and peanut field in Suffolk, VA, and grass fields near a greenhouse in Virginia Beach, VA, and a high tunnel in Chesapeake, VA, as well as within these structures. Baited and non-baited sticky cards were arranged in a completely randomized design, with a pan trap located in the center of each plot. Traps were collected approximately twice weekly. F. fusca numbers were low and catches on sticky cards were not significantly affected by either lure. Sticky cards baited with the kairomone caught more flower thrips than traps baited with the pheromone, or the non-baited traps, especially when thrips numbers were high. Several biologically derived insecticides including: essential oils, spinetoram, spinosad, pyrethrins, and azadirachtin, were evaluated in their efficacy against thrips in several different crops. Randomized complete block design experiments were carried out in: tomatoes, snap beans, collards, soybeans, cotton and peanuts grown in several locations in southeastern Virginia in 2009 and 2010. Both spinetoram and spinosad reduced thrips numbers the most effectively compared with the untreated control. Peanut and cotton treated with spinosad, and treatments containing spinetoram suffered less thrips injury compared with the control, and yield was higher in cotton plots treated with spinetoram. / Master of Science in Life Sciences