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Field-collected nymphs and adults of Bagrada hilaris (Burmeister) (Hemiptera: Penatatomidae) from three locations were evaluated for susceptibility to insecticides representing 10 classes of insecticide chemistry. Although relative susceptibilities differed between leaf-spray and leaf-dip Petri dish bioassays, consistently low LC50 values were determined for chlorpyrifos, bifenthrin, and lambda-cyhalothrin. Fenpropathrin and methomyl had intermediate values. Susceptibility to dinotefuran varied depending on the bioassay, possibly owing to leaf substrates used in the two bioassays. In soil systemic bioassays, the LC50 value of dinotefuran was significantly greater than that of two other neonicotinoids, imidacloprid and thiamethoxam, and the anthranilic diamide, cyantraniliprole. Mortality and feeding damage of B. hilaris and plant growth on insecticide-treated plants in greenhouse trials were consistent with the laboratory bioassays; the best results were seen with bifenthrin, methomyl, and chlorpyrifos. Mortality to the neonicotinoids was not evident; however, feeding damage and plant growth responses on dinotefuran-treated plants damage were similar to the noninfested control. This highlights the apparent antifeedant properties of dinotefuran that may have prevented adults from injuring broccoli plants after exposure to foliar spray residues. Data presented serve as baseline susceptibilities that can be used to monitor for resistance development in field populations of B. hilaris. [ABSTRACT FROM AUTHOR]

BACKGROUND:Bemisia tabaci biotype B is a resistance-pronepest of protected and open agriculture. Systemic uptake bioassays used in resistance monitoring programs have provided important information on susceptibility to neonicotinoid insecticides, but have remained decoupled from field performance. Simultaneous bioassays conducted in field and laboratory settings were compared and related to concentrations of imidacloprid in plant tissue for clearer interpretation of resistance monitoring data. RESULTS: Mean mortalities of adult whiteflies confined on cantaloupe leaves field-treated with three rates of imidacloprid did not exceed 40% in two trials. In contrast, laboratory bioassays conducted on different subsets of the same whitefly populations yielded concentration-response curves suggestive of susceptibility to imidacloprid in five populations (LC50 values from 1.02 to 6.4) relative to a sixth population (LC50 =13.8). In the field, densities of eggs and nymphs were significantly lower on the imidacloprid-treated cantaloupes compared with the untreated control, but the margin of control was greater in 2006 than in 2007. The potential impact of imidacloprid on whitefly eggs was explored in a greenhouse test that showed egg mortality occurring in both early (one-day-old) and late (three-day-old) eggs on cotton leaves systemically treated with imidacloprid. Quantification of imidacloprid residues in cotton leaves used routinely in systemic uptake bioassays revealed concentrations that greatly exceeded concentrations found in the field-treated cantaloupe leaves, at least at the three highest solution concentrations used for uptake. CONCLUSION: Systemic uptake bioassays have been widely used formonitoring B. tabaci resistance to imidacloprid, but without knowledge of imidacloprid concentrations that occur in test leaves relative to field concentrations. Higher mortality observed in systemic uptake bioassays relative to field-treated cantaloupes in this study suggests that field rates of imidacloprid are only partially effective against B. tabaci adults, in contrast to systemic uptake bioassays that showed susceptibility to imidacloprid. The discrepancy between field- and laboratory-based mortalities is probably due to extraordinarily high concentrations of imidacloprid that can occur in leaves of systemic uptake bioassays, potentially skewing perception of susceptibility to imidacloprid. Published 2013. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

A study on the compatibility of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) with neem was conducted against sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), on eggplant. Initially, three concentrations of B. bassiana (106, 107, and 108 conidia ml−1) and three concentrations of neem (0.25, 0.5, and 1.0%) were used as individual treatments against B. tabaci. The highest concentration of B. bassiana yielded the highest B. tabaci egg (25.2%) and nymph mortalities (73.0%), but this was not significantly different from the mortalities caused by the 107 conidia ml−1 suspension. Similarly, the highest concentration of neem yielded the highest egg (27.3%) and nymph mortalities (75.5%), which was also not significantly different from the 0.5% suspension. Therefore, 0.5% neem was used along with 107 B. bassiana conidia ml−1 suspension as an integrated pest management program against B. tabaci. The combination of B. bassiana and neem yielded the highest B. tabaci egg (29.5%) and nymph mortalities (97.2%), and the lowest LT50 (2.08 day) value. Moreover, an integrated combination of B. bassiana with neem caused 27.6 and 20.5% more nymphal mortality than individual treatments of B. bassiana and neem, respectively, 7 days post-application. Thus, a combined application of an entomopathogenic fungus and a botanical insecticide may benefit from both, and it has proven effective for the control of B. tabaci on eggplant. [ABSTRACT FROM AUTHOR]

Titers of two systemic neonicotinoid insecticides in citrus trees were measured in conjunction with conventional evaluations of their impact on glassy-winged sharpshooter (Homalodisca coagulata (Say); GWSS) populations. Xylem fluid samples were collected at regular intervals and from multiple locations within field-grown citrus trees to determine imidacloprid and thiamethoxam concentrations using commercial ELISA kits. Uptake profiles varied considerably with peak mean titers of imidacloprid occurring 6-8 weeks after application compared with 2 weeks for thiamethoxam. The persistence of each compound also varied as near-peak levels of imidacloprid were sustained for another 6-10 weeks before gradually declining. In contrast, thiamethoxam titers declined more rapidly after the initial peak, possibly reflecting an application rate only one-quarter of that used for imidacloprid. Within-tree distributions were more similar for the two compounds, with no significant effect due to height of the sample (upper or lower half) or to the quadrant location within the tree, with the exception of one quadrant in the thiamethoxam-treated trees. Substantial reductions in GWSS nymphs and adults were observed in imidacloprid-treated trees during the 2001 trial and were sustained for 4-5 months after treatment. Treatment effects on nymphs were not as well pronounced in the 2002 trial, when overall GWSS infestations were much reduced from the previous year. However, consistently lower adult infestations were still observed in 2002 for both treatments compared with untreated trees. Information on the spatial and temporal profiles in citrus trees was obtained for both compounds to complement field impact data and improve understanding of their pest management potential. [ABSTRACT FROM AUTHOR]