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United States Department of Agriculture

Agricultural Research Service

Title: Field Evaluation of Beauveria Bassiana Isolates for Control of Plant Bug (Lygus SPP.)

Authors
item Leland, Jarrod
item McGuire, Michael
item Jaronski, Stefan

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 5, 2005
Publication Date: January 5, 2005
Citation: Leland, J.E., Mcguire, M.R., Jaronski, S. 2005. Field evaluation of beauveria bassiana isolates for control of plant bug (lygus spp.). National Cotton Council Beltwide Cotton Conference.

Interpretive Summary: A fungus (Beauveria bassiana) that kills insects is being tested for control of plant bugs. Previous studies showed that specific strains of the fungus from the tarnished plant bug in MS and the western tarnished plant bug in CA produced large quantities of spores, were highly pathogenic to the plant bugs, produced low concentrations of toxins, and were more tolerant to high temperature and sunlight. One strain each from MS and CA and the commercial strain (GHA) were evaluated in field trials against tarnished plant bug on wild host plants and cotton (MS), and western tarnished plant bug on alfalfa (CA). Incidence of infection in plant bugs was high in wild host plant trials (40-60%) and alfalfa trials (60-90%), but much lower in cotton trials (20-30%), which was likely related to coverage problems. Infection in beneficial insects was negligible in all trials. Although infection was high in wild host plants and alfalfa, in most cases, plant bug populations were not significantly reduced by the fungi. The lack of significant population reduction may in part be attributed to the heterogeneity of populations in experimental plots and migration between small plots. However, it may also be an indicator that infection is not progressing to mortality at the high temperatures present during the field tests. Studies using caged adult tarnished plant bugs in cotton indicated similar mortality of insects sprayed directly and those exposed to treated plant surfaces, however, the ability of the fungus to infect plant bugs was greatly reduced after 24 hr, indicating a need for formulations to improve persistence.

Technical Abstract: New isolates of the entomopathogenic fungus, Beauveria bassiana (Balsamo), are being tested for control of Lygus spp. Previous studies showed that specific isolates from the tarnished plant bug L. lineolaris (Palisot de Beauvois) in MS and the western tarnished plant bug L. hesperus (Knight) in CA are prolific conidia producers, highly pathogenic, low mycotoxin producers, and more tolerant to high temperature and solar radiation. One isolate each from MS and CA and the commercial isolate (GHA) were evaluated in field trials against L. lineolaris on wild host plants and cotton (MS), and L. hesperus on alfalfa (CA). Incidence of infection in Lygus was high in wild host plant trials (40-60%) and alfalfa trials (60-90%), but much lower in cotton trials (20-30%), which was likely related to coverage problems. Infection in beneficial insects was negligible in all trials. Although infection was high in wild host plants and alfalfa, in most cases Lygus populations were not significantly reduced by B. bassiana application. The lack of significant population reduction may in part be attributed to the heterogeneity of populations in experimental plots and migration between small plots. However, it may also be an indicator that infection is not progressing to mortality at the high temperatures present during the field tests. Studies using caged adult L. lineolaris in cotton indicated similar mortality of insects sprayed directly and those exposed to treated plant surfaces, however, efficacy of the B. bassiana was greatly reduced after 24 hr, indicating a need for formulations to improve persistence.

Last Modified: 7/23/2014
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