Beauveria bassiana (Deuteromycotina: Moniliales) Effects on Lygus lineolaris (Hemiptera: Miridae)

Abstract

The fungal entomopathogen, Beauveria bassiana (Balsamo) Vuillemin, was isolated from a naturally-infected tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), in Arkansas. This is the first report of a tarnished plant bug naturally infected with B. bassiana. In laboratory tests this isolate (ARSEF 3769) was highly infective to L. lineolaris nymphs and adults. The LC50 for nymphs and adults was 9 × 104 and 8.4 × lfj4 conidia per ml deionized water containing 0.01% Tween 80, respectively, when mortality was recorded 7 days after treatment. In a 1993 field test, cotton plants treated with ARSEF 3769 conidia at a rate of 5.8 × 107 conidia per ml deionized water containing 0.01% Tween 80 resulted in 88.8% and 100% mortality (n = 143) in exposed L. lineolaris adults at 5 and 7 days after treatment, respectively, compared with 7.4% and 11.4% mortality in the controls (n = 150). Persistence tests on field cotton showed that B. bassiana conidia could infect adult L. lineolaris for up to 4 days under ambient environmental conditions. A 1995 field test with the commercial B. bassiana product, Mycotrol WP, and the insecticide imidacloprid (Provado formulation) on L. lineolaris adults caged on canola resulted in 97.9% mortality at 5 days after treatment in L. lineolaris adults when Mycotrol (280 g per ha) and imidacloprid (50 g ai. per ha) were applied together, compared with 67.3% in the imidacloprid alone (50 g a.i. per ha), 52% in the Mycotrol alone (280 g per ha), and 7.6% and 13.6% mortality in the controls. The combination of Mycotrol and imidacloprid was significantly more effective than either material alone. These studies show that the fungus B. bassiana may be useful for control of L. lineolaris in cotton and other crops.