Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 9, 2007
Publication Date: August 12, 2007
Citation: Wraight, S.P., Ramos, M. 2007. Integrated applications of Bacillus thuringiensis serovar. tenebrionis and Beauveria bassiana for biologically-based integrated pest management of Colorado potato beetle. Society for Invertebrate Pathology Annual Meeting Proceedings. 40:113. Technical Abstract: Research conducted over the past decade has indicated a low level of synergism and potentially high degree of complementarity between Bacillus thuringiensis (Bt)- and Beauveria bassiana (Bb)-based biopesticides applied for management of the Colorado potato beetle, Leptinotarsa decemlineata. In view of these findings, we have designed an integrated control program based on the hypothesis that early-season applications of the fast-acting (toxic) Bt will provide rapid control of early-instar larval populations (protecting the crop from defoliation), while subsequent applications of the slow-acting Bb against late-instar larvae that survive Bt intoxication will provide control of mature larvae after they enter the soil to pupate (reducing the summer adult and over-wintering beetle populations). Demonstration trials of this integrated biocontrol program were initiated in 2006 in 0.17 ha plots of potatoes at the Cornell Entomology Research Farm in Freeville, NY. Novodor FC® (Bt tenebrionis) and BotaniGard ES® (Bb strain GHA) were applied at rates of 5 L (103 million Leptinotarsa units) and 1.25 L (2.5 E 13 conidia) in 468 L water per ha, respectively. A program of three spray applications: 1) Bt alone applied at time of ca. 50% egg hatch, 2) Bt + Bb (tank mix) applied vs. second-instar larvae, and 3) Bb alone applied vs. late-instar larvae was compared to a biorational chemical control check (spinosad formulated as Entrust®) and an untreated control. Levels of defoliation, potato yields, and reductions in first-generation (summer) adult beetles were statistically equivalent to those achieved with spinosad.