ARS | Publication request: Integrated use of Beauveria bassiana and Bacillus thuringiensis serovar. tenebrionis for microbial biocontrol of Colorado potato beetle

Submitted to: Journal of Anhui Agricultural University
Publication Type: Proceedings
Publication Acceptance Date: November 20, 2006
Publication Date: April 16, 2007
Citation: Wraight, S.P., Ramos, M. 2007. Integrated use of Beauveria bassiana and Bacillus thuringiensis serovar. tenebrionis for microbial biocontrol of Colorado potato beetle. Journal of Anhui Agricultural University. 34:174-184.

Technical Abstract: This paper reviews the potential for using insect pathogens to control the Colorado potato beetle, Leptinotarsa decemlineata, and summarizes results from nearly 10 years of research by USDA-ARS-PPRU scientists aimed at developing methods and strategies for integrated use of Bacillus thuringiensis and Beauveria bassiana for biologically-based management of potato beetles in the northeastern USA. The described studies have resulted in 1) design of a tractor-mounted hydraulic spray system that improved targeting and consequent efficacy of microbial control agents, 2) discovery of synergism between the bacterial pathogen Bacillus thuringiensis (Bt) and the fungal pathogen Beauveria bassiana (Bb), 3) findings that substantial mortality of beetle larvae treated with B. bassiana during foliar spray programs did not occur until after they entered the soil to pupate, and 4) observations that spray applications made in the evening (at sunset) were significantly, but not substantially, more effective than applications made during the morning hours. These findings have led to development of a bio-based pest management system based on three spray applications made in the following order at 3-5-day intervals: Bt alone, Bt and Bb mixed, and Bb alone. This spray program, with the applications initiated at 50% egg hatch, is intended to control the actively feeding larval stages (providing protection from defoliation) and reduce survivorship to the adult stage (providing long-term control by reducing populations of overwintering adults). In the initial test of the integrated management system, beetle control and potato yields were statistically equivalent to those in chemical insecticide-treated plots. Demonstration of the effectiveness of this program will continue over the next 2-3 field seasons.