Submitted to: International Coloquim on Invertebrate Pathology and Microbial Control
Publication Type: Proceedings
Publication Acceptance Date: August 18, 2002
Publication Date: August 18, 2002
Citation: GRODEN, E., WRAIGHT, S.P., DRUMMOND, F.A. MICROBIAL CONTROL OF COLORADO POTATO BEETLE IN RAIN-FED POTATO AGROECOSYSTEMS IN THE NORTHEASTERN U.S.. INTERNATIONAL COLOQUIM ON INVERTEBRATE PATHOLOGY AND MICROBIAL CONTROL. 2002. v. 8. p. 265-269.
Small plot field studies in both NY and ME have demonstrated that the combination of the two microbial agents, Beauveria bassiana and Bacillus thuringiensis tenebrionis (Btt), may provide an efficacious alternative to chemical insecticides for management of Colorado potato beetles in rain-fed potato agroecosystems the Northeastern U.S. Although not always consistent, laboratory and field evidence suggests that efficacy of foliar applications may be enhanced with oil formulations applied in the evening against early-instar larval populations using drop-nozzle spray booms. The combination of agents does significantly reduce defoliation and subsequent beetle populations. Horizontal transmission from primary infected cadavers to soil dwelling stages of the beetle results in secondary cycling of the disease and continued pest suppression. The combination of Btt and B. bassiana have been used for management of Colorado potato beetle as part of a biological IPM program in a long-term study of the potato agroecosystem conducted at the University of Maine Potato Research Farm in Presque Isle, ME. One to four applications of the combination (2.3 l/ha Mycotrol with 3.5-7 l/ha Btt products) has successfully reduced populations of large larvae and emerging summer adult beetles below economic thresholds, and to levels as low or lower than those achieved with conventional insecticides since 1993 (Gallandt et al. 1998, Groden, unpublished). Biological management of this severe pest can be regularly achieved with microbials. However, at the cost of ca. $85-125/ha for the B. bassiana product and $30-75/ha for Btt products, per application, less expensive chemical insecticides have limited its adoption.