Evaluation of organically acceptable insecticides as stand-alone treatments and in rotation for managing yellowmargined leaf beetle, Microtheca ochroloma (Coleoptera: Chrysomelidae), in organic crucifer production

摘要

BACKGROUND: Yellowmargined leaf beetle, Microtheca ochroloma, is the most damaging pest of organic crucifer crops in the southern United States. Experiments were conducted over four growing seasons (2007-2010) in Alabama to evaluate some botanical and microbial insecticides approved by the Organic Materials Review Institute (OMRI) against M. ochroloma in organically grown crucifer crops. Insecticides evaluated included PyGanic~R (pyrethrum), Aza-Direct~R (azadiractin). Entrust~R (spinosad), Mycotrol O~R (Beauverla bassiana strain GHA) and NOFLY~R [Isaria (= Paecilomyces) fumosoroseus strain FE 9901]. Two experimental organic formulations, Tick-Ex (Metarhizium anisopliae strain F52) and MBI-203 [Chromobacterium subtsugae), and one non-OMRI-listed formulation, Novodor~R [Bacillus thuringiensis subspecies tenebrionis), were also evaluated. The insecticides were applied as stand-alone treatments at recommended field rates on a weekly schedule. In 2010, some of the treatments were also evaluated in rotation/alternation with Entrust~R. Insecticide efficacy was determined by comparing densities of M. ochroloma larvae and adults and crop damage ratings in treated versus untreated turnip plots. RESULTS: Entrust~R consistently performed well in suppressing M. ochroloma adults, larvae and crop damage. PyGanic~R was the second best treatment. PyGanic~R or NOFLY~(?) can be applied in rotation with Entrust~R for effective management of M. ochroloma. CONCLUSION: Entrust~R applied weekly or in alternation with PyGanic~R or NOFLY~(?) provided acceptable control of M. ochroloma in organic crucifer production.