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ABSTRACT
Microtheca ochroloma Stål, the yellowmargined leaf beetle, is a pest in crucifer crops during the late fall and winter months in Florida. On organic farms, it is difficult to control due to the restricted use of insecticides, in addition to the lack of specific natural enemies. The objective of this study was to evaluate a blastospore-formulated product of Isaria fumosorosea (PFR-97TM 20% WDG) against this beetle. In the first experiment, four of the beetle's life stages were treated with a suspension of 3 × 107 blastospores/ml. Mean corrected mortality of treated insects was significantly higher in 1st and 3rd instars than in the egg, pupal, and adult stages. Larvae infected by I. fumosorosea exhibited reduced growth and unsuccessful molting. The second experiment quantified mortality of first instars of M. ochroloma by four concentrations of PFR-97TM. Mean corrected larval infection/treatment was significantly (2.6 times) higher with a concentration of 4 g of product per 100 ml of water compared to concentrations of 1–3 g per 100 ml of water. Different factors that might have affected the pathogenicity of I. fumosorosea against M. ochroloma are discussed.
Acknowledgements
We are grateful to Valerie Quant, owner of White Rabbit Acres in Vero Beach, FL, for allowing the collection of beetles on her farm. We thank Rodrigo Diaz for assistance with data analysis and Susan Webb and Edward Skvarch for their critiques and suggestions that made substantial improvements to this study. In addition, we acknowledge the Ministry of Economy and Finances of Panama and the Florida Department of Agriculture and Consumer Services for being the major sponsors of this research.
Disclosure statement
No potential conflict of interest was reported by the authors.