Submitted to: Arthropod Management Tests
Publication Type: Research Notes
Publication Acceptance Date: April 1, 1997
Publication Date: N/A
Interpretive Summary: The diamondback moth is the most important and abundant pest, world-wide, of cabbage & related crucifer crops. Larvae damage leaves and harvestable heads through direct feeding. Chemical insecticides are used extensively against this pest, but it has developed resistance to most, including the microbial agent Bacillus thuringiensis. In this study we report the result tof a broad screening program designed to detect differences in the speed with which fungal spores can kill diamondback moth larvae. We tested 55 strains of 4 fungal species and found few differences among them. Notable exceptions were a few strains of 2 fungal species that killed larvae in an average of 3 to 4 days compared to the standard of 5 days. These strains provide an important source for developing biological control agents of the diamondback moth.
Fifty-five strains of four fungal species were tested for their virulence toward second-instar larvae of the diamondback moth, Plutella xylostella. All strains were compared to a standard strain of Beauveria bassiana originally isolated from the diamondback moth in New York, which gave an average survival time of 5.2 days when larvae were inoculated with 312 spores per square centimeter. The fungal species tested were B. bassiana, Fusarium sp., Metarhizium anisopliae, and Paecilomyces farinosus. Of 46 strains of B. bassiana, only strains 1564, 1627, 1850, 3404, and 3530 resulted in significantly lower survival times compared to standard strain 4543. All other strains did not differ significantly from the standard. All 5 M. anisopliae strains resulted in survival times of 3 to 4 days; strains of this fungus will be tested further.