ENTOMOPATHOGENICITY OF BEAUVERIA-BASSIANA TOWARD FLEA BEETLES, PHYLLOTRETA-CRUCIFERAE GOEZE (COL, CHRYSOMELIDAE)

A series of bioassays were conducted on flea beetle, Phyllotreta cruci ferae ae using various strains/isolates of Beauveria bassiana. Flea be etles were sprayed with a conidiospore suspension of 10(8) spores/ml i n different experiments. Fungus-treated and water-treated beetles were placed in groups of 10-50 insects in various bioassay containers incl uding cups, jars, and cages and maintained on a fresh supply of host p lant. Insect mortality was monitored daily. The LT(50) values found in B. bassiana ranged from a low of 1.9 for DAOM 210569 to a high of 16. 6 for ATCC 44860. In addition to this, the results of 6 experiments of two most stable and highly sporulating strains of B. bassiana GK 2016 and SG 8702 in our laboratory showed a variation in their LT(50) valu es 4.3 +/- 1.7 and 2.8 +/- 1.6 days, respectively. The mortality data was supported by examination of mummified cadavers. In different exper iments 50-90% of the cadavers showed fungal mummification within 7 day s depending upon the isolate tested. The results indicated that some s trains of B. bassiana are pathogenic toward the flea beetle.