Susceptibility of four cereal and legume pests to Beauveria bassiana and Metarhizium anisopliae isolates

The aim of this study is to carry out a preliminary assessment of the pathogenicity of three different isolates of entomopathogenic fungi (EPF), Beauveria bassiana OF08, the commercial Beauveria bassiana strain ATCC74044 (Naturalis), and Metarhizium anisopliae CIST8 against adults of four grain and legume pest species, Cathartus quadricollis, Callosobruchus maculatus, Sitophilus granarius and Oryzaephilus surinamensis. Three conidial suspension concentrations were used 10 3 , 10 5 , and 10 7 conidia/ml for all isolates. Five repetitions per isolate/concentration were carried out. In Petri assay, 20 adult insects were sprayed with the conidial suspension mixed with tween 80 (0.002%). Plates were then incubated in climatic cells at 26C°. The mortality was checked daily and the final mortality rate was considered after 7 days. Our laboratory assays revealed that EPF species caused different levels of mortality. The virulence of B. bassiana OF08 and ATCC 74040 isolates was different for each species tested. Concerning the total cumulative mortality, the OF08 isolate was less effective than ATCC74040 causing 42 % and 56% mortality rate, respectively. The highest concentration (107 conidia/ml) of the M. anisopliae CIST8 and B. bassiana ATCC74044 isolates induced high mortality rates against C. maculatus (85% and 97%, respectively). Metarhizium anisopliae CIST8 isolate showed a low efficacy against O. surinamensis (25-30%) compared to the other isolates. Our results indicate that EPF could be used as part of an integrated pest management program for control of legumes and grain pests.