فریبا سهرابی

Date sap beetle, Carpophilus hemipterus (Col.: Nitidulidae) is one of the post-harvest pests of date palm fruits which causes a lot of damages under store conditions. There are several methods for controlling stored product pests and one of the major one is applying entomopathogenic fungi as biological control agents. In this study, the fungus B. bassiana Iran 1395C and M. asisopliae isolate Iran 1018C were used to control fourth instar larvae and adults. Bioassay method for larvae was performed with filter paper impregnated with spore suspensions in sterile Petri dishes and for adults by immersing insects in spore suspension. Spore suspension at concentrations of 3×108, 3×107, 3×106, 3×105 conidia/ml was prepared in Tween 0.02%, then mortality rate of adults was examined after 3, 7 , 9, 11, 13 days and for larvae after 3, 7 and 9 days. Experiments were performed in three replicates; each consisted of 10 larvae or adults, at 25 ? C under dark conditions. The results showed that mortality rate increased by increasing time and concentration of spore suspension. Mortality rates of adults for abovementioned concentrations using B. bassiana were 24.4, 14.4, 12.8 and 10.5% and for larvae were 83.3, 76.7, 72.2 and 71.1%, respectively. Moreover, it is revealed that fungal application at a concentration of 3×108 after 15 days and at all concentrations lead to the highest mortality rate of adults (30%) and larvae (100%), respectively. Regarding M. anisopliae, mortality rates of larvae for were 78.9, 75.6, 73.3 and 54.4% and for adults were 51.7, 20.6, 12.2 and 10%, respectively. On the other hand results showed that the fungus at a concentration of 3×108 after 15 days and at a concentration of 3×105 after seven days caused the highest mortality rate of adults (63.3%) and larvae (97%), respectively. Results indicate that fungal isolates have high insecticidal activity against larvae and adults of date sap beetle, and can be used for product protection after harvest.