The effect of the pathogenic fungus, Beauveria bassiana, on the biological characteristics of the parasitoid wasp, Habrobracon hebetor

Knowledge about natural enemy’s interactions in biological pest control programs in agricultural systems is important to increase their effectiveness. In this research, the effect of the pathogenic fungus, Beauveria bassiana (Hypocreales: Cordycipitaceae), on the fertility-life table parameters of the parasitoid wasp, Habrobracon hebetor (Say) (Hym.: Braconidae) was investigated. The experiment was conducted in a fully randomized design using 12 treatments in Twenty-five replications. The flour moth larvae were contaminated by four different conidia concentration (0, 103, 106, and 109 conidia/ml) of B. bassiana, then these larvae in three periods of 24, 48 and 72 hours after contamination were used as the host for female wasps. Based on results, larval and pupal periods of the wasps significantly increased under fungus application, so with increasing conidia concentration, larval and pupal periods increased from 2.94 and 6.36 days to 4.13 and 7.45 days, respectively. The adult longevity of female wasps decreased significantly from 18.97 days to 16.27 days by using B. bassiana. The intrinsic rate of population increase (r) and the finite rate of population increase (λ) of wasps showed a decrease with increasing the concentration of fungus and increasing time, while the mean generation time (T) increased from 16 days to 19 days by increasing conidia concentrations. Our results indicate that infection of host larvae with pathogenic fungus has a negative effect on the biological characteristics of parasitoid wasps and can reduce the efficiency of H. hebetor in pest control.