EFFECTS OF LOCAL ENTOMOPATHOGENIC BEAUVERIA BASSIANA ISOLATES AGAINSTSITOPHILUS GRANARIUS (COLEOPTERA)

The granary weevil Sitophilus granarius L. is one of the most damaging grains pest in many parts of the World and Turkey. Chemical insecticides have been widely employed for the control of stored grain pests. This has caused such problems as insecticide resistance along with contamination of foodstuffs with chemical residues. Thus, there is a growing interest in using pathogenic control agents as an alternative. This study aimed to evaluate the efficacy of entomopathogenic fungus Beauveria bassiana isolates (F-52, F-53, and F-56) on adults of granary beetle S. granarius. Five different doses, including 1×10³, 1x10^5, 1×10^7, 1x10^8, and 1×10^9 conidia/ml for insect dipping, had been used. The experiment was laid out in a completely randomised block design with five replications and replicated two times.Mortalities were recorded on the 1st, 3rd, 5th, and seventh days of incubation. The highest mortality rate of 70% was observed at the end of the five-day incubation period with isolate F-53. Mortality increased with increase in the incubation period, and the highest mortality was observed after seven days of incubation period. Although the results indicated that isolate F-53 was effective against S. granarius and resulted in a high mortality 98% at the end of seventh day incubation period at 1×109 conidia/ml and followed by isolates F-52 and F-56 with 94% mortality. LC50 values confirmed that S. granarius was more susceptible to the isolate F-52 than the other two isolates F-53 and F-56 where the LC50 s were 1x10^5, 2x10^5, and 5x10^5 conidia/ml respectively. Mycosis was observed in all the treatments except the control. Our study indicates that all the isolates could be used as potential biological control agents. Further studies are ongoing for determination of the efficacy of this isolate under storage conditions.