The first report on entomopathogenic effect of Fusarium avenaceum (Fries) Saccardo (Hypocreales, Ascomycota) against rice weevil (Sitophilus oryzae L.: Curculionidae, Coleoptera)

Abstract

This study aimed to evaluate the entomopathogenic activity of Fusarium avenaceum (strain 10A) against adults of Sitophilus oryzae infesting wheat grain. Bioassays were carried out to determine the adult mortality of S. oryzae when the conidial suspension of the fungus strain was applied using three types of fungus treatment. Results obtained have indicated significant differences (P=0.05) in the mean percentage of adult mortality due to the treatment with the fungus compared to the control. The highest mean percentage of adult mortality was obtained by the direct spraying of S. oryzae adults with the fungus conidial suspension before introduction of the treated adults into pots containing wheat grain; the lowest mean percentage of adult mortality was obtained by spraying the inner surfaces of pots with the fungus conidial suspension before introducing the grain and insects. This study demonstrated the typical growth of F. avenaceum on the outer surfaces of the dead treated adults of S. oryzae. Presence of the external fungus growth on the dead insects indicated that the death of S. oryzae adults was attributed to the fungus infection. Results obtained in the present paper represent the first record of efficacy of F. avenaceum against a coleopteran stored-grain insect, mainly including S. oryzae