Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2007
Publication Date: 7/31/2007
Citation: Lord, J.C. 2007. Desiccation increases the efficacy of Beauveria bassiana for stored grain pest insects. Journal of Stored Products Research 43: 535-539. Interpretive Summary: Fungi that infect only insects can be used for environmentally benign pest control, but they are often dismissed as inappropriate for the dry conditions of stored products. Beauveria bassiana, a fungus that is registered for insect control on crops, was tested for comparative efficacy against stored-grain insects under various moisture conditions. The fungus’ efficacy for larvae of the Indianmeal moth and adults of the rice weevil and maize weevil was greatest under dry conditions that caused desiccation stress. Moisture conditions did not affect the fungus’ performance for adult rusty grain beetle or larvae of the cigarette beetle or sawtoothed grain beetle. These results demonstrate that dry stored-grain conditions are favorable for B. bassiana efficacy and will encourage the manufactures to make it available for that use.
Technical Abstract: The effect of desiccation stress on the efficacy of Beauveria bassiana for stored-product insects was investigated in laboratory bioassays. The mortality of B. bassiana-treated Plodia interpunctella larvae was greater at a vapor pressure deficit (VPD) of 2.42 kPa or 1.87 kPa than at 1.06 kPa. Moisture had significant effects on the mortalities of adult rice weevils, Sitophilus oryzae and maize weevils, S. zeamais. Maize weevil mortality was higher at 2.42 and 1.87 kPa than at 1.06 kPa, while rice weevil mortality was higher at 1.87 kPa than at either 2.42 or 1.06 kPa. Higher control mortality at the higher two VPDs indicated that S. zeamais were less desiccation-tolerant than S. oryzae. The mortalities of B. bassiana-treated adult C. ferrugineus, larval Lasioderma serricorne, and larval Oryzaephilus surinamensis were not significantly affected by VPD. These results demonstrate that dry stored-grain conditions are favorable for B. bassiana efficacy.