Effect of the Combined Use of Beauveria bassiana (Balsamo) Vuillemin and Diatomaceous Earth for the Control of Tribolium castaneum (Herbst) and Trogoderma granarium Everts

The red flour beetle Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) are important insect pests of stored commodities in Pakistan and other parts of the world. The laboratory study was carried out to investigate the insecticidal properties of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) in combination with commercial diatomaceous earth (DE) formulation Inert-PMS alone and in integrate manners against these pests. Beauveria bassiana was applied at 1x106 and 1x107 conidia/ml alone, or in combination with DE at 50 and100 ppm. Adult insects were exposed to the treated wheat for 5, 10 and 15 days at 27 +/- 2 oC and 65 +/- 5% r.h. in an incubator. The mortality of Tribolium castaneum adults was 100% even after 10 days of exposure at the dosages in combination of highest dose of B. bassiana and DE. While, after last exposure 100% mortality was achieved at highest dose rate of B. bassiana and both doses of DEs. Contrarily, 100% mortality of Trogoderma granarium was recorded after 15 days of exposure at highest dose rate ofB. bassiana and both DEs. The progeny emergence was significantly lower in combined treatments of B. bassiana and DE at highest dose rate for both insect species, while highest was recorded at low dose of B. bassiana.