Lethal Strength and Compatability of Bacillus thuringiensis with Beauveria bassiana and Metarhizium anisopliae in Stored Date Pest (Oryzaephilus surinamensis and Ephestia kuehniella) Control

The most common stored pests of date palm in Khuzestan province are Ephestia kuehniella Zeller and Oryzaephilus surinamensis (Linnaeus). Considering the importance of using microbial control agents in the integrated management of date palm pests, the interaction of these pathogens on control of these pests was investigated. In this study, we investigated the lethal concentration, compatibility and interaction effects of Bacillus thuringiensis and pathogenic fungi Metarhizium anisopliae and Beauveria bassiana on populations of two species of pest. For this purpose, after larvae infestation using selective isolates tested and 10 days elapsed using combined cumulative mortality data of 50 and 99% for saw-toothed beetle larvae and the flour moth was calculated. Among the tested cases, the lowest LC50 was for M. anisopliae on moth larvae with 3.49×103 spores/ml. The highest amount of LC50 belonged to B. thuringiensis on saw-toothed beetle larvae equivalent to 2.69× 104 spores/ml. The highest mortality time of 50% for B. thuringiensis was 7.07 days. The lowest time of 50% lethality was 4.69 days for saw-toothed beetle larvae affected by B. bassiana. Spores of B. bassiana and M. anisopliae at all concentrations showed good computability with B. thuringiensis On the other hand, with increasing concentration of B. thuringiensis, the amount of compatibility index decreased. B. thuringiensis had synergistic effects in all treatments but the highest synergistic effect was observed in LC50 B. bassiana + LC50 Bt mixing on moth egg. Given the high compatible potential of B. bassiana and Bt, the possibility of exploiting this synergy is highly efficient to produce biocontrol.