بررسی اثر حشره‌کش‌های زیستی تنداکسیر و پالیزین روی Galleria mellonella L. (Lepidoptera: Pyralidae) و تعامل آنها با قارچ‌های بیمارگر حشرات

The Greater Wax Moth Gallaria mellonella L. is an important pest of honeybee combs worldwide. In this study, two botanical insecticides, tondexir (TON) and palizin (PAL) were tested against seventh instar larvae of this pest using dipping bioassay. The mean values of LC50 for TON and PAL were 1868 and 735.68 ppm, respectively. In the second part of this study, three fungal pathogens of Beauveria bassiana (Bals.) Vuill., Lecanicillium (=Verticillium) lecanii (Zimm.) Zare & Gams, and Metarhizium anisopliae (Metsch.) Sor. were tested against seventh instar larvae larvae of G. mellonella. The lowest LC50 values of 4.64 × 105 and 1.83 × 106 conidia ml-1 were estimated for B. bassiana and L. lecanii, respectively. The effect on spore germination of B. bassiana and L. lecanii of direct exposure for 24 h to TON and PAL was determined. B. bassiana germination was not affected by both insecticides. However, L. lecanii germination was negatively affected by TON (at concentrations of 1500, 2500, and 4000 ppm) and PAL (in all the tested concentrations). Subsequent tests were carried out to evaluate the combination of a sub-lethal concentration of either insecticides TON (414.24 ppm) or PAL (1‌‌16.44 ppm), and LC50 of B. bassiana and L. lecanii. We found both insecticides significantly reduced the susceptibility of G. mellonella larvae to B. bassiana infection. PAL reduced the effectiveness of L. lecanii against G. mellonella larvae. However, the infectivity of L. lecanii did not affect when combined with a sublethal concentration of TON. This study reveals that although plant-based insecticide, TON and PAL, were effective against G. mellonella larvae, the levels of control achieved did not increase by the mixture of these insecticides and fungi, and in fact were usually lower than when fungi were used alone.