Abstract
Third instar larvae of Galleria mellonella were fed for five days on beeswax dipped for 20 sec into 0.5, 1 and 2 g/L water concentrations of the commercial preparations of Bacillus thuringiensis aizawai viz. XenTari registered and 20, 40 and 80 ppm azadirachtin A, viz. NeemAzal registered -T/S. The larvae were then given ad libitum access to untreated artificial diet. Effects on wax consumption, larval growth and mortality were determined. The speed of action of the two bio-insecticides was determined as well. Beeswax treated with NeemAzal T/S was consumed at all concentrations tested uniformly; on the contrary XenTari- treated wax (20 mg/L) was almost not consumed. The growth of larvae was delayed by the treatments, especially in XenTari. The highest concentration of NeemAzal T/S (80 ppm) caused 100% mortality within a month; while XenTari (20 ppm) reached 68% corrected mortality within 10 days (whereas NeemAzal T/S had induced 25% corrected mortality). The final corrected mortality, reached by XenTari (20 mg/L), after four weeks, was 77%. The emergence of moths was delayed by four days in XenTari-treatments, even when no mortality occurred. The significance of the findings for the protection of honey bees is discussed, concerning the efficacy against the greater wax moth and the additional effect on the Varroa mite. copyright 2012 Friends Science Publishers