Efficacy of the larval parasitoid, Bracon hebetor Say. (Hymenoptera: Braconidae) on the greater wax moth larvae, Galleria mellonella (L.) (Lepidoptera: Pyralidae) under laboratory and field conditions

Abstract

The greater wax moth, Galleria mellonella Linnaeus (Lepidoptera: Pyralidae), is considered one of the most important pests effecting honeybee industry. The present study was carried out to evaluate the efficacy of the larval parasitoid, Bracon hebetor Say. (Hymenoptera: Braconidae), on G. mellonella in laboratory, honeybee colonies, and stored wax combs. In the laboratory studies, the pre-ovipositoinal, ovipositional, and post-ovipositional periods of the parasitoid were 0.27 ± 0.45, 20.87 ± 1.5, and 4.33 ± 0.48 days, respectively. The total number of eggs/female of the parasitoid on the 5th larval instar of G. mellonella reached 71.77 ± 7.84 eggs. B. hebetor females paralyze their hosts, the percentage of paralyzed 2nd larval instar of G. mellonella was 30% and parasitoid could not lay eggs on them, while the percentage of paralyzed 5th larval instar was 100% and parasitoid could lay eggs. In the field studies, the parasitoid, B. hebetor was released in honeybee colonies and stored wax combs to evaluate its efficacy. By releasing the parasitoid, the mean numbers of dead larvae of G. mellonella in treated honeybee colonies were greater than in the untreated, (91.8 ± 5.319 and 53.3 ± 24.373) larvae/colony, respectively. Also, releasing of B. hebetor against G. mellonella in stored wax combs reduced the number of survived G. mellonella larvae in treated storage wax combs to 3.2 ± 2.38 than in the untreated (using formic acid) 9.3 ± 5.52 larvae/store colonies. This is the first work to study efficacy of the parasitoid, B. hebetor on G. mellonella larvae in honeybee colonies and stored wax combs. The results suggested that the parasitoid had the efficacy to be used for controlling G. mellonella in beehives and stored wax comb in Egypt.