Asian Journal of Biology

Abstract

Aims: In 2016, suddenly a pile of dead honey bees, Apis mellifera with unfolded wings had been noticed adjacent to the Langstroth bee boxes on the daily interval for a consecutive period of 2-3 months. The present study was an attempt to investigate the reason for this abnormal death.

Place and Duration of Study: Department of Agricultural Entomology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India between May 2016 and February 2018.

Methodology: Forty-eight numbers of sick bees with stiff-unfolded wings and 50 healthy bees were collected and maintained at a temperature of 30 ± 2°C and 70 ± 5% relative humidity. Maggots developed in the unfolded winged bees and adult flies emerged from pupae were examined. Duration of larval and pupal emergence was recorded at a fixed atmospheric condition. Relative mortality and parasitization rate of A. mellifera was also investigated for a period of one year.

Results: Parasitoid larvae emerged from the stiff-unfolded winged dead bees were identified as being Megaselia scalaris and further observation revealed that the parasitized bees contained empty body cavities while; normal honey bees were found to be non-parasitized. Matured phorid maggots emerged from the dead honey bees on an average 6 days after collection with the range of 1-14 larvae per honey bee. Maximum 12 pupae per honey bee were found after 18 days of the collection with the emergence of adults at 22^nd day. Infestation rate was highest in May and lowest in January.

Conclusion: From this study, M. scalaris can be considered as one of the facultative endo-parasitoids of A. mellifera and further research should be done about the impact of phorids in Indian commercial beekeeping.