Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2017
Publication Date: 11/29/2017
Citation: De Guzman, L.I., Frake, A.M., Simone-Finstrom, M. 2017. Comparative flight activities and pathogen load of two stocks of honey bees reared in gamma-irradiated combs. Insects. 8, 127. doi:10.3390/insects8040127
Interpretive Summary: Various contaminants including pathogens that cause serious honey bee diseases are known to persist in combs. Gamma irradiation has been used to sanitize beekeeping equipment in an attempt to kill these pathogens such as spores of American foulbrood, and has also been shown to inactivate various viruses. We asked whether or not worker bees (Russian or Italian honey bees) reared in combs that were gamma irradiated (presumably free from pathogens) are healthier and thus, perform more flight activities than bees reared in non-irradiated combs. The major finding concerned honey bee type and showed that Russian bees accumulated longer flight time since they performed more flights over their life span than the Italian bees. With regards to comb treatment, the bees reared in non-irradiated combs foraged prematurely than the bees reared in irradiated combs. Early foraging of bees may be associated with the higher levels of DWV in bees reared in untreated combs and also with the lower amount of pollen stores in colonies with untreated combs. The overall long term effects of comb irradiation on colony performance need to be assessed.
Technical Abstract: Gamma irradiation is known to inactivate various pathogens that negatively affect honey bee health. Bee pathogens such as Deformed wing virus (DWV) and Nosema spp. have deleterious impact on foraging activities and bee survival, and have been detected in combs. In this study, we assessed the effects of gamma irradiation on the flight activities, pathogen load and survival of two honey bee stocks that were reared in irradiated and non-irradiated combs. Overall, bee genotype influenced the average daily flights, total number of foraging flights and total flight duration in which the Russian bees outperformed the Italian bees. Exposing combs to gamma irradiation only affected the age at first flight with worker bees that were reared in non-irradiated combs foraged prematurely compared to those reared in irradiated combs. Precocious foraging may be associated with the higher levels of DWV in bees reared in non-irradiated combs and also with the lower amount of pollen stores in colonies that used non-irradiated combs. These data suggest that gamma irradiation of combs can help minimize the negative impact of DWV in honey bees. Since colonies with irradiated combs stored more pollen than those with non-irradiated combs, crop pollination efficiency may be improved when mite-resistant stocks are used since they perform more flights and had longer flight durations.