Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2011
Publication Date: 8/1/2011
Citation: Kirrane, M.J., De Guzman, L.I., Rinderer, T.E., Frake, A.M., Wagnitz, J.J., Whelan, P.M. 2011. Asynchronous development of Honey Bee host and Varroa destructor (Mesostigmata: Varroidae) influences reproductive potential of mites. Journal of Economic Entomology. 104(4):1146-1152. Interpretive Summary: A high proportion of non-reproductive (NR) varroa mites is often observed in varroa-resistant stocks. Although it has been associated with hygienic behavior, the mechanism involved has yet to be resolved. By transferring varroa between cells of having different aged larvae and pupae, we observed that mites collected from newly sealed larvae (SL) and inoculated into SL produced both mature male and a mature female. Mites from older brood and mites transferred to older brood did not often reproduce. This inability to reproduce was not associated with mites having a lack of stored sperm. Our results suggest that the ability of honey bees to remove varroa-infested brood may enhance the pool of NR mites and negatively affect mite population growth in hygienic colonies.
Technical Abstract: A high proportion of non-reproductive (NR) Varroa destructor, is commonly observed in honey bee colonies displaying the Varroa sensitive hygienic trait (VSH). These studies were conducted to determine the influence of brood removal and subsequent host re-invasion of Varroa mites on mite reproduction. We collected foundress mites from different stages of brood [newly sealed larvae (SL), pre-pupae (PP), white-eyed pupae (WE), and pink-eyed pupae (PE)] and phoretic (PH) mites from adult bees. We then inoculated these mites into cells containing newly sealed larvae. Successful reproduction (foundress laid both a mature male and female) was low (13%) but most common in mites coming from SL. Unsuccessful reproductive attempts were most common in mites from SL (22%) and PP (61%). Lack of any progeny was most common for mites from WE (83%) and PE (92%). We also collected foundress mites from SL and transferred them to cells containing SL, PP, WE or PE. Successful reproduction only occurred in the transfers to SL (26%). Unsuccessful reproductive attempts were most common in transfers to SL (40%) and to PP (25%). Unsuccessful attempts involved the production of immature progeny (60%), the production of only mature daughters (26%) or the production of only a mature male (14%). Generally, lack of progeny was not associated with mites having a lack of stored sperm. Our results suggest that mites exposed to the removal of pre-pupae or older brood due to hygiene are unlikely to produce viable mites if they invade new hosts soon after brood removal. Asynchrony between the reproductive status of re-invading mites and the developmental stage of their re-invasion hosts may be a primary cause of NR mites in hygienic colonies. Even if re-invading mites use hosts having the proper age for infestation, only a minority of them will reproduce.