Title: Examination on the Reproductive Success of Re-Invading Varroa Mites Authors
Submitted to: American Bee Journal
Publication Type: Abstract Only
Publication Acceptance Date: March 3, 2011
Publication Date: May 1, 2011
Citation: Kirrane, M.J., De Guzman, L.I., Rinderer, T.E., Whelan, P.M. 2011. Examination on the Reproductive Success of Re-Invading Varroa Mites. American Bee Journal. 151(5):507. Technical Abstract: High proportions of non-reproductive (NR) Varroa mites have been reported in honey bee colonies exhibiting resistance to this parasite. This non-reproduction is associated with hygienic behavior (Harris et al., 2010 Ann. Entomol. Soc. Am. 103: 146-152); however, the mechanism by which this occurs is unknown. Two experiments were designed to assess the reproductive output of re-invading Varroa mites. The first involved the transfer of foundress Varroa from adult bees (PH) and different stages of brood into newly sealed larvae. The brood stages were: newly sealed larvae (SL), pre-pupae (PP), white-eyed (WE) and pink-eyed (PE) pupae. For experiment 2, Varroa mites were obtained from SL and inoculated into SL, PP, WE and PE cells. The transfer technique described by De Ruijter et al. (1987 Apidologie 18:321-326) was used. Reproductive mites were defined as those that produced both a mature male and a mature female offspring. In experiment 1 reproductive success was low overall and mostly observed in the SL to SL transfer (13%, Table). Unsuccessful repro- ductive attempts were highest in SL to PP (61%) transfer followed by SL to SL (22%). A high proportion of Varroa mites coming from WE (83%), PH (89%), and PE (92%) did not produce any progeny. Similar trends were observed in Experiment 2. Successful reproduction only occurred in the transfers to SL (26%). Generally, lack of progeny was not associated with mites having a lack of stored sperm. Our results suggest that mites removed from pre-pupae or older brood cells are unlikely to produce viable daughters. Similarly, if mites enter brood stages other than SL they will likely be non-reproductive. Hence, the ability of honey bees to remove Varroa-infested brood will enhance the pool of NR mites and negatively affect mite population growth in hygienic colonies.