# Varroa vigor linked to life cycle stage of the phoretic host



## JWChesnut (Jul 31, 2013)

Dr. Zachary Huang (now at MSU) releases a research report on the phoretic host selection by Varroa. Varroa prefer nurse bees, and have better success on this age class.

One undiscussed implication of this research is the protocol step in sugar (and alchohol) sampling -- select sample bees from the brood frame -- is highly important. I have observed many otherwise responsible samplers take bees on a "grab and go" basis from anywhere in the hive.

A brood break would disrupt the demography of the hive and age the worker bee population, leading to a large reduction in Varroa fecundity.

The open access report is here:
http://www.nature.com/articles/srep28228

A popular account is here:
http://msutoday.msu.edu/news/2016/bee-vampire-picks-the-right-host-to-suck/


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## Lburou (May 13, 2012)

Thank you for linking the article...It refers to this article: Rosenkranz, P., Aumeier, P. & Ziegelmann, B. Biology and control of Varroa destructor. J Invertebr Pathol 103, 96–119 (2010). That paper reports a SIX day average phoretic period for varroa mites. I'd heard many numbers and welcome some science to the discussion as we speak of timing for OAV with active brood nests.


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## Juhani Lunden (Oct 3, 2013)

From Huang paper: "Future studies should focus on identifying the chemicals responsible for decreasing mite reproduction (as is the case for foragers as phoretic hosts) and utilizing them to reduce the reproduction of this serious honey bee parasite."

Rosenkranz paper: "Unfortunately, the reasons for the infertility of Varroa females, in general, are unknown. As unfertilized females are not able to reproduce (Martin et al., 1997) it was assumed that these infertile mites represent young Varroa females which failed to copulate during their maturation (Harris and Harbo, 1999). Fuchs (1994) supposed that infertile females had lost their reproductive ability. Two observations contradict these hypotheses: In the phoretic mite populations on adult bees nearly all mites have ﬁlled spermatheca (Garrido, 2004) and ‘‘infertile” brood mites, which were transferred artiﬁcially to other newly sealed brood cells, were still able to reproduce (Weller, 2008). This suggests that temporary infertility of Varroa females is induced by host factors.... Causing infertility in mites can be a powerful mechanism to resist Varroa. "


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