Continuing on risk avoidance:

> The behaviour of animals can be influenced, sometimes dramatically, by parasites. The changes in behaviour may reflect an adaptive response to avoid being parasitised in the first place, or they may be a consequence of having already been parasitised.

> Three-spined sticklebacks are known to avoid conspecifics carrying the fish louse, Argulus canadensis (Dugatkin et al. 1994). Interestingly, however, the fish show no obvious avoidance behaviour to the louse itself, suggesting that the cues that the fish respond to are derived from the coupling of the louse with an infected stickleback and so may be chemical cues relating to the damage caused by an attached louse. In fact, the identification of conspecifics that are infected by parasites is very often mediated by chemical cues ... 

the above is an example of avoidance. Many animals show the opposite, being attracted to the healthiest, most vigorous mates, which is essentially avoiding the weak and possibly ill as a potential mate. Hence, the most vigorous males of some species end up with a harem of females, while the rest of them get no partners at all. And completely the opposite is where the parasite influences the host in order to create improved conditions for itself:

> The strepsipteran parasite, Xenos vesparum, induces a series of changes in the behaviour of its paper wasp host (Polistes dominulus) including making them more gregarious. Following infection, the wasp ceases to contribute to normal tasks within its colony and eventually leaves the colony altogether to form into an aggregation with other parasitised wasps. The function of these wasp aggregations appears to be to allow the parasites to mate. Following this, those hosts that are infected with male parasites die, while those infected by females overwinter in the aggregation.

the above makes you wonder if Varroa exerts a similar control over honey bees, causing them to perform behaviors which redistribute the mites. If true, it would certainly explain the steep spike in mites in healthy colonies in late summer, even in colonies which have recently been treated 

Ward, A., & Webster, M. (2016). Development, Ontogeny and Parasite-Mediated Changes in Social Behaviour. In Sociality: The Behaviour of Group-Living Animals (pp. 175-190). Springer International Publishing.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html