RO:  We actually know a goodly amount, but still have much to learn. See Nazzi

(2015) Ecology of Varroa destructor,
The Major Ectoparasite of the Western Honey Bee, Apis mellifera

Very nice, but still...not much information compared to what we know about behaviors of the host A. mellifera.   The paper is full of "we don't knows".  See clips below.  We still know almost nothing about mite olfactory cues, or how they work, thus efforts to trap them with various pheromones and other compounds like drone "smell" have failed.   A recent thread here on Bee-L about how mites populate individual cells yielded very little information from participants on the List.

Here are excerpts emphasizing just some of what we DON'T know:


"In a brood comb, it is common to find larvae infested by two, three, or more mites as well

as many cells that are not infested. This observation illustrates that the distribution of the mite

among brood cells is not random but rather aggregated (31, 33). Aggregation, which has also been

observed under laboratory conditions (21), could indeed favor exogamy and may have an adaptive

value for the mite. However, it is not known whether this phenomenon is related to an aggregation

pheromone or to the higher attractiveness of certain larvae either to the mite or to the nurse bees

carrying the mite to the brood cell. Moreover, other findings, resulting from different statistical

approaches, are contradictory and do not support the aggregation hypothesis (72, 106)."....


"Altogether these studies collectively demonstrate that the invasion of the brood cell by the mite

is a complex mechanism involving several attractive and arrestant compounds coming from both

the bee larva and the brood cell together with repellent chemicals from royal jelly. The identification

of several compounds as well as the demonstration of the activity of some of them under

natural conditions represents a promising step toward novel control methods based on behavioral

manipulation of the parasite. However, to our knowledge few such efforts have been undertaken."....


"During the host’s pupal stage feeding takes place on a site prepared by the mother mite. To

suck the hemolymph from the bee, the mother mite pierces a hole through the host’s cuticle (27).

The same feeding site is used by the offspring, but there is no information about the cues involved

in this feeding choice."....


"Challenging the immune system of bees with lipopolysaccharides or nonliving immune

stimulants can change the CH profile of the bees, which can lead to modified and aggressive

conspecific contacts (96, 97). Bees infected with DWV showing altered CH profiles can also be

ejected from healthy hives (7). In contrast, McDonnell et al. (74) confirmed that the mite can

alter the CH profile of the adult bees but did not observe any differential interaction between

infested bees and other bees. Both the mechanisms and the factors responsible for this effect need

to be clarified within the context of the intricate interactions between virus, mite, and the host’s

immune system (84)."...


"In any case, the stimuli that trigger oviposition have not been identified, and this remains an important objective for future

research in view of the possible practical implications for controlling the mite."...


"During this time mites are frequently found hiding between the abdominal sternites of the bee in a position

that is difficult for other bees to reach. How the mite locates this position is unknown, but both

mechanical chemical and thermal cues are probably used. Radioactive tracer studies documented

that mites can feed on adult bees during this phase, although the relevancy of these meals for both

mite and bee is not clear (24)."...


"By contrast, the transfer of mites from forager bees robbing an infested colony to foragers from

another colony, contributing to the horizontal transmission of the parasite between colonies, has to

be a common phenomenon in view of the high number of mites imported into noninfested colonies

during periods of nectar shortage (42). Kraus (53) hypothesized that compounds from the sting

apparatus, which contaminate bees stung to death during fights that occur during robbing, are

responsible for this host shift, although the dosages used in those bioassays were rather unrealistic.

Future studies are needed to clearly identify the chemicals involved in this process."...


"Many years after its arrival in the Western world, V. destructor still represents a major problem

for apiculture and the search for novel alternative control methods is therefore an essential task

for researchers. In this respect, detailed studies of the ecological interactions of the parasite are

urgently needed to unravel essential aspects that are still poorly understood. Such studies may lead

to promising strategies to sustainably manage this parasite."


So, yes, there is a LOT that we don't know.



Christina

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