Stimulation of Varroa jacobsoni Oud. oviposition with semiochemicals from honeybee brood

Abstract

-The oviposition of female Varroa jacobsoni kept with worker larvae of honeybees (Apis mellifera) in artificial gelatine cells was stimulated when 5-larva equivalents of extracts of L5 worker larvae were applied on the inner side of the walls of the cells. Most of the stimulating activity was recovered in the most polar fraction of the larval extract. The corresponding fraction of an extract of pupae did not stimulate oviposition. Semiochemicals present on the surface of L5 worker larvae, but not on pupae, may play a role in the regulation of V. jacobsoni reproduction. © Inra/DIB/AGIB/Elsevier, Paris

Toluidine blue staining as a rapid measure for initiation of oocyte growth and fertility inVarroa jacobsoniOud

“…The nature of this hypothetical activation factor remains unknown and, since the rejection of the JH hypothesis [12,19,21], no other specific host-derived compound with a distinct peak shortly after cell capping has yet been identified. The very quick physiological reaction of mites supports the conclusions of Trouillier and Milani [26] that V. jacobsoni reproduction is stimulated by a chemotactic signal.…”

“…The supposed stimulation by host derived hormone [12] or other trophogenous factors [20] has not been confirmed [19,21]. Recent studies indicate a stage-specific semi-chemical stimulation of V. jacobsoni reproduction [26]: the polar fraction of host larval cuticle induced egg maturation, though only if extracted from larvae of the fifth instar.…”

Natural Varroa mite-surviving Apis mellifera honeybee populations

“…Delayed egg-laying by mother mites and dead mite offspring were reported as the most common causes of failure to reproduce successfully (Locke and Fries 2011). A potential explanation for the reduced reproductive success in the Gotland population could be altered brood volatiles that are responsible for initiating oogenesis in mites (Garrido and Rosenkranz 2004;Nazzi and Milani 1996;Trouiller and Milani 1999; Natural Varroa mite-surviving Apis mellifera honeybee populations et al 2013). The higher proportion of dead mite offspring observed in the Gotland colonies may be an additional consequence of delayed egg-laying since soft-bodied immature mites are vulnerable to damage when exposed to older bee pupae that are molting or have increased movement in the cell (Calderon et al 2012;Martin 1994).…”

Varroamites and honey bee health: canVarroaexplain part of the colony losses?

“…Mite reproduction is an important trait in Varroa population dynamics and differential reproduction rates had been observed since the first infestations on HB were detected (Anderson, 2000). Changes in the hostparasite chemical ecology can influence Varroa populations and mite reproduction as the mite can be differentially attracted depending on inhibitory and stimulatory factors coming from different types of brood (Nazzi and Milani, 1996;Trouiller and Milani, 1999).…”