Using an in vitro system for maintaining Varroa destructor mites on Apis mellifera pupae as hosts: studies of mite longevity and feeding behavior

Abstract

Varroa destructor mites (varroa) are ectoparasites of Apis mellifera honey bees, and the damage they inflict on hosts is likely a causative factor of recent poor honey bee colony performance. Research has produced an arsenal of control agents against varroa mites, which have become resistant to many chemical means of their control, and other means have uncertain efficacy. Novel means of control will result from a thorough understanding of varroa physiology and behavior. However, robust knowledge of varroa biology is lacking; mites have very low survivability and reproduction away from their natural environment and host, and few tested protocols of maintaining mites in vitro are available as standardized methods for varroa research. Here, we describe the 'varroa maintenance system' (VMS), a tool for maintaining in vitro populations of varroa on its natural host, and present best practices for its use in varroa and host research. Additionally, we present results using the VMS from research of varroa and host longevity and varroa feeding behavior. Under these conditions, from two trials, mites lived an average of 12 and 14 days, respectively. For studies of feeding behavior, female mites inflicted wounds located on a wide range of sites on the host's integument, but preferred to feed from the host's abdomen and thorax. Originally in the phoretic-phase, female mites in VMS had limited reproduction, but positive instances give insights into the cues necessary for initiating reproduction. The VMS is a useful tool for laboratory studies requiring long-term survival of mites, or host-parasite interactions.

A novel system for maintaining Varroa destructor mites on artificial diets and its application for studying mites as a vector for honey bee viruses

“…With this system, many mites survived consistently for 4 days (rarely, 7 days Posada et al unpublished), and an average longevity for up to five days, which is similar to the longevity of mites reported using other artificial systems [5]. The finding of live mites and excretory pellets on the parafilm membranes strongly suggests that the mites were feeding repeatedly on the diet, similar to the numerous excretory pellets found by Egekwu et al [18] for mites surviving on honey bee pupae. Notably, the greatest number of excretory deposits were found in the devices in which the mites survived the longest as supported by finding FITC-labeled fluorescent beads in the mite excreta.…”

“…These findings show that Varroa mites can not only survive on the artificial diet, but also can remain vigorous and suitable for experiments of viral transmission such as the current study showing virus acquisition and transmission from diet to pupae. Thus, the important question was not whether mites survived for long periods like those fed exclusively on pupae [18], but whether enough mites fed and survived during the period of the experiments in which they were used.…”

“…In each trial 10µL of diet plus beads were placed within the parafilm sachet.As a positive control for survival, female Varroa mites were allowed to feed on honey bee pupae. Pupae were collected from bee hives, placed in clear gelatin capsules (Capsuline, Pompano Beach, FL) with several mites, and mite and bee survival were monitored daily.Pupae were replaced after 3-4 days with fresh bee pupae to ensure that the pupal hosts had not deteriorated, transformed into an adult bee, or were otherwise unsuitable, as described previously [18]. As a negative control for mite survival, mites were housed in devices but membrane sachets contained only water.…”

“…Pupae were replaced after 3-4 days with fresh bee pupae to ensure that the pupal hosts had not deteriorated, transformed into an adult bee, or were otherwise unsuitable, as described previously [18]. As a negative control for mite survival, mites were housed in devices but membrane sachets contained only water.…”

Honey bee suppresses the parasitic mite Vitellogenin by antimicrobial peptide

“…192 5A, B, and Supplementary Table 4). These results suggest that expression of T. 193 mercedesae Vg genes is downregulated by honey bee Hymenoptaecin. To test this 194 hypothesis, we first established Drosophila melanogastar S2 cells expressing honey bee 195 Hymenoptaecin ( Supplementary Fig.…”