|SONENSHINE, DANIEL - Volunteer|
|POSADA-FLOREZ, FRANCISCO - Orise Fellow|
|EGEKWU, NOBLE - University Of Florida|
|GULBRONSON, CONNOR - Orise Fellow|
Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2019
Publication Date: 9/25/2019
Citation: Li, A.Y., Cook, S.C., Sonenshine, D.E., Posada-Florez, F., Egekwu, N., Mowery, J.D., Gulbronson, C.J., Bauchan, G.R. 2019. Insights into the feeding behaviors and biomechanics of Varroa destructor mites on honey bee pupae using electropentography and histology. Journal of Insect Physiology. 119:103950.
Interpretive Summary: The mite Varroa destructor is a harmful ectoparasite of the honey bee, Apis mellifera. The damage they inflict on their hosts is believed by researchers as a leading cause of recent decline in honey bee colony health. Economic losses to the beekeeping industry from mite parasitism is threatening the viability of this industry, and thus US food security. Controlling this ectoparasite has eluded researchers despite many efforts that include chemical control agents, many of which mites have gained resistance. Future novel control agents should better incorporate Varroa mite biology, and focus on IPM approaches rather than relying solely on chemical means of control. Here we present results from a study that seeks to understand the feeding behavior of the mite using tools that can monitor feeding actions such as probing, sucking, chewing, salivation etc and feeding frequency and intervals. The findings have a potential to determine feeding mechanisms and behaviors of the mite. These in turn will become valuable tools to design and develop novel control methods and integrated pest management practices for the control of Varroa destructor. These control methods will be methods that are not detrimental to the honey bee and the environment.
Technical Abstract: Feeding behaviors of female mites, Varroa destructor, on pupae of the honeybee, Apis meliffera, are described using electrophysiological (EPG) and video recordings. Relatively little information is available concerning the feeding on these mites on their host bees, e.g., how they access host hemolymph, how much fluid they can collect in a single feeding episode, and how often they feed and the duration of each feeding episode. In this study, EPG and simultaneously acquired video recordings of a mite free to move and feed on an early stage pupa showed patterns consistent with cuticle penetration and sucking activity. EPG waveforms characteristic of sucking behavior comprised a series of pulsations, ~ 25 spikes/s, separated by brief intervals of inactivity, and then repeated over a period of 70 – 90 s. Other waveforms characteristic of salivary secretion were recorded between periods of sucking activity. Video recordings indicated that the mite pierced the host cuticle with rapid pulses, aided by strong movements of the second and third pairs of legs, and interspersed with periods of movements of the chelicerae and palps. These behaviors suggest thrusting of the cornuae and hypostome into the feeding hole, followed by sucking of host hemolymph fluid into the buccal cavity, pharynx and digestive tract. These feeding and salivating episodes were separated by longer intervals of inactivity or locomotion. Feeding mites survived for at least18 – 20 hours, with frequent feeding episodes. Each mite fed repeatedly from a single location. However, different mites created feeding holes in different locations on the host bee pupa. Ingestion of hemolymph was confirmed by finding fluorescent microspheres, previously injected into the pupae, in the bodies of the mites.