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United States Department of Agriculture

Agricultural Research Service

Research Project: Determining the Impacts of Pesticide- and Nutrition-Induced Stress on Honey Bee Colony Growth and Survival

Location: Honey Bee Research

Title: Population growth of Varroa destructor (Acari: Varroidae) in colonies of Russian and unselected honey bee (Hymenoptera: Apidae) stock as related to numbers of foragers with mites )

Author
item Degrandi-hoffman, Gloria
item Ahumada, F.
item Danka, Robert - Bob
item Chambers, Mona
item Watkins De Jong, Emily
item Hidalgo, Geoffrey

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Varroa mites are an external parasite of honey bees and a leading cause of colony losses worldwide. Varroa populations can be controlled with miticides, but mite resistant stocks such as the Russian honey bee (RHB) also are available. RHB and other mite resistant stock limit Varroa population growth by reducing mite reproduction. However, mite population growth is not entirely due to reproduction. The number of foragers with mites (FWM) entering and leaving hives also affects the growth of mite populations. If FWM are detected in RHB and significantly contribute to Varroa population growth, then mite levels in RHB might not differ from unselected (i.e., non-resistant) lines (USL). We monitored FWM at the entrances of RHB and USL hives from August to November at two apiary sites. At site 1, RHB colonies had fewer FWM than USL and mite populations were smaller in the RHB colonies. RHB also had fewer infested brood cells and lower percentages with Varroa offspring than USL. At site 2, FWM did not differ between RHB and USL, and phoretic mite populations were not significantly different between the two stocks. At both sites, there were sharp increases in phoretic mite populations from September to November that corresponded with increasing numbers of FWM. Under conditions where populations of FWM are similar between RHB and USL, attributes that contribute to mite resistance in RHB may not keep Varroa population levels below that of USL.

Technical Abstract: Varroa mites are an external parasite of honey bees and a leading cause of colony losses worldwide. Varroa populations can be controlled with miticides, but mite resistant stocks such as the Russian honey bee (RHB) also are available. RHB and other mite resistant stock limit Varroa population growth by affecting factors that contribute to mite reproduction. However, mite population growth is not entirely due to reproduction. Numbers of foragers with mites (FWM) entering and leaving hives also affects the growth of mite populations. If FWM significantly contribute to Varroa population growth, mite numbers in RHB colonies might not differ from unselected lines (USL). FWM were monitored at the entrances of RHB and USL hives from August to November at two apiary sites. At site 1, RHB colonies had fewer FWM than USL and smaller phoretic mite populations. RHB also had fewer infested brood cells and lower percentages with Varroa offspring than USL. At site 2, FWM did not differ between RHB and USL, and phoretic mite populations were not significantly different. At both sites, there were sharp increases in phoretic mite populations from September to November that corresponded with increasing numbers of FWM. Under conditions where FWM populations are similar between RHB and USL, attributes that contribute to mite resistance in RHB may not keep Varroa population levels below that of USL.

Last Modified: 8/24/2016
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