DEVELOPMENT AND USE OF MITE RESISTANCE TRAITS IN HONEY BEE BREEDING
Location: Honey Bee Breeding, Genetics, and Physiology Research
Title: Functionality of Varroa-Resistant Honey Bees (Hymenoptera: apidae) when used in migratory beekeeping for crop pollination
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2011
Publication Date: April 1, 2012
Citation: Danka, R.G., De Guzman, L.I., Rinderer, T.E., Sylvester, H.A., Wagener, C.M., Bourgeois, A.L., Harris, J.W., Villa, J.D. 2012. Functionality of Varroa-Resistant Honey Bees (Hymenoptera: apidae) when used in migratory beekeeping for crop pollination. Journal of Economic Entomology 105(2):313-321.
Interpretive Summary: Crop pollination by honey bees is vital to U.S. agriculture. This service is jeopardized by threats to honey bee health, notably parasitism by Varroa mites. Two types of honey bees that have genetically based mite resistance to Varroa mites (Russian honey bees [RHB], and bees with the trait of Varroa sensitive hygiene [VSH]) are useful for some beekeeping applications but previously have not been tested for functionality when used in beekeeping for pollination. Successful pollination requires that colonies maintain large populations of bees despite being stressed by trucking to crop sites and by other hazards associated with agricultural settings. We tested RHB and VSH bees in a commercial beekeeping operation by managing them without miticide treatments, and comparing them to commercial Italian honey bees that served as experimental controls. Half of the control colonies (group CT) were treated against Varroa mites and half were untreated (CU).
In two 1-year trials, RHB and VSH colonies compared favorably to the standard control bees. Resistant bees had adult and brood populations similar to those in the standard CT group (in terms of meeting pollination requirements) while usually maintaining lower levels of Varroa mites than the CU colonies. For pollination of almonds in February, percentages of colonies meeting the required =6 frames of adult bees were 57% (VSH), 56% (CT), 39% (RHB), and 34% (CU). Other research has shown that RHB populations can be increased by supplemental feeding. For pollination later in the season, much higher percentages (94 to 100%) of colonies of all bee types had =6 frames of adult bees (required for apples and cranberries) or =6 frames of brood (required for blueberries).
The study demonstrated that RHB and outcross VSH bees offer functional options for beekeeping engaged in crop pollination. The adoption of resistant bees would help beekeepers, who currently rely extensively on miticides for managing Varroa mites, to maintain colony health while avoiding problems related to in-hive pesticide use.
Two types of honey bees, Apis mellifera L., that were bred for resistance to Varroa destructor Anderson & Trueman were evaluated for performance when used for beekeeping in an intensive, migratory crop pollination system. Colonies of these stocks (Russian honey bees [RHB] and outcrosses of bees with Varroa sensitive hygiene [VSH]) were managed without miticide treatments and compared to colonies of commercial Italian honey bees that served as experimental controls. The control colonies were managed as groups which either were treated twice each year against V. destructor (CT) or kept untreated (CU). A total of 240 and 247 colonies were used for trials in 2008 and 2009, respectively.
RHB and outcross VSH colonies compared favorably with the control colonies. Overall, test colonies had sufficient size to rent for pollination in spring and summer: 94-99% of the colonies had =6 frames of adult bees for pollination of apples in early May, and 95-100% had =6 frames of adult bees for the pollination of cranberries in June. Similarly, all bee types satisfactorily met the rental requirement for blueberry pollination with 94-98% of the colonies having =6 frames with brood in late May. For almond pollination in February, a lower percentage of the colonies met the rental requirement of =6 frames of bees. Furthermore, VSH outcross (57%) and CT (56%) colonies performed favorably as compared to RHB (39%) and CU (34%) colonies. RHB are known to have small colonies in early spring unless continuous feeding is provided in the preceding fall and winter.
Managing problems from V. destructor currently relies on the use of miticides. This study demonstrates that outcrosses of bees with the VSH trait and pure RHB colonies offer alternatives for beekeepers to use for commercial crop pollination. Adopting mite-resistant stocks can reduce the reliance on miticides.