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United States Department of Agriculture

Agricultural Research Service

Title: Bees with Varroa-Sensitive Hygiene Preferentially Remove Mite-infested Pupae Aged <5 Days Postcapping

Author
item Harris, Jeffrey

Submitted to: Journal of Apicultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 14, 2007
Publication Date: October 1, 2007
Citation: Harris, J.W. 2007. Bees with Varroa-Sensitive Hygiene Preferentially Remove Mite-infested Pupae Aged <5 Days Postcapping. Journal of Apicultural Research 46(3):134-139

Interpretive Summary: Suppressed mite reproduction (SMR) is a heritable trait of the honey bee (Apis mellifera L.) that provides resistance to thee ectoparasite, Varroa destructor. The primary mechanism of resistance in SMR bees is the hygienic removal of infested pupae from capped brood, and a better name for them is VSH bees (acronym for Varroa-sensitive hygiene). The major goals of this study were to compare the removal of infested brood between VSH bees and commercial controls in a short test and to determine whether VSH bees removed infested pupae of different ages at similar rates. Colonies with or without the VSH trait were given pairs of naturally infested combs that contained all stages of pupal development. A pair of combs was transferred from each of 12 different source colonies into a host colony (6 VSH and 6 controls) for a 40-hour period. Each host received a pair of combs from a single source colony. VSH bees removed 55% of all infested cells, while controls only removed 13%. The two types of bees differed significantly in removal of singly-infested pupae that were aged 1-5 days postcapping (cohort A) at the start of the test. VSH bees removed 66% of singly-infested pupae from cohort A, and controls removed 16%. The two types of bees did not differ in the removal of singly-infested pupae that were aged 5.6-8.5 days postcapping (cohort B). VSH bees removed 22% of infested pupae from cohort B, and controls removed 5%. These results suggest that stimuli that trigger removal of infested pupae are associated with host bees aged ' 5 days postcapping.

Technical Abstract: Suppressed mite reproduction (SMR) is a heritable trait of the honey bee (Apis mellifera L.) that provides resistance to thee ectoparasite, Varroa destructor. The primary mechanism of resistance in SMR bees is the hygienic removal of infested pupae from capped brood, and a better name for them is VSH bees (acronym for Varroa-sensitive hygiene). The major goals of this study were to compare the removal of infested brood between VSH bees and commercial controls in a short test and to determine whether VSH bees removed infested pupae of different ages at similar rates. Colonies with or without the VSH trait were given pairs of naturally infested combs that contained all stages of pupal development (1 comb with prepupae and young pupae and 1 comb with older pupae). A pair of combs was transferred from each of 12 different source colonies into a host colony (6 VSH and 6 controls) for a 40-hour period. Each host received a pair of combs from a single source colony. VSH bees removed 55% of all infested cells (singly and multiply infested), while controls removed 13%. The two types differed significantly in the removal of singly-infested pupae that were aged 1-5 days postcapping (cohort A) at the start of the test. VSH bees removed 66% of singly-infested pupae from cohort A, and controls removed 16%. The two types of bees did not differ in the removal of singly-infested pupae that were aged 5.6-8.5 days postcapping (cohort B). VSH bees removed 22% of infested pupae from cohort B, and controls removed 5%. These results suggest that stimuli that trigger removal of infested pupae are associated with host bees aged ' 5 days postcapping. In addition to the complete removal of pupae from brood cells, VSH bees had significantly more uncapped brood cells that still contained the pupae (410 uncapped pupae from 6 pairs of combs) than control bees (76 uncapped pupae from 6 pairs of combs). The infestation rate for uncapped pupae was not different between VSH bees (62%) and controls (75%). However, the infestation of uncapped pupae exceeded the natural infestation rate (25%), indicating that hygienic bees in both types of colonies preferred to uncap cells that were infested by mites.

Last Modified: 9/10/2014
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