Submitted to: American Bee Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 1999
Publication Date: N/A
Interpretive Summary: Honey bees are infested with a large parasitic mite called Varroa. These mites often fall off bees or are groomed off by the bees themselves and fall to the bottom of the hive. These mites will normally re-enter the colony, but if they could be prevented from re-entry it would act to lower the mite population. This research reports on a simple physical excluder, made of wire mesh screen, that prevents fallen Varroa from re-entering the the colony. This hive modification is proposed to be used in conjunction with other control measures as part of an integrated pest management program to reduce Varroa mites. Additionally, the hive modification resulted in increased rearing of young bees by the colony, an added benefits to its use. The hive modification can be readily adopted by the beekeeping community at minimal cost and should result in a reduction in the number of pesticide treatments currently needed to control Varroa.
Technical Abstract: A simple modification to the hive bottom board was tested as a non-chemical or cultural control method for Varroa mites. Wire mesh hardware cloth was used to replace the majority of the surface area of the bottom board underneath the brood area, allowing Varroa to fall through and potentially excluding them from re-entering the colony. Thirty colonies received no chemical treatment but were fitted with screen bottom boards, sticky boards or normal bottom boards. Mite fall was monitored in these colonies on a monthly basis and revealed approximately 14% and 28% lower mite fall in the two modified bottom boards compared to the normal bottom board in June and July respectively. However, by September mite levels in all three sets of colonies had reached damaging levels. Thus the bottom board modification slowed the growth rate of Varroa but is not sufficient alone. Additionally, colonies with mesh bottom boards had significantly more sealed brood than colonies on normal bottom boards, an added benefit to using this hive modification. The use of a screen bottom board or screen insert in conjunction with resistant lines of bees, smoke, dusts, or other control agents should provide a more integrated approach to Varroa Control and could reduce the number of chemical treatments required.