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Research Project: Colony survival, Population Size, Cost and Return on Investment of Two Overwintering Strategies for Varroa Control

Location: Carl Hayden Bee Research Center

Project Number: 2022-21000-018-022-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Apr 15, 2016
End Date: Feb 28, 2017

1) Determine Varroa population growth from May until October based on a miticide application schedule. 2) Determine colony growth and survival over winter when hives are either placed in cold storage or taken to Texas where they will open forage and rear brood throughout the winter. 3) Compare costs and benefits (measured in survival over winter and colony size prior to transport to California for almond pollination) of placing colonies in cold storage over the winter or keeping them actively foraging and rearing brood in Texas.

The Varroa mite is the leading cause of colony losses worldwide. The cooperative agreement will determine the economic feasibility of reducing Varroa populations and colony losses with targeted miticide applications and storage of colonies from November until late January when they will be moved to California for almond pollination. The cost of storing colonies as opposed to letting the bees continue to forage in Texas throughout the winter will be compared as will colony survival, strength and value for almond pollination for these two management strategies. This research will be conducted in collaboration with Randy Verhoek of Harvest Honey Inc. The study will begin in late April or early May when colonies return to Texas. The first miticide treatments will be made after colonies are split, and they do not yet have sealed brood so all mites will be in the phoretic stage and exposed to the miticide. Mite sampling will be repeated in July before colonies are moved to North Dakota for the summer. If mite numbers are high, a second treatment will be made. Mite numbers will be monitored in late August in North Dakota and a miticide treatment will be applied. In October, colonies will be broodless, and a final miticide treatment will be made. At this point, half of the colonies will be put in cold storage, and half will be moved back to Texas for the winter. Comparisons will be made between storage fees and feeding colonies in Texas. Additional miticide treatments will probably be needed in Texas as bees will be foraging and brood will be reared. Labor, transportation costs and materials will be included in all feeding and miticide treatments. The return on investment in cold storage vs free-foraging colonies will be measured in colony survival and strength and rental value for almond pollination.