Spring Varroa destructor (Mesostigmata: Varroidae) density predicts honey production losses and indicates an action...

Infestations of Varroa destructor Anderson and Trueman can influence many aspects of honey bee (Apis mellifera L.) colony performance. Treatment thresholds have typically focused on overwintering colony survival, but impacts on colony productivity during the spring and summer, including honey production, also require consideration. We analyzed 320 colonies across 2 New Zealand sites, measuring Varroa densities and colony strength from spring to harvest, and relating patterns of mite growth to honey yield. Mite populations grew in an exponential fashion during the spring-to-honey-yield period of 24 wks. Spring mite density strongly predicted seasonal honey yield losses. Each additional mite/100 bees was predicted to reduce yield by ∼2.29 kg. Colonies with >3 mites/100 bees produced ∼40% less honey. Colony strength also influenced honey production. More brood frames significantly increased yield, while increasing numbers of adult bee frames showed a nonsignificant positive trend. Honey production was highly variable. After controlling for apiary effects, spring mite density explained only 4.7% of yield variation, indicating multiple drivers and influences on honey production. Nevertheless, early-season mite infestation rates are actionable predictors of honey yield. To avoid yield losses, we suggest keeping spring Varroa densities below 3 mites/100 bees and a spring action threshold of 2 mites/100 bees, consistent with Canadian research on honey yield losses.