Tropilaelaps mercedesae management: Combining cultural and chemical control methods

Tropilaelaps mercedesae is a parasitic mite that causes severe colony impacts on the Western honey bee (Apis mellifera) and has shown the ability to outcompete another parasitic mite, Varroa destructor mites causing colony losses at a quicker rate. T. mercedesae has recently expanded its geographic range from its native area of Asia and there is increasing concern of the impacts the mite could have on the U.S. honey bee industry if introduced. Our research exploited the dependence of Tropilaelaps mites on honey bee brood by combining a cultural control (brood break) with additional chemical controls to manage T. mercedesae infestation. We compared four treatment groups: 1) Brood Break; 2) Brood Break + formic acid (FormicPro®); 3) Brood Break + oxalic acid dribble; and 4) untreated control. We found that T. mercedesae brood infestation rapidly increased in Control colonies from 0.4% to 15.25% over 60 days, while no other treatment group had an infestation rate over 0.11%. Similarly, sticky boards showed 15.48 mites dropped per 24 hours on Day 60 for Control colonies, whereas, no other treatment group was over 0.2 mites per 24 hours. Colony strength metrics showed a slight reduction in adult honey bee populations for the Brood Break + formic acid treatment group. No treatment exhibited complete efficacy, so additional measures may be needed to eradicate Tropilaelaps mites from colonies if introduced to a new area.