Revamping current pest management tools to target Varroa destructor

Honey bees, Apis mellifera, are rented by apple growers to use as pollination “insurance” for their crop. Their eusocial behavior and attraction to large scale blooms can make them an asset in orchards. One of their primary threats, Varroa destructor, can overwhelm colonies and transmit viruses at disruptive levels. Current management strategies are restrictive, costly, and have active ingredients that are long lasting in the environment. Varroa have developed resistance to a number of synthetic miticides. This work evaluates the efficacy of a commercially available bioinsecticide, Spear-T, as a potential in-hive varroacide. Experiments focus on pinpointing a concentration that kills Varroa without impacting Apis mellifera adults or developing larvae. The active ingredient in the is a peptide derived from the venom of spider, Hadronyche versuta. It kills small arthropods on contact by targeting nicotinic acetylcholine receptors. It is already being used in apple orchards to combat pests and has been deemed safe for foraging honey bees that may encounter residues. Experiments combine Spear-T with adjuvants and other additives to try and enhance penetration through Varroa cuticle. Searching for new tools that can be used in rotation with current strategies can help prevent overuse of any one product and delay mites becoming resistant. The search for new mite management techniques is timely in light of the international spread of Tropilaelaps mite.