When friends become unfriendly: testing repellents against a stingless bee (Trigona corvina Cockerell) that damages medfly-monitoring traps

Bees are acknowledged as a key, beneficial element in agriculture because of the pollination service they provide. Thus, great conservation efforts are carried out to protect them. On the other hand, insect pests cause important economic loses by, among other things, forcing producers to finance strategies aimed to reduce their populations. What if bees started causing some sort of damage? Should we treat them like we do with insect pests? We found that foragers of a stingless, Trigona corvina Cockerell, removed the glue from medfly monitoring traps, impairing the ability of the Mexican Federal Program “Moscamed” to make prompt and evidence-based decisions. Instead of using insecticides, we decided to test four repellents: Trimedlure, N, N-diethyl-meta-toluamide (DEET), mint oil and propylene glycol. Basically we mixed each substance with Stick-em glue and applied it onto the traps; next, traps were deployed and we started monitoring any loss in glue. We found that DEET was the most efficient substance to repel the bees. We further tested if DEET was repellent to fruit flies as well, but no evidence of repellence was observed. Now we are planning in using DEET in those areas where glue depletion is reported, knowing that such intervention will not affect native bee populations.