Higher toxin tolerance to triptolide, a terpenoid foraged by a sympatric honeybee

The thunder god vine, Tripterygium hypoglaucum, is a toxic nectar plant distributed across China. A terpenoid, called triptolide (TRP), found in nectar can impair honeybees' foraging responses, dance communication, and olfactory learning. In the present study, we tested the tolerances of the native honeybee Apis cerana and the introduced honeybee A. mellifera to short-term and long-term exposure to TRP. The results showed that introduced A. mellifera is more vulnerable in fatality to high concentrations of TRP sucrose solution (5 and 10 µg TRP mL^-1) than A. cerana. We also compared the short-term and long-term exposure effects of TRP on olfactory learning and memory between the two honeybee species, and the olfactory learning and memory of both honey bee species showed impaired performance after both 2 h or 7 days of being fed with TRP sucrose solution. However, A. cerana showed a higher tolerance and resistance to TRP toxin than A. mellifera. Our results support a coevolution hypothesis in that the native species A. cerana has higher toxin tolerance than the introduced species A. mellifera.