[Pollinator] Neonicotinoid effects on male honey bees

[David Inouye]

Straub, L., et al. (2016). "Neonicotinoid insecticides can serve as 
inadvertent insect contraceptives." Proceedings of the Royal Society of 
London B: Biological Sciences 283(1835).
     There is clear evidence for sublethal effects of neonicotinoid 
insecticides on non-target ecosystem service-providing insects. However, 
their possible impact on male insect reproduction is currently unknown, 
despite the key role of sex. Here, we show that two neonicotinoids (4.5 
ppb thiamethoxam and 1.5 ppb clothianidin) significantly reduce the 
reproductive capacity of male honeybees (drones), Apis mellifera. Drones 
were obtained from colonies exposed to the neonicotinoid insecticides or 
controls, and subsequently maintained in laboratory cages until they 
reached sexual maturity. While no significant effects were observed for 
male teneral (newly emerged adult) body mass and sperm quantity, the 
data clearly showed reduced drone lifespan, as well as reduced sperm 
viability (percentage living versus dead) and living sperm quantity by 
39%. Our results demonstrate for the first time that neonicotinoid 
insecticides can negatively affect male insect reproductive capacity, 
and provide a possible mechanistic explanation for managed honeybee 
queen failure and wild insect pollinator decline. The widespread 
prophylactic use of neonicotinoids may have previously overlooked 
inadvertent contraceptive effects on non-target insects, thereby 
limiting conservation efforts.