Flupyradifurone impairs the processing of sound signals by the ascending interneurons AN1 and AN2 that convey auditory information to the cricket brain
摘要
Flupyradifurone is a butenolide insecticide with growing agricultural significance as a substitute for classical neonicotinoids, which have been partially banned in the EU and other countries. It also acts as an agonist on acetylcholine receptors in the insect central nervous system, but its neurophysiological effects on individual interneurons are poorly understood. Here, we investigated the effects of sublethal flupyradifurone intoxication on the neural processing of auditory information in the field cricket Gryllus bimaculatus. Using a suction electrode on the brain surface, we recorded the spiking activity of the two ascending auditory interneurons AN1 and AN2 while injecting the insecticide into the prothorax. Flupyradifurone caused a dose-dependent decrease in sound-evoked spike responses and an increase in spontaneous spiking activity in both ascending auditory interneurons, eventually leading up to a collapse of all spiking activity the highest dose tested (20 µl of 10− 3 mol/l). The substantial increase of spontaneous spiking activity in AN1 and AN2, which started with 20 µl of 10− 5 mol/l flupyradifurone treatment, will mask the neuronal coding of relevant acoustic signals required for auditory feature detection in the higher brain circuits. Field crickets rely on AN1 to transmit low-frequency auditory information for pattern recognition in phonotactic mate finding, and on AN2 to transmit high-frequency auditory information for sound source localization in predator avoidance behaviour. The disruption of auditory processing at the level of ascending interneurons by this insecticide will negatively impact the chances for reproduction and survival in crickets.