Effects of the ambient CO2 level on the neurophysiology and behavior of lepidopterans

BRATOVICH C; GUERENSTEIN P.G.

Congreso; 5th Meeting of the Latin American Association for Chemical Ecology,; 2018

As other insects, lepidopterans use their olfactory system to accomplish different tasksduring their life cycle, including searching for a mate and for a food source. To detectodors they possess a variety of olfactory receptor neuron types, including receptors tunedto sense ambient CO2. It has been suggested that for lepidopterans CO2 would be one ofthe cues used during foraging. Surprisingly, CO2 receptor neurons are located on amouthpart, the labial palp, and not on the antenna as it would be expected. Also,surprisingly, those sensory neurons project into the antennal lobe of the brain, which isthe primary olfactory information processing center, to which antennal olfactory receptorneurons project. Therefore, it is conceivable that at the level of antennal lobe, integrationof information about general odors and about ambient CO2 occurs. Using multichannelrecording techniques, we explored possible modulatory effects of ambient CO2 levels onthe olfactory neurophysiology of adult lepidopterans (including Spodoptera frugiperda).Our results suggest that different modulatory phenomena occur at the level of antennallobe: the ambient CO2 level appears to modulate responses to odors (especially floralodors) in diverse ways. We also investigated behavioral effects in a wind tunnel andfound that high levels of ambient CO2 (i.e., 900 ppm) interfere with sex pheromoneorientation in male S. frugiperda. Our results suggest that the predicted rise in ambientCO2 levels, as part of the ongoing global climate change, will affect the physiology of theinsect brain, in particular at the level of antennal lobe. We also suggest that the generalolfactory behavior will also be affected.