[Ontogenetic changes of effects of carbon dioxide on the electroretinographic responses of Locusta migratoria cinerascens: influence of the animal breeding conditions].

Short term exposition of locusts to CO2 (1 min) greatly reduces the amplitude of electroretinographic responses induced by a lengthened light stimulation (5 s). The effects are significant immediately at the end of the treatment and may alter the visual responses for a prolonged period (10 min up to 60 min). In the course of ontogenesis, the reactivity of animals to CO2 decreases as shown by the increased delay necessary to obtain the maximum effect and by the reduction of the time-course of the effects. The breeding condition of locusts influences their responsiveness to CO2. Animals bred in grouping are less sensitive to CO2 action than isolated animals or crowded ones submitted to a daily CO2 narcosis. Discussion of the results is developed in relation with the CO2 action mechanisms and the functioning of the compound eye of the insect as well as in relation with the inhibition of the effects of crowding induced by CO2, possibly as a result of the reduction of the "sensorial flux" in high density population.