An exploration of the function of the lateral nerve and the femoral chordotonal organ in the African desert locust (Schistocerca gregaria)

Abstract

An investigation of proprioception in the African Desert Locust (Schistocerca gregaria) is the basis of the following work. Experiments were performed on the adults and 5th instars to investigate the relation between the size of the animal and their jumping and kicking ability. This lead to a study of the effects of proprioception, specifically proprioception of the lateral nerve and the chordotonal organ on the jump and kick of adults. In order to study these effects, the simplest method was used. The lateral nerves and chordotonal organs (of the metathoracic leg) were severed, both separately, and in combination. The consequences of this loss of information about the position of the tibia in relation to the femur resulting, was judged by the behavioural and electrophysiological effects on the jump and kick of the locust. Results indicate that the loss of the information supplied via the lateral nerve is not sufficient to significantly alter the jumping or kicking performance of the animal, and neither is that loss resulting from the severance of the chordotonal organ. Loss of information from both proprioceptors appeared to prohibit kicking in the locust, but it did not prevent the locust from jumping. This surprising finding was taken as meaning that when the locust jumps, it can get positional information from other sources, such as tibial-tarsal chordotonal organs, which are in contact with the ground prior to the jump, and that this information is sufficient to enable the expression of the motor programme. However, these additional sources of information are not available when the locust kicks, and thus the motor programme is not expressed.