Effects of the aphid <i>Rhopalosiphum padi</i> on the leafhopper <i>Psammotettix alienus</i> under laboratory conditions

Abstract

Abstract The aphid Rhopalosiphum padi (L.) coexists with the leafhopper Psammotettix alienus (Dahlbom) in the same cereal crops. However, dense populations of the aphid were never observed to be associated with dense populations of the leafhopper. This laboratory study focuses on the effect of the aphid at various densities on the development and reproductive biology of the leafhopper and constitutes a preliminary test to understand the interactions between these insects in the field. Independently of food quantity, an increase in aphid numbers caused a lengthening of development duration and increased mortality of leafhopper nymphs. In the absence of aphids, leafhopper nymphs preferred to feed on the lower part of the plant. In the presence of aphids, the leafhoppers moved towards the upper part of the plant. An increase in aphid numbers had no significant influence on the longevity of leafhopper females, although the daily fecundity decreased significantly. These data demonstrate the negative effect of R. padi on the development and fecundity of P. alienus and corroborated the field observations. Because food quantity was not the limiting factor, further experiments are underway to elucidate the factors modifying leafhopper biology. Such factors could be used to manipulate leafhopper populations.