Influence of individual body size on reproductive traits in melanopline grasshoppers (Orthoptera: Acrididae)

Abstract

Body size affects many aspects of an organism's performance, including reproduction. Ecologists have shown an increased interest in linkages between body size variation and population dynamics. Fecundity in a number of insect orders is often positively correlated with body weight or structural size, but reproductive characteristics and body size are not always positively correlated, particularly in field studies. Numerous biotic and environmental factors can influence individual body size and reproduction in grasshoppers under field conditions. Intraspecific relationships between reproductive traits and individual body size in melanopline grasshoppers were examined using data from four field experiments. Significant positive correlations between body size and reproductive traits occurred in three of four field experiments involving Melanoplus sanguinipes (Fabricius) and Phoetaliotes nebrascensis (Thomas) where per capita resource availability was manipulated, with a highly significant relationship between femur length and functional ovarian follicles when statistical results were combined from all correlations. In addition, individual femur length was a significant covariate for at least one reproductive trait in three experiments. Biotic factors such as food availability and predation could be more important than body size in determining reproductive output under field conditions, but further work is required to examine under what conditions individual body size affects reproduction in grasshoppers. CR - Copyright © 2008 Orthopterists' Society