The effect of food availability on fat content was investigated in two species of pit digging ant-lion larvae in Tanzania. Macroleon quinquemaculatus (Hagen), a large species living in a crowded food poor habitat, is subject to strong intraspecific competition. The much smaller Morter sp. occurs in both food poor and food rich habitats. In the food poor habitat small Morter individuals are frequently food stressed while in the food rich habitat all sizes of individuals are occasionally subject to starvation during rainy periods. Rates of mass loss in starved larvae stabilised after a few days at -0.44%. larva-1 day-1. This rate did not differ across instar or species. Larvae used fat during starvation. Fed third instar Macroleon larvae had steeper growth rate-body size regression slopes than the first two instars because of increased allocation to fat stores: the slopes varied with hunger level. Growth rate slopes did not vary with instar in Morter. The proportion of fat in Macroleon and Morter from the food poor habitat increased rapidly in the third instar but in Morter from the food rich habitat the proportion was higher and less size dependent. The species showed similar percentages of fat at pupation. On two occasions, during 316 d surveyed during the dry season, rain-induced starvation was sufficient to kill > 65% of the first two instars of Morter.
|Publication status||Published - Mar 1991|