Growth energetics in relation to temperature of the larvae of Rhopaea verreauxi (Coleoptera: Scarabaeidae).

Instantaneous energy budgets were constructed at a range of constant temperatures (7.5°-27.5°C) for the larval stages of the scarabaeid Rhopaea verreauxi. It was found that as larvae increased in size the temperature optima/maxima for the components of the energy budget shifted to lower temperatures. Also, as larvae increased in size the instantaneous assimilation efficiency (A/C) decreased and the temperature range over which energy could be assimilated narrowed. Within this narrowing range, temperature was found to have an increasingly greater influence upon A/C. This was attributed to its influence upon the post-consumption energetics processes rather than upon consumption itself. The instantaneous net production efficiency (P/A) also decreased with increasing body size. Also, the temperature range over which assimilated energy could be partitioned to growth production became narrower as body size increased. These findings are discussed in relation to those of other energy budget studies. Some comment is made on the importance of temperature acclimation in studies such as this, and on the relation of energetics conversion efficiencies to ectothermy and endothermy and to trophic status. It was concluded that in terms of instantaneous conversion efficiences R. verreauxi could be described as a typical ectothermic herbivore, a moderately efficient converter.