The influence of diet on the duration and thermal sensitivity of development in the linden bug Pyrrhocoris apterus L. (Heteroptera: Pyrrhocoridae)

摘要

Temperature and nutrition are crucial environmental variables that determine rates of growth and development in insects. However, the simultaneous effect of these factors on life-history traits is rarely addressed. In the present study, the influence of two diets (linden fruit and sunflower seeds) on the duration of immature stages and thermal reaction norms for development is tested in the bug Pyrrhocoris apterus L. (Heteroptera: Pyrrhocoridae). Eggs and larvae are reared at five constant temperatures (20, 22, 24, 26 and 28 degrees C) under an LD 20 : 4 h photocycle. Development rates deviate from linearity in the studied thermal range, especially in larvae; therefore, a nonlinear (power-law) approximation is also attempted. Parental diet causes no change in thermal reaction norms for egg development. However, the progeny of sunflower-fed bugs are more variable in terms of their development time, suggesting a transgenerational effect. Larval mortality rates increase in cooler conditions and are always higher on sunflower seeds. This is accompanied by more variable, less temperature-dependent and generally slower larval development. A review of previously published case studies on temperature-diet interactions in the control of insect development leads to two general conclusions. First, there are two approaches for assessing the temperature-dependent development in insects: one based on the concept of the sum of degree-days and the other based on the concept of reaction norm. Despite an obvious non-exclusiveness, the two approaches appear to have developed in isolation from each other. Second, three principal patterns of temperature-diet interactions can be recognized. The pattern found in P. apterus (the direct effects of diet are stronger at higher temperatures and much weaker or absent at lower temperatures) appears to be the most widespread