TRADE-OFFS IN BODY WEIGHTS, EGG LOADS, AND FAT RESERVES OF FIELD-COLLECTED PODISUS-MACULIVENTRIS (HETEROPTERA, PENTATOMIDAE)

The spined soldier bug, Podisus maculiventris (Say), was collected in 8 field sites in Indiana during the summers of 1987-1989. The insects were collected using both pheromone traps and sweep nets. Insect weigh ts were recorded for all 3 yrs, and egg loads and lipid content in the fat body were recorded for 1988 and 1989. Analysis of the weights rev ealed that females were heavier than males. Female body weight, egg lo ad, and lipid content were compared against corresponding measurements of predators subjected to different prey regimens in the laboratory. These comparisons indicate that field populations often had measuremen ts similar to predators provided 1 prey item every 3-9 d. Predators co llected during the summer of 1988 revealed higher mean lipid content, smaller egg loads, and lower weights than those collected in 1989. The se traits, together with the relative scarcity of predators found in 1 988, suggest that the predators were responding to greater food stress by conserving energy reserves in the fat body and diverting then away from reproduction. We discuss possible implications of these observat ions.