Proximate Factors Regulating Maternal Options in the Eggplant Lace Bug, Gargaphia solani (Heteroptera: Tingidae)

Abstract

The eggplant lace bug, Gargaphia solani, was used to investigate the proximate factors regulating maternal care and a noncaring, condition dependent strategy called egg dumping. We hypothesize that the act of delaying oviposition while searching for a dumping opportunity suppresses oogenesis and triggers guarding behavior. We examined several predictions of this hypothesis by measuring: (1) whether females do delay oviposition in the absence of dumping stimuli, (2) whether females in transition between egg dumping and egg guarding are capable of expressing either reproductive option, (3) the effect of nymphal interactions and antennal ablation on the duration of maternal care, and (4) oogenesis in guarding and dumping females. We found that females without a dumping opportunity wait, on average, 30 h longer to oviposit than females exposed to a dump mass. Females that had initiated their own egg mass could resume eggdumping if they had laid less than half of their eggs but were unlikely to abandon their eggs when most had been laid. Maternal care in G. solani can be prolonged if interactions with nymphs are artificially prolonged. Females require antennae to maintain maternalcare. Presumably antennae transduce cues from eggs and nymphs. Dissections of dumping and guarding females 72 h after their first oviposition demonstrated that dumpers continue to produce primary oocytes after a dumping event but guarders terminate oogenesis whilecaring for their first brood. We interpret all of these results within the context of the hypothesis that juvenile hormone titers regulate the expression of both egg dumping and egg guarding.