Quantifying the costs and benefits of parental care in female treehoppers

Parental protection of eggs represents one of the most basic forms of parental care. Theory suggests that even such basic parental investment represents a trade-off between current offspring survival and future reproductive success. However, few studies have quantified the underlying costs and benefits of parental care for marked individuals across an entire lifetime. I marked and followed 370 females of Publilia concava (Hemiptera: Membracidae) that exhibited a range of guarding durations for their first clutch. Greater hatching success was correlated with longer guarding durations, and a removal experiment verified that female presence was responsible for a twofold increase in hatching success. On the other hand, females that remained to guard eggs had a lower number and size of future broods, suggesting that parental care may reduce lifetime fecundity. Marked females exhibited a bimodal distribution of guarding durations, reflecting the extreme tactics of immediate abandonment or remaining through hatching. Estimates of lifetime number of nymphs produced by females that abandon eggs early versus guard eggs through hatching revealed roughly equivalent levels of fitness. I discuss the conditions under which we might expect a female to adopt each of the alternative tactics, given the costs and benefits of parental care that were quantified in this study.