Distribution of care-giving effort in a communally breeding lace bug: fair guarding without coercion

Cooperative care of offspring is a hallmark of animal sociality, but it is unclear how conflicts over care-giving effort are resolved in taxa that do not use dominance and physical force to induce cooperation efforts in others. To ascertain if taxa without dominance-enforcing traits such as stings or biting mouthparts show conflicts over offspring care, we used a lace bug (Heteroptera: Tingidae) that has communal guarding of young but lacks morphologies for dominance or coercion. In Leptobyrsa decora females oviposit communally and then aggressively guard communal broods from arthropod predators. Since guarding has mortality risks, we tested if individuals lower their own risk by behaving less aggressively than the partner guard. We show that effort towards protecting brood, and thus guard risk of death, is strongly positively correlated between guarding partners. This finding suggests that mechanisms other than dominance or coercion are used by L. decora to establish an equitable and possibly conflict-minimizing distribution of care-giving effort.[PUBLICATION ABSTRACT]