ADAPTIVE VALUE OF COOPERATIVE BREEDING: HELPER FEMALES ENHANCE OFFSPRING SURVIVAL IN A NEOTROPICAL SOCIAL ARACHNID

Cooperative breeding typically occurs in related groups, where non-breeding individuals assist in caring for offspring, enhancing both offspring survival and group fitness. While rare among pseudoscorpions, some species exhibit aggregative behaviors or form cooperative societies. In the Brazilian savanna, the pseudoscorpion <i>Paratemnoides nidificator</i> forms large cooperative colonies of breeding females and non-breeding helpers beneath the rough bark of live trees. This study investigated the effects of cooperative maternal care on offspring survival through four experiments assessing the influence of helper females on reproductive decisions and brood cannibalism. Our results showed that nymphs cared for in the presence of helpers exhibited higher survival rates and lower cannibalism levels. Moreover, females discriminated their own brood sacs, with mixed broods exhibiting reduced cohesion and increased cannibalism. The absence of helpers disrupted the reproduction of breeding females. These findings underscore the critical role of cooperative maternal care in the evolution of social behavior in pseudoscorpions.