ABSTRACT

Using the Hemiptera as a model, this chapter develops an alternative hypothesis for the evolution of subsocial behavior, one that challenges the traditional view that maternal behavior is an exceptional and relatively recent evolutionary leap forward. Data are presented that support the argument that maternal care is not a recent behavioral innovation of the Arthropoda; indeed, it is a common phenomenon in phyla as primitive as the Cnidaria. Evidence that parental behavior has been a constant trait throughout the evolution of the Hemiptera is weak, but there is solid support for a claim of plesiomorphy in the Membracoidea, the Cimicomorpha, and the Pentatomoidea. Hemipteran maternal care is not a behavior restricted to occupants of unusually harsh environments and it does not appear to provide taxa that express it with superior survivorship or with an unusual capacity to radiate. Instead, maternal behavior is a trait fraught with ecological costs. When compared with females of related asocial taxa, mothers and the young they seek to protect are subject to increased exposure to predators, reduced fecundity, and lower intrinsic rates of natural increase. Maternal costs are so high that subsocial species have developed cost–reducing mechanisms such as egg–dumping, ant mutualism, and the avoidance of maternal risks during periods of high reproductive value. Through various permutations of clutch placement and size, most hemipterans have abandoned the maternal option in favor of dozens of alternatives that protect eggs from environmental dangers without loss of life or fecundity.