Parental Care

Most cockroaches show some form of parental care, in the broad sense: any form of parental behavior that promotes the survival, growth, and development of immatures, including the care of eggs or young inside or outside the parent's body, and the provisioning of young before or after birth (Tallamy and Wood, 1986; Clutton-Brock, 1991). Hinton (1981) considered cockroaches by far the largest group of insects that exhibit parental care, because he included ovoviviparity and viviparity in the category. Regardless of their reproductive mode, cockroaches characteristically care for their eggs in elaborate ways. In oviparous species, the care includes the production of oothecal cases, preparation of oothecal deposition sites, concealment of the oothecae, and defense of deposited oothecae. In ovoviviparous and viviparous females, the embryos are both protected and provisioned within the body of the female (Chapter 7). In this chapter the scope of parental care will be limited to enhancement of post-hatch offspring survival by one or both parents. The type of reproduction exhibited by a species

Fig. 8.2 Aposematically colored (dark brown with yellow-orange banding) female and nymphs of Desmozosteria grosse-punctata found under a stone in mallee habitat, Western Australia. Photo courtesy of Edward S. Ross; identification by David Rentz.

does, however, influence parent-offspring interactions. The majority of cockroaches that exhibit any form of post-partition parental care are ovoviviparous; the internal retention of the egg case guarantees that the female is in the immediate vicinity of nymphs at hatch (Nalepa and Bell, 1997). Oviparous females that deposit the egg case shortly after its formation depart before neonates emerge and may produce several more egg cases before the first one deposited hatches. Thus, ovoviviparity results in a generational overlap in both time and space, providing ample opportunity for brooding behavior. The multiple origins of parental care among the ovoviviparous Bla-beridae suggest that more elaborate forms of parent-offspring interactions then evolved from that starting point (Nalepa and Bell, 1997).

In 1983 Breed wrote that very little is known concerning post- hatching parent-offspring relationships in cockroaches. The situation has improved only slightly since that time. The majority of the cockroach species described as subsocial are known solely from brief notes taken during field collections, documenting females collected with offspring from harborages under bark, within logs, or under stones (Fig. 8.2). Examples include Poe-ciloblatta sp. (Scott, 1929), Aptera fusca (Skaife, 1954), and Perisphaerus armadillo (Karny, 1924). The variety of known subsocial interactions in cockroaches, however, is among the richest in the insects, and ranges from species in which females remain with neonates for a few hours, to biparental care that lasts several years and includes feeding the offspring on bodily fluids in a nest.

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