Parental Care on the Body

In several species of cockroach the protection and feeding of young nymphs occurs while the offspring are cling ing to or attached to the body of the female. A simple form of this type of parental care is exhibited by Blattella vaga, an oviparous species that carries the ootheca until nymphs emerge. The female raises her wings, allowing freshly hatched nymphs to crawl under them. They appear to feed on material covering her abdomen, then scatter shortly afterward (Roth and Willis, 1954b, Fig. 65). More complex forms of this behavior are found among cockroaches in the Epilamprinae. Females in three genera (Phlebonotus, Thorax, and Phoraspis) (Roth, 2003a) have an external brood chamber, allowing them to serve as "armoured personnel carriers" (Preston-Mafham and Pres-ton-Mafham, 1993). The tegmina are tough and dome-shaped, and cover a shallow trough-like depression in the dorsal surface of the abdomen, forming a space for protecting and transporting the young. The aquatic species Phlebonotus pallens carries about a dozen nymphs beneath its wing covers (Shelford, 1906b;Pruthi, 1933) (Fig. 8.4). In Thorax porcellana the maternal behavior lasts for about 7 weeks; 32-40 nymphs scramble into the brood chamber immediately after hatch and remain there during the first and second instars. Their legs are well adapted for clinging, with large pulvilli and claws. It is probable that nymphs feed on a pink material secreted from thin membranous areas on the dorso-lateral regions of the fourth, fifth, sixth, and seventh tergites of the mother. The mouthparts of first instars are modified with dense setae

Fig. 8.4 Female of Phlebonotus pallens carrying nymphs beneath her tegmina. After Pruthi (1933).

Fig. 8.5 Perisphaerus sp. from the Philippines. (A) Ventral view of adult female from Mt. Galin-tan; arrows indicate orifices between coxae. (B) Orifices (arrows) between coxae. (C) Head of probable first instar that was attached to an adult female. (D) Head of probable second instar that was attached to an adult female. From Roth (1981b); photos by L.M. Roth.

Fig. 8.5 Perisphaerus sp. from the Philippines. (A) Ventral view of adult female from Mt. Galin-tan; arrows indicate orifices between coxae. (B) Orifices (arrows) between coxae. (C) Head of probable first instar that was attached to an adult female. (D) Head of probable second instar that was attached to an adult female. From Roth (1981b); photos by L.M. Roth.

on the maxillae and labium, suggesting that they feed on a liquid diet. Midguts of young instars are filled with a pink material rather than the leaf chips they eat when older (Reuben, 1988). Jayakumar et al. (1994) and Bhoo-pathy (1998), however, suggest that young instars of this species may use a long, sharp mandibular tooth to pierce the tergites of the female and withdraw nourishment. First-instar nymphs removed from the mother do not live. Second-instar nymphs begin to make short forays from their maternal dome home to feed on dry leaves, and will survive if removed from their mother.

Among the Perisphaeriinae there are two recorded cases of nymphs clinging to the ventral surface of the mother for protection and nutrition. Nymphs of Peris-

phaerus cling to the female for at least two instars (Roth, 1981b). There are 17 species in this genus, but they are known almost exclusively from the study of museum specimens. First-instar nymphs are eyeless and have an elongate head and specialized galeae that suggest the intake of liquid food from the mother. There are four distinct orifices on the ventral surface of the female, with one pair occurring between the coxae of both the middle and hind legs (Fig. 8.5). Females have been collected with the mouthparts of a nymph inserted into one of these orifices; the "proboscis" of nymphs is 0.3 mm wide, about the same width as the intercoxal opening. The food of the nymphs may be glandular secretions or possibly he-molymph. The female can roll up into a ball with her clinging nymphs inside, rendering both the female and the nymphs she surrounds relatively impervious to attacks by ants (Fig. 1.11B). At least nine nymphs may be enclosed when the female assumes the defensive position. Other genera with the ability to conglobulate (e.g., Pseudoglomeris) may also exhibit this type of parental care. A similar defensive behavior occurs in species where the female "cups" her underside against a hard substrate (Fig. 8.6). In Trichoblatta sericea, well-developed pulvilli and claws of first-instar nymphs allow them to cling to the underside of the female for the first 2 to 3 days after hatching. The female secretes a milky fluid from her ventral side, which probably serves as food for the nymphs. Neonates isolated from their mother did not survive past the second instar (Reuben, 1988).

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