Neural influence on corpus allatum activity and egg maturation in starved virgin Periplaneta americana

Abstract

Of sixty-seven adult female Periplaneta americana (L.) isolated when less than 8 h old and kept without food at 25-30°C in LD 12:12, only six produced oothecae during 25-35 days. Growth of the basal oocytes was retarded, and maximal oocyte volume, only one-third of that in fed virgins, was achieved after about 12 days. By day 14, 60% of the basal oocytes were being resorbed in the starved females, and corpora lutea were usually all that remained beyond day 20. Oocyte growth was potentiated in starved, virgin females by severing either of the two nervi corporis allati 1 (NCA l), and oothecae were then produced in 45-80% of cases. Sham-operated controls oviposited in fewer than 27% of the trials. Because oocyte maturation was prevented by extirpating both corpora allata (CA), but not when the glands were replaced, and because the juvenile hormone analogue, ZR 5 15, was highly effective in causing the starved cockroaches to produce oothecae, the starvation-induced reproductive failure probably reflects diminished hormone production by the CA. The most likely consequence of severing NCA 1 is de-repression of juvenile hormone production. The directness of the neural influence was shown by removing the one denervated CA, in which case stimulation of oogenesis was minimal even though the contralateral innervated gland was present. The incidence of ootheca production was not enhanced by transecting the NCA 2, which suggests that the CA of starved cockroaches are not inhibited via this pathway.

Physiological investigation on the role of the innervation in the regulation of the prothoracic gland in Periplaneta americana

“…It is evident from the previous experiments of separating the brain by transection of the esophageal connectives that this activity increase cannot be a kind of operation shock; nor is it in the case of high initial activity in 20-day-old ganglionic chain or isolated ganglionic preparations. Obviously, the subesophageal ganglion acts as an inhibition center on prothoracic gland nerve activity, comparable in principle to the inhibitory innervation of the corpora allata in Periplunefu umericuna [29]. Malh et a1 [30] and Mala and Sehnal [3] suggest a similar situation in Galleria mellonellu.…”

The effect of nutrient stress on development and reproduction in an aphid

“…This growth was achieved by utilizing both lipoidal and non-lipoidal somatic reserves. Starvation is known to reduce the activity of the corpora allata in some insects (Khan et al, 1982;Pipa, 1982). In Periplaneta americana a low juvenile hormone titre results in the oocytes growing slowly (Pipa, 1982).…”

Starvation‐induced oviparae in the black bean aphid, Aphis fabae

“…If this mimicking of long days by JH is due to a direct reprogramming of female embryos from oviparous to viviparous development then, conversely, low JH titres in long-day insects might be expected to induce the appearance of oviparae when viviparae are expected. In some insects starvation is known to reduce the activity of the corpora allata (e.g, Khan et al, 1982;Pipa, 1982) and it is possible that starvation-induced oviparae result from lowered JH levels in aphids. Indeed, long-day alatae have given birth to oviparous/viviparous intermediates after treatment with an anti-JH compound (precocene 3: Hardie, 1984).…”