The effect of enforced virginity and subsequent mating on the activity of the corpus allatum of Periplaneta americana measured in vitro, as related to changes in the rate of ovarian maturation

Abstract

ABSTRACT. Female P. americana, reared with males from the time of adult emergence, mated on the 4th–5th day after metamorphosis, produced the first ootheca on the 8th or 9th day, and then produced successive oothecae at intervals of 3.0 days, whereas, only 50% of virgin females had produced their first ootheca by the 28th day after adult emergence. Examination of the ovaries indicated that oocyte development is normal in virgins until shortly after the time when they first become receptive to males. When mating was not allowed there was a dramatic reduction in the rate of vitellogenic growth of the terminal batch of oocytes which persisted until mating was allowed, and was often accompanied by resorption of a percentage of the oocytes. Short‐term, in vitro, radiochemical assay of juvenile hormone (JH III) biosynthesis by corpora allata (CA) showed that, in females reared with males, the cycles of ovarian development are accompanied by regular pulses of CA activity. There is a small, possibly preparatory peak of JH III biosynthesis before vitellogenesis of the first wave of oocytes, followed by a larger peak of JH III production during vitellogenesis of this batch of eggs and one peak of CA activity between ovulation of each subsequent wave of oocytes. Activities as low as 0.25 pmol C16JH/CA pair/h and as high as 48.38 pmol/CA pair/h were observed in CA from mated females after the onset of cyclic activity. Stimuli received during mating are somehow responsible for the cyclic activity of the CA, for when females were subjected to enforced virginity the first small peak was normal but the second peak was not fully realized and there was then a gradual decline in CA activity until approximately 2 weeks post‐emergence. Thereafter the glands exhibited a more or less constant rate of JH biosynthesis (mean = 3.45 ± 0.32 pmol/CA pair/h.) When females were mated after 21 days of enforced virginity the activity of the CA was enhanced. By 48 h after mating the mean glandular activity was at least four times that found in virgins of the same age, and by 72 h rates as high as 40 pmol/CA pair/h were observed. This was followed by normal cyclic activity of the CA. The increase in rate of JH biosynthesis appears to result in a recommencement of oocyte development in these ‘delayed‐mated’ females.

Regulation of cockroach oothecin synthesis by juvenile hormone

“…Figure la-c shows the combined rates of synthesis of oothecins C and D together with the rates of biosynthesis of juvenile hormone [22] and the titers of ecdysteroid [24]. In Periplunetu, there is virtually no juvenile hormone synthesis immediately after the nymphal-adult molt (Fig.…”

“…lc) [1,14,24]. When the adults are sexually mature, there is a sixfold difference between the maximum and minimum activities of the corpora allata during each cycle of juvenile hormone biosynthesis [22]. However, measurement of the rates of oothecin synthesis in physiologically synchronized animals shows only moderate cyclic variation in rate (Fig.…”

“…Reliable quantitation of juvenile hormone titers has only recently become possible [20,21]. Titers of juvenile hormone in Periplunetu have not yet been determined, and until they are, we can only assume that the in vitro juvenile hormone biosynthetic activity that has been determined in Periplunetu at different stages during sexual maturation is correlated with hormone titer [22]. This has been shown to be the case in the cockroach Diploptera punctutu [23].…”

Long‐term effects of diet on the neuroendocrine system of the sheep blowfly, Lucilia sericata

“…In common with other insect species, it seems certain that morphometric changes in the MNC and CA of L.sericata indicate the synthesis and/or release of hormones (Applin, 1979;Schooneveld et al, 1977;Weaver & Pratt, 1977;Johnson & Hill, 1975;Steel & Morris, 1975;Engelmann, 1970;Highnam & Mordue, 1970). Employment of light-microscopic methods t o measure changes in the oogenesis neuroendocrine system is convenient but the data require careful interpretation.…”

Activity of the corpora allata of adult female Leucophaea maderae: Effects of mating and feeding

“…JH synthesis by virgin females shows a peak on day 9 as in mated females, but it is fivefold smaller. In P. americuna and B. germanica, mating leads to an increase in JH synthesis and the maintenance of a cyclic activity of the CA promotes a rapid succession of gonotrophic cycles [20,18]. In S. longipalpa, mating does not lead to an increase in JH synthesis but only to an acceleration of the gonotrophic cycles [12].…”