Reappraisal of Proctodone Involvement in the Hormonal Regulation of Larval Diapause

Abstract

1. No evidence was found that the larval ileum of the corn boners, Diatraea grandiosella and Ostrinia nubilalis, secretes a developmental hormone, "proctodone." 2. An abdominal ligature which isolated the ileum of diapause larvae of both species caused high mortality but did not retard the pupation rate. 3. Extracts prepared from the ileal epithelium of mature nondiapause larvae of D. grandiosella were injected into diapause larvae and did not cause premature diapause termination. 4. Marked cytological changes occurred in the ileum at the onset of metamorphosis. At times the ileal epithelium of both species displayed auto and acridine orange-induced fluorescence, characteristic of lysosomes. 5. An electron microscopic examination of the autofluorescent ileal epithelium of D. grandiosella revealed organelles which had typical lysosomal features and stained positively for acid phosphatase activity. 6. The secretory activity of the ileum can be accounted for by lysosomal involvement in its metamorphic reorganization, and by its osmoregulatory functions.

Juvenile Hormone.....in Retrospect and in Prospect

“…Thus, as discussed elsewhere (Nijhout and Williams, 1974b; see also Yagi and Fukaya, 1974;Chippendale and Yin, 1975), the indications are that the CA remain continuously active in diapausing larvae and are shut off only after exposure to the environmental conditions that potentiate escape from diapause. Evidently, in non-diapausing larvae the shutting-off of the CA during the second half of the final ins tar does two things: it allows the brain to secrete PTTH and thereby stimulate the pro thorcic glands and, secondly, it permits the resulting ecdysone to activate the pupal gene-set.…”

Constraints and Opportunities for the Evolution of Metamorphic Organisms in a Changing Climate

“…Diapause is a dormant stage in insects that is equivalent to hibernation in vertebrates. Depending on the species, diapause can occur during different life history stages but metamorphic hormones often play prominent roles in regulating both the entry and duration of diapause (Chippendale and Yin, 1975;Zdarek and Denlinger, 1975;Denlinger, 2008, 2013). Environmental conditions, such as temperatures, can impact metamorphic hormones to influence the timing and duration of diapause (Turnock et al, 1986;Green and Kronforst, 2019;Cambron et al, 2021).…”

Histone deacetylase 3 is required for development and metamorphosis in the red flour beetle, Tribolium castaneum

“…Juvenile hormones secreted by the corpora allata have multiple functions in an insect's life cycle and regulate diverse biological processes, including larval development, molting, metabolism, polyphenism, diapause, reproduction, and metamorphosis [17][18][19][20][21]. The JH signals are transduced through JH receptor, Methoprenetolerant (Met) [22,23], Steroid receptor co-activator (SRC) [24], and CREB-binding protein (CBP) [25][26][27] (binding partners).…”