Supernumerary instars produced by chilled wax moth larvae: Endocrine mechanisms

20-hydroxyecdysone and juvenile hormone analog prevent precocious metamorphosis in recessive trimolter mutants of Bombyx mori

“…In most, though not in all insects, the number of larval molts varies under the influence of environmental conditions (Wigglesworth, 1972;Kingsolver, 2007). It has been ascertained that temperature, light, and nutritional conditions can change the manifestation of molting (Nijhout, 1975;Pipa, 1976;Kingsolver, 2007). B. mori normally has five larval instars with developmental commitment to metamorphosis occurring early in the 5th (final) instar.…”

Monitoring of rice weevil, Sitophilus oryzae, feeding behavior in maize seeds and the occurence of supernumerary molts in low humidity conditions

“…Manduca sexta (L.) larvae kept without food for the first three days of the last instar undergo a supernumerary larval molt (Bhaskaran & Jones, 1980). In Galleria mellonella (L.), exposure of freshly ecdysed last instar larvae to 0 C for at least 30 min resulted in a supernumerary larval molt (Pipa, 1976). Our results with rice weevil immatures suggest that supernumerary molts are associated with low humidity conditions.…”

“…The novel finding of a supernumerary molt contradicts the current view that the rice weevil has only four instars (Longstaff, 1981). In other insect species, supernumerary molts are known to occur under adverse conditions (Bhaskaran & Jones, 1980;Pipa, 1976;Seaman & Woodruff, 1939). Blattella germanica (L.) nymphs amputated between the trochanter and femur often display a supernumerary molt (Seaman & Woodruff, 1939).…”

Chilled Galleria mellonella larvae: mechanism of supernumerary moulting

“…Among the various environmental factors influencing the growth and development of wax moth larvae, both photoperiod (Kryspin et al, 1974) and temperature (Bogus & Cymborowski, 1977) play important roles. Chilling stress applied to Galleria mellonella L. (Lepidoptera) has been shown to have profound consequences for development in that even short exposure of last instar larvae to cold (OOC) causes supernumerary moults (Cymborowski & Bogus, 1976;Pipa, 1976). Similar results can be obtained after corpora allata (CA) implantation or topical application of juvenile hormone (JH) or its mimics (Sehnal, 197 1 ;Sehnal & Schneiderman, 1973 ;Pipa, 1976).…”

“…Chilling stress applied to Galleria mellonella L. (Lepidoptera) has been shown to have profound consequences for development in that even short exposure of last instar larvae to cold (OOC) causes supernumerary moults (Cymborowski & Bogus, 1976;Pipa, 1976). Similar results can be obtained after corpora allata (CA) implantation or topical application of juvenile hormone (JH) or its mimics (Sehnal, 197 1 ;Sehnal & Schneiderman, 1973 ;Pipa, 1976). This suggests that chilling stress has a juvenilizing effect on final instar Galleria larvae.…”