Glucagon-like and insulin-like hormones of the insect neurosecretory system

Aqueous extracts of corpus cardiacum-corpus allatum complexes of the adult tobacco hornworm Manduca sexta produced both glycogenolysis and hypoglycaemia when injected into the larval form of the same species. Application of specific radioimmuno assays to similar extracts showed also that these gland complexes contain both glucagon-like and insulin-like peptides. Further, the partially purified immunoreactive peptides had the expected biological activities. The former decreased the glycogen content of the fatbody and the latter the circulating trehalose levels in recipient animals. These results suggest the existence of hormones in these invertebrates having both biological and structural similarities to vertebrate insulin and glucagon.

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Effect of aqueous extracts from vermicomposts on attacks by cucumber beetles (Acalymna vittatum) (Fabr.) on cucumbers and tobacco hornworm (Manduca sexta) (L.) on tomatoes

Pedobiologia ◽

10.1016/j.pedobi.2009.08.002 ◽

2010 ◽

Vol 53 (2) ◽

pp. 141-148 ◽

Cited By ~ 24

Author(s):

Clive A. Edwards ◽

Norman Q. Arancon ◽

Marcus Vasko-Bennett ◽

Ahmed Askar ◽

George Keeney

Keyword(s):

Manduca Sexta ◽

Tobacco Hornworm ◽

Aqueous Extracts ◽

Cucumber Beetles

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Correlation between changes in host behaviour and octopamine levels in the tobacco hornworm Manduca sexta parasitized by the gregarious braconid parasitoid wasp Cotesia congregata

Journal of Experimental Biology ◽

10.1242/jeb.200.1.117 ◽

1997 ◽

Vol 200 (1) ◽

pp. 117-127 ◽

Cited By ~ 3

Author(s):

S Adamo ◽

C Linn ◽

N Beckage

Keyword(s):

High Performance Liquid Chromatography ◽

Manduca Sexta ◽

High Performance ◽

Parasitoid Wasp ◽

Tobacco Hornworm ◽

The Body ◽

Larval Form ◽

Cotesia Congregata ◽

Host Behaviour ◽

Increased Activity

The parasitoid wasp Cotesia congregata lays its eggs within the body of its host, the larval form of the tobacco hornworm Manduca sexta. Host behaviour appeared normal until approximately 8 h prior to the emergence of the parasitoids from their host at which time M. sexta feeding and locomotion declined irreversibly. This change in host behaviour may be to the advantage of the wasp since unparasitized M. sexta presented with wasp pupae ate them. Despite the decline in feeding and locomotion, hosts with emerged parasitoids had normal reflexes and showed no other signs of debilitation. Concomitant with the change in host behaviour, octopamine concentration measured using high-performance liquid chromatography with electrochemical detection (HPLC-ED) increased from 22.2±2.1 pg µl-1 to 143.7±7.8 pg µl-1 in the haemolymph of the host. In unparasitized M. sexta, however, increased octopamine levels were correlated with increased activity. We discuss possible explanations for the co-occurrence of high haemolymph octopamine levels and low behavioural arousal in parasitized M. sexta.

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