In vitro and in vivo effects of myo‐active peptides on larvae of the tomato moth Lacanobia oleracea and the cotton leaf worm Spodoptera littoralis (Lepidoptera; Noctuidae)

Abstract

Neuropeptides from five different neuropeptide families [Manduca sexta allatostatin (Manse-AS), and Manse-AS deletion analogue(5-15), M. sexta allatotropin (Manse-AT), leucomyosuppressin, perisulfakinin, and myoinhibitory peptide I (MIP I)] were assayed for their ability to affect the development and food consumption of penultimate and last larval instars of two lepidopteran species, L. oleracea and S. littoralis. Injections of Manse-AS deletion analogue(5-15), Manse-AT, perisulfakinin, and MIP I had no observable effects on development, food consumption, or mortality compared to controls. Single injections of Manse-AS significantly reduced the weight gain and increased mortality of L. oleracea and S. littoralis larvae compared to controls. By contrast, feeding Manse-AS to L. oleracea had no such effects. These differences were probably due to the degradation of the peptide by digestive enzymes in the foregut of L. oleracea. In studies in vitro, perisulfakinin, and MIP I had no effect on the spontaneous foregut contractions of L. oleracea larvae. Leucomyosuppressin, however, had myoinhibitory effects on the foregut. Single injections of leucomyosuppressin significantly reduced the weight gain and food consumption of L. oleracea and S. littoralis larvae and increased mortality. These data suggest that the deleterious effects observed in vivo were due to the myoinhibition by Manse-AS and leucomyosuppressin of the normal peristaltic movements of the gut either by the intact peptide or by its cleavage products resulting from degradation in the haemolymph.

Control of the release of digestive enzymes in the larvae of the fall armyworm, Spodoptera frugiperda

“…Interestingly, in almost all other Lepidoptera larvae an in vitro contraction of the foregut is seen. However, in S. littoralis (Matthews et al, 2008) and S. frugiperda (current study), foregut motility is not observed. Therefore, in the current study the ilium was employed to assay myoactivity.…”

Allatostatin A-like immunoreactivity in the nervous system and gut of the larval midge, Chironomus riparius (Meigen): Modulation of hindgut motility, rectal K+ transport and implications for exposure to salinity

“…In particular, the ASTs have been shown to inhibit contractions of visceral muscle including the foregut and hindgut (Lange et al, 1993;Sarkar et al, 2003;Predel et al, 2001;Matthews et al, 2008), and have been localized to endocrine cells of the gut (Veenstra et al, 1995;Veenstra, 2009;Reichwald et al, 1994;Robertson and Lange, 2010), suggesting that they may have a role in feeding and digestion. In the cockroach, ASTs have been shown to decrease food consumption (Aguilar et al, 2003).…”

Effects of Manduca sexta allatostatin and an analogue on the peach‐potato aphid Myzus persicae (hemiptera: aphididae) and degradation by enzymes in the aphid gut

“…([M1H] contractions in the foregut of larval Lepidoptera are inhibited by Manse-AS (Duve et al, 2000;Audsley et al, 2001;Matthews et al, 2006Matthews et al, , 2007, and injection of Manse-AS into Lacanobia oleracea L. and Spodoptera littoralis (Boisduval) larvae reduced feeding, growth, and survival. It was proposed that the effects of Manse-AS in vivo were probably due to the inhibitory actions of the peptide on foregut peristalsis, preventing the movement of food through the alimentary canal, resulting in suppression of feeding activity (Matthews et al, 2008). It is possible that both Manse-AS and dR 3 dR 5 Manse-AS act in a similar manner when fed to aphids.…”

“…Despite the ability of Manse-AS to adversely affect lepidopteran and aphid pest species, its potential as an insect control agent may be hindered because of its susceptibility to gut enzymes. Although Manse-AS is active when fed to aphids, feeding this peptide to larvae of L. oleracea had no effect, most likely due to degradation by digestive enzymes Effects of Manse-AS and an Analogue on M. persicae in the foregut (Matthews et al, 2008). Foregut extract from L. oleracea has been shown to rapidly degrade Manse-AS, with a half-life of approximately 5 min (Audsley et al, 2002a).…”

“…In addition, the potential use of Manse-AS in the suppression of feeding in two species of larval Lepidoptera was demonstrated by injection of the peptide, resulting in reduced growth and increased mortality. However, when the peptide was fed to the larvae of these species there was no effect, probably due to the degradation of the peptide by digestive enzymes in the foregut (Matthews et al, 2008).…”