Phase-related morphological changes induced by [His7]-corazonin in two species of locusts, Schistocerca gregaria and Locusta migratoria (Orthoptera: Acrididae).
The effects of a neurohormone, [His(7)]-corazonin, on phase-related morphological traits (F/C and E/F ratios; F = length of the hind femur, C = maximum width of the head; E = length of fore wing) were re-examined in the desert locust, Schistocerca gregaria Forskål. The F/C ratio was significantly different between adults with five and six nymphal instars, respectively, indicating that they need to be analysed separately. Injections of the synthesized peptide (1 nmol) into individually-reared (solitary) nymphs at the second and third instars caused a shift in classical morphometric ratio towards the value typical for crowded (gregarious) individuals in both sexes. The E/F ratio, which is smaller in solitary locusts than in gregarious ones, was also influenced significantly by injections of [His(7)]-corazonin into individually-reared locusts. The effect of [His(7)]-corazonin on E/F ratios was shown more clearly when the nymphs were injected at a higher dose (2 nmol) at the beginning of the third instar. Single injections of the peptide into individually-reared nymphs at different instars revealed that the earlier the injection the larger the 'gregarizing' effects of the peptide on F/C and E/F ratios. The same tendency was also detected in Locusta migratoria Linnaeus. These results supported the hypothesis that [His(7)]-corazonin plays an important role in the control of phase polymorphism in locusts.
Laboratroy of Insect Life Cycles and Physiology, Division of Insect and Animal Sciences, NIAS Independent Administrative Institution, Tsukuba, Ibaraki, Japan.
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Maeno
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Gotoh
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Tanaka
D000818:Animals; D005121:Extremities / Q000033:anatomy & histology; D005260:Female; D006110:Grasshoppers / Q000033:anatomy & histology* / Q000502:physiology; D006257:Head / Q000033:anatomy & histology; D019476:Insect Proteins / Q000502:physiology; D008297:Male; D009479:Neuropeptides / Q000502:physiology*; D009758:Nymph; D014921:Wings, Animal / Q000033:anatomy & histology
D019476:Insect Proteins; D009479:Neuropeptides; C060602:corazonin protein, insect