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.
Maeno
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K
Laboratroy of Insect Life Cycles and Physiology, Division of Insect and Animal Sciences, NIAS Independent Administrative Institution, Tsukuba, Ibaraki, Japan.
Gotoh
T
T
Tanaka
S
S
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