Circadian variation in metabolite and enzyme activities in the femoral and thoracic muscles of adult variegated grasshoppers, Zonocerus variegatus (Linnaeus, 1758) (Orthoptera: Pyrgomorphidae)

Abstract The African variegated grasshopper, Zonocerus variegatus, exhibits daily variations in its feeding and destructive activities. A study to investigate circadian variation in metabolites (lipids, protein, glucose, K+, Ca2+, Mg2+, Cl−) concentrations and enzymes (lipase, amylase, proteinase, α-glucosidase) activities in the femoral and thoracic muscles of adult Z. variegatus was carried out by collecting samples at 06:00, 12:00, 18:00 and 24:00 hrs GMT. The four enzymes were present throughout the day in both thoracic and femoral muscles but at varying levels. Significantly (p<0.05) higher enzymes activities were measured during the day (between 06:00 and 18:00 hours GMT) (except proteinase) than at night (24:00 hrs). Organic substances in the two tissues were present in significantly higher concentrations during the day than at night. Similarly, significantly more inorganic substances were recorded in the afternoon (12:00-18:00 hrs) than at night in both femoral and thoracic muscles. It can thus be concluded that locomotor activities in Z. variegatus reach a peak during the day.