Carbohydrates in eggs of the grasshopper, Aulocara elliotti, during development

Abstract

Qualitative and quantitative carbohydrate changes occurring in eggs of the grasshopper species Aulocara elliotti at various stages of development were investigated. Temperature effects were considered. Mannose, glucose, fructose, trehalose, mannitol, and glycerol were identified in 70% ethanolic extracts of eggs using paper and gas-liquid chromatography. Mannose was detected in early prediapause eggs but was not detected in diapause or post-diapause eggs. As mannose levels declined, mannitol accumulated but the quantity of free mannose was not sufficient to serve as the only precursor for mannitol synthesis. Neither trehalose nor glycogen levels declined as mannitol accumulated. Mannitol was temporally associated with diapause. Although mannitol synthesis does not depend on cold exposure, cold might have an elevating effect. Glycerol appeared to be an extremely variable compound, was not associated with diapause, and would not appear to greatly depress freezing points of eggs. There appeared to be slight early and late utilization of glycogen but levels were higher in the definitive egg than in the newly laid egg. Trehalose, which was generally 91±5 per cent of the free neutral sugars in eggs, increased by two- to three-fold during diapause and then declined following blastokinesis.