Gravimetric Method for the Measurement of Sugar Consumption by Adult Velvetbean Caterpillar (Lepidoptera: Noctuidae)

Abstract

Determination of food consumption by adult Lepidoptera, especially noctuid species, has not been well studied, possibly because of a lack of appropriate methodology. In order to measure sugar consumption by velvetbean caterpillar, Anticarsia gemmatalis Hubner, a gravimetric method was developed and is presented here together with results obtained using this method. After 24-h exposure to a moth, liquid consumption by the moth was determined by weighing the remaining solution on an electronic balance. The amount of solution consumed was calculated by converting the difference between the weight of the remaining solution and that of the unfed control to a volumetric value. Velvetbean caterpillar moths consumed a significantly greater volume of solution at lower sugar concentrations than at higher concentrations. Female moths from larvae reared on soybean foliage in field cages consumed three times that of moths from larvae reared on artificial diet in the laboratory. This method was simple, accurate, and required minimum handling of test insects. It was suitable for the measurement of food consumption of velvetbean caterpillar moths and could also be suitable for other lepidopteran species.