Sugar-Feeding Strategy of Adult Velvetbean Caterpillar (Lepidoptera: Noctuidae)

Abstract

Although nectar availability has long been recognized as the major cause of outbreaks of some important lepidopteran pests, basic knowledge on nectar feeding by adults of any single noctuid species is very limited. Understanding of adult feeding behavior also is essential to the development of adult control technology for these pests. This study measured sucrose consumption, using a gravimetric method, and investigated related sugar feeding behavior of adult velvetbean caterpillar, Anticarsia gemmatalis Hubner. Adult females reared in field cages on soybean foliage consumed 3 times as much sucrose solution as females reared in the laboratory on artificial diet. Glucose, fructose, and sucrose were all equally acceptable to velvetbean caterpillar moths. Various concentrations of sucrose solution (1–40%) also were equally acceptable to the moths. However, much greater volumes of sucrose solution were consumed by female moths at lower concentrations than at higher concentrations. When fed with low concentrations (<20%), the moths regurgitated large volumes of excess water through their proboscis. Surprisingly, there was no sugar in the regurgitant although regurgitation occurred soon after or during the process of feeding. When provided with both 30% (wt:vol) sucrose solution and distilled water, lifetime total liquid consumptions by field-reared females and males were 849.3 ± 104.0 (mean ± SE) μ l and 964.0 ± 60.0 μ l, respectively, with no significant differences in consumption between sexes. Both sexes fed heavily in the initial 2 d of their adult lives with the peak consumption on the 1st day after emergence.