Morphology of egg and larva of the semi-looper Autographa nigrisigna (Walker) (Lepidoptera: Noctuidae: Plusiinae)

Abstract

The semi-looper Autographa nigrisigna (Walker) is a polyphagous pest in Plusiinae (Lepidoptera: Noctuidae). However, the egg and larval morphologies have not been studied in detail to date. Here the eggs and larvae of A. nigrisigna were investigated using light and scanning electron microscopy. The egg is domed and is of an upright type, with two or three micropyles at the top and vertical ribs on the chorion. The micropyles are surrounded by a rosette-like pattern of radiating ribs. The eruciform larva possesses three pairs of thoracic legs and three pairs of abdominal prolegs each on A5, A6, and A10, the most remarkable larval character of Plusiinae. The crochets are uniordinal in a mesal penellipse. In chaetotaxy, SV2 is present on abdominal segments I–IV and X, but is absent on other segments. The roles of egg and larval characters in taxonomic and phylogenetic analyses are briefly discussed.