Sexuals of the Aphid Dermaphis autumna (Hemiptera)

Abstract

The aphid Dermaphis autumna (Monzen) (Hormaphidinae: Nipponaphidini) forms small cone-shaped galls on leaves of the evergreen Distylium racemosum in Japan. Alates emerging from the galls are sexuparae and produce sexuals on the host tree from early winter onwards. Unlike those of other nipponaphidines, the adult male of the species has a bizarre knob-like protrusion on the frons. Our laboratory experiments revealed that the male uses the knob-like protrusion to push a rival male off on the back of a female. It was also shown that first-instar males of Dermaphis autumna develop into the adult stage after two molts without taking food, and that first-instar females have long stylets accompanied by a long flagelliform labrum and feed on twigs of the host tree to mature into adults. The adults and first-instar nymphs of both sexes are described.