Larval Diapause Inheritance Mode in Two Ecotypes of the Yellow-Spotted Longicorn Beetle, Psacothea hilaris(PASCOE)(Coleoptera:Cerambycidae)

Abstract

The yellow-spotted longicorn beetle, Psacothea hilaris, a serious pest of fig and mulberry trees in Japan, has two ecotypes in Honshu. The eastern type (E) does not diapause while the western type (W) enters a larval diapause under short-day conditions. These two ecotypes, which have been maintained for more than 10 generations in our laboratory, were crossed reciprocally. When reared at 25°C under dark (24D) conditions, most larval progeny from E(female)×W(male) and female progeny from W(female)×E(male) pupated within 100 d after hatching. The majority of male progeny from W(female)×E(male) did not pupate within the 100 d period. These results suggest that a recessive gene located on the X-chromosome is the main determinant of diapausal response to short-day conditions, and that other genes on the autosome also control diapause. Sex-controlled inheritance was also noted in the diapausal response and in the stripe patterns on the pronotum. The possible mechanisms of the rapid spreading of the ecotypes with sex-linked diapause is discussed.