PROTOGYNY IN DIAMONDBACK MOTH, PLUTELLA-X YLOSTELLA (LEPIDOPTERA, YPONOMEUTIDAE)

This study was carried out to clarify protogyny in the Diamondback Mot h, Plutella xylostella. Pupae were collected from cabbage fields in Mi yazaki, southern Japan, from 23 January to 7 July 1990. They were kept in chambers controlled at 20 degrees C, 14L-10D, to measure the numbe r of days until adult emergence (NDAE). The NDAE ranged from 1 to 8 da ys. Median NDAE in females were 1 or 2 days shorter than in males. Fem ales always developed faster than males in rearing experiments at thre e constant temperatures and two fluctuating ambient temperatures. The results suggest the occurrence of seasonal protogyny in the Diamondbac k Moth. The significance of protogyny is discussed.