Protogyny in Diamondback Moth, Plutella xylostella (Lepidoptera: Yponomeutidae).

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