Factors affecting fecundity of diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae)

Diamondback moth, Plutella xylostella, pupae were collected from fields in March, August, and December 1988, and in May and July 1990 in Miyazaki, southern Japan. The number of eggs laid per day per female (NEDF) which emerged from the collected pupae was measured in chambers (20°C, 14L 10D) and meteorological screen boxes. Age-specific fecundity curves were analyzed based on mating age. The highest NEDF was observed on the mating day or next day. (Means were from 93.4 to 125 for the March population.) The fecundities of females mating successfully within 48h after emergence were 480.6 (March), 374.4 (May), 277.3 (July), 263.2 (August), and 478.8 (December), when the females were supplied with 2% sugar solution. The fecundities decreased by 60% to 70% when females were supplied only with water. Fluctuating ambient temperature in the warmer seasons of May and July had no effect on fecundity. In winter (December), oviposition lasted for about 1 month, although it was frequently suppressed by low temperature. The fecundity of females in the meteorological screenbox in winter was smaller than at a constant temperature of 20°C, suggesting that fluctuating winter ambient temperature lowers fecundity in the diamondback moth.