Mating, Longevity, Fecundity, and Egg Fertility of Chilo partellus (Lepidoptera: Pyralidae): Effects of Delayed or Successive Matings and Their Relevance to Pheromonal Control Methods

Abstract

Male and female Chilo partellus (Swinhoe) were paired on days 0–7 after eclosion to determine the effect of aging on mating ability, and the effects of delayed mating on longevity, preoviposition and oviposition periods, fecundity, and egg fertility. When the moths were of equal age, 58% mated on the night of eclosion, 80–85% 1–2 d after, and then significantly fewer. Mating ability of the males remained high for 5 d and then declined significantly, whereas in females it decreased progressively starting 2 d after eclosion. Female longevity and the preoviposition period both increased with increasing age at mating, but the oviposition period decreased in late-mated females. Mean fecundity and egg fertility of females mated 1 and 4 d after eclosion were 538.2 and 91% and 345.4 and 51%, respectively. Both were reduced significantly when mating was delayed beyond 4 dafter eclosion. A 4-d delay in mating could cause a 67% reduction in viable egg production. Given the opportunity, males copulated an average of 4.6 times, while females usually mated once. The spermatophores transferred during the first six matings by the male were equally effective in producing fertile eggs. These observations suggest that mass trapping of males using pheromone traps as a control method for C. partellus would not be feasible. However, delaying and disrupting mating by permeating the field with female sex pheromone would be a more effective behavioral control strategy.