MATING-BEHAVIOR AND REPRODUCTIVE POTENTIAL IN THE TURNIP MOTH AGROTIS-SEGETUM (LEPIDOPTERA, NOCTUIDAE)

We investigated the lifetime mating potential and the reproductive beh avior of male and female turnip moths Agrotis segetum (Schiff.) under field and laboratory conditions, The sex ratio was 1:1 in a lab-reared population as well as in two wild populations. Males were capable of mating repetitively a relatively large number of rimes (mean of 6.7 +/ - 2.7 matings) when given access to new virgin females throughout thei r lifetimes. Females seldom mated more than once (mean +/- 1.3 +/- 0.6 matings), indicating a male-biased operational sex ratio. The mean po tential lifetime mating was Jive times higher in males, while the coef ficient of variance was lower in males. There was no differences in lo ngevity between animals that were allowed to mate and animals not allo wed to mate, indicating no direct costs or benefits of mating in physi ological terms. In males, the number of matings was positively correla ted with longevity, but this was not the case in females. Nor was ther e a correlation between the number of female matings and the number of fertilized eggs. There was a negative correlation between the number of eggs fertilized and the number of times males had previously mated, indicating that male ejaculates were limited. Male spermatophore size also decreased with number of achieved matings. Laboratory-reared fem ales attracted males in the field throughout their lifetimes, with a p eak at 3-7 days of age. Wild males, allowed to choose between pairs of caged females in the field,,were attracted in equal numbers to female s of different ages. Females did not show any mate-rejection behavior in the field. They mated with the first male that courted them. No inc idence of mate replacement by males arriving later to already courted females were recorded.