AGE AND CROWDING AFFECTS THE AMOUNT OF SEX-PHEROMONE AND THE OVIPOSITION RATES OF VIRGIN AND MATED FEMALES OF HELICOVERPA-ZEA (LEPIDOPTERA,NOCTUIDAE)

The quantity of sex pheromone and the egg-deposition rate was recorded for mated and virgin adult females of Helicoverpa zea (Boddie) for 2 wk following eclosion. When a female was mated, the amount of pheromon e in the pheromone gland decreased and remained low. The rate of ovipo sition increased the day after mating, peaked 2 d following mating, an d then gradually declined. This inverse correlation between pheromone quantity and oviposition rate also was seen in aging virgin females. T he amount of sex pheromone present in the glands of virgin females dec reased during the 1st wk after eclosion and then increased during the 2nd wk to about half the amount found in 1-d-old females. Egg depositi on by virgin females held singly increased steadily during adult life. The number of eggs laid when 2, 5, or 10 females were combined into o ne cage was the same, but these groups of females laid 3.5 times more eggs on average per female than single females.