Johanne DELISLE-1, Jeremy N. McNEIL-2 and
Sheila M. FllZPATRICK-3
1- Natural Resources Canada. CP 3X00. Sainte-Foy. Quebec, Canada,
G 1V 4C7,
2- Department of Biology. Laval University. Sainte-Foy, Quebec
Canada. G1K 7P4.
3- Agriculture Canada Research Station, 6660 NW Marine Drive.
Vancouver. B. C. Canada. V6T 1X2
The effect of two larval diets (a Pinto bean artificial diet and oats), Steered in excess or in restricted quantities. was examined on the pheromone biology of males and females of the true armyworm, Pseudaletia unipuncta. Irrespective of the type of larval food consumed. there were no significant effect on the age at which females initiated calling, the overall calling patterns or the quantity of pheromone produced by large and smad virgin females. However, a marked effect was observed on the production of benzaldehyde in the male hairpencils. Males reared with excess food. regardless of the type, exhibited a typical age-related pattern, with pheromone tithe increasing over the first 48h, remaining stable for several days before declining after 6 days. However, males with limited larval resources produced significantly less benzalhdehyde than controls at all ages. Given that male pheromone plays an important role in female acceptance of mates, one would expect significant differences in the mating success of dffferent-sized males. Using individuals fed on artificial diet, we demonstrated that the smaller males resulting from limited food during larval development, were less successful in acquiring mates than larger individuals although the differences were only significant when males were paired with large females. Furthermore, all larger females initially mated with small mates remated, presumably to compensate for the poor quality of their first mate. These results support the idea that female mate choice may exist in the true armyworm but that its relative importance in the reproductive biology may vary depending on ecological conditions.