Ovarian development in female armyworm moths, Pseudaletia unipuncta: its relationship with pheromone release activities

Abstract

Following a chronological evaluation of ovarian maturation in virgin females, the temporal relationship between oocyte development and the initiation of calling in Pseudaletia unipuncta (Haw.) (Lepidoptera: Noctuidae) was investigated. One hundred and sixty females were observed daily during the last 2 h of the scotophase for a period of 2–8 days after emergence. Every day, females that called for the first time were sacrificed at lights-on for pheromone titer analysis and oocyte measurements and egg counts. Concurrently, noncallers of the same age were randomly selected and submitted to the same analyses. Although some females started calling and synthesizing pheromone before their oocytes reached maturity (0.59 mm in width), none with basal oocytes smaller than 0.33 mm in width (N = 17) called and only three had detectable pheromone titers (ca. 2 ng). First-time callers on days 2–5 after emergence had greater (i) numbers of mature eggs, (ii) basal oocyte widths, and (iii) pheromone titers than noncallers of the same age, although differences were not always statistically significant. Ovaries of females that initiated calling on days 3–5 were at a similar developmental stage, but were significantly more mature than those of females calling for the first time on day 2.