Abstract

Life-history strategies of insect are controlled by fitness-related trait tradeoffs, in particular, the age at which either one of the two sexes copulate and this demonstrated to influence insect reproductive output and longevity. The banded sunflower moth, Cochylis hospes Walsingham, is one of the most important lepidopteran pests of cultivated sunflower, Helianthus annuus L., in North America. Larvae of C. hospes feed on the head of sunflower, causing extensive damage and a reduction in the number of seeds produced (Royer and Walgenbach, 1987). Individual virgin females of either species, age 1, 2, 3, 4 and 5 days, were placed with a single conspecific virgin male (2–4 days old) in a 20 ml glass vial 3 h prior to the onset of the scotophase, in a room under the same conditions as those of the respective colonies. The percentages of copulations, and percentages of females with spermatophore in their bursa copulatrix, were compared by χ2 analyses; if there were any significant differences, each pair was compared by a χ2 analysis. The distributions of time that copulation started for the different age females and males were compared, respectively, by chi-squared tests. The percentage of female C. hospes that copulated was significantly influenced by female age. Significantly higher proportions of females aged 3 and 5 days old copulated than did females of the other ages. The percentage of female C. hospes that copulated that had spermatophores in their bursa copulatrix was also significantly influenced by female age.