Behavioural and Physiological Evidence of Monandry in the Tomato Fruit Borer, Neoleucinodes elegantalis (Guen.) (Lepidoptera: Pyralidae)

ABSTRACT

Despite the benefits of multiple mating to females, many moths appear to be monandrous. A curious case involves the tomato fruit borer, Neoleucinodes elegantalis (Guenée); this species is supposedly monogamous particularly due to its short adult lifespan. However, N. elegantalis males can engage in a second courtship and copulate 1 day after their first mating. Based on these observations, we hypothesized that N. elegantalis is monandrous rather than monogamous, as previously suggested. We tested this hypothesis by determining whether (1) altered sex ratios affect mating frequency and (2) whether repeated mating opportunities impose a longevity cost on males while assessing the occurrence of female remating. Our results showed that (i) increasing the number of males did not increase the propensity of females to remate; (ii) males that copulated only once lived longer than those that copulated twice; and (iii) only four of the 96 females accepted a second mating opportunity despite repeated exposure to virgin males. Because only four females remated, the effects of multiple mating on female longevity and fecundity could not be evaluated robustly. These findings support the conclusion that N. elegantalis exhibits a predominantly monandrous mating system.