Physiological factors regulating polyandry in Lobesia botrana (Lepidoptera: Tortricidae)

Abstract. The effects of several physiological factors related to female multiple mating in the monandrous Lobesia botrana Denis and Schiffermuller (Lepidoptera: Tortricidae) were studied under laboratory conditions. Polyandry was assessed observing the induction of re-calling in previously once-mated females. Female age at first mating had no effect on induction of re-calling during practically the whole of the female lifetime, but in older females it was significantly lower. The percentage of re-calling was negatively correlated with the volume of the spermatophore received, ranging from ≅ 23% with the largest spermatophores to ≅ 75% with the smallest ones. Furthermore, the smaller the spermatophore volume, the earlier the re-calling was induced, significantly reducing die female refractory period after the first mating. Heavy females showed a significantly higher rate of re-calling (52.8%) than light ones (37.0%), but no differences were observed when females received only small spermatophores. This finding was explained by die allometric relationship between me female weight and the size of its reproductive system that affects relative replenishment by the spermatophore. Females with a supply of water displayed a significantly higher rate of re-calling (41.2%) than control females (22.8%), highlighting the effect of adult feeding (or drinking) status on the re-calling behaviour. The short-distance presence of virgin males with once-mated females promoted a re-calling rate (and subsequent matings) close to 37%, significantly higher than that of isolated females (20%). It is concluded mat re-calling and polyandry in L. botrana are controlled, as expected, by a number of mating-derived stimuli, but also to a great extent by other physiological stimuli unrelated to mating. The reproductive strategies in relation to polyandry and the mechanisms controlling female sexual inhibition are discussed.