PHYSIOLOGICAL FACTORS REGULATING POLYANDRY IN LOBESIA-BOTRANA (LEPIDOPTERA, TORTRICIDAE)

The effects of several physiological factors related to female multipl e mating in the monandrous Lobesia botrana Denis and Schiffermuller (L epidoptera: Tortricidae) were studied under laboratory conditions. Pol yandry was assessed observing the induction of re-calling in previousl y once-mated females. Female age at first mating had no effect on indu ction of re-calling during practically the whole of the female lifetim e, but in older females it was significantly lower. The percentage of re-calling was negatively correlated with the volume of the spermatoph ore received, ranging from approximate to 23% with the largest spermat ophores to approximate to 75% with the smallest ones. Furthermore, the smaller the spermatophore volume, the earlier the re-calling was indu ced, significantly reducing the female refractory period after the fir st mating. Heavy females showed a significantly higher rate of re-call ing (52.8%) than light ones (37.0%), but no differences were observed when females received only small spermatophores. This finding was expl ained by the allometric relationship between the female weight and the size of its reproductive system that affects relative replenishment b y the spermatophore. Females with a supply of water displayed a signif icantly 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 wit h once-mated females promoted a re-calling rate (and subsequent mating s) close to 37%, significantly higher than that of isolated females (2 0%). It is concluded that re-calling and polyandry in L. botrana are c ontrolled, as expected, by a number of mating-derived stimuli, but als o to a great extent by other physiological stimuli unrelated to mating . The reproductive strategies in relation to polyandry and the mechani sms controlling female sexual inhibition are discussed.