Effect on female remating behaviour of post-teneral treatment to improve sterile male mating competitiveness.

ABRAHAM, S.; LIENDO, M.C.; DEVESCOVI, F.; SEGURA, D. F.; CLADERA, J. L.; WILLINK, E.; VERA, M. T.

Pereybere, Isla Mauritius

Workshop; Final RCM on Improving Sterile Male Performance in Fruit flies SIT; 2009

IAEA

Quality related traits of the male can affect female sexual receptivity after a first mating. Under an SIT scenario, females exhibiting a high remating rate or a short refractory period may have greater chances to find and copulate with a fertile male than females that mate just once. Although a lot of studies have been undertaken to develop post-teneral treatments (hormonal (JH) and/or nutritional supplements) that improve male mating competitiveness, the impact of these treatments on female remating behaviour has been relatively neglected addressed. Here we evaluated the remating rate, the refractory period and the amount of sperm stored in Anastrepha fraterculus females mated with males that received different post-teneral treatments both under laboratory and field cage conditions. Under laboratory conditions, we evaluated four types of males according to the adult diet they were provided: (1) sugar (2) low quality protein (sugar and brewer´s yeast, 3:1) (3) high quality protein (sugar and MP Biomedical® hydrolyzed yeast (MP), 3:1) (4) standard adult diet (sugar, MP, hydrolyzed corn and vitamins). Both laboratory and wild flies were evaluated; but for wild males treatment (3) was not included. Under field cage conditions, we evaluated laboratory sterile males that received one of the following six treatments involving different diets and hormone supplements: (1) 6 days-old males, dipped as pupae in JH and fed on a 12: 1 diet (sugar: MP). (2) 10 days-old males (without JH treatment) fed with standard adult diet and desiccated peaches. (3) 6 days-old males topically treated as adults with JH, fed with 12:1 diet (sugar:MP) (4) 6 days-old males dipped in JH, fed with sugar only (5) 6 days-old males dipped in JH, fed with 3:1 diet (sugar:brewer´s yeast) (6) 6 days-old males dipped in JH, fed with a 3:1 diet (sugar:MP). Wild females were offered the different males and as control we used wild sexually mature males fed with the standard adult diet and desiccated peaches. In all cases, after the first copulation a set of females was used to determine female remating rate and refractory period, and another set was dissected for sperm count. Under laboratory conditions, wild females mated with males that were fed only sugar presented a higher remating rate and a shorter refractory period than those mated with males that received the standard diet. The amount of sperm stored in females mated with sugar or low quality protein fed males was significantly lower than that stored in females that mated with males fed with the standard diet. Laboratory females also showed a lower refractory period when mated with males fed with sugar compared to females mated with males fed with protein irrespective of its quality. However, both remating rate and amount of sperm stored was not affected by the diet the male received. Under field cage conditions, remating rate and amount of sperm stored were not affected by the treatments but the refractory period was affected. Females mated with males that received topical application of JH remated sooner than the control, whereas the other treatments were equal to the control. It was also found that JH dipping treatment had no adverse impact on female remating behaviour. Our results showed that post-teneral treatments that enhance mating competitiveness also modulate female remating behaviour, specially nutritional supplements. The fact that this was evident mainly for wild flies may indicate that laboratory flies received in their larval stage, sufficient proteins that can overcome possible deficits at the adult stage. Even when A. fraterculus females showed high remating rate (in most cases higher than 50%), the refractory periods were in general longer than 10 days. In nature, this period of time is probably too long and the proportion of survivals is expected to be low. If we consider that it is possible to treat the males in order to decrease remating rate, enlarge the refractory period, and ensure an important amount of sperm being transferred, it can be proposed that for the SIT the occurrence of remating in this species is negligible.