Female receptivity modulation in Anastrepha fraterculus: the role of sperm and male accessory glands products.

ABRAHAM SOLANA; WILLINK EDUARDO; CLADERA, JORGE; VERA MARIA TERESA

Valencia

Simposio; 8th International Symposium on Fruit Flies of Economic Importance; 2010

Background: Renewal of receptivity in females may reduce reproductive success of the first male. It is expected that males develop ways to manipulate female receptivity and avoid mixture of rival's sperm. In several fruit flies, at least two mechanisms were examined: sperm effect and male accessory glands products (AGPs) effect. Here we evaluated the role of sperm and AGPs in the renewal of A. fraterculus female receptivity and how this was affected by the diet the male was provided and male origin. Methods: First, females were mated with males fed either sugar, low quality protein (3:1 sugar:protein ratio), high quality protein (same ratio) and the standard adult diet (sugar, protein, vitamins and corn hydrolyze). Wild and laboratory flies were evaluated. After the first copulation, different sets of females were used to determine female remating rate, refractory period, and sperm stored. Second, we evaluated the receptivity of females microinjected with AGPs in two set of trials. In the first, laboratory females were injected with AGPs of laboratory males fed either with sugar or the standard diet. In the second, laboratory and wild females were injected with AGPs of laboratory and wild males, all of them fed with standard diet. Female receptivity was evaluated 48 h after injection and the control were females injected only with saline. Differences in the frequency of remating females among treatments were compared with c2-tests with Bonferroni correction. Refractory period and amount of sperm stored were analysed with ANOVA coupled with Tuckey test. Results: Wild females mated with sugar males presented a higher remating rate and a shorter refractory period than those mated with standard diet males. Amount of sperm stored in females mated with sugar or low quality protein males was significantly lower than that stored in females that mated with standard diet males. Laboratory females also showed a lower refractory period when mated with sugar males compared to females mated with protein males irrespective of the protein quality. However, remating rate and amount of sperm stored was not affected by the diet. Additionally, females injected with AGPs of laboratory standard diet males had lower receptivity than females injected with AGPs of laboratory sugar males, which in turn were equal to control females. Females injected with AGPs from laboratory males had lower receptivity than females injected with AGPs from wild males (which were equal to the control), irrespective of female origin. Conclusions: Male nutritional status and origin affects female renewal of the receptivity. In wild flies this seems to be related with the sperm stored in the female. However in laboratory flies, the sperm effect seems to be not the only responsible of modulating these changes. Male nutritional status and origin also affected female receptivity trough an AGPs effect. The later may be related to the crowded conditions under laboratory rearing where laboratory males may need to increase the effectiveness of their AGPs to ensure its paternity.