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8 th International Symposium on Fruit Flies of Economic Importance. Valencia 2010.
FEMALE RECEPTIVITY MODULATION IN ANASTREPHA FRATERCULUS: THE
ROLE OF SPERM AND MALE ACCESSORY GLANDS PRODUCTS.
Abraham, Solana *1,2 ; Willink, Eduardo 1 , Cladera, Jorge L. 3 & Vera, M. Teresa 1,2
1 Sección Zoología, EEAOC, Tucumán, Argentina; Email: solanaabraham@yahoo.com.ar; 2 CONICET, Argentina;
3 Instituto de Genética, INTA Castelar, Buenos Aires, Argentina.
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
� 2 -tests with Bonferroni’s correction. Refractory period and amount of sperm stored were
analysed with ANOVA coupled with Tuckey’s 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.
Keywords: polyandry, remating inhibition, sperm effect, accessory gland effect, South American fruit fly.