Effects of body pigmentation mutations on Drosophila melanogaster mating behavior

The model of congenic strains of Drosophila melanogaster was used to investigate the peculiarities of the effect of mutations in yellow (y), ebony (e), and black (b) genes involved in biogenesis of cuticle pigments on imago mating behavior indicators. The aim of this study was to find out if the effect of the given mutations on Drosophila imago mating behavior depends on the general genetic background on which they are realized. To achieve this goal, pairs of congenic strains were constructed using successive saturation crosses followed by selection for the marker phenotype resulted in each of the mutant alleles introduced in homozygous condition into the genotype of either Canton-S or Oregon-R wild-type stock instead of the corresponding wild-type allele present in these stocks initially. Individuals of strains resulted were tested for mating receptivity of females and mating activity of males. Each of the indicators was evaluated as a proportion of sexually mature but virgin individuals of a particular sex copulated successfully within the first hour after placing them in a test chamber with an excess of individuals of the opposite sex. According to the data obtained and the results of their statistical analysis, it was proved that the introduction of a mutation into the genetic background of the wild-type stock is accompanied with a change in the studied characteristics of imago mating behavior. The effect depends on the mutation introduced and on the genotype of the recipient stock. Thus, males of the yC-S strain are characterized by increased mating activity comparatively to males of the wild-type Canton-S stock. These results expand the known effects of yellow mutation. Males of the bC-S and eC-S strains, on the contrary, are less active than the males of the wild-type Canton-S stock. The most pronounced effects on mating receptivity of females were fixed for b (an increase in the indicator when introduced into Oregon genetic background) and e (a decrease when introduced into Canton-S genetic background) mutations. The indicators studied under the conditions of the given experimental scheme change in direct proportion (rS = 0,76; p < 0,05). In other words, if the strain is characterized by high mating activity of males, as a rule, a high mating receptivity of females will be also observed.

Behavioural induction of unreceptivity to mating from a post-copulatory display in the red mason bee, Osmia bicornis

In monandrous species, females have to manage their mating receptivity not only to gather an appropriate sperm supply, but to avoid further male sexual harassment as well. The shutdown of female receptivity to mating is often an irreversible process and therefore should result from a reliable signal. Females of the red mason bee, Osmia bicornis (syn. O. rufa), mate only once within the first day after their emergence from the maternal nest. The unreceptivity to mating of a mated female is induced by a male post-copulatory display, which takes place for about 10 min after ejaculating. During this display the male obviously applies an anti-aphrodisiac that reduces female’s attractiveness resulting in protection from other rival male sexual harassment. Protection by odour is only temporarily needed because females eventually reduce their attractiveness and receptivity to mating by themselves within a few days after emergence. The autonomous decrease in virgin female’s receptivity to mating is simply age driven and independent from mating status. In summary, the involvement of ejaculate substances in causing a loss of female receptivity to mating can be excluded for this species.