Asymmetric Mating Interference between Two Related Mosquito Species: Aedes (Stegomyia) albopictus and Aedes (Stegomyia) cretinus

Abstract

Aedes (Stegomyia) albopictus (Skuse) and Aedes (Stegomyia) cretinus Edwards are closely related mosquito species with common morphological features and bio-ecological similarities. Recent mosquito surveillance in Athens, Greece, showed that they are sympatric mosquito species, with Ae. albopictus [corrected] developing quite higher population densities than Ae. cretinus [corrected] . The potential of mating interference between these species was investigated by reciprocal and homologous mating experiments in cages under laboratory conditions. In non-choice interspecific crosses (groups of males and females) females of both species produced sterile eggs. Insemination rate was 58% for Ae. cretinus females and only 1% for Ae. albopictus [corrected] females. Aedes albopictus males were sexually aggressive and inseminated Ae. cretinus females (31%) in choice experiments, where males of one species had access to mate with females of both species. Whereas, interspecific mating of Ae. albopictus [corrected] females with Ae. cretinus males in the co-occurrence of Ae. cretinus females was weaker (4%). Aedes cretinus females from non-choice crossing with Ae. albopictus [corrected] or Ae. cretinus males were paired individually with conspecific males. The percentage of fertile Ae. cretinus females was 17.5% when had encaged before with Ae. albopictus [corrected] males, compared to 100% when Ae. cretinus [corrected] females were encaged with conspecific males only. Probable ecological consequences of asymmetric mating between these ecologically homologous species in nature are discussed.

Fig 1. Percentage (%) of inseminated females after intra- and inter- specific crosses of 20 virgin Ae. albopictus and Ae. cretinus males and females.

*Percentages in a column followed by different letter are significantly different (P< 0.05), 95% Wald Confidence Interval. ** “albo” = Aedes albopictus, “cre” = Aedes cretinus.

Fig 2. Percentage (%) of inseminated females after choice crosses of 20 virgin males of Ae. albopictus or Ae. cretinus with 20 Ae. albopictus and 20 Ae. cretinus virgin females.

*Percentages in a column followed by different small or capital letter are significantly different (P< 0.05, McNemar test for related samples). ** “albo” = Aedes albopictus, “cre” = Aedes cretinus.