Could Sterile Aedes albopictus Male Releases Interfere with Aedes aegypti Population in Reunion Island?

Abstract

Simple SummaryThe Sterile Insect Technique consisting of inundative and repeated releases of sterile males that induce sterility in the wild population is currently tested as a new strategy to control Ae. albopictus. Considering that Ae. albopictus and Ae. aegypti thrive in sympatry in some regions, and that mating between both species is known to occur at low rates, we hypothesize that releasing millions of sterile male Ae. albopictus in could affect female Ae. aegypti reproduction. To study this potential mating interference, the newly established marking technique has been applied using the rhodamine B that is administered to males through sugar meal. It is internally incorporated into the mosquito’s male body and during mating, the rhodamine is transferred into the females. In laboratory-based experiments rhodamine marking proved to be a powerful means of detecting mating in females of both Aedes species, whatever the mating crosses between males and females. Some mated females were able to lay eggs, but all were not viable. However, despite the promiscuity of the adults in small experimental cages, 95% of the female Ae aegypti showed no evidence of insemination following mating with sterile male Ae. albopictus, suggesting that in the field, an inundative and repeated releases of sterile male Ae. albopictus will not influence the reproduction of female Ae aegypti.In Reunion Island, the feasibility of an Aedes albopictus control program using the Sterile Insect Technique (SIT) is studied. Because, in some regions, Ae. albopictus is living in sympatry with Aedes aegypti, the impact of releasing millions of sterile male Ae. albopictus on female Ae. aegypti reproduction needs to be assessed. Thus, to study the potential heterospecific matings, a marking technique using rhodamine B has been used. Rhodamine is given in solution to male mosquitoes to be incorporated into the male body and seminal fluid and transferred during mating into the bursa inseminalis and spermathecae of females. The presence of rhodamine in females occurred in 15% of cases when Ae. aegypti females were offered non-irradiated Ae. albopictus males, 5% when offered irradiated Ae. albopictus males and 18% of cases in the inverse heterospecific matings. Moreover, our results also showed that these matings gave few eggs but were not viable. Finally, the results showed that whatever the type of mating crosses, females in cages previously crossed with males of another species can re-mate with males of their species and produce an equivalent amount of egg compared to females only mated with conspecific males. Despite the promiscuity of the males and females in small cages for three days, heterospecific mating between sterile male Ae. albopictus and female Ae aegypti, 95% of the females have not been inseminated suggesting that in the field the frequency satyrization would be very low.