Demonstration of resistance to satyrization behavior in Aedes aegypti from La Réunion island

Abstract

Aedes aegypti and Aedes albopictus are competent vectors of arboviruses such as dengue and chikungunya viruses which co-exist in some areas, including La Réunion island, Indian Ocean. A type of reproductive interference called satyrization has been described in sympatric species where dominant species mating fails to produce hybrids and thus reduces the fitness and tends to control the spread of the other species. Here, we investigated satyrization in laboratory experiments to provide insights on the potential impact on Ae. aegypti of a control campaign including a sterile insect technique component against Ae. albopictus. Different mating crosses were used to test sympatric, conspecific-interspecific and allopatric effects of irradiated and non-irradiated male Ae. albopictus on female Ae. aegypti, including in a situation of skewed male ratio. Our results suggest that there was only a low level of satyrization between sympatric populations of Ae. aegypti and Ae. albopictus colonized from La Réunion island. A male Ae. albopictus to female Ae. aegypti ratio of 3:1 did not increase the level of satyrization. Female Ae. aegypti previously mated to male Ae. albopictus were not prevented from being inseminated by conspecific males. A satyrization effect was not seen between allopatric Ae. albopictus and Ae. aegypti strains from La Réunion Island either. The tested Ae. aegypti strain from La Réunion island has therefore developed full resistance to satyrization and so releasing sterile male Ae. albopictus may not suppress Ae. aegypti populations if an overflooding of irradiated male Ae. albopictus leads to similar results. The management strategy of two competent species in a sympatric area is discussed.

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

“…aegypti females have autogenous activity [28] as observed in one cage of controls. Our results agree with those of Harper and Paulson [29] and Maiga et al [24] who demonstrated that the mating of Ae. aegypti and Ae.…”

“…Although such a reduced egg hatch rate might presumably reflect the cost of satyrisation, no such changes were observed in our study. Consistent with a recent study reported by Maiga et al [24], this suggests that in our conditions, even if interspecies induction of refractory period occurred, it is very limited and has no impact on the final product of mating: the quantity of offspring. Despite this, in the context of SIT that involve the inundative release of sterile males to selectively control the target species, future research under natural conditions should aim at gaining a quantitative understanding of the potential impact of an increased heterospecific mating rate following sterile male release on the dynamics of coexisting Aedes species and subspecies (if any).…”

“…albopictus and Ae. aegypti females, as observed by Carrasquilla and Lounibos [17] and Maiga et al [24]. The presence of semen in bursa inseminalis but not in spermatheca supports the suggestion of Vick [25] that the transfer of male accessory gland material could occur independently of sperm transfer in spermatheca.…”

“…albopictus are known to have low levels of autogeny (see review in [26]) which could explain the presence of eggs in heterospecific cages and the absence in control ones. Maiga et al [24] also observed a low number of eggs after the same heterospecific matings with no presence of sperm observed in the spermatheca. However, this egg-laying could be from a female that has stored a very small amount of sperm that was not observed in the DAPI coloring experiment.…”

Assessment of a Novel Adult Mass-Rearing Cage for Aedes albopictus (Skuse) and Anopheles arabiensis (Patton)

“…A feasibility assessment of an area-wide integrated pest management (AW-IPM) program with an SIT component against Ae. albopictus is also ongoing on La Réunion island [ 20 , 21 ] and in Mauritius [ 22 ]. Moreover, the invasion of Europe by this species has triggered the development of a vector control management plan [ 23 ], and several countries, including Albania, Greece, Germany, Montenegro, and Spain, have initiated pilot trial releases of sterile males against Ae.…”