Experimental Crossing of Aedes (S.) Polynesiensis Marks and A. Scutellaris Malayensis Colless (Diptera: Culicidae)

Publisher Website
Google Scholar
Abstract
The Aedes (S.) scutellaris subgroup is comprised of many species and possible subspecific populations distributed throughout a vast area of the South and Central Pacific and southeastern Asia. The genetic relationships of most of these populations are unknown, as experimental cross breeding has been carried out with relatively few of them. This paper presents the results of such studies with Aedes scutellaris malayensis and 3 populations of A. polynesiensis (from Samoa, Tahiti, and Taiaro). The opposite sexesof the 2 specieswere attracted to one another in precopulatory mating activity. In mating choice experiments, the females were inseminated more readily by their own males than by males of the opposite species; however, under proper conditions and when no choice was possible, A. polynesiensis females were inseminated about as frequently by A. s. maloyensis males as were A. s. malayensis females. There was no hatching of any of the eggs produced by the cross-inseminated females of all 3 strains of A. polynesiensis. Cross-insemination of A. s. malayensis females by Tahiti and Taiaro A. polynesiensis males occurred readily, but eggs laid by these females did not hatch. In contrast, although a relatively small proportion of A. s. malayensis females were inseminated by Samoan A. polynesiensis males, these females produced viable eggs, and most of the F1 larvae were reared to the adult stage. It was not possible to obtain an F2 generation by inbreeding the F1 hybrids. Only a few of the F2 eggs hatched. Backcrossing of F1 (M♀ × P♂) hybrids to A. polynesiensis and A. s. malayensis females was unsuccessful. However, backcrossing of the F1 females to A. s. malayensis males was possible, and beginning with this 1st generation of backcross progeny, 2 lines of successivebackcrosses were carried out, one to A. s. malayensis males and the other to A. s. malayensis females. As these progressed, there was an increase in viable egg production, and by the 5th backcross, viable egg production exceeded that of control A. s. malayensis females. Also, inbreeding of the 3rd and 4th backcross generations was successful. There was no hatching of eggs from A. polynesiensis females inseminated by males of the 3rd and 4th backcross generations. Conversely, the females of these generations were able to produce viable eggs after insemination by A. polynesiensis males. It is concluded that A. s. malayensis and A. polynesiensis are specifically distinct. However, introgressive hybridization is possible between some, although not all of the populations belonging to these species. If this is true of species which occur at the extreme eastern and western areas of the A. scutellaris subgroup range, it seems possible that hybrid populations exist in nature and that some of the recognized species are polytypic.

This publication has 0 references indexed in Scilit: