Crossing relationships among seven members of the group ofAedes scutellaris(Walker) (Diptera: Culicidae)

Abstract

A rickettsia-free (aposymbiotic) stock of Aedes polynesiensis Marks (POLY-A) was crossed with (a) three symbiont-infected stocks of A. polynesiensis (POLY-S from Samoa and POLY-N and POLY-T from Fiji), (b) A. pseudoscutellaris (Theo.) (PSE) from Fiji, (c) A. alcasidi Huang (ALC), A. scutellaris katherinensis Woodhill (KATH), A. s. malayensis Colless (MAL) and A. s. scutellaris (Wlk.) (SCUT), which occur to the west of Fiji and (d) an aposymbiotic stock of A. cooki Belkin (CO) from Niue. It was bidirectionally compatible with CO, but in all other crosses compatibility was high when POLY-A was the male parent and very low when it was the female parent. Backcross data suggested that the crossing type was maternally inherited. ALC and KATH were bidirectionally compatible; both were virtually incompatible with POLY-S and PSE, compatible with SCUT when the latter was the female parent, and compatible with CO when the latter was the male parent. POLY-S females were moderately compatible with a third Fijian stock of A. polynesiensis (POLY-V), and POLY-N and POLY-V were compatible with PSE. If, as in Culex pipiens L., rickettsia-like symbionts are responsible for cytoplasmic incompatibility, then aposymbiotic males should cross successfully with symbiont-infected females, whereas the reciprocal cross should be unsuccessful. Since PSE, MAL and SCUT contain symbionts, their crossing relationships are consistent with the hypothesis. However, ALC and KATH appear to be aposymbiotic and their crossing relationships conflict with the hypothesis. There is little evidence of behavioural barriers to mating between species, but whereas male hybrids of two eastern species were capable of normal insemination, male hybrids between western and eastern species gave very low insemination rates. The egg-hatch rates from backcrosses of female hybrids between western and eastern species to the parents were reduced.

Population differentiation andWolbachiaphylogeny in mosquitoes of theAedes scutellarisgroup

“…pseudoscutellaris and Ae. polynesiensis are partially compatible in laboratory crosses (Rozeboom & Gilford, 1954; Dev & Rai, 1982; Meek & Macdonald, 1984).…”

Generation of a novel Wolbachia infection in Aedes albopictus (Asian tiger mosquito) via embryonic microinjection

“…The latter would be similar to prior transfection experiments with Drosophila (Rousset et al, 1999). To reduce complications associated with generation of artificial associations, closely related Wolbachiainfected Aedes mosquitoes may be initially selected as donors (Sherron and Rai, 1983;Meek and Macdonald, 1984;Dean and Dobson, 2004). However, prior transfers between divergent hosts have been successful, including the transfer of Wolbachia from Ae.…”

Characterization ofWolbachiaInfections and Interspecific Crosses ofAedes(Stegomyia)polynesiensisandAe.(Stegomyia)riversi(Diptera: Culicidae)

“…polynesiensis shows a similar egg hatch resulting from crosses of Ae. polynesiensis strains (Sherron andRai 1983, Meek andMacdonald 1984). However, the CI level previously reported in crosses of aposymbiotic Ae.…”

“…Wolbachia-induced CI in the Ae. scutellaris group has attracted signiÞcant research effort to deÞne the role of Wolbachia in the reproductive isolation between species of the group (Trpis et al 1981, Sherron and Rai 1983, Meek and Macdonald 1984. Studies have demonstrated that the removal of Wolbachia infections (generating aposymbiotic strains) can increase egg hatch in crosses of Aedes polynesiensis Marks with members of the Ae.…”