Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Aphids of the genus Sitobion occurring on grasses in southern Australia.

Abstract

The relationships between populations of Sitobion spp. feeding on grasses in southern Australia were investigated using allozyme electrophoresis. A species of this genus near S. fragariae, collected in Tasmania, Victoria, New South Wales, South Australia and Western Australia, had a diploid chromosome number of 18 and differed in electrophoretic mobility of enzymes at several loci from S. miscanthi (also 2n=18). A 3rd form was regarded as being derived from S. miscanthi, but differed from it in enzyme mobility at 2 loci and a diploid number of 17, apparently resulting from an autosomal fusion. A 4th form, with 2n=20, was collected in the Sydney region on 2 occasions. It was electrophoretically identical to the 2n=17 form. The 2n=17 and 2n=20 forms are concluded to be chromosomal races of S. miscanthi. S. fragariae was common in spring, S. miscanthi (2n=18) was collected only during November-December and S. miscanthi (2n=17 or 20) was collected in November-December and March-July. It is suggested that the 3 major forms have different environmental tolerances.