Host Plant Relationships of Aphis gossypii Glover (Hemiptera: Aphididae) in Australia

Aphis gossypii Glover is morphologically variable and polyphagous, and is a vector of many plant viruses. We investigated the ability of A. gossypii from different host plants and geographical areas within Australia to colonise a range of host plants in the laboratory. Samples differed in their success rates on particular laboratory hosts, but there was no absolute host specificity. Colonisation was significantly more likely if the previous host was of the same species, but hosts of the same plant family were not equally suitable. the success rate of colonisation increased when aphids were repeatedly transferred to plants of the same species, suggesting that conditioning was occurring. When aphids were placed on “poor” hosts, such as broad bean, or on stressed plants, they gave birth to offspring which developed into very small “yellow dwarf” adults. While some populations showed variant alleles, allozyme electrophoresis did not group aphids from different geographic or host plant sources, nor indicate the presence of sibling species.