Performance of cotton aphid Aphis gossypii (Hemiptera : Aphididae) lineages on cotton varieties
The performance of three clonal lineages of Aphis gossypii Glover originating from central Greece was studied on six commercial cotton cultivars that differ with respect to leaf pubescence traits (Zeta-2, Zeta-5, Eva, Korina, Acala-SJ2 and Sindos-80). Two main laboratory experiments were conducted: (i) one clonal lineage was studied on all six varieties; and (ii) four varieties were assayed with two other lineages. Aphid development, fecundity, longevity and mortality were recorded and life-table characteristics estimated for all varieties. The results showed that leaf trichome density was significantly correlated with aphid performance (i.e. positive correlation with intrinsic rate of increase and fecundity, and negative correlation with developmental time) in both experiments. Leaf hairiness was at least partly responsible for the poorer performance in cotton aphid lineages. We hypothesise that other factors such as allelochemicals (e.g., gossypol, tannins), which are known to affect hemipteran insects, also might be involved.