Predominance of parthenogenetic reproduction in Aphis gossypii populations on summer crops and weeds in Greece

Abstract

The photoperiodic response of 56 parthenogenetic lineages of Aphis gossypii Glover was examined by rearing the aphids for three generations under short day conditions (SD, L 10:13 14) and 17 degrees C. The lineages were derived from aphid samples collected in central and northern Greece from various crops and uncultivated plants of the families Asteraceae [chrysanthemum Chrysanthemum sp., smooth sow-thistle Sonchus oleraceus L. and dahlia Dahlia variabilis (Willd.)], Cucurbitaceac [watermelon Citrullus lanatus (Thunb.) and zucchini Cucurbita pepo L.] and Malvaceae [cotton Gossypium hirsutum L., okra Abelmoschus esculentus (L.), and rose of Sharon Hibiscus syriacus L.]. The results showed that the predominant life cycle category in both central and northern Greece (despite possible differences in winter severity among regions) was obligate parthenogenetic (anholocyclic) as 55 out of the 56 lineages belonged to this category. These lineages produced mostly wingless parthenogenetic females at percentages 59-83% and 48-86% in the first and late born progeny of the second generation under SD, respectively. The remaining percentages refer to winged parthenogenetic females. The only lineage capable of sexual reproduction was an 'intermediate' one which was sampled on cotton in northern Greece. Most of its progeny in the second generation under SD were wingless parthenogenetic females (65%). The percentage of winged parthenogenetic females, males and 'intermediate' females (produce wingless parthenogenetic and a few sexual females) were 8, 22, and 5%, respectively. The results reported here are considered as the first for southern European populations and support the general belief that A. gossypii is mostly anholocyclic in Europe.