Life histories of generalist predatory species, control agents of the Cotton aphid Aphis gossypii (Hemiptera: Aphididae)
Biological traits of two populations of each of the predators Coccinella septempunctata Linnaeus 1758, Hippodamia convergens Guérin- Méneville 1842 (Coleoptera: Coccinellidae) and Chrysoperla carnea sl (Neuroptera: Chrysopidae) from different regions of Greece reared on Aphis gossypii Glover 1877 (Hemiptera: Aphididae) were studied in the laboratory. The demographic traits in one population from each species were also examined. Egg mortality and preimaginal development were the lowest and highest, respectively in C carnea, while larval, pupal and total preimaginal mortality were the lowest in H convergens. Larvae of C carnea were the most voracious among species, while the last larval instar was the most voracious in all species. Female longevity, fecundity and net reproductive rate were the greatest in C carnea (62.1 days, 581.3 eggs and 148.9 females/female, respectively). Hippodamia convergens showed the shortest preoviposition period (2.6 days) and generation time (34.3 days) and the highest intrinsic rate of population increase (0.124 females/female/day). Significant intrapopulation variation in the preoviposition periods and oviposition rates of C septempunctata was observed. The study highlighted the potential of the three predators as control agents of the cotton aphid. Each species demonstrated relative advantages toward the others, which could be beneficial in certain phases of aphid control in natural conditions. © 2007 E. Schwcizerbart'sche Verlagsbuchhandlung.