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Comparative life-history studies of nearctic and palearctic populations of Coccinella septempunctata (Coleoptera: Coccinellidae)

Phoofolo, M.W., Obrycki, J.J.
Environmental entomology 1995 v.24 no.3 pp. 581-587
Coccinella septempunctata, life tables, oviposition, geographical variation, predators, population, life cycle (organisms), Central European region, Iowa, France, Delaware
Life-history characteristics of four populations of Coccinella septempunctata L. were quantified and compared at 26 degrees C and 18:6 (L:D) h on a diet of pea aphids, Acyrthosiphon pisum (Harris). Populations were from two locations in the United States (Iowa and Delaware) and two locations in Eurasia (France and Ukraine/Moldavia/Crimea). Large intrapopulation variation was observed in preoviposition, interoviposition, and number of days on which eggs were laid. This variation was a result of 10-35% of females entering diapause, whereas most females initiated oviposition within 12 d of eclosion and continued egg laying with interoviposition periods of <6 d. No significant differences among the four populations were detected in preoviposition, interoviposition, or number of days on which eggs were laid. In addition, preimaginal development time, sex ratio, and life table parameters, including intrinsic rates of increase and fecundity, did not differ significantly among the four populations. On the basis of the parameters measured, we conclude that these four populations of C. septempunctata have not undergone local adaptation that would define these populations on the basis of geographical origin.