COMPARATIVE LIFE-HISTORY STUDIES OF NEARCTIC AND PALEARCTIC POPULATIONS OF COCCINELLA-SEPTEMPUNCTATA (COLEOPTERA, COCCINELLIDAE)

Life-history characteristics of four populations of Coccinella septemp unctata 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 t wo locations in Eurasia (France and Ukraine/Moldavia/Crimea). Large in trapopulation variation was observed in preoviposition, interovipositi on, and number of days on which eggs were laid. This variation was a r esult of 10-35% of females entering diapause, whereas most females ini tiated oviposition within 12 d of eclosion and continued egg laying wi th interoviposition periods of < 6 d. No significant differences among the four populations were detected in preoviposition, interovipositio n, or number of days on which eggs were laid. In addition, preimaginal development time, sex ratio, and life table parameters, including int rinsic rates of increase and fecundity, did not differ significantly a mong the four populations. On the basis of the parameters measured, we conclude that these four populations of C. septempunctata have not un dergone local adaptation that would define these populations on the ba sis of geographical origin.