An investigation was carried out to study the developmental time, reproduction and life table of three populations of the onion thrips, Thrips tabaci Lindeman, on onion (Khorasan and Golestan populations) and also on tobacco (Mazandaran population) in the laboratory at 25°C, 50% RH and 16: 8 h L: D. The total life cycle from egg to adult of Khorasan, Golestan and Mazandaran populations were gauged as 15.22, 14.66 and 17.82 days, respectively. However, theses populations showed 30%, 38% and 58% immature mortality, respectively. The females of T. tabaci laid 29.5, 27.7 and 26.3 eggs averagely, and had a mean longevity of 18.0, 17.78 and 19.07 days in Khorasan Razavi, Golestan and Mazandaran populations, respectively. The net reproductive rate (R0) was 19.75, 18.48 and 10.84, and the intrinsic rate of increase (rm) was 0.143, 0.141 and 0.096 in Khorasan Razavi, Golestan and Mazandaran populations, respectively. Khorasan Razavi and Golestan populations (both reared on onion) had similar developmental time, mortality and life table parameters, while Mazandaran population (on tobacco) yielded significantly different values. Based on the differences of development, fecundity and life table parameters, there might be two distinct populations exploiting onion and tobacco in Iran.

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