Frankliniella occidentalis (Pergande) and Frankliniella intonsa (Trybom) are sympatric pests of many greenhouse and field crops in Korea. We compared the influence of constant (27.3°C) and fluctuating temperatures (23.8–31.5°C, with an average of 27.3°C) on the life table characteristics of F. occidentalis and F. intonsa held at a photoperiod of 16:8 (L:D) h and 45 ± 5% relative humidity. The development times of both F. occidentalis and F. intonsa were significantly affected by temperature fluctuation, species, and sex. The development time from egg to adult of F. intonsa was shorter than that for F. occidentalis at both constant and fluctuating temperatures. Survival of immature life stages was higher under fluctuating than constant temperature for both thrips species. The total and daily production of first instars was higher in F. intonsa (90.4 and 4.2 at constant temperature, and 95.7 and 3.9 at fluctuating temperatures) than that of F. occidentalis (58.7 and 3.3 at constant temperature, and 60.5 and 3.1 at fluctuating temperatures) under both constant and fluctuating temperatures. The percentage of female offspring was greater in F. intonsa (72.1–75.7%) than in F. occidentalis (57.4–58.7%) under both temperature regimes. The intrinsic rate of natural increase ( r m) was higher at constant temperature than at fluctuating temperature for both thrips species. F. intonsa had a higher r m value (0.2146 and 0.2004) than did F. occidentalis (0.1808 and 0.1733), under both constant and fluctuating temperatures, respectively. The biological response of F. occidentalis and F. intonsa to constant and fluctuating temperature was found to be interspecifically different, and F. intonsa may have higher pest potential than F. occidentalis based on the life table parameters we are reporting first here.

Temperature has significant effects on the development, survival, and reproduction of ectothermic organisms. In this study, we examined the effect of temperature on the demographic characteristics of two predatory mite species, Neosciulus womersleyi (Schicha) and N. longispinosus (Evans), reared on Tetranychus urticae Koch. The developmental and reproductive traits of both species were examined at 10 constant temperatures between 15 °C and 37.5 °C. The preadult development time of N. womersleyi and N. longispinosus decreased with increasing temperature until 32.5 °C and 35 °C, respectively. The lower developmental threshold (T₀) and thermal constant (K) estimated by using a linear model were 11.61 °C and 69.36 DD for N. womersleyi and 11.92 °C and 61.5 DD for N. longispinosus, respectively. Total preoviposition period and total longevity of females and males of N. womersleyi and N. longispinosus decreased with increasing temperature. The mean generation time (T) first decreased with temperature until 32.5 and 35 °C for N. womersleyi and N. longispinosus, respectively, and then increased at higher temperatures. The R₀ and r values first increased with temperature until 32.5 and 30 °C for N. womersleyi and N. longispinosus, respectively, and then decreased at higher temperatures. The R₀ and r values for N. longispinosus at 37.5 °C were 0.3 offspring and −0.143 d⁻¹, respectively. These results show that N. longispinosus is less fit than N. womersleyi at 37.5 °C.