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We explored the effects of elevated CO2 on the population performance and interspecific interactions of three thrips pests. The dominance of the three thrips in the field was Frankliniella occidentalis ≈ Frankliniella intonsa > Thrips hawaiiensis. The performance of these thrips, alone and in combination, was evaluated in the laboratory under elevated CO2 (800 μl L−1) and ambient CO2. Compared with ambient CO2, elevated CO2 significantly accelerated the developmental rates and decreased the survival rates of all thrips species. Significant differences in fecundity, intrinsic rate of increase (rm), and net reproductive rate (R0) were observed among these thrips, and their values were significantly increased in F. occidentalis but decreased in F. intonsa and T. hawaiiensis under elevated CO2, compared that in the ambient CO2 treatments. In treatments where thrips species coexisted, F. occidentalis and F. intonsa accounted for similar proportions of the population, and both were dominant over T. hawaiiensis within 10 generations under ambient CO2. Under elevated CO2, F. occidentalis was the dominant species and completely displaced F. intonsa and T. hawaiiensis by the ninth or eighth generation. Where the three species coexisted, no displacement occurred within 10 generations, but the pattern of dominance shifted to F. occidentalis > F. intonsa > T. hawaiiensis. Our results show that the population development of F. occidentalis benefits from elevated CO2 and that it can become the dominant species in interspecific interactions with native thrips species. Thus, compared with native thrips species, F. occidentalis has greater adaptability and competitive capacity under elevated CO2, and it may become a more dangerous crop pest under environmental change in the future. [ABSTRACT FROM AUTHOR]

Gardenia jasminoides and Rosa chinensis are economically important horticultural plants in China. Frankliniella occidentalis and Thrips hawaiiensis are serious coexisting pests that previously demonstrated opposite population trends on G. jasminoides and R. chinensis flowers. To further study the different performances between F. occidentalis and T. hawaiiensis, we investigated their population dynamics in the field (for 5 years) and their life history characteristics on the two flowers in the laboratory. In the field, the density of F. occidentalis was lower than that of T. hawaiiensis on G. jasminoides but was higher than that of T. hawaiiensis on R. chinensis. Under laboratory conditions, F. occidentalis showed significantly slower development, and lower survival and fecundity levels than T. hawaiiensis on G. jasminoides, but the opposite was true on R. chinensis. Significant differences in the net reproductive rate ( R ) between F. occidentalis and T. hawaiiensis were observed, with respective values of 38.66 ± 2.85 and 47.91 ± 2.70 on G. jasminoides, and 55.64 ± 2.15 and 32.45 ± 2.16 on R. chinensis. The intrinsic rates of increase ( r ) of F. occidentalis and T. hawaiiensis were 0.156 ± 0.008 and 0.198 ± 0.007, respectively, on G. jasminoides, and 0.172 ± 0.003 and 0.165 ± 0.002, respectively, on R. chinensis. Thus, the performances of both thrips with respect to population size in the laboratory were in accordance with those in the field, suggesting that the innate capacity for insect population increases may directly impact their population dynamics in fields. Thus, the population performance of different thrips species on flowers is species-dependent, which could be exploited in thrips control programs by breeding pest-resistant cultivars. [ABSTRACT FROM AUTHOR]