Invasive Species Compendium

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Abstract Full Text

Effects of elevated CO2 on the digestive enzyme activities in the adults of Frankliniella occidentalis and F. intonsa (Thysanoptera: Thripidae) on different host plants.

Abstract

Aim: To clarify the physiological mechanisms of the effects of elevated CO2 on western flower thrips, Frankliniella occidentalis and its local related species F. intonsa. Methods: The activities of the digestive enzymes (amylase, trypsin and lipase) in the adults of the two species of thrips reared on different host plants (kidney bean, garden chrysanthemum, pepper and cucumber) in elevated CO2(800 µL/L) and ambient CO2(400 µL/L) for three generations were determined and compared. Results: The amylase activities in F. occidentalis and F. intonsa adults reared on the four host plants in elevated CO2 were all lower than those in ambient CO2. The amylase activities in F. occidentalis adults on kidney bean, cucumber, pepper and garden chrysanthemum decreased by 21.39%, 25.33%, 44.59% and 42.27%, respectively, while those in F. intonsa adults decreased by 48.79%, 49.47%, 38.86% and 38.92%, respectively. In addition, the activities of lipase and trypsin increased significantly in F. occidentalis and F. intonsa adults reared on kidney bean, cucumber and pepper in elevated CO2 than those in ambient CO2 (P<0.05). The activities of lipase and trypsin in F. occidentalis adults on kidney bean foliages in elevated CO2 were 2.00- and 2.49-fold as high as those in the control (in ambient CO2), respectively, while those in the populations reared on cucumber foliages were 2.36- and 2.27-fold as high as those in the control, respectively, while those in the populations reared on pepper foliages were 3.61- and 3.59-fold as high as those in the control, respectively. For F. intonsa, the lipase activities in elevated CO2 were only 1.76-, 2.18- and 2.69-fold as high as that in the control, respectively, while the trypsin activities in elevated CO2 were only 1.72-, 2. 19- and 2.42-fold as high as that in the control, respectively. Conclusion: Both of CO2 concentration and host plant species are the main factors altering the activities of these three digestive enzymes. Although F. occidentalis and F. intonsa may both alter the activities of their digestive enzymes to adapt the future elevated CO2 environment, the invasive species F. occidentalis would be more adaptable to the changed environment than the local related species F. intonsa.