Effect of elevated CO on the interaction between invasive thrips, Frankliniella occidentalis, and its host kidney bean, Phaseolus vulgaris.

Background: Elevated CO can alter the leaf damage caused by insect herbivores. Frankliniella occidentalis (Pergande) is highly destructive invasive pest of crop production worldwide. To investigate how elevated CO affects F. occidentalis fed with Phaseolus vulgaris and, in particular, the interaction between plant defense and thrips anti-defense, nutrient content and antioxidant enzyme activity of P. vulgaris were measured, as well as the detoxifying enzyme activity of adult thrips.

Results: Elevated CO increased the soluble sugar, soluble protein and free amino acid content in non thrip-infested plants, and decreased superoxide dismutase (SOD) and peroxidase (POD) activity in these plants. Feeding thrips reduced the nutrient content in plants, and increased their SOD, catalase and POD activity. Variations in nutrient content and antioxidant enzyme activity in plants showed an opposite tendency over thrip feeding time. After feeding, acetylcholinesterase, carboxylesterase, and mixed-function oxidase activity in thrips increased to counter the plant defenses. Greater thrip densities induced stronger plant defenses and, in turn, detoxifying enzyme levels in thrips increased over thrip numbers.

Conclusion: Our study revealed that F. occidentalis can induce not only an antioxidant-associated plant defense, but also detoxifying enzymes in thrips. Elevated CO might both enhance plant defense against thrip attack, and increase thrip anti-defense against plant defenses. © 2018 Society of Chemical Industry.