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Elevated CO2 (eCO2) can affect the environmental adaptability of herbivorous insects by affecting the quality and quantity of host plants' nutrients under climate change. In this study, the impacts of eCO2 on carbohydrate metabolism, chitin synthesis and cuticle thickness of western flower thrips (Frankliniella occidentalis) fed on kidney bean (Phaseolus vulgaris) leaves were studied to elucidate the physiological responses of F. occidentalis to eCO2 and provide a theoretical basis for the occurrence trend of thrips under future climate change. The results indicated that the trehalose and glycogen contents in F. occidentalis adults significantly increased with corresponding regulation of key genes related to carbohydrate metabolism under eCO2 compared to ambient CO2 (aCO2), which was closely related to the increased foliar contents of starch and soluble sugars in P. vulgaris grown under eCO2. Subsequently, since trehalose is a precursor of chitin, changes in its content would further affect the chitin synthesis. With the up-regulation of genes related to chitin synthesis and the down-regulation of most genes related to chitin hydrolysis, the chitin content in F. occidentalis adults significantly increased resulting in their increased cuticle thickness and layers, which might enhance their resistance under eCO2 and become "thick-skinned thrips" under climate change condition. [ABSTRACT FROM AUTHOR]

Plant volatile organic compounds (VOCs) are an important link that mediates chemical communication between plants and plants, plants and insects, and plants and natural enemies of insect pests. In this study, we tested the response in the selective behavior of western flower thrips, Frankliniella occidentalis, to the VOCs of kidney bean, Phaseolus vulgaris L., to explore their "attraction" or "repellent" effects regarding their application in integrated pest management (i.e., IPM). The results indicated that 12.7 μL/mL (E, E, E, E)-squalene, 3.2 μL/mL dioctyl phthalate, and 82.2 μL/mL ethyl benzene had a significantly attractive effect on the selective behavior of F. occidentalis, while 10.7 μL/mL and 21.4 μL/mL 2,6-ditert-butyl-4-methyl phenol had a significantly repulsive effect on the selective behavior of F. occidentalis, showing that F. occidentalis responds differently to specific concentrations of VOCs from P. vulgaris plant emissions. Interestingly, the three compounds with the specific above concentrations, after being mixed in pairs, significantly attracted F. occidentalis compared to the control treatment; however, the mixture with the three above compounds had no significant different effect on F. occidentalis compared to the control treatment. It can be seen that the effect with the mixtures of three kinds of VOCs had the same function and may not get better. Simultaneously, the reasons for this result from the transcription levels of odorant-binding protein genes (OBPs) were determined. There were differences in the types and transcription levels of OBPs, which played a major role in the host selection behavior of F. occidentalis under the mixed treatment of different VOCs. It is presumed that there are specific VOCs from P. vulgaris plants that have a good repellent or attracting effect on the selective behavior of F. occidentalis, which can be used for the development of plant-derived insect attractants and repellents to serve as IPM in fields. But attention should be paid to the antagonism between plant-derived preparations and VOCs produced by plants themselves after application. [ABSTRACT FROM AUTHOR]

β‐Glucosidase is validated as an elicitor for early immune responses in plants and it was detected in the salivary glands of Frankliniella occidentalis in previous research. Seven differentially expressed genes encoding β‐glucosidase were obtained by comparing the transcriptomes of F. occidentalis adults grown under two different CO2 concentrations (800 vs. 400 ppm), which might be associated with the differences in the interaction between F. occidentalis adults and its host plant, Phaseolus vulgaris under different CO2 levels. To verify this speculation, changes in defense responses based on the production and elimination of reactive oxygen species (ROS) in P. vulgaris leaves treated with three levels of β‐glucosidase activity under ambient CO2 (aCO2) and elevated CO2 (eCO2) were measured in this study. According to the results, significantly higher levels of ROS were noticed under eCO2 compared to aCO2, which was caused by the increased β‐glucosidase activity in thrips due to increased cellulose content in P. vulgaris leaves under eCO2. Together with the lower activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in injured leaves under eCO2, P. vulgaris leaves would be negatively affected on redox‐based defense by eCO2, thus facilitating thrips damage under climate change. Summary Statement: β‐Glucosidase secreted by the Frankliniella occidentalis adults could induce early immune responses in the leaves of their host plant, Phaseolus vulgaris based on reactive oxygen species (ROS) and antioxidant enzymes, which was significantly affected by CO2 level. The higher β‐glucosidase activity of F. occidentalis adults under elevated CO2 (eCO2), which was probably caused by the increased cellulose content in P. vulgaris leaves, would lead to increased ROS levels in P. vulgaris leaves infested with thrips under eCO2, and the activities of antioxidant enzymes for scavenging ROS damage would be correspondingly increased but their overall levels were still lower than that under ambient CO2, which was beneficial to the feeding damage of thrips [ABSTRACT FROM AUTHOR]

Globally rising atmosphere CO2 has been predicted to affect the emission of plant volatile organic compounds (VOCs) and the interaction with insect herbivores. CO2‐mediated plant VOCs change might contribute to develop effective management strategies for insect pests by using VOCs related biological control methods. In this study, we analysed the effect of elevated CO2 on the host‐selection behaviour of western flower thrips (Frankliniella occidentalis) and studied how they were affected by the release of VOCs from kidney bean plants (Phaseolus vulgaris). A four‐chamber olfactometer was used to quantify the host‐selection of F. occidentalis for P. vulgaris. Elevated CO2 increased F. occidentalis' selection for P. vulgaris wounded by mechanical damage (MD) and thrips infestation (TI) that might via regulating the gene expression of CSP1, CSP1‐q, OBP1 and OBP1‐q in F. occidentalis. Besides, we cultivated kidney beans at ambient CO2 (400 ppm) and elevated CO2 (800 ppm), and quantified the emission of plant VOCs by using GC‐MS. Thirty VOCs belonging to ten chemical groups were identified from P. vulgaris, including aromatic hydrocarbons, ethers, alkanes, cycloalkanes, alcohols, alkenes, aromatic derivatives, phenols, ketones and esters. Furthermore, six VOCs from P. vulgaris were significantly affected by CO2 level, wounding way and the interaction between them, including ethyl benzene, 1,3‐dimethyl benzene, 1,3‐dimethyl‐4‐ethyl benzene, (E,E,E,E)‐squalene, 2,6‐ditert‐butyl‐4‐methyl phenol and dioctyl phthalate. Our study indicates that elevated CO2 might increase the host‐selection of F. occidentalis for wounded P. vulgaris due to the changed plant VOCs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Elevated CO2 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 CO2 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 CO2 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 CO2 might both enhance plant defense against thrip attack, and increase thrip anti‐defense against plant defenses. © 2018 Society of Chemical Industry Elevated CO2 alters the leaf damage and plant defense responses caused by insect herbivores. This article presents an analysis of antioxidant‐associated plant defense and detoxifying‐associated thrips anti‐defense. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine how elevated CO2 impacts on life-history traits and life table parameters in three successive generations of invasive species Frankliniella occidentalis ( Pergande) ( Thysanoptera: Thripidae) and its related native species, Frankliniella intonsa ( Pergande), fed with kidney bean leaves grown in ambient CO2. The oviposition period, sex ratio, net reproductive rate (R0), intrinsic rate of increase (rm), and finite rate of increase (λ) of F. occidentalis increased in elevated CO2, and larval duration, survival rate, mean generation time (T), and population doubling time ( DT) decreased. For F. intonsa, larval duration, survival rate, oviposition period, longevity of female adults, R0, rm, and λ decreased in elevated CO2, whereas sex ratio, T, and DT increased. These results indicated that the effects of elevated CO2 would be beneficial to F. occidentalis, whereas it would be detrimental to F. intonsa. However, the effects of elevated CO2 on F. occidentalis and F. intonsa differed over generations. In elevated CO2, larval duration, survival rate, oviposition period, sex ratio, rm, and λ of F. occidentalis increased linearly through successive generations, whereas T and DT decreased linearly, which suggested that the effects of elevated CO2 on F. occidentalis would be slowly accentuated over time. For F. intonsa, larval duration, survival rate, oviposition period, rm, and λ decreased linearly over generations, whereas sex ratio, T, and DT increased linearly. This indicated that the effects of elevated CO2 on F. intonsa would slowly accentuate over time. We conclude that F. occidentalis would be more adapted to elevated CO2 than F. intonsa. [ABSTRACT FROM AUTHOR]

As atmospheric CO 2 concentration continues to increase, plants using CO 2 as raw materials for photosynthesis will inevitably be affected, which in turn affects the life history and behavior of herbivorous insects. Our previous research has shown increased food intake and aggravated damage of western flower thrips, Frankliniella occidentalis to kidney bean (Phaseolus vulgaris) caused by elevated CO 2 (eCO 2), however the molecular mechanism of this phenomenon is unclear. In this study, the comparative transcriptome analysis combined with corresponding phenotypic changes were studied to reveal the molecular mechanism of interaction between F. occidentalis and P. vulgaris under eCO 2. Inferred from the results, eCO 2 had different degrees of inhibition to the defense responses caused by thrips infestation in P. vulgaris leaf sap based on nutrients, plant hormones and secondary metabolites, making P. vulgaris leaves less resistant to thrips under eCO 2 compared to ambient CO 2 (aCO 2). Besides, the contents of glucose, trehalose, triglycerides and free fatty acids in F. occidentalis adults increased significantly after feeding on the P. vulgaris leaf sap with significantly increased soluble sugars content under eCO 2 , which might lead to glucolipid metabolic disorders and increased food intake of F. occidentalis adults. The results indicated that decreased plant defense of P. vulgaris and increased food intake of F. occidentalis adults were combined to aggravate the thrips damage under eCO 2 , providing a theoretical basis for future occurrence trend of thrips under eCO 2. [Display omitted] • Elevated CO 2 (eCO 2) mainly increased soluble sugars in leaf sap of kidney beans. • Increased accumulation of sugars and lipids in thrips caused metabolic disorders under eCO 2. • Defensive responses in leaf sap of kidney beans were relatively weakened under eCO 2. • The thrips damage to kidney bean leaves was aggravated under eCO 2. [ABSTRACT FROM AUTHOR]

β‐Glucosidase is validated as an elicitor for early immune responses in plants and it was detected in the salivary glands of Frankliniella occidentalis in previous research. Seven differentially expressed genes encoding β‐glucosidase were obtained by comparing the transcriptomes of F. occidentalis adults grown under two different CO2 concentrations (800 vs. 400 ppm), which might be associated with the differences in the interaction between F. occidentalis adults and its host plant, Phaseolus vulgaris under different CO2 levels. To verify this speculation, changes in defense responses based on the production and elimination of reactive oxygen species (ROS) in P. vulgaris leaves treated with three levels of β‐glucosidase activity under ambient CO2 (aCO2) and elevated CO2 (eCO2) were measured in this study. According to the results, significantly higher levels of ROS were noticed under eCO2 compared to aCO2, which was caused by the increased β‐glucosidase activity in thrips due to increased cellulose content in P. vulgaris leaves under eCO2. Together with the lower activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in injured leaves under eCO2, P. vulgaris leaves would be negatively affected on redox‐based defense by eCO2, thus facilitating thrips damage under climate change. Summary Statement: β‐Glucosidase secreted by the Frankliniella occidentalis adults could induce early immune responses in the leaves of their host plant, Phaseolus vulgaris based on reactive oxygen species (ROS) and antioxidant enzymes, which was significantly affected by CO2 level. The higher β‐glucosidase activity of F. occidentalis adults under elevated CO2 (eCO2), which was probably caused by the increased cellulose content in P. vulgaris leaves, would lead to increased ROS levels in P. vulgaris leaves infested with thrips under eCO2, and the activities of antioxidant enzymes for scavenging ROS damage would be correspondingly increased but their overall levels were still lower than that under ambient CO2, which was beneficial to the feeding damage of thrips [ABSTRACT FROM AUTHOR]