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Gossypol‐induced fitness gain and increased resistance to deltamethrin in beet armyworm, Spodoptera exigua (Hübner)

Hafeez, Muhammad, Liu, Sisi, Jan, Saad, Ali, Bahar, Shahid, Muhammad, Fernández‐Grandon, G Mandela, Nawaz, Muhammad, Ahmad, Aqeel, Wang, Mo
Pest management science 2019 v.75 no.3 pp. 683-693
Spodoptera exigua, cotton, crops, cytochrome P-450, deltamethrin, diet, enzyme activity, esterases, fecundity, females, gene expression, gossypol, larvae, longevity, males, ornamental plants, pests, phytophagous insects, phytotoxins, plant-insect relations, reproductive performance, secondary metabolites, vegetables, xenobiotics
BACKGROUND: In plant–insect interactions, phytotoxins such as gossypol, exert a defensive role on behalf of the plant by interfering with the essential metabolic, biochemical and physiological pathways of herbivorous insects. The beet armyworm, Spodoptera exigua (Hübner), is a key pest for many important crops including a range of vegetables, ornamentals, and cotton. In this study, we investigated how resistance to deltamethrin relates to enzyme activity in gossypol‐pretreated larvae of S. exigua. RESULTS: Following selection with deltamethrin insecticides on gossypol‐pretreated larvae for 10 generations, the Gos‐SEL population developed a 113.29‐fold resistance. Under the same conditions, the Delta‐SEL selected population showed a 69.76‐fold increase in resistance along with corresponding levels of xenobiotic defense enzyme activity. Similarly, the fecundity of the Delta‐SEL population together with male and female longevity were found to be significantly lower when compared with the Gos‐SEL population and the laboratory susceptible‐strain group (SS‐Strain). In addition, the activities of cytochrome P450s in S. exigua were significantly enhanced when the insects were fed on a deltamethrin and gossypol‐pretreated diet compared with being fed on deltamethrin alone. CONCLUSION: The reproductive capacity of S. exigua is significantly reduced in Delta‐SEL and Gos‐SEL populations compared with the control group (SS‐Strain). Elevation of the major detoxification enzyme cytochrome P450 monooxygenase and esterase might have an important role in inducing tolerance to deltamethrin in gossypol‐fed S. exigua populations. This study enhances our understanding of detoxification enzyme pathways for S. exigua gene expression and their role in responses to insecticides and plant secondary metabolites. © 2018 Society of Chemical Industry