Glutathione S-Transferase Genes are Involved in Lambda-Cyhalothrin Resistance in Cydia pomonella via Sequestration

Abstract

Pest management is mostly accomplished by the use of insecticides. However, the overuse of insecticides has led to the development of resistance. Glutathione S-transferases (GSTs) are vital detoxification enzymes involved in insecticide resistance in insects. In this study, we report the involvement of GSTs in insecticide resistance to lambda-cyhalothrin in Cydia pomonella, a globally quarantined fruit pest. A total of 25 GST, including 22 cytosolic genes and 3 microsomal genes, are identified from the genome database of C. pomonella. These cytosolic genes are further classified into six classes, including four in delta, eight in epsilon, three in omega, three in sigma, one in theta, and one in zeta class, as well as two unclassified genes. The real-time quantitative polymerase chain reaction (RT-qPCR) shows that the majority of these genes are mainly expressed throughout the larval stage and in the midgut of the fourth-instar larvae. Exposure to an LD10 dose of lambda-cyhalothrin resulted in the upregulation of 17 GST genes. Moreover, mRNA levels of most GST genes, with the exception of CpGSTe6, CpGSTd2, CpGSTd4, and CpGSTz1, are considerably higher in a lambda-cyhalothrin-resistant population (ZW_R) than those of susceptible strains. Recombinant CpGSTd1, CpGSTd3, CpGSTe3, and CpGSTs2 can bind and metabolize lambda-cyhalothrin, with the highest metabolic rate observed for CpGSTd3 but no metabolite(s) was detected, supporting the role of GSTs in sequestration of lambda-cyhalothrin. Molecular dynamics simulation analysis indicates that key residues of hydrophobic pocket-derived lipophilic energy S­(lipo) interactions with a hydrophobic pharmacophore of lambda-cyhalothrin are crucial for metabolism by CpGSTd3 and further lead to resistance. Our study is the first to experimentally confirm the involvement of GSTs in lambda-cyhalothrin resistance via sequestration and provides new insights into resistance management in C. pomonella.

Metabolic functional redundancy of the CYP9A subfamily members leads to P450-mediated lambda-cyhalothrin resistance in Cydia pomonella

“…A susceptible strain of C. pomonella (SS) is reared in the laboratory without insecticides exposure for more than 50 generations. 10 A field field-evolved lambda -cyhalothrin-resistant population (ZW_R) of C. pomonella 18 was used in this study. This strain was reared in the laboratory under the same conditions as the SS strain.…”

“…In almost all pome fruit-producing countries, effects to control the C. pomonella have mainly relied on synthetic insecticides such as lambda -cyhalothrin, particularly widely used. 5, 7, 8 However, with the extensive application of insecticides, field-evolved resistance has been widely documented in C. pomonella worldwide 1, 8–10 aside potential multiple occurring side effects of pesticides on non-target organisms. 11 The evolution of resistance to insecticides not only demonstrated the striking ability of this species to adapt to insecticides stress, which may explain its worldwide expansion, but also an ongoing challenge to sustainable management of this species.…”

“…13 Recently, overexpression of GSTs and ABC genes was involved in insecticide resistance in C. pomonella . 8, 10 Besides, the increased production of P450s has been linked to resistance to insecticides including lambda -cyhalothrin in field-evolved resistant populations from Spain, France, Greece, Turkey, and China. 1, 8 However, the underlying molecular mechanisms of P450-mediated insecticide resistance remain largely unknown in C. pomonella .…”

Polyphagous insect Olepa sps. feeding on cardenolide rich Calotropis gigantea (L.) leaves and detoxification mechanism involving GST

“…ability to ingest and tolerate toxic cardenolide strophanthidin by specialized biochemical mechanism involving GST in strophanthidin sequestration as glutathione-strophanthidin conjugate facilitating insect fitness. Recombinant soluble GST proteins and in silico simulation studies confirmed the interaction and conjugation reaction of GST proteins with λ-cyhalothrin insecticide as a means of tolerance mechanism in codling moth ( Hu et al., 2022 ). Molecular docking and dynamic results predict a stronger interaction between delta variant of GST and glutathione-strophanthidin conjugate (Figures 7 and 8 ).…”

“…GST enzymes of delta and epsilon subclasses are involved in the metabolism of λ-cyhalothrin insecticide in codling moth (Cydia pomonella) larvae (Hu et al, 2019;Wang et al, 2019). The expression levels of GST genes were upregulated on exposure to LD 10 dose of lambda-cyhalothrin in codling moth and the levels were considerably higher in lambda-cyhalothrin-resistant codling moth populations (Hu et al, 2022). HR-LC MS analysis of Olepa sps.…”