Comparative toxicity and P450-mediated detoxification of flonicamid in Lygus lineolaris and Lygus hesperus

Authors: Du, Yuzhe; Scheibener, Shane; Zhu, Yu Cheng; Pierce Iii, Calvin; Perera, Omaththage; Portilla, Maribel

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2025
Publication Date: 7/23/2025
Citation: Du, Y., Scheibener, S.A., Zhu, Y., Pierce Iii, C.A., Perera, O.P., Portilla, M. 2025. Comparative toxicity and P450-mediated detoxification of flonicamid in Lygus lineolaris and Lygus hesperus. Insects. 16(8):757. https://doi.org/10.3390/insects16080757.
DOI: https://doi.org/10.3390/insects16080757

Interpretive Summary: The tarnished plant bug (Lygus lineolaris, TPB) and the western tarnished plant bug (Lygus hesperus, WTPB) are economically significant agricultural pests that damage a wide variety of crops in the southeastern and southwestern regions of the United States. These pests feed on plants, causing substantial losses for farmers.A recent study evaluated the effectiveness of flonicamid (marketed as Carbine 50WG), an insecticide targeting sap-sucking pests such as tarnished plant bugs. Researchers tested flonicamid's efficacy on TPB and WTPB in laboratory conditions using two methods: spraying and dipping. The results revealed that WTPB is significantly more susceptible to flonicamid than TPB, indicating that controlling WTPB with Carbine is more efficient.The study also investigated the reasons for TPB's higher resistance. When researchers introduced piperonyl butoxide (PBO), a chemical that inhibits detoxification enzymes like P450, flonicamid's effectiveness increased substantially against both species. Further experiments demonstrated that enzyme inhibitors like PBO enhance flonicamid’s performance.These findings are critical for improving pest management strategies. Understanding the differing responses of TPB and WTPB to Carbine allows farmers to optimize its use. This research provides valuable insights into the practical application of flonicamid for managing plant bugs in the field.

Technical Abstract: The tarnished plant bug (Lygus lineolaris) and the western tarnished plant bug (Lygus hesperus) are major agricultural pests, causing significant damage to a wide range of crops in the southeastern and southwestern United State. Flonicamid (commercial name: Carbine 50WG) is an insecticide known for its effectiveness against various sap-feeding pests, including L. hesperus and L. lineolaris. This study evaluated the toxicity of flonicamid on third-instar nymph and adults of both Lygus species under laboratory conditions. Two bioassay methods were used: spray application to assess both contact and oral toxicity and dipping to evaluate oral toxicity. The results showed that flonicamid was significantly more toxic to L. hesperus than to L. lineolaris across both bioassays. While no significant differences in toxicity were observed between the spray and dipping bioassay methods, however, third-instar nymphs exhibited significantly higher sensitivity than adults for both assays and species. Furthermore, the addition of piperonyl butoxide (PBO), an inhibitor of cytochrome P450-monooxygenases (P450s), significantly increased flonicamid toxicity, suggesting that P450 enzyme plays a key role in detoxifying the insecticide. Sublethal doses of flonicamid also induced a significant increase in P450 activity in both Lygus species, further supporting this conclusion. These findings provide valuable insights into the differences in susceptibility between L. lineolaris and L. hesperus to flonicamid and highlight the pivotal role of P450s in the detoxification metabolism of flonicamid. This information is instrumental in optimizing the use of flonicamid within integrated pest management strategies.