Response of eggs and larvae of the corn earworm to sublethal lambda-cyhalothrin exposure and chlorantraniliprole

Authors: Elkins, Blake; Mullen, Regina; Little, Nathan; Allen, Kerry; Dixon, Kenya; Scheibener, Shane; Du, Yuzhe

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2025
Publication Date: 8/19/2025
Citation: Elkins, B.H., Mullen, R.M., Little, N., Allen, K.C., Dixon, K.L., Scheibener, S.A., Du, Y. 2025. Response of eggs and larvae of the corn earworm to sublethal lambda-cyhalothrin exposure and chlorantraniliprole. Crop Protection. 198(107370):01-10. https://doi.org/10.1016/j.cropro.2025.107370.
DOI: https://doi.org/10.1016/j.cropro.2025.107370

Interpretive Summary: The corn earworm is a significant pest affecting numerous crops, demonstrating resistance to multiple insecticides, including pyrethroids. Although pyrethroids are no longer recommended for its control, the corn earworm continues to encounter this class of insecticides in the field. While such off-target exposure does not result in mortality, it can still influence the insect’s growth, fitness, and behavior, leading to sublethal effects.An alternative insecticide, chlorantraniliprole, has proven highly effective against the corn earworm and serves as a primary chemical control method for managing its populations. To investigate resistance and assess sublethal effects, we conducted a study examining multiple field colonies and a laboratory colony exposed to a pyrethroid insecticide. Additionally, we evaluated whether the sublethal effects of pyrethroid exposure influence mortality when the insect is later exposed to chlorantraniliprole.Our findings indicate that field colonies exhibit resistance to pyrethroids but experience sublethal effects comparable to those observed in the laboratory colony. Furthermore, results show that a strong sublethal dose of pyrethroids can increase mortality from chlorantraniliprole, regardless of when the insect initially encountered the pyrethroid exposure. This research provides valuable insights into the combined effects of different insecticides, helping to refine strategies for managing corn earworm infestations in agricultural settings.

Technical Abstract: The corn earworm (Helicoverpa zea (Boddie)) (Lepidoptera: Noctuidae) is a major economic pest of multiple crops. It has some tolerance to pyrethroid insecticides and may become exposed to sublethal concentrations in the field. It is unclear how sublethal exposure to pyrethroids impacts mortality from a diamide insecticide, a preferred chemical management option for the corn earworm. A laboratory bioassay was conducted on eggs, neonates, and third instar larvae from multiple field colonies and a susceptible laboratory colony to estimate the sublethal effects of '-cyhalothrin and mortality to subsequent exposure from chlorantraniliprole. The results indicated significant differences in susceptibility to '-cyhalothrin between life stages and colonies of the corn earworm. Elevated cytochrome P450 activity was observed but did not indicate significant differences in pyrethroid susceptibility. Significant sublethal effects, which were indicated by the decreased weight of third instar larvae, were found from the LC5 and LC50 exposure levels across colonies and life stages. The LC50 also led to significantly more mortality from a single concentration of chlorantraniliprole in a diet-incorporated assay. These results reiterate the importance of monitoring corn earworm for pyrethroid susceptibility. They also provide a better understanding of the efficacy of mixtures and rotations of other chemistries with pyrethroids.