Sublethal impacts of novaluron on tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), adults

Authors: CATCHOT, B.D. - Mississippi State University; MUSSER, F. - Mississippi State University; GORE, J. - Mississippi State University; KRISHNAN, N. - Mississippi State University; COOK, D.R. - Mississippi State University; STEWART, S.D. - University Of Tennessee; LORENZ, G.M. - University Of Arkansas; BROWN, S. - Louisiana State University; SEITER, N. - University Of Illinois; CATCHOT, A.L. - Mississippi State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2021
Publication Date: 2/14/2021
Citation: Catchot, B., Musser, F., Gore, J., Krishnan, N., Cook, D., Stewart, S., Lorenz, G., Brown, S., Seiter, N., Catchot, A. 2021. Sublethal impacts of novaluron on tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), adults. Journal of Economic Entomology. 114:739-746. https://doi.org/10.1093/jee/toab007.
DOI: https://doi.org/10.1093/jee/toab007

Interpretive Summary: Tarnished plant bug (TPB) is the most economically important pest of cotton in the Mid-South. Management of this pest relies heavily of chemical insecticides. The insect growth regulator Novaluron plays an important role in TPB management. Although novaluron is lethal to immature stages, it does not kill adults. Therefore, nuvaluron has been used when nymphs are the primary stage present on cotton. However, cotton yield protection was observed from an application of novaluron when adults were the predominant stage present. To explain this, a series of studies were conducted to examine sublethal impacts of novaluron to L. lineolaris adults. Novaluron ingestion by adults reduced hatch rate and sometimes reduced oviposition rate. Ingestion by either males or females reduced hatch rates, but the reduction was greater from female exposure. Contact exposure of adults with novaluron residues within 1 d of application reduced hatch rate by about 50%, but the impact on oviposition was inconsistent. A field study showed reduced hatch rate from contact exposure to mixed-age natural populations, but the overall net reproductive rate was not reduced. Surface exposure of eggs to novaluron did not reduce hatch rate. Overall, exposure of tarnished plant bug adults to novaluron, regardless of adult age or exposure route, reduced egg viability. However, the impact on oviposition rate and net reproductive rate varied with adult age and exposure route. This understanding of sublethal impacts of novaluron, in addition to lethal impacts on nymphs, should be considered when choosing application times to maximize effects on TPB populations.

Technical Abstract: Tarnished plant bug, Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae), has become a primary pest of cotton in the Midsouthern United States. Insect growth regulators such as novaluron are an important part of L. lineolaris management. While novaluron is lethal to nymphs, it does not kill adults, so it has been used when nymphs are the primary stage present. However, cotton yield protection was observed from an application of novaluron when adults were the predominant stage present. To explain this, a series of studies were conducted to examine sublethal impacts of novaluron to L. lineolaris adults. Novaluron ingestion by adults reduced hatch rate and sometimes reduced oviposition rate. Ingestion by either males or females reduced hatch rates, but the reduction was greater from female exposure. Contact exposure of adults with novaluron residues within 1 d of application reduced hatch rate by about 50%, but the impact on oviposition was inconsistent. A field study showed reduced hatch rate from contact exposure to mixed-age natural populations, but the overall net reproductive rate was not reduced. Surface exposure of eggs to novaluron did not reduce hatch rate. Overall, exposure of tarnished plant bug adults to novaluron, regardless of adult age or exposure route, reduced egg viability. However, the impact on oviposition rate and net reproductive rate varied with adult age and exposure route. This understanding of sublethal impacts of novaluron, in addition to lethal impacts on nymphs, should be considered when choosing application times to maximize effects on L. lineolaris populations.