Sampling optimization and crop interface effects on Lygus lineolaris populations in Southeastern U.S. cotton

Authors: Dorman, Seth; TAYLOR, SALLY - Virginia Tech; MALONE, SEAN - Virginia Tech; ROBERTS, PHILLIP - University Of Georgia; GREENE, JEREMY - Clemson University; REISIG, DOMINIC - North Carolina State University; SMITH, RONALD - Auburn University; JACOBSON, ALANA - Auburn University; REAY-JONES, FRANCIS - Clemson University; PAULA-MORAES, SILVANA - University Of Florida; HUSETH, ANDERS - North Carolina State University

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2022
Publication Date: 1/13/2022
Citation: Dorman, S.J., Taylor, S.V., Malone, S., Roberts, P.M., Greene, J.K., Reisig, D.D., Smith, R.H., Jacobson, A.L., Reay-Jones, F.P., Paula-Moraes, S., Huseth, A.S. 2022. Sampling optimization and crop interface effects on Lygus lineolaris populations in Southeastern U.S. cotton. Insects. 13(1). Article 88. https://doi.org/10.3390/insects13010088.
DOI: https://doi.org/10.3390/insects13010088

Interpretive Summary: Tarnished plant bugs (Hemiptera: Miridae) are an important agricultural pest in cotton across the United States. Tarnished plant bugs reduce cotton yields and lower lint and seed quality by feeding on fruiting structures. Effective management of this pest depends on timely chemical control when populations are above economically damaging thresholds. Reliable determination of economic thresholds in cotton depends on timely, effective scouting. To evaluate the efficacy of current tarnished plant bug scouting strategies, we surveyed 120 commercial cotton fields across the southeastern U.S. to quantify 1) variation in tarnished plant bug populations across the production region, 2) evaluate current sampling plans for economic threshold determinations, and 3) examine landscape scale risk factors associated with tarnished plant bug infestations in cotton. We observed the greatest variability in tarnished plant bug density at the field scale followed by within-field variation, emphasizing the importance of scouting each individual fields. Additionally, we determined the sampling size needed for accurate threshold estimates for sweep net (8 sample units of 100 sweeps/sample) and drop cloth sampling (23 sampling units of 1.5 row-m/sample). Furthermore, tarnished plant bugs were positively related to the proportion of agriculture and double-crop winter wheat and soybeans and negatively related to contiguous cotton.

Technical Abstract: Lygus lineolaris (Hemiptera: Miridae), the tarnished plant bug, is an economically damaging pest in cotton production systems across the southern United States. We systematically surveyed 120 commercial cotton fields across five southeastern states during susceptible growth stages in 2019 and 2020 to investigate sampling optimization and effect of interface crop and landscape composition on L. lineolaris abundance. Variance component analysis determined that field and within-field spatial scales, compared to district and state, accounted for more variation in L. lineolaris density using sweep net and drop cloth sampling. This result highlights the importance of field-level scouting efforts. Using within-field samples, a fixed-precision sampling plan determined eight and 23 sampling units were needed to determine L. lineolaris population estimates with 0.25 precision for sweep net (100 sweeps per unit) and drop cloth (1.5 row-m per unit) sampling, respectively. A spatial Bayesian hierarchical model was developed to determine local landscape effects on L. lineolaris in cotton. The proportion of agricultural area and double-crop wheat soybeans were positively associated with L. lineolaris density, and fields with more contiguous cotton areas negatively predicted L. lineolaris populations. These results will improve L. lineolaris monitoring programs and treatment management decisions in southeastern U.S. cotton.