Population trends of the sugarcane borer (Lepidoptera: Crambidae) in Louisiana sugarcane

Authors: WILSON, BLAKE - LSU Agcenter; WHITE, WILLIAM - Retired ARS Employee; Richard, Randy; Johnson, Richard

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2020
Publication Date: 10/31/2020
Citation: Wilson, B.E., White, W.H., Richard, R.T., Johnson, R.M. 2020. Population trends of the sugarcane borer (Lepidoptera: Crambidae) in Louisiana sugarcane. Environmental Entomology. 49(6):1455-1461.
DOI: https://doi.org/10.1093/ee/nvaa127

Interpretive Summary: The sugarcane borer is the primary pest of sugarcane in Louisiana. Spring populations are not considered economically damaging, but by estimating borer infestations at this time we can predict the damaging summer populations. Statewide spring surveys from 2003 to 2020 determined the density of sugarcane tillers killed (deadhearts) by sugarcane borers from sugarcane fields across the state. Deadheart density varied greatly among years with a high of 1,318/ha in 2003 to a low of 0/ha in 2018. Linear models of the three-year rolling average showed that declines in both spring sugarcane borer populations and the percentage of acreage treated with insecticides have occurred for 17 years. Weather factors including minimum winter temperatures and average spring temperatures were poor predictors of sugarcane borer populations. Only total precipitation in the month of April was significantly correlated with numbers of deadhearts per hectare, following a positive relationship. Results suggest overwintering mortality is not a key factor influencing populations of the first generation of sugarcane borers in Louisiana. Total precipitation in the month of July was positively associated with percentage of treated acreage. Spring deadheart density was directly related to percentage of acreage treated with insecticides during the summer. Determining first generation sugarcane borer populations by recording deadheart density can aid in predicting pest pressure later in the growing season. This information can serve both as an indication of the effectiveness of current pest management strategies and also potentially offer directions for improvement in the management system.

Technical Abstract: The sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), is the primary pest of sugarcane, Saccharum spp., in Louisiana. Spring populations are not considered economically damaging, but quantifying infestations can provide an indication of the spatial and temporal character of the damaging summer populations. Statewide surveys quantified the density of sugarcane tillers killed by D. saccharalis (deadhearts) from sugarcane fields across the state in spring from 2003–2020. Deadheart density varied greatly among years with a high of 1,318/ha in 2003 to a low of 0/ha in 2018. Linear regressions of the three-year rolling average showed declines in spring D. saccharalis populations and the percentage of acreage treated with insecticides have occurred for 17 years. Weather factors including minimum winter temperatures and average spring temperatures were poor predictors of D. saccharalis populations. Only total precipitation in the month of April was significantly correlated with numbers of deadhearts per hectare, following a positive relationship. Results suggest overwintering mortality is not a key factor influencing populations of the first generation of D. saccharalis in Louisiana. Total precipitation in the month of July was positively associated with percentage of treated acreage. Spring deadheart density was directly related to percentage of acreage treated with insecticides during the summer. Quantifying first generation D. saccharalis populations by recording deadheart density can aid in predicting pest pressure later in the growing season.