Submitted to: Agricultural Engineering Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2009
Publication Date: 5/1/2009
Citation: Lan, Y., Ring, D.R., Benedict, J.H., Hoffmann, W.C. 2009. Evaluation of bollworm-tobacco budworm control strategies with ICEMM. International Agricultural Engineering Journal. XI:1114.
Interpretive Summary: Several factors have an impact on net returns of cotton injured by bollworm and tobacco budworm (heliothines). The choice of a management strategy for these insects may differ depending on the impact of such factors on net returns. Two factors that strongly influence net returns are in-season rainfall conditions and density of insect pests. One method of comparing management strategies when utilized under different in-season rainfall conditions and heliothine densities is the use of a simulation model. The Integrated Crop Ecosystem Management Model (ICEMM) is well suited to make such comparisons. The analyses show that under scenarios of precipitation and heliothine density, no single strategy provides highest net returns. However, the use of conventional non-Bt cotton with an abundance of beneficial insects (natural enemies that attack heliothines) and no insecticide application provides the optimum strategy for managing heliothine pests. Cotton farmers and researchers can use this model to better evaluate heliothine control strategies under their production scenario.
Technical Abstract: Economic comparisons of insect pest management strategies were made for bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Heliothis virescens (f.), under 18 different combinations of in-season rainfall, pest densities, insecticide use, insect resistant cotton, and densities of beneficial insects. Comparisons were made using a mechanistic simulation model of insect-plant interactions. The model, referred to as the Integrated Crop Ecosystem Management Model (ICEMM), combined modified versions of the insect model, TEXCIM 5.0, and the cotton plant model, GOSSYM. Economic returns were calculated for each management strategy under each combination of in-season rainfall condition and heliothine density. In-season rainfall conditions were categorized as dry, average, optimum, and wet. Heliothine budworm densities wee none, low, medium, and high. Management strategies were: no insect management when heliothines were absent; no insect management when bollworm-tobacco budworm were present; no insect management when heliothines wee present with a light or heavy density of beneficials; one insecticide application at a low or high rate when heliothines were present; one insecticide application at a low or high rate when heliothines were present with a light or heavy density of beneficials; transgenic cotton expressing a Cry1A gene encoding an insecticidal delta-endotoxin from Bacillus thuringensis var. kurstaki, (Bt cotton), with no pest management; Bt cotton with a light or heavy density of beneficials; and Bt cotton with one application of insecticide at a low or high rate. The greatest net returns were obtained when heliothines were absent and insect management was not employed. When heliothines were present, the management strategy with doing nothing plus heavy beneficials resulted in the highest net returns. Optimum rainfall also improved net returns compared to other in-season rainfall rates.