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ARS Home » Southeast Area » Stoneville, Mississippi » Southern Insect Management Research » Research » Publications at this Location » Publication #236209
Title: Influence of Within-season Densities of Heliothines and Tarnished Plant Bugs on Variability in End-of-season Cotton Yield Mapping

Author
item Allen, Clint
item LUTTRELL, R. - UNIV. OF ARKANSAS
item PARKER, JR., C. - NATIONAL COTTON COUNCIL

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2009
Publication Date: 4/1/2009
Citation: Allen, K.C., Luttrell, R.G., Parker, Jr., C.D. 2009. Influence of Within-season Densities of Heliothines and Tarnished Plant Bugs on Variability in End-of-season Cotton Yield Mapping . Journal of Cotton Science. 13:11-22

Interpretive Summary: Plant responses to insect feeding are fundamental to developing economic injury levels, which are a major component of integrated pest management. Processes such as plant compensation may complicate estimates of injury levels by allowing some damage by insects to occur to immature fruit without reducing final yield. Multiple experiments were compiled to examine the effect of varying densities of three major insect pests of cotton on ultimate survival and seedcotton weight of particular cotton plant fruits at harvest. Populations of bollworms and tobacco budworms observed on non-Bt cotton at six different stages of plant development (based on total mainstem plant nodes) were related to decreased survival of fruit within some fruiting cohorts. Eggs and caterpillars on Bt cotton were related to reduced fruit survival when infestations were present on plants with four and three different total mainstem nodes, respectively. Based on these relationships, most damage caused by observed populations of bollworm and budworm caterpillars and plant bugs occurred to cotton fruit ranging from 3 to 15 days old at the time of infestation. Collectively, these data indicate that important insect injury can be followed through the growing season and recorded on end-of-season cotton yield maps.

Technical Abstract: Nineteen different experiments were compiled to examine temporal trends in fruit accumulation among various insect related treatments based on end-of-season yield mapping of cotton, Gossypium hirsutum L., plants. Fourteen of these data sets were used to examine the effect of varying densities of bollworm, Helicoverpa zea (Boddie), tobacco budworm, Heliothis virescens (F.) (heliothines) and tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), on survival and seedcotton weight of particular fruit cohorts at harvest. Regression equations using only sample dates where insects were present described end-of-season fruit loss better than equations using all insect sample dates. More fruit loss occurred when populations of heliothines were observed on cotton varieties not expressing an insecticidal protein from Bacillus thuringiensis Berliner (Bt) than Bt varieties. Populations of heliothines observed on non-Bt cotton at six different stages of plant development (based on total mainstem nodes) were related to decreased survival of fruit within some fruiting cohorts. Heliothine eggs and larvae on Bt cotton were related to reduced fruit survival when infestations were present on plants with four and three different total mainstem nodes, respectively. Based on these regression analyses, most damage caused by observed populations of heliothine larvae and plant bugs occurred to cotton squares ranging from 3 to 15 d old at the time of infestation. Collectively, these data indicate that important insect injury can be followed through the growing season and recorded on end-of-season yield maps. The dynamic nature of the impact and the probable role of plant compensation further support continued development of dynamic insect thresholds.