COTTON YIELD RESPONSE TO COTTON FLEAHOPPER (HEMIPTERA, MIRIDAE) INFESTATIONS ON THE LOWER GULF-COAST OF TEXAS

Insect density-crop yield response functions were developed for the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), attacking cotton, Gossypium hirsutum L., on the Lower Gulf Coast of Texas. Yield response to insect injury (yield with injury divided by yield without injury or yield without insecticide divided by yield with insecticide) was regressed on insect density. Densities of insects were manipulated by controlling plant exposure to cotton fleahopper using field cages or treating indigenous cotton fleahopper infestations with insecticides. Density-yield regression equations were developed for seven cultivars of cotton during the phenological period of plant development when cotton is susceptible to cotton fleahopper injury; i.e., from fifth true-leaf through first week after initiation of anthesis (flowering). Significant differences were observed among cultivars in response of yield to cotton fleahopper densities. These differences were influenced by trichome density and other factors. 'TAMCOT SP 37H', one of the most hirsute cottons, was very tolerant of high cotton fleahopper densities. 'Stoneville 213' was intermediate in trichome density and in response to cotton fleahopper densities, whereas, 'TAMCOT CAB-CS', 'TAMCOT CAMD-E', 'TAMCOT SP21', 'TAMCOT SP21S', and 'TAMCOT SP37' were very susceptible to cotton fleahopper densities. 'TAMCOT SP37' was the most hirsute cultivar, 'TAMCOT CAMD-E' was intermediate in trichome density, and 'TAMCOT CAB-CS', 'TAMCOT SP21', and 'TAMCOT SP 21S' were glabrate. Methods are presented to calculate distinct economic injury levels for varying combinations of management costs and market values using the density-yield regression equations for each cultivar.