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 co tton fleahopper, Pseudatomoscelis seriatus (Reuter), attacking cotton, Gossypium hirsutum L., on the Lower Gulf Coast of Texas. Yield respon se to insect injury (yield with injury divided by yield without injury or yield without insecticide divided by yield with insecticide) was r egressed on insect density. Densities of insects were manipulated by c ontrolling plant exposure to cotton fleahopper using field cages or tr eating indigenous cotton fleahopper infestations with insecticides. De nsity-yield regression equations were developed for seven cultivars of cotton during the phenological period of plant development when cotto n is susceptible to cotton fleahopper injury; i.e., from fifth true-le af through first week after initiation of anthesis (flowering). Signif icant differences were observed among cultivars in response of yield t o cotton fleahopper densities. These differences were influenced by tr ichome density and other factors. 'TAMCOT SP 37H', one of the most hir sute cottons, was very tolerant of high cotton fleahopper densities. ' Stoneville 213' was intermediate in trichome density and in response t o cotton fleahopper densities, whereas, 'TAMCOT CAB-CS', 'TAMCOT CAMD- E', 'TAMCOT SP21', 'TAMCOT SP21S', and 'TAMCOT SP37' were very suscept ible to cotton fleahopper densities. 'TAMCOT SP37' was the most hirsut e cultivar, 'TAMCOT CAMD-E' was intermediate in trichome density, and 'TAMCOT CAB-CS', 'TAMCOT SP21', and 'TAMCOT SP 21S' were glabrate. Met hods are presented to calculate distinct economic injury levels for va rying combinations of management costs and market values using the den sity-yield regression equations for each cultivar.