Ovicide, Larvicide Trials, 1989

Abstract

Abstract A greenhouse study was conducted at the Texas A&M University Research and Extension Center in Corpus Christi, TX, to measure the efficacy of binary mixtures combining Orthene and 3 pyrethroids against cypermethrin-susceptible (S) and -resistant (R) eggs/ neonates of TBW. Treatment efficacy was evaluated on eggs obtained from S and R strains of TBW (from ICI Americas). Cotton was planted in 1 gal pots on 4 Feb. Eggs (less than 24 h old) were placed on the upper surface of separate leaves (16-25 eggs/leaf) located near the shoot terminal of 4 flowering cotton plants/treatment (4 leaves with S eggs, 4 leaves with R eggs) with a camel's hair brush moistened with distilled water. The plants were placed in a row and spray application of each treatment was made 15 min after placement of eggs on leaves. Insecticide treatments were made with a CO2-pressurized (40 psi) backpack sprayer calibrated to deliver 4.4 gal/acre through 2, size 3X hollow-cone nozzles/row. All leaves that contained eggs were collected immediately after treatment and placed in covered plastic Petri dishes containing moistened filter paper. The eggs were held for 72-h in the laboratory, then inspected for unhatched eggs and dead or live larvae. Each treatment was replicated 4 times in a randomized block design. A replicate consisted of 1 leaf and 16-25 eggs, depending upon the number of eggs remaining on the leaf after removal from the plant and placement in the dish.