Insecticidal Management of Eoreuma loftini (Lepidoptera: Pyralidae) on Texas Sugarcane: A Critical Review

Large-plot field experiments using aerially applied insecticide treatments composed of different insecticides, seasonal and diurnal timing, and carriers were used to determine the effectiveness of chemical control against Eoreuma loftini (Dyar) on southern Texas sugarcane. In 1983, plots with at least 17 monocrotophos applications initiated after above-ground internode formation contained lower numbers of dead hearts and dead tops and higher levels of sugarcane yield and quality than did late-season applied or untreated plots. These results documented the reduction of bored internodes, increased yield and sugarcane quality, and provided evidence for the financial incentive to control E. loftini only under conditions of high borer pressure and weekly insecticide applications. Using regression equations derived from data collected in this experiment (dependent variable = metric ton sugar/ha, independent variable = percent bored internodes), monetary loss to growers was estimated to be $287, $431, and $575/ha, for 10, 15, and 20% bored internodes, respectively. Results from recent studies with different insecticides showed statistically significant reductions in percent bored internodes but rarely an increase in sugarcane yield or commercially recoverable sugar, because insecticide efficacy was not improved to the level apparently needed to be associated with increases in sugar quality and yield or to provide an economic return on the insecticide investment. Cottonseed oil as a carrier and the use of different diurnal application times did not influence the effect of insecticides.