Pheromone trap assisted scouting and management of the Mexican rice borer (Lepidoptera: Crambidae) in sugarcane

A large plot aerial insecticide application study (4 replications, 14-43 ha) was conducted in the Rio Grande Valley (Cameron and Hidalgo County, Texas) in 2009 and 2010 to evaluate the use of pheromone traps to help better focus scouting efforts for chemical control of the Mexican rice borer, Eoreuma loftini (Dyar), in sugarcane. In 2009, a pheromone trap catch of >20 moths/trap/week was used as an action threshold to verify treatable larval infestations with scouting. On August 20, the infestation averaged 13.8% of stalks with larvae in leaf sheaths exceeding the treatment threshold, and aerial application was initiated on August 21. Novaluron showed the best control with 6.9% bored internodes, significantly less than both the untreated (20.4% bored) and the pyrethroid (â-cyfluthrin) treated plots (12.6% bored). In 2010, season long larval scouting was conducted with a significant correlation between trap catch and larval infestations recorded (R2=.650). In 2010, treatments were comparable. Sugarcane yield parameters were recorded for each 4 ha plot in both years; however, differences were not detected between treatments in 2009 (possibly due to a hurricane). Concurrently, a greenhouse study was conducted to investigate E. loftini neonate feeding behavior on two phenological stages of sugarcane cultivars HoCP 85-845 and HoCP 00-950. Differences among treatments were not detected. The duration of larval exposure while feeding in the leaf sheath (eclosion to stalk entry) averaged 7.3 days across all treatments. These studies demonstrate the potential for using pheromone traps to assist and minimize scouting efforts.