Advanced management of the Mexican rice borer (Eoreuma loftini) in sugarcane

Abstract

Insecticide, greenhouse and varietal resistance experiments were conducted in Texas to develop management tactics for the Mexican rice borer, Eoreuma loftini (Dyar), sugarcane. A 3-treatment, large plot aerial application study was set up in 5 commercial sugarcane fields (35-84 acres) to evaluate the utilization of pheromone traps to improve chemical control strategies for E. loftini during 2009 and 2010 growing seasons. A threshold of 20-25 moths/trap/wk was used as an indicator to initiate monitoring for E. loftini larval infestations. Larval infestations were directly related to the no. of moths/trap/wk (R2=0.71). Reductions in borer injury and adult emergence (60% and 40% for novaluron and â-cyfluthrin, respectively) were detected when a threshold of 5% of stalks with treatable larvae was used for timing an insecticide application. Data revealed novaluron treatments increased sugar production by 14%. A greenhouse study assessed the establishment and behavior of E. loftini neonates on two phenological stages of stalkborer resistant (HoCP 85-845) and susceptible (HoCP 00-950) cultivars. Approximately half (55%) of neonates on HoCP 00-950 and 28% on HoCP 85-845 tunneled inside the leaf mid-ribs within 1d of eclosion. Duration of neonate exposure ranged from 3.5 - 6.4 d. This research shows a short window of vulnerability of E. loftini to insecticide applications, and demonstrates the potential to use pheromone traps and new chemistries for enhancing chemical control. A 5-replication field test evaluated stalkborer resistance in 25 sugarcane cultivars. Differences were detected between cultivars in E. loftini injury which ranged from 1.0-20.3% bored. The resistant standard HoCP 85-845 and a South African cultivar, N-21, were the most resistant. HoCP 96-540, which represents the majority of sugarcane acreage in Louisiana, was among the most susceptible. Assessment of stalkborer resistance in sugarcane cultivars is needed as host plant resistance will continue to be important to E. loftini IPM.