Potential impact of Mexican rice borer non-crop hosts on sugarcane IPM
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The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), was detected in Louisiana in 2008, having first spread from Mexico into Texas. E. loftini is a severe pest of sugarcane, but it also feeds on rice and a wide range of other grasses. Research on E. loftini management has focused on studying the pest in its main crop host plants, with the role of non-crop grasses only recently studied. Two four-replication sentinel plant studies were conducted in 2006 and 2007 to assess naturally occurring E. loftini infestations in five selected weed species: Leptochloa panicoides, Sorghum halepense, Paspalum urvillei, Urochloa platyphylla and Echinochloa crus-galli. Results showed that L. panicoides, a common weed in Louisiana rice fields, was a highly suitable host, harbouring the highest E. loftini infestations with as many as 78% of the plants infested with at least one larva. In addition, S. halepense and P. urvillei, two ubiquitous perennial grasses, also supported complete larval development of E. loftini. On the other hand, both U. platyphylla and E. crus-galli, which are two common weeds in and near rice fields in Louisiana, proved to be poor E. loftini host plants. Continuous pheromone trapping in the southeast Texas rice area showed that adult moths are active throughout the year. Our studies showed that non-crop hosts could play a key role in E. loftini population build-up, thus warranting a better characterisation of E. loftini source-sink interactions in Louisiana sugarcane producing areas. The manipulation of E. loftini non-crop sources has the potential to decrease a significant proportion of area-wide populations, minimising damaging infestations in sugarcane fields.