Economic assessment of controlling stem borers (Lepidoptera : Crambidae) with insecticides in Texas rice
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A 4-year field study was conducted to evaluate insecticide applications on infestations of the stem borers Diatraea saccharalis (F.) and Eoreuma loftini (Dyar) in rice, Oryza sativa L. Except for rice yield in 2002, whiteheads per square meter and rice yield were significantly affected by insecticide treatments in each year of the study. Biorational insecticides (diflubenzuron, novaluron and tebufenozide) did not significantly (P>0.05) reduce injury and yield in 2002. Applications of diflubenzuron and novaluron at 14 days after flood were not as effective in reducing injury as lambda-cyhalothrin. In 2005, applications of methoxyfenozide at the 2.5-5 cm panicle stage significantly (P<0.05) reduced injury, but differences in yield were not detected. The greatest reduction in whiteheads (14-fold) was achieved with two applications of lambda-cyhalothrin (at the 5 cm panicle and heading stages) with and without the seed treatment fipronil in 2002. Economic analyses showed outcomes ranging from a net loss of -$594/ha for lambda-cyhalothrin applied at before flood in 2005 to a net benefit of $172/ha for lambda-cyhalothrin applied twice at the 5 cm panicle and late boot/heading stages in 2004. Foliar applications generally resulted in net increased benefit for all treatments. Combined with other management tactics such as the use of resistant cultivars, judicial use of insecticides can help farmers manage stem borers in rice in Texas. 2006 Elsevier Ltd. All rights reserved.