Individual study: Evaluation of action thresholds for chronic rice insect pests in the Philippines. I. Less frequently occurring pests and overall assessment
Litsinger J.A., Bandong J.P., Canapi B.L., Dela Cruz C.G., Pantua P.C., Alviola A.L. & Batay-An E.H. (2005) Evaluation of action thresholds for chronic rice insect pests in the Philippines. I. Less frequently occurring pests and overall assessment. International Journal of Pest Management, 51, 45-61
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Use pesticides only when pests or crop damage reach threshold levels
A 13-year randomised, replicated, controlled study in the Philippines (Litsinger et al. 2005, the same study as Litsinger et al. 2006a and 2006b) found that spraying based on thresholds of pest abundance or damage typically resulted in less control of rice Oryza sativa leaf damage (averaging 31-34% control) than a full protection regime (60%), and similar control to preventative (41%) and farmers’ practice regimes (24%). Rice yields were lower in threshold-based spraying regimes (4.5-4.6 t/ha) than for full protection (5.0 t/ha), similar to preventative (4.8 t/ha) and farmers’ practice (4.5 t/ha) regimes but greater than in untreated plots (4.4 t/ha). Average monetary return from threshold-based spraying ranged from a US$-23/ha loss to a US$48/ha gain, compared to US$-34/ha to US$24/ha with the preventative regime and US$-9/ha to US$28/ha with farmers' practice. Thresholds were studied at 4-9 farms/year in four sites totalling 68 rice crops overall. Plots receiving full protection were sprayed with insecticides weekly. Plots receiving the preventative regime received carbofuran granules and two insecticide (chlorpyrifos) sprays. Farmers' practice involved low insecticide doses and timing based on prevention or very low pest thresholds. Plots measured 100-200 m². Leaf damage was measured relative to 0% control in untreated plots. Effects on natural enemies were not presented.