Individual study: Evaluation of action thresholds for chronic rice insect pests in the Philippines. III. Leaffolders
Litsinger J.A., Bandong J.P., Canapi B.L., dela Cruz C.G., Pantua P.C., Alviola A.L. & Batay-An E.H. (2006) Evaluation of action thresholds for chronic rice insect pests in the Philippines. III. Leaffolders. International Journal of Pest Management, 52, 181-194
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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. 2006a, the same study as Litsinger et al. 2005 and 2006b) found that spraying based on thresholds of leaffolder (Crambidae and Pyralidae) abundance or damage typically resulted in greater rice Oryza sativa yields than unsprayed controls (averaging 41-263 kg/ha greater). Yields were improved with five out of eight different spraying thresholds tested during initial rice growth, and with six out of eight thresholds tested in the flowering and ripening stages. The most effective threshold was that of 10-15% leaffolder leaf damage, which enabled correct decisions to spray/not spray on 93-99% of occasions. Thresholds based on the numbers of leaffolder larvae or moths led to 91-100% and 62-96% correct decisions, respectively. Synthetic insecticides (endosulfan, monocrotophos, BPMC and azinphos-ethyl) controlled 60-100% of leaffolder larvae but only 13-53% of leaf damage. Thresholds were studied at 4-9 farms/year in each of four sites across the Philippines, totalling 68 rice crops overall. Thresholds and unsprayed controls were tested in 100-200 m² plots. Decisions were considered correct if leaf damage reached 10-15% and yield loss exceeded 250 kg/ha (in additional control plots). Comparisons to a conventional spraying regime and effects on natural enemies were not presented.