Simplified method for sampling leaffolders (LFs) and planthoppers [Philippines].
1988
Shepard B.M. | Minnick D.R. | Soriano J.S. | Ferrer E.R. | Magistrado O.N.
A sequential sampling plan was developed and a simple pegboard was designed for recording LF [leaffolder], planthopper (brown planthopper [BPH] and whitebacked planthopper [WBPH]) and predator field populations. The goal was a simplified procedure that farmers can use in making IPM [integrated pest management] decisions. Sampling models were based on distribution patterns and thresholds generated on the IRRI [International Rice Research Inst., Los Banos, Laguna, Philippines] farm; in Mabitac and Liliw towns, Laguna and in several fields in Batangas, Philippines. LF distribution fitted the negative binomial distribution with a clumping coefficient (K) of 1.1. Thresholds were 1-2 larvae/hill, assuming a 20% chance of making an incorrect pest control decision. Sequential sampling for BPH and WBPH was based on a binomial distribution model. It was developed from a regression curve drawn by correlating percentage of hills infested with 10 or more planthoppers and average number of hoppers per hill. This relationship allows samples to be classified into "presence" or "absence" of pest. A hill with fewer than 10 planthoppers is classified as 0; one with 10 or more is classified as 1. Predators (predatory spiders, beetles, and crickets) were included in the model by counting major predators on the first five hills.
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