Effect of chlorpyrifos + BPMC [insecticides spray on the population density, damage and natural enemies of leafminer (Liriomyza trifolii (burgess)] on onion (Allium cepa Linn.) grown after rice (Oryza sativa Linn.)
2009
Arida, G.S., Punzal, B.S., Philippine Rice Research Inst., Maligaya Science City of Muñoz, Nueva Ecija (Philippines). Crop Protection Div. | Rajotte, E.G., Pennsylvania State Univ., University Park (USA)
A 2-year study was conducted on the population density of adults, larvae, extent of damage, and larval parasitoids of the onion leafminer (LM) Liriomyza trifolii (Burgess) in weekly-sprayed and unsprayed onion fields in Bongabon, Nueva Ecija, Philippines. The area is known for large-scale cultivation of onion during the dry months from Dec to May. Changes in population density of LM larvae, number of oviposition punctures, mines, damaged leaves, natural enemies and adult flies caught in yellow board traps were recorded over a cropping period. There were little differences observed in the parameters studied between sprayed and unsprayed plots except for a significant reduction in larval parasitism and number of generalist predators recorded on the weekly-sprayed plot. Spraying onion field with the farmers' most commonly used insecticide (Chlorpyrifos + BPMC) was not effective against LM but detrimental to its naturally-occurring parasitoids and predators.
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