Movement of the different larval instars of Asian corn borer, Ostrinia furnacalis (Guenee),on non-Bt corn hybrid
2018
Caasi-Lit, M.T. | Lontoc, M.B.A. | Pescadero, G.R. | Bigcas, J.P. | Elladora, E.V. | Dacuba, R.H.
There are only very limited studies on larval movement of the Asian corn borer (ACB) in non-Bt and Bt corn in the Philippines. Little is known about ACB larval behavior especially on how they move from one plant to another. We determined the movement of ACB in a non-Bt corn hybrid as influenced by larval stages and density at four, eight, 12 and 16 days after infestation (DAI) in corn plots of three rows x nine hills with 21 plants per plot. The center plant was infested using three ACB stages in two densities: blackhead- stage egg masses with densities of two and four egg masses; day-old neonates and 4-day old second instar larvae both with 30 and 80 larval densities. In all larval stages, most of those recovered stayed on the central plant even until 16 DAI. Neonates tend to move from plant to plant and disperse more, compared to second instar larvae. Larval movement is also influenced by infestation rate. Only few larvae were recovered when infested with blackhead-stage egg masses. When 80 second instar larvae were infested, more ACB were recovered compared to only 30 larvae. Neonates dispersed uniformly for the first four DAI while second instar larvae stayed mostly on the central plant. Larval movement was greatly influenced by larval age and density. This has great implication in formulating recommendations for refuge (seed mixes or planting in separate blocks, appropriate and effective under local conditions.
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