Management of onion armyworm, Spodoptera exigua (Hubner) through the use of Spodoptera exigua nucleopolyhedrovirus (NPV)
2018
Guerrero, M.S. | Cayabyab, B.F. | Alforja, L.M. | Perez, E.A. | Aquino, A.G. | Sagado, W.S. | Valdez, R.B.
Onion, Allium cepa L., is a high value crop in the Philippines and in 2016, approximately 20M dollars were lost due to the infestation of onion armyworm (OAW), Spodoptera exigua (Hubner). Significant losses resulted from that insect outbreak exacerbated by climate change. To address the use of nucleopolyhedrovirus (NPV), being highly specific, environmentally safe and effective, is an ideal part of IPM strategy. Efficacy of NPV against AOW was evaluated through laboratory and potted experiments. Local strains of OAW NPV were collected and isolated from field collected and laboratory reared larvae. NPV were collected and isolated from field collected and laboratory reared larvae. NPV infected larvae were placed in microcentrifuge tubes and stored in the refrigerator until use. Two treatments, one with NPV infection and other control, replicated three times for three trials were conducted at the NCPC, UPLB [National Crop Protection Center, University of the Philippines Los Baños]. Field application of NPV for efficacy tests showed promising results. NPV infected larvae were already observed in the field. NPV infected larvae apparently stopped feeding, were soft, shiny, and fragile. Upon death, larval bodies liquefy and disintegrate having characteristically foul odor. Microscopy of NPV infected larvae showed polyhedra appearing as irregular, thickened particles enveloped in a cell. Laboratory and potted experiments resulted to 72 and 62.5 percent mortality, respectively. Hence, NPV was effective in killing OAW larvae indicating high potential for use in biocontrol as part of an IPM strategy.
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