Downloaded By: [Univ Publi ca de Navarra - Biblioteca Univ] At: 19:38 29 March 2007 Efficacy of Spodoptera exigua multiple nucleopolyhedrovirus as a biological insecticide for beet armyworm control in greenhouses of southern Spain RODRIGO LASA 1 , IN ˜ AKI PAGOLA 1 , ITXASO IBAN ˜ EZ 1 , JOSE ´ E. BELDA 2 , TREVOR WILLIAMS 1 ,& PRIMITIVO CABALLERO 1 1 Departamento de Produccio ´n Agraria, Universidad Pu ´blica de Navarra, Pamplona, Spain, and 2 Departamento de Biologı ´a Aplicada, Universidad de Almerı ´a, Almerı ´a, Spain (Received 22 May 2006; returned 12 July 2006; accepted 26 July 2006) Abstract Chemical control measures targeted at Spodoptera exigua in greenhouse sweet pepper crops in Spain have resulted in pest resistance to virtually all commercially available insecticidal products. A multicapsid nucleopolyhedrovirus (SeMNPV), isolated from diseased S. exigua in Spain, was produced in laboratory reared larvae, tested for insecticidal activity in a laboratory bioassay, and was then applied in eleven commercial greenhouses planted with sweet pepper. Virus occlusion bodies (OBs) were applied on two occasions, at an interval of 7 days, at a rate of 5 10 8 OBs/L of spray in a volume of 600 L/ha, depending on crop phenology and greenhouse area. The percentage of plants showing recent ( B48 h old) feeding damage fell dramatically in greenhouses with high infestations of S. exigua ; the same pattern was observed, although less dramatically, in greenhouses with low infestations. Average mortality of larvae collected from treated plants at 4 days after each application, and reared in the laboratory until death, was high (70  89%) and was not significantly affected by the degree of crop infestation. In a separate trial, the rate of acquisition of infection was examined in larvae that fed on plants treated with 1 10 8 or 5 10 8 OBs/L of spray. Of the 27 and 60% of larvae, respectively, that acquired infection in the 48 h period after spraying, about half became infected in the first 6 h post-application, irrespective of application rate. Acquisition of infection proceeded more slowly during the night-time compared to the daytime period, underlining the advantages of early morning applications of the virus. We conclude that the Spanish SeMNPV isolate merits registration as a biological insecticide for use in greenhouse crops in this region. Keywords: Acquisition of infection, baculovirus, biological insecticide, greenhouse crops, Spodoptera exigua, sweet pepper Correspondence: Primitivo Caballero, Departamento de Produccio ´n Agraria, Universidad Pu ´ blica de Navarra, 31006 Pamplona, Spain. Tel: 34 948 169 129. Fax: 34 948 169 732. E-mail: pcm92@unavarra.es ISSN 0958-3157 print/ISSN 1360-0478 online # 2007 Taylor & Francis DOI: 10.1080/09583150701211335 Biocontrol Science and Technology, 2007; 17(3): 221  232