Efficacy ofSpodoptera exiguamultiple nucleopolyhedrovirus as a biological insecticide for beet armyworm control in greenhouses of southern Spain

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 Â7 days, at a rate of 5)10 8 OBs/L of spray in a volume of Â600 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 Á89%) 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.

Gender-Mediated Differences in Vertical Transmission of a Nucleopolyhedrovirus

“…The multiple nucleopolyhedrovirus of S. exigua (SeMNPV) has been developed as the basis for several bioinsecticide products [12]. Vertical transmission of SeMNPV was a common feature in field-collected adults of S. exigua in southern Spain [13].…”

Natural populations of Spodoptera exigua are infected by multiple viruses that are transmitted to their offspring

“…This virus constitutes the active 67 ingredient of a number of bioinsecticides, including: SPOD-X Ò 68 (Certis, USA), SPEXIT Ò (Andermatt Biocontrol, Switzerland) and 69 VIR-EX Ò (Biocolor, Spain). In Europe, SeMNPV-based insecticides 70 are being incorporated into pest management programs including 71 those in Europe's largest area of horticultural production, in Alme-72 ria, southern Spain (Lasa et al, 2007). 73 The intra-and inter-generational transmission of nucleopoly-74 hedroviruses (NPVs) among individuals in a population of insects 75 is a key factor in understanding the ecology of the virus, and for 76 the efficient use of these pathogens as pest control agents.…”

Intra- and Intergenerational Persistence of an Insect Nucleopolyhedrovirus: Adverse Effects of Sublethal Disease on Host Development, Reproduction, and Susceptibility to Superinfection

“…Recently, an SeMNPV isolate was successfully commercialized for use in biological pest control programs for the extensive greenhouse horticultural crops grown in Almería, southern Spain (20,21). Fieldcollected adults from natural populations of S. exigua collected in and around Almerian greenhouses show evidence of sublethal SeMNPV infection by analysis of the presence of viral gene transcripts.…”