title: A Novel Binary Mixture of Helicoverpa armigera Single Nucleopolyhedrovirus Genotypic Variants Has Improved Insecticidal Characteristics for Control of Cotton Bollworms.
abstract: The genotypic diversity of two Spanish isolates of Helicoverpa armigera single nucleopolyhedrovirus (HearSNPV) was evaluated with the aim of identifying mixtures of genotypes with improved insecticidal characteristics for control of the cotton bollworm. Two genotypic variants, HearSP1A and HearSP1B, were cloned in vitro from the most pathogenic wild-type isolate of the Iberian Peninsula, HearSNPV-SP1 (HearSP1-wt). Similarly, six genotypic variants (HearLB1 to -6) were obtained by endpoint dilution from larvae collected from cotton crops in southern Spain that died from virus disease during laboratory rearing. Variants differed significantly in their insecticidal properties, pathogenicity, speed of kill, and occlusion body (OB) production (OBs/larva). HearSP1B was ∼3-fold more pathogenic than HearSP1-wt and the other variants. HearLB1, HearLB2, HeaLB5, and HearLB6 were the fastest-killing variants. Moreover, although highly virulent, HearLB1, HearLB4, and HearLB5 produced more OBs/larva than did the other variants. The co-occluded HearSP1B:LB6 mixture at a 1:1 proportion was 1.7- to 2.8-fold more pathogenic than any single variant and other mixtures tested and also killed larvae as fast as the most virulent genotypes. Serial passage resulted in modified proportions of the component variants of the HearSP1B:LB6 co-occluded mixture, suggesting that transmissibility could be further improved by this process. We conclude that the improved insecticidal phenotype of the HearSP1B:LB6 co-occluded mixture underlines the utility of the genotypic variant dissection and reassociation approach for the development of effective virus-based insecticides.
authors.affiliation: Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, CSIC-UPNA, Gobierno de Navarra, Mutilva Baja, Navarra, Spain.
authors.forename: Maite
authors.initials: M
authors.lastname: Arrizubieta
authors.affiliation: Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, CSIC-UPNA, Gobierno de Navarra, Mutilva Baja, Navarra, Spain.
authors.forename: Oihane
authors.initials: O
authors.lastname: Simón
authors.affiliation: Instituto de Ecología AC, Xalapa, Veracruz, Mexico.
authors.forename: Trevor
authors.initials: T
authors.lastname: Williams
authors.affiliation: Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, CSIC-UPNA, Gobierno de Navarra, Mutilva Baja, Navarra, Spain Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de Navarra, Pamplona, Navarra, Spain pcm_92@unavarra.es.
authors.forename: Primitivo
authors.initials: P
authors.lastname: Caballero
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D005838:Genotype; D003368:Gossypium; D007306:Insecticides; D007814:Larva / Q000821:virology*; D008969:Molecular Sequence Data; D009036:Moths / Q000502:physiology / Q000821:virology*; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology; D010572:Pest Control, Biological / Q000379:methods; D013030:Spain
chemical_list: D007306:Insecticides
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