Selection of a nucleopolyhedrovirus isolate from Helicoverpa armigera as the basis for a biological insecticide

BACKGROUND: The cotton bollworm, Helicoverpa armigera, is an insect that causes damage in a wide range of crops in Spain. Seven isolates of H. armigera single nucleopolyhedrovirus (HearSNPV) from the Iberian Peninsula were subjected to molecular and biological characterization and compared with a Chinese genotype (HearSNPV-G4). RESULTS: The estimated sizes of the Iberian genomes varied between 116.2 and 132.4 kb, compared to 131.4 kb of the HearSNPV-G4 reference genome. Phylogenetic analysis based on the lef-8, lef-9 and polh genes revealed that the Iberian strains were more closely related to one another than to other HearSNPV isolates. Occlusion body (OB) concentration-mortality responses (LC50 values) did not differ significantly among Iberian isolates when tested against a Helicoverpa armigera colony from Oxford (UK). Despite being the fastest killing isolate, HearSNPV-SP1 was as productive as isolates with lower virulence, with an average yield of 3.1¿×¿109 OBs larva-1 . OBs of HearSNPV-SP1 and HearSNPV-G4 were similarly pathogenic against a recently established colony from southern Spain, although HearSNPV-SP1 was faster killing than HearSNPV-G4 against a range of instars. CONCLUSION: The insecticidal properties of HearSNPV-SP1 mean that this strain is likely to prove useful as the basis for a biological insecticide for control of Helicoverpa armigera in Spain.This study was funded by MEC project numbers AGL2008-05456-CO3-01 and AGL2011-30352-CO2-01 as well as the Gobierno de Navarra project IIQ14065.RI1. M.A. received a pre-doctoral fellowship from CSIC.Peer Reviewe

Selection of a nucleopolyhedrovirus isolate from Helicoverpa armigera as the basis for a biological insecticide

BACKGROUND: The cotton bollworm, Helicoverpa armigera, is an insect that causes damage in a wide range of crops in Spain. Seven isolates of H. armigera single nucleopolyhedrovirus (HearSNPV) from the Iberian Peninsula were subjected to molecular and biological characterization and compared with a Chinese genotype (HearSNPV-G4). RESULTS: The estimated sizes of the Iberian genomes varied between 116.2 and 132.4 kb, compared to 131.4 kb of the HearSNPV-G4 reference genome. Phylogenetic analysis based on the lef-8, lef-9 and polh genes revealed that the Iberian strains were more closely related to one another than to other HearSNPV isolates. Occlusion body (OB) concentration-mortality responses (LC50 values) did not differ significantly among Iberian isolates when tested against a Helicoverpa armigera colony from Oxford (UK). Despite being the fastest killing isolate, HearSNPV-SP1 was as productive as isolates with lower virulence, with an average yield of 3.1¿×¿109 OBs larva-1 . OBs of HearSNPV-SP1 and HearSNPV-G4 were similarly pathogenic against a recently established colony from southern Spain, although HearSNPV-SP1 was faster killing than HearSNPV-G4 against a range of instars. CONCLUSION: The insecticidal properties of HearSNPV-SP1 mean that this strain is likely to prove useful as the basis for a biological insecticide for control of Helicoverpa armigera in Spain.This study was funded by MEC project numbers AGL2008-05456-CO3-01 and AGL2011-30352-CO2-01 as well as the Gobierno de Navarra project IIQ14065.RI1. M.A. received a pre-doctoral fellowship from CSIC.Peer Reviewe