Costa Rican soils contain highly insecticidal granulovirus strains against Phthorimaea operculella and Tecia solanivora

The aim of this work was to isolate and characterize novel Phthorimaea operculella granulovirus (PhopGV) strains from Costa Rican soils. Three novel strains, named PhopGV-CR3, PhopGV-CR4 and PhopGV-CR5, were isolated from three locations in Costa Rica, Alvarado, Zarcero and Abangares, respectively, by means of soaking potato tubers with diluted soil samples. An additional strain, PhopGV-CR2, was identified from diseased larvae from a Tecia solanivora laboratory culture. Restriction fragment length polymorphisms obtained for each isolate with six restriction endonucleases (RENs) allowed their identification as four distinct PhopGV strains. Both REN and Polymerase chain reaction analyses indicated the existence of an array of genotypic variants present in all isolates. Bioassays in P.similar to operculella and T.similar to solanivora showed that PhopGV-CR3 was well adapted to the two coexisting hosts with high levels of pathogenicity against both pest species. The mean lethal dose values of this strain were 2.8 OBs/mm2 for P.similar to operculella and less than 0.5 OBs/mm2 for T.similar to solanivora. We conclude that PhopGV-CR3 shows great promise for soil application against these pests in Costa Rican potato crops