Methods for detection of Anticarsia gemmatalis nucleopolyhedrovirus DNA insoil

Two methods, phenol-ether and magnetic capture-hybridization (MCH), were de veloped and compared with regard to their sensitivities and abilities to ex tract the DNA of the insect baculovirus Anticarsia gemmatalis nucleopolyhed rovirus (AgMNPV) from soil and to produce DNA amplifiable by PCR. Laborator y experiments were performed with 0.25 g of autoclaved soil inoculated with different viral concentrations to optimize both methods of baculovirus DNA extraction and to determine their sensitivities. Both procedures produced amplifiable DNA; however, the MCH method was 100-fold more sensitive than t he phenol-ether procedure. The removal of PCR inhibitors from the soil appe ared to be complete when MCH was used as the viral DNA isolation method, be cause undiluted aliquots of the DNA preparations could be amplified by PCR. The phenol-ether procedure probably did not completely remove PCR inhibito rs from the soil, since PCR products were observed only when the AgMNPV DNA preparations were diluted 10- or 100-fold. AgMNPV DNA was detected in held -collected soil samples from 15 to 180 days after virus application when th e MCH procedure to isolate DNA was coupled with PCR amplification of the po lyhedrin region.