Effect of nuclear polyhedrosis virus infection in Spodoptera ornithogalli larvae on post larval stages and dissemination by adults

Abstract

Nuclear polyhedrosis virus (NPV) infection in fourth-instar yellow striped armyworm, Spodoptera ornithogalli (SoNPV), larvae had little effect on individuals that survived to post larval stages. Pupal mortality, pupal sex ratio, days in the pupal and adult stages, and egg fertility were not altered by the disease. Fecundity, however, was significantly reduced in moths that had survived the viral disease as larvae ( P < 0.05). Survivors did not transmit the disease to progeny, but when the virus was applied to the body surface of females by any of several methods the disease was spread to progeny in the laboratory and in field-caged soybean. Transmission by contaminated females in oviposition cages in the laboratory differed by the method of contamination. Mortality in progeny was highest (77.3%) when moths were wetted with 0.005% sodium dodecyl sulfate and dusted with 10 10 polyhedral inclusion bodies per gram of SoNPV. Mortality of progeny decreased as the time moths were held in the oviposition cage increased and with moth activity prior to placing them in the oviposition cage. Viral infection was much lower in progeny on field-caged soybean with the mean mortality from SoNPV varying with the method of moth contamination from 3.3 to 19.6%.