Yield, Biological Activity, and Field Performance of a Wild-TypeHelicoverpaNucleopolyhedrovirus Produced inH. zeaCell Cultures

Abstract

This paper reports studies of thein vitroproduction of a virus fromHelicoverpa armigera(HaSNPV) and its possible use as a specificHelicoverpa/Heliothislarvicide. Growth kinetics ofHelicoverpa zea(H. zea) cells and virus occlusion body yields were compared in three SF900II-based media, namely, SF900II (serum-free), SF900II + 1% serum, or SF900II + 10% serum. Viable cell densities were usually higher in the media supplemented with serum than in the serum-free medium; however, in the serum-free medium, cell diameters were 1.7 times greater (i.e., individual cell volumes were five times larger). Both volumetric production of virus occlusion bodies and production per cell were higher in the serum-free medium than in the media supplemented with serum. However, the infectivity of the occlusion bodies from the serum-free medium was less than that with those from the medium supplemented with 10% serum, when compared in bioassays employing newly hatched larvae. The infectivity of thein vitroproduced occlusion bodies was also less than that ofin vivoproduced occlusion bodies in a commercially available virus product, GemStar. High levels of infection ofH. armigeralarvae obtained in a preliminary field assessment on preflowering tomatoes using thein vitroproduced occlusion bodies indicated the suitability of thein vitroprocess for biopesticide production.