ダイズ葉に散布されたハスモンヨトウ核多角体病ウイルス製剤「ハスモンキラー」の残効性について

Abstract

We developed a microbial pesticide “Hasumon killer®”, which included Spodoptera litura nucleopolyhedrovirus (SpltNPV) as the effective ingredient. It is known that this insect virus is rapidly inactivated by sunlight; however, the persistence of the formulated SpltNPV under field condition was not clear. To quantify the effect of the virus on soybean foliage, leaves from different positions of the plant were examined for insecticidal activity. The bioassay showed that loss of activity was rapid on the upper leaf. At 7 hr post spraying, the upper leaves retained about one-fourth of their initial activity, and most activity was lost by 48 h post spraying. The retention of the virus on the leaf surface was investigated by qt-PCR analysis. Approximately one-half of the initial virus amount was lost from the surface of upper leaves at 7 hr post spraving. After 72 hr the virus adhered to leaf was reduced to 20% or less of the initial virus amount on the whole foliage. These result indicate that exfoliation of the virus from the leaf surface was the major factor responsible for the loss of activity.