Safety of Baculoviruses used as Biological Insecticides

Abstract

About 1100 viruses are known to infect insects, more than 60% of them being baculoviruses (1). The members of the virus family Baculoviridae are characterized by double stranded circular DNA, included in rod-shaped capsids which are formed mostly in the nucleus of the host cells. As a feature in common with some insect viruses from other virus families, the virions of most baculoviruses are contained within the matrix of proteinaceous particles, the so called occlusion bodies (OB), which provide protection against adverse physical and chemical factors in the environment. Based on the morphology of the OBs, baculoviruses are divided into 3 subgroups: (a) nuclear polyhedrosis viruses (NPV), where many virions are contained in an OB, (b) granulosis viruses (GV), where every virion has its own OB and (c) the small group of non-occluded baculoviruses, where no OB is formed (2). The natural way of infection is by ingestion of food contaminated with virus. In the gut of the susceptible host the matrix protein of the OB is dissolved and virus particles are relaesed. They enter the gut epithelial cells, where they multiply and subsequently quickly spread to several other tissues of the host. Baculoviruses do not produce toxins, but their massive multiplication in vital tissues eventually leads to the death of the insect, usually within 1 to 2 weeks after infection.