Caracterização do Baculovirus spodoptera quanto as variações de pH e temperatura

Abstract

The reduction in maize production could reach 73% in high attack conditions Spodoptera frugiperda, a major pest. To combat armyworm, it was developed a biopesticide in powder capable of producing on an industrial scale to be used by the farmer and this product based on baculoviruses Spodoptera strains. In 2006, Embrapa Maize and Sorghum researchers isolated a baculovirus Spodoptera strain that does not break the caterpillar tissues after his death (isolated 6 NR). Tests carried out with this new isolated showed positive results achieved over 90% mortality of larvae. All baculovirus have the same basic structure, a covered capsid rounded. The nucleocapsid is a cylindrical structure of DNA and protein. Inside, the double-stranded DNA is associated with heterogeneously with a basic protein and form a "core" cylindrical. The VPN genus is characterized by having two subgenres: "Simple virus nucleocapsid" - SNPV where only one capsid is found by envelope and those called "Multi-nucleocapsid Virus" - MNPV, where multiple nucleocapsids are found in a common envelope. The VGs has only one capsid per envelope, the viral occlusions have the form of granule, and rarely containing two or more virions per bead. Occlusion of viral particles in protein matrix is an extremely important feature. This is what ensures protection and enables the horizontal transmission of the virus, or an insect to another. The caterpillar cartridge by feeding the corn leaf containing the baculovirus particles, it infects by viral penetration bodies in the digestive system. The pH of alkali present in the midgut of the caterpillar breaks the protein matrix of virus protection, releasing virions where their proteins bind to proteins present in the membranes of intestinal epithelial cells. In the process of infection, the insect is debilitated, losing motor and power capacity, moving to the upper parts of the host plant, where he died in 5-8 days, showing the body discolored (pink-white) compared to a healthy caterpillar. Two days after the death of the caterpillar, insect body breaks down, releasing large amounts of virus on plant parts. Thus, infected or dead caterpillars serve as inoculum for horizontal transmission of the virus.