Infecção mista de Diatraea saccharalis (Fabr., 1974) (Lepidoptera-pyralidae) com dois tipos de boculovirus

AUTOR(ES)
DATA DE PUBLICAÇÃO

1989

RESUMO

Two baculoviruses, the Diatraea saccharalis Granulosis Virus (DsGV) and the Anticarsia gemmatalis Nucleopolyhedrosis Virus (AgNPV), were studied infecting the sugarcane borer (SCB), D. saccharalis. The effects of the infecting of these two viruses were analysed by their inoculation simultaneously, sequencially and individually. Being a original virus of the SCB, the DsGV was inoculated in a dose 100 fold smaller than the AgNPV whose original host belongs to a different family of Lepidoptera. Regardless of the inoculation timing being simultaneous or sequencial in one order or the other, a high inclusion body production was observed for both viruses. This type of result discards the possibility of interference between the two pathogens. A comparative study of the infection process of both viruses in the fat body and intestinal tissue, in phase-contrast microscopy, showed their ability to replicate and produce normal inclusion bodies in high amounts in different fat body cells. In the intestinal cells only AgNPV was able to develop and produce polyhedra while no sign of the granules of DsGV were observed. In the fat body, even though neighboring cells were found to bear both types, thus, suggesting some type of inhibitory mechanism. Despite the fact that the AgNPV is developing in an alternate host, thus, having a high LD50 value, once it infects the larvae it is able to develop in a typical infection process. The AgNPV develops in several tissues, producing regular polyhedra in graet amounts, in most cases, more than the capsule production by DsGV. These observations suggest a barrier in host at invasion level being determined by a Iow frequency of genetic variants being able to start infection in the population. The DsGV and AgNPV in the SCB present different infection processes being the AgNPV faster in killing the insect, thus, showing more effectiveness in older larvae. The interaction observed between the two baculoviruses was of the aditive type while no synergism or interference type of effect was observed suggesting independent and non competitive behavior between the two pathogens. As suggested by previous data, the viral replication seems to be fast enough as to eliminate any significant mortality increase by a second inoculation performed after 24 hours following the first inoculum. The simultaneous development of the two different virus in the same individual and same body tissue could result in genetic recombinants. However, further studies should be conducted to confirm these preliminary observations

ASSUNTO(S)

baculoviroses lepdoptero lagarta

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