Multiplicação de Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) em lagartas de Spodoptera frugiperda (Lepidoptera: Noctuidae)

• Autor(a) principal: Paiva, Carlos Eduardo Costa
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4617
• topic: Baculovírus; Spodoptera frugiperda; Idade larval; Controle biológico; Baculovirus; Spodoptera frugiperda; Larval age; Biological control; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The use of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) based biopesticide has the potential to control Spodoptera frugiperda (Lepidoptera: Noctuidae), but large scale production depends on maximizing virus production from infected larvae. The suitable temperature, time of exposure to the pathogen, the age at which the larvae are inoculated with the virus, the viral solution concentration and isolate used are important for viral replication. The experiments were performed in the Biological Control Laboratory of Insects at Embrapa Maize and Sorghum Research Center (CNPMS), located in Sete Lagoas, Minas Gerais, Brazil. The first study aimed to verify the effect of inoculation and incubation (multiplication) temperatures in viral production and the inoculation period. Cannibalism among the larvae of S. frugiperda was similar (around 4%) in different periods and temperatures baculovirus inoculation. The inoculation period did influence mortality and viral production. The higher mortalities of larvae were achieved at 28 °C, however, the production of polyhedral inclusion bodies (PIB) per larvae were higher at 25 °C, reducing the number of larvae needed for the production of a dose of baculovirus expressed larval equivalent (LE/ha). The total production of polyhedral inoculation at the different temperatures was similar, but the incubation at 25 °C produced a larger amount of virus (24.56 x 109 PIB at 25 °C and 20.81 x 109 PIB at 28 °C). In the second study, the lethal concentrations were determined for larvae SfMNPV six, seven and eight days and the best age to perform the inoculation of SfMNPV order to maximize viral production. The lethal concentration (LC50) ranged from 1.89 x 105 to 5.01 x 106 PIB/mL. The LC50 I6 was higher than the I19 to six days old larvae of similar for seven days and for those less than eight days. Total polyhedra production was higher with eight days old larvae for the isolate I6. The highest yields were obtained in viral concentrations above 1.00 x 107 PIB/mL. The production of PIB/larvae increased when I6 was used in eight days old larvae, which reduces the number of larvae needed to achieve dose of baculovirus (LE/ha). The third study aimed to verify the production parameter which is more correlated with viral production, mass, or the number of dead larvae by SfMNPV and also determine the parameters weight equivalent per hectare (estimated larval weight necessary to achieve a dose of baculovirus, based on the application of 2.00 x 1011 PIB/ha) and larvae dead weight due to SfMNPV infection caused by I6. All correlations were positive and significant for the total weight (r= 0.958, n= 60, P< 0.0001) even when considered in each age or concentration separately. For the number of tracks the correlation was also significant when considering the amount of treatment (r= 0.723, n= 60, P< 0.0001) within each age group and in each concentration was significant only at concentrations of 1.00 x 106 PIB/mL (r= 0.643, n= 12, P< 0.0242) and 1.00 x 108 (r= 0.657, n= 12, P< 0.0202), but the correlations are less strong. Larvae of S. frugiperda, killed by SfMNPV inoculated at eight days old had the highest average mass. The equivalent weight per hectare did differ among different viral concentrations of solutions used. The maximization of viral production baculovirus for control of S. frugiperda should be made with the isolated I6 in larvae eight days old maintained at a temperature of 25 °C and the weight of dead larvae by baculoviruses can be considered a more reliable parameter than the number of larvae to produce a commercial product based SfMNPV in view that shows strong and significant correlation with the total polyhedra production.