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The efficacy of bioinsecticides that act by ingestion can be improved by the use of phagostimulant formulations that increase the consumption of the pathogen. A granule recipe comprising of pregelatinized flour, starch, ground maize cob, maize oil, and water was identified that was highly palatable to Spodoptera frugiperda larvae. To compare the performance of a multiple nucleopolyhedrovirus (SfMNPV) in aqueous spray and phagostimulant granules, multiple linear regression procedures were employed to analyze the results of seven independent field trials involving spray applications and eight independent field trials involving application of phagostimulant granules for control of S. frugiperda in maize. Prevalence of infection was positively correlated with the quantity of inoculum applied but negatively correlated with the interval between application and sampling of larvae for both granular and spray formulations. Virus-induced mortality was greater when inoculum was applied in granular than in spray formulation. A field experiment involving the application of 1.5¡Á1012 occlusion bodies (OBs)/ha in quantities of 6, 18, and 32 kg granules/ha indicated that the quantity of granules applied did not significantly affect viral mortality at any timepoint. Inglés

Persistence of activity of viral inoculum applied in spray or granular formulations was significantly greater when applied in the granular formulation, with approximately 23% of the original activity remaining at 8 days postapplication compared to <1% in the spray-treated plants. We conclude that the efficacy of SfMNPV was improved by formulation; the granular formulation caused a higher prevalence of infection in S. frugiperda larvae and persisted longer on crop foliage compared to an aqueous spray application. The cost of the formulation ingredients alone was approximately US$0.50/kg. When combined with the virus, the cost of the basic bioinsecticide components would be about US$17/ha, although this estimate does not include additional costs involved in the commercialization of a potential bioinsecticide product. Inglés