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This study describes four multiple nucleocapsid nucleopolyhedrovirus isolates recovered from infected larvae of beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on crops in two different geographical regions of Mexico. Molecular and biological characterization was compared with characterized S. exigua multiple nucleopolyhedrovirus (SeMNPV) isolates from the United States (SeUS1 and SeUS2) and Spain (SeSP2). Restriction endonuclease analysis of viral DNA confirmed that all Mexican isolates were SeMNPV isolates, but molecular differences between the Mexican and the reference isolates were detected using PCR combined with restriction fragment length polymorphism (RFLP). Amplification of the variable region V01 combined with RFLP distinguished the two Mexican isolates, SeSLP6 and SeSIN6. BglII digestions showed that the majority of the isolates contained submolar bands, indicating the presence of genetic heterogeneity. Amplification of the variable regions V04 and V05 distinguished between American and the Spanish isolates. Biological characterization was performed against two laboratory colonies of S. exigua, one from Mexico, and another from Switzerland. Insects from the Mexican colony were less susceptible to infection than insects from Se-Swiss colony. In the Se-Mex colony, SeSP2 was the most pathogenic isolate followed by SeSIN6, although their virulence was similar to most of the isolates tested. In Se-Swiss colony, similar LD50 values were observed for the five isolates, although the virulence was higher for the SeSLP6 isolate, which also had the highest OB (occlusion body) yield. We conclude that the Mexican isolates SeSIN6 and SeSLP6 possess insecticidal traits of value for the development of biopesticides for the control of populations of S. exigua.

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El desequilibrio de agroecosistemas es uno de los problemas más importantes que afectan, desde luego, al sector agrícola. Las dificultades más recurrentes son: la incidencia de insectos plaga y malezas o microorganismos patógenos de plantas. Para contrarrestarlos es necesario conocer la biodiversidad que puede ayudar a disminuir los daños ocasionados por insectos, plantas o microorganismos patógenos. Por ejemplo, existen insectos parasitoides o depredadores que se han utilizado con éxito en México y el mundo, así como microorganismos antagonistas (bacterias, hongos etcétera) que son capaces de inhibir el crecimiento de otros microorganismos patógenos de plantas (hongos, bacterias), o bien, hay microorganismos que se utilizan con éxito en la actualidad como promotores de crecimiento vegetal (hongos micorrícicos y bacterias). La agrobiodiversidad en los agro-ecosistemas tiene como objetivo resarcir los daños causados por la agricultura convencional, logrando un equilibrio en la conservación de recursos presentes en éstos. En general, este artículo muestra la biodiversidad benéfica que puede encontrarse en los agroecosistemas, su efecto en cultivos y su acción como parte esencial de un manejo agroecológico.