RESUMEN
Los barrenadores del tallo del género de Diatraea spp. (Lepidoptera:Crambidae) han sido reconocidos por ser la plaga de mayor impacto en el cultivo de caña de azúcar, en el que causan importantes pérdidas económicas. Para su control, una cepa colombiana de Beauveria bassiana (Bals.) Vuill (aislamiento Bv062) que demostró alta virulencia frente a larvas de D. saccharalis (Fabricius), fue utilizada para el desarrollo de un bioinsecticida formulado como un concentrado emulsionable (CE). Con el fin de integrar este bioinsecticida en un esquema de manejo integrado de plagas, es necesario evaluar su compatibilidad con los agroquímicos utilizados comúnmente en el cultivo de caña de azúcar. Para tal fin se evaluó el efecto in vitro de 11 agroquímicos (fungicidas, insecticidas y herbicidas) sobre la germinación y actividad insecticida de conidios formulados. Inicialmente el CE y los agroquímicos fueron ajustados al doble de la concentración recomendada y mezclados en proporción 1:1, se incubaron durante dos horas, y se determinó el porcentaje de germinación. Los conidios expuestos a los agroquímicos fueron también purificados y utilizados para un bioen-sayo frente a larvas de segundo instar de D. saccharalis. El CE resultó ser compatible con los herbicidas e insecticidas evaluados, manteniendo una germinación y eficacia superior al 80%. Por el contrario, el CE fue incompatible con todos los fungicidas evaua-dos. Estos resultados permiten sugerir recomendaciones de aplicación del bioplaguicida a base de B. bassiana Bv062, junto con insecticidas y herbicidas empleados en el cultivo de caña, pero se recomienda no aplicarlo de manera simultánea con fungicidas como el benomil y del grupo de triazoles. Se recomienda validar estos resultados en condiciones de campo.
Sugarcane stem borers of the genus Diatraea spp. (Lepidoptera:Crambidae) have been recognized as the pest of the greatest impact on sugarcane crops causing significant economic losses. For its control, a colombian strain of Beauveria bassiana (Bals.) Vuill (code Bv062) that showed a high virulence against D. saccharalis (Fabricius) larvae was used for a biopesticide development, formulated as emulsifiable concentrate (EC). In order to include the EC into an integrated pest management (IPM) scheme, it is necessary to evaluate its compatibility with the agrochemicals commonly used in sugarcane crops. For this purpose, the in vitro effect of 11 agrochemicals (fungicides, insecticides and herbicides) on the germination and insecticidal activity of Bv062 formulated conidia was evaluated. Initially, the EC and agrochemicals were adjusted to double the recommended concentration and mixed in a 1:1 ratio. The mixes were incubated for two hours, and the germination percentage was calculated. The conidia exposed to the agrochemicals were also purified and used for a bioassay against second instar larvae of D. saccharalis. The EC was compatible with the herbicides and insecticides, maintaining germination and efficacy higher than 80%. In contrast, EC was incompatible with all the fungicides evaluated. These results allow us to suggest recommendations for the application of the biopesticide based on B. bassiana Bv062 with insecticides and herbicides used in sugarcane crops, but it is not recommended to apply it simultaneously with fungicides such as benomyl and the triazole group. It is recommended to validate these results under field conditions.
RESUMEN
AIMS: The leaf-feeding pest Cerotoma arcuata tingomariana (Bechyné) (Coleoptera: Chrysomelidae) produces huge economic losses in different crops. This study aimed to produce conidia by semisolid-state fermentation and to establish the insecticidal activity of two formulation prototypes based on a native Beauveria bassiana isolate for controlling this pest. METHODS AND RESULTS: A novel fabric-based semisolid-state fermentation strategy for quick and large-scale conidia production was performed and characterized. Conidia were formulated as an emulsifiable concentrate (EC) and a water-dispersible granulate (WG). Afterwards, the mortality of C. a. tingomariana adults was assessed. A conidia concentration of 2.9 × 109 conidia cm-2 was obtained after 9 days-course fermentation and a yield of 33.4 g kg-1 dry-substrate. CONCLUSIONS: The polyester fabric-based fermentation is an efficient technique for producing and collecting B. bassiana spores. Regarding LC90 , the potency analysis showed that the EC was 21-fold more potent than the non-formulated conidia, and ~ 2.6-fold more potent than the WG. SIGNIFICANCE AND IMPACT OF STUDY: A high throughput fermentation based on polyester fabric as support for B. bassiana conidia production and subsequent formulation as an EC comprises a promising strategy for obtaining a bioproduct to control adults of C. a. tingomariana and other Chrysomelidae pests.
