Efficacy of microencapsulated nucleopolyhedroviruses from Colombia as biological insecticides against Spodoptera frugiperda (Lepidoptera: Noctuidae)

إنجليزي. Wettable powder formulations by microencapsulation of viral occlusion bodies (OBs) of both Spodoptera frugiperda multiple nucleopolyhedrovirus from Colombia (SfCOL) and a genotypic variant (SfCOL-A) were evaluated for controlling the fall armyworm S. frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in maize crops. Microencapsulation preserved OBs activity after three months of storage at 35ºC, where insecticidal activity loss was not greater than 12%. Additionally, the formulation protected the OBs against inactivation caused by UV-B radiation, retaining its insecticidal activity after 6 hours of UV laboratory exposure, in contrast to unformulated viral suspensions, which presented an Original Activity Remaining (OAR) between 12.1 and 50%. Under greenhouse conditions, the insect mortality was greater than 80% with microencapsulated viruses. In field trials, treatments reduced the percentage of damaged plants to levels below the economic injury level (35%) when the formulated and unformulated virus were applied at 8x1011 OBs/ha (800g/ha) dose, while the damage in the control treatment was close to 60%. Microencapsulation of SfCOL and SfCOL-A OBs provides useful advantages related to half-life and photostability of both viruses, which showed the same efficacy under field conditions.

الأسبانية؛ قشتالية. Wettable powder formulations by microencapsulation of viral occlusion bodies (OBs) of both Spodoptera frugiperda multiple nucleopolyhedrovirus from Colombia (SfCOL) and a genotypic variant (SfCOL-A) were evaluated for controlling the fall armyworm S. frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in maize crops. Microencapsulation preserved OBs activity after three months of storage at 35ºC, where insecticidal activity loss was not greater than 12%. Additionally, the formulation protected the OBs against inactivation caused by UV-B radiation, retaining its insecticidal activity after 6 hours of UV laboratory exposure, in contrast to unformulated viral suspensions, which presented an Original Activity Remaining (OAR) between 12.1 and 50%. Under greenhouse conditions, the insect mortality was greater than 80% with microencapsulated viruses. In field trials, treatments reduced the percentage of damaged plants to levels below the economic injury level (35%) when the formulated and unformulated virus were applied at 8x1011 OBs/ha (800g/ha) dose, while the damage in the control treatment was close to 60%. Microencapsulation of SfCOL and SfCOL-A OBs provides useful advantages related to half-life and photostability.