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Increased efficacy and extended shelf life of spinosad formulated in phagostimulant granules against Spodoptera frugiperda

Tamez‐Guerra, Patricia, Tamayo‐Mejía, Fernando, Gomez‐Flores, Ricardo, Rodríguez‐Padilla, Cristina, Damas, Gabriela, Tamez‐Guerra, Reyes S, Ek‐Ramos, Maria J, Williams, Trevor
Pest management science 2018 v.74 no.1 pp. 100-110
Bacillus thuringiensis, Spodoptera frugiperda, active ingredients, application rate, bioassays, chemical treatment, corn, corn flour, field experimentation, grain yield, granules, larvae, mortality, pest control, phagostimulants, shelf life, spinosad, temperature
BACKGROUND: Spinosad is recommended for control of Spodoptera frugiperda (J.E. Smith) larvae; its application with phagostimulants may reduce the quantity of active ingredient required for effective pest control. Spinosad (Tracer®) was formulated in maize flour matrix granules and three field tests compared 10–100 ppm a.i. granules (equivalent to 0.24–2.4 g a.i. ha–¹) with Tracer as an aqueous spray (200 ppm a.i.; 60 g a.i. ha–¹), and the recommended application rates of Bacillus thuringiensis, a chemical and an untreated controls were performed. RESULTS: The 100 ppm spinosad granules resulted in similar S. frugiperda mortality compared with the chemical treatments in all three field trials, and resulted in a significantly higher maize grain yield compared with unformulated and control treatments (4141 vs. 2857 and 2407 kg ha–¹, respectively) that was similar to the chemical treatment (3778 kg ha–¹). Bioassays of granules stored at room and cold temperatures showed that after 5 years, ∼ 70% of the original activity remained (OAR) of spinosad when formulated as granules. Nevertheless, after 9 years, efficacy was reduced (26.2% and 48.5% OAR) at both room (25 °C) and refrigerated temperatures (4 °C). CONCLUSION: Spinosad, in the granular phagostimulant formulations evaluated in this study, had advantages measured as high efficacy and long shelf life. © 2017 Society of Chemical Industry