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.
Keywords: Spodoptera exigua; Trichoplusia ni; maize field trials; shelf-life; spinosad efficacy at lower rate.
© 2017 Society of Chemical Industry.