Formulation Process Analysis of a Virus-based Biopesticide to Control the Tomato leafminer Tuta absoluta

ABSTRACT

Abstract Virus-based biopesticides are effective biocontrol agents of crop insect pests. Development of suitable formulations and production processes are necessary to obtain high-quality products easily adopted by farmers. A detailed unit operation study was carried out for the production process of a Phthorimaea operculella granulovirus-based biopesticide to control the tomato leafminer, Tuta absoluta, one of the most important pests affecting this crop. Physicochemical, microbiological, and insecticidal parameters were implemented in the process and applied to the finished product, and a scaling strategy was developed. A Quantitative Polymerase Chain Reaction (Q-PCR) technique was implemented to quantify viral concentrations in the active ingredient (5.34 ± 1.44 x109 Occlusion Bodies mL-1) and in the finished product (>1.6x109 OB mL-1), without contaminant interferences. The Q-PCR methodology was also useful to select the appropriate solid mixing time following Lacey´s mixing index (8 min). Factors and similarity principles influencing the liquid mixing process were identified in the scaling evaluation. Furthermore, the drying kinetics analysis enabled identifying a drying temperature of 35 °C, with an efficacy under controlled conditions higher than 97%. Contaminant concentration was lower than 1%, indicating controlled and aseptic formulation process conditions. A simple statistical method was used to estimate the reproducibility and repeatability of the parameters assessed in the finished product. These results enable to establish and extrapolate important parameters in the standardization, scale-up, and quality control for the granulovirus-based biopesticide.