Abstract
Tomato leafminer, Tuta absoluta (Meyrick), (Lepidoptera: Gelechiidae), poses severe threats to sustainable tomato production globally with a high capacity to develop resistance to pesticides. Recently, the management programs for this cosmopolitan pest have relied on combinations of chemical insecticides which exacerbate the problems of cross-resistance and adverse environmental effects. A novel concept of integrated formulates through combining a chemical insecticide model of lambda-cyhalothrin with Bacillus thuringiensis (Bt) products as the formulation core was explored and evaluated. The susceptibility of the second instar larvae of tomato leafminer to the original formulation of lambda-cyhalothrin, Dipel, XenTari, and Agree products was assessed and compared to the combined formulations. The positive and negative impacts of lambda-cyhalothrin on the viability and pathogenicity of Bt strains were tracked and documented. The physicochemical properties of the combined formulates were examined and compared to the international standards of pesticide formulations. The proposed integrated combined formulates of Dipel, XenTari, and Agree biopesticides with lambda-cyhalothrin showed an enhancing effect and had a higher potential than the originally manufactured formulations alone for about a 3.67-10.08-fold impact on larval mortality. Lambda-cyhalothrin had no significant adverse effect on either the viability of Bt strains or the physicochemical properties of combined co-formulates. Therefore, such integrated combined formulates would have the potential to be involved as an alternative or a complementary approach in pest management and pest resistance management tools for sustainable pest management.