Assessment of the suitability of Tinopal as an enhancing adjuvant in formulations of the insect pathogenic fungus Beauveria bassiana (Bals.) Vuillemin

• Published in: Pest management science 2008-09, Vol.64 (9), p.909-915
• Main Authors: Reddy, Narasimha P, A Khan, Pathan Akbar, Devi, Koduru Uma, Victor, John S, Sharma, Hari C
• Format: Article
• Language: English
• Subjects: Adjuvants, Pharmaceutic; adverse effects; Animals; application rate; Beauveria - drug effects; Beauveria - growth & development; Beauveria - radiation effects; Beauveria bassiana; Benzenesulfonates - pharmacology; bioassays; Biological and medical sciences; Biological control; biological control agents; Biomass; Biopesticides; Chemistry, Pharmaceutical; conidia; Control; entomopathogenic fungi; entomopathogenic fungus; Fundamental and applied biological sciences. Psychology; Fungi; Helicoverpa armigera; insect development; insect pests; Insects; Larva - drug effects; Larva - growth & development; Larva - microbiology; larvae; lethal concentration 50; lethal dose; microbial growth; microbial insecticides; mortality; Moths - drug effects; Moths - growth & development; Moths - microbiology; optical brightener; Pest control; Pest Control, Biological; pesticide adjuvants; photostability; Phytopathology. Animal pests. Plant and forest protection; plant pests; Protozoa. Invertebrates; solar radiation; spore germination; Spores, Fungal - drug effects; Spores, Fungal - growth & development; Spores, Fungal - radiation effects; Studies; sunscreen; synergism; synergistic effect; Tinopal; Ultraviolet radiation; Ultraviolet Rays; UV protectant
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.1581

BACKGROUND: Biopesticides based on Beauveria bassiana (Bals.) Vuillemin hold great promise for the management of a wide range of insect pests. The conidia in the biopesticide formulation require an adjuvant to protect them from photoinactivation by sunlight. The suitability of Tinopal, an optical brightener used as sunscreen for baculovirus formulations, for use with B. bassiana was assessed. The aim was to study the effect of Tinopal on the growth and photoprotection of B. bassiana, and its effect on the susceptibility of insects to B. bassiana.RESULTS: Tinopal was found to have no adverse effect on the growth of B. bassiana. It was found to confer total protection (~95% conidial germination at 10 g Tinopal L⁻¹) from sunlight up to 3 h of exposure, and a better survival rate than controls even up to 4 h. Helicoverpa armigera Hübner larvae fed on diet with 5 g kg⁻¹ Tinopal were found to have reduced growth. The duration of the larval stage increased by 3-4 days in 1 and 5 g kg⁻¹ Tinopal treatments. Among the moths that emerged from larvae fed on diet with 5 g kg⁻¹ Tinopal, a significantly high number were malformed compared with controls. The larvae that were fed diet with Tinopal showed quicker and higher mortality and required a lower effective lethal dose (LC₅₀) than the controls. Tinopal was found to have a synergistic effect with B. bassiana in causing insect mortality.CONCLUSIONS: Tinopal was found to be a suitable adjuvant for B. bassiana-based biopesticide formulations. It conferred tolerance to sunlight and caused stress in the insect, leading to a synergistic effect with B. bassiana. Copyright