Assessment of the suitability of Tinopal as an enhancing adjuvant in formulations of the insect pathogenic fungus Beauveria bassiana (Bals.) Vuillemin.
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 (approximately 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 (LC(50)) 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.
Reddy
Narasimha P
NP
Department of Botany, Andhra University, Visakhapatnam 530 003, Andhra Pradesh, India.
A Khan
Pathan Akbar
PA
Devi
Koduru Uma
KU
Victor
John S
JS
Sharma
Hari C
HC
D000277:Adjuvants, Pharmaceutic; D000818:Animals; D052982:Beauveria / Q000187:drug effects* / Q000254:growth & development / Q000528:radiation effects; D001557:Benzenesulfonates / Q000494:pharmacology*; D018533:Biomass; D002626:Chemistry, Pharmaceutical; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology; D009036:Moths / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology*; D010572:Pest Control, Biological; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D014466:Ultraviolet Rays
D000277:Adjuvants, Pharmaceutic; D001557:Benzenesulfonates; C011556:Tinopal