Efficacy of different oil formulations of bio-agent, Beauveria bassiana (Balsano) Vuillmin on the viruliferous and non-viruliferous Bemisia tabaci Genn. populations.

摘要

Bemisia tabaci, the vector of tomato leaf curl virus, is reported to be affected by Beauveria bassiana both at larval and adult stages. In the present investigations, an attempt was made to assess the effectiveness of Beauveria bassiana in various oil formulations (1% each of groundnut, sunflower, coconut and castor oils) on both viruliferous and non-viruliferous whiteflies and also to evaluate whether there is any effect on acquisition and transmission of the virus and mortality of the vector. Mortality was observed more in coconut oil formulation (100.0%) followed by groundnut (97.8%), sunflower (95.6%) and castor (80.0) oils. Furthermore, mortality was higher when these oil formulations were sprayed on tomato leaf curl virus source plants compared with formulations sprayed on healthy tomato plants. The whiteflies fed on virus source plant sprayed with oil formulations of B. bassiana were further tested for their acquisition and inoculation. The results revealed that they did not acquire the virus from such source plants. In another experiment, viruliferous whiteflies were released in healthy tomato test plants sprayed with the oil formulation of B. bassiana. The results revealed that the mortality of adult viruliferous whiteflies was more in coconut oil formulated B. bassiana (90.7%) followed by groundnut oil (86.7%), sunflower oil (82.7%) and castor oil (78.7%). The results also revealed that the percentage transmission of virus to B. bassiana sprayed healthy test plants was low (27.8%) compared with that of 100% transmission on unsprayed healthy test plants. These results indicate that various oil formulations of B. bassiana, not only kill the adult whiteflies when sprayed on to source plants but also inhibits the acquisition of virus. In addition, the various oil formulations of B. bassiana kill the viruliferous whiteflies and also make the viruliferous ones to be ineffective in transmitting the virus to test plants which were sprayed..