Preliminarily Investigating The Lepidopteran-larvicidal Activity And Performance On The Composite With Nanostructured Manganese Dioxide And Bacillus Thuringiensis Preparation

So far, as a new type of nano-materials with superior performance, it is applied in abroad field. In medicine, it has made a rapid progress. In biological pesticide, it seems to have gone back square one. The research on the complex of nano-materials and B. thuringiensis still does not have relevant report. As the most widely used microbial insecticides, B. thuringiensis has many excellent insecticidal properties, This is a new domain for microbial insecticides. The complex has two major properties: characteristics of nano-materials and characteristics of carriers. Both of them have increased larvicidal activity.This article studies the insecticidal performance on the composite, including absolute virulence, anti UV ability and storability, hoping for laying the foundation for a development of new formulations of Bt preparation.Persistence of the complex is associated with the anti UV ability. From the results, whether the samples were immediately determinated after UV irradiated, or indirectly determinated after irradiation, nano-birnessite improved the B. thuringiensis anti ultraviolet ability by20%-30%. It was shown that nano-birnessite did not possess larvicidal activity. Being a carrier, unlike some other additives with larvicidal capacity, such as chemical insecticides, or viruses and microbes, it didn’t do much with the absolute toxicity. In addition, nano-birnessite increased B. thuringiensis resistant storage, in other words, that increased the stability of B. thuringiensis.On the other hand, the preparation of nano-silica particles is easily to achieved by the sol-gel method. We obtained nano-silica particles by this method, which was blue and transparent and over200nm. It was shown that nano-silica did not increase the absolute virulence of B. thuringiensis, on the contrary it was reduced. However, the ability of UV protection had greatly improved, So, nano-silica can block out the damage from ultraviolet light, enhancing UV resistance of crystals and spores of Bt mixture.