| Predatory behavior usually refers to animal behavior. In fact, in nature, there are many interesting predatory microorganism. In this study, a strain CNm2012with the ability to prey on the conidia of powdery mildew was found and isolated frommulberryleaf infected with the powdery mildew in southwest China.Through morphological comparisonand molecular taxonomic identification, the strains were identified and named Pseudozyma aphidis CNm2012.So far, the biological characteristics of the strains with the ability to prey on the conidia of Phyllactinia moricolahave not seen relevant reports at home and abroad. This biological characteristic has highlighted the potential of the isolates as a bio-control agent to control the powdery mildew, Phyllactinia moricola by theirunique mode of action-predation. Now, the strains CNm2012keep in Laboratory of Invertebrate Pathology and Applied Microbiology, College of Biotechnology, Southwest University, Chongqing, China.This research, to confirm the strains CNm2012hasthe potential as a bio-control agent to control powdery mildew, Phyllactinia moricola, theisolates CNm2012cells cultured mixed with conidia of Phyllactinia moricola. Following, Safety testing of the strain CNm2012to mulberry tree and silkworm was worked.In meet the premise of strain CNm2012with the safety of mulberry and silkworm strains, we conducted a field experiment to evaluate the field control effect. The experimental results are as follows:1.According to the observation of the isolates cell mixed with Ph. Moricolaconidias, the isolates cell can use the conidias of Ph. moricola to grow. The cells of isolates CNm2012were attracted by the conidias of powdery mildew, and they moved towards the conidias. Later, the cells were growth and breeding on the surface of the Pathogen conidiospores, and formed the chains of conidia. At last, the conidias were broken because of the growth of the isolates.Compared with the control, the isolates cells mixed with conidias of ph. moricola were growth quickly. Besides, with the increasing of the concentration of the conidias of Ph. moricola, the absorbance of the broth increased gradually. The results showed that strain CNm2012can certainly use nutrients of the conidia of mulberry powdery mildew to meet their growth and reproduction.2.The isolates CNm2012were sprayed on mulberry tree in different concentration for half a month. There were not different in all these trees, and we did not found any disease in all the dealt leaves and shoot, even at concentrations as highas109cfu/ml, mulberry also showed no symptoms. It means that stain CNm2012is safety to mulberry tree.3.Fed on the mulberry leaves treated with the strain CNm2012, even at concentrations as high as10’cfu/ml, the individual size, colour and harvesting time^cocoon weight and cocoon layer weight were not affected.Soakingtreatment of Bombyx Mori with CNm2012suspension, even at concentrations as high as109cfu/ml, the individual size, colour and lustre of silkworm cocoon and cocoon weight were not affected too. It demonstrates that it is safe to economic efficiency of silkworm by using the strain CNm2012.4.Field experiment showed that in first three days, the strain can significantly inhibit the increase of spot numbers and the spot size of mulberry powdery mildew andsignificantly reduce the production, diffusion and infection of powdery mildew conidias. Application for seventh days, the strain can still significantly inhibit the increase of the spot size of mulberry powdery mildew. The analyzing of the growth ratio of new infected leave showed thatthe ratio of the negative control reached30.90%and the ratio of the mulberry treated with the carbendazim was19.47%, but the ratio of the mulberry treated with CNm2012is11.24%. The result showed that strain CNm2012prevention effect is better than that of carbendazim. |
