Surveying Hainan Melon Fly Entomopathogenic Microbial Resources And Screening Of High Germ Strains

Melon fly [Bactrocera (Zeugodacus) cucurbitae (Coquillett)] is an important invasive pest of vegetables and melons on the south, the main host is bitter gourd, cucumber, gourd and other cucurbits. The damage is particularly serious in bitter gourd. With the increasing of domestic vegetable acreagerecent in recent years, the distribution of damage in Hainan was spreading upward trend, and Cucurbitaceae is especially serious damage,such as bitter gourd (Momordica charantia L.)As one of the important preventive measures integrated control, biological control is friendly to the human and environment, biological control strengthen research, prevention and treatment of pathogenic microorganisms, especially for melon fly, looking for the development of a new security control measures, has become the control of invasive pests research and development hotspot. Hainan has rich microbial resources, the project uses local resources, conduct research of entomopathogenic microbial resources for Hainan melon fly. In order to facilitate the indoor determination of reproduction and virulence of melon fly. Firstly, we focus on exploration of melon fly large-scale breeding and development pattern, the sensitivity of insecticides on fruit flies was determined, The research focus on surveying melon fly entomopathogenic microbial resources, such as host crops and soil, besides, conducting extensive research in serious damage area. Through a variety of ways such as collecting melon fly of field natural infection, screening out high virulence strains to lay the foundation for the research and development of biopesticide. The main results were as follows:1. After oberserving the artificial diet, feeding methods and the growth development, we found that, when the temperatures is as high as28～32℃, their developmental duration will be shortened. Egg incubation time was20h～48h, larvae feeding inside the gourd, larval duration was4-5d; pupal duration was6-11d. Adult favorite feeding was cooked pumpkin, like spawning in fresh cucumber on the whole, the best choice of rearing larval was fresh cucumber.2. The toxicity of13pesticides against mature larvae and pupae of B.cucurbitae were determined by the residual film method and dipping method. Comparison of two methods found immersed membrane method is simpler than the insect method is more stable and the results. Better screening out four kinds of pesticides virulence demand for precision and LC50values of the regression equation. Abamectin is the most effective against B.Cucurbitae, it has higher virulence for mature larvae and pupae, followed by emamectin benzoate, Chlorfenapyr, poor efficacy was acetamiprid.3. Separating a lot of melon fly entomopathogenic microorganisms from the death melon fly, Most of the strains are fungus and a few are bacteria, For the above microorganisms, we take the method of hypha spore suspension or bacteria suspension to spray inoculation, and to determine the above strains pathogenicity. There are13strains have pathogenic to melon fly, screening out6strains of high virulence in the end. The four strains was identified by morphological and molecular biology, the results prove that:the strain BC-212is Aspergillus tamari,the strain BC-D-1and BC-22is Aspergillus flavus, the strain BC-Bi and BC-HB is Beauveria bassiana, the srain BC-hn is Serratia marcescens.4. Results of indoor insecticidal toxicity showed:the pathogenicity of strain BC-B1to adult and larvae was highest,and highest mortality rates of98.3%,66.8%within8days respectively.The pathogenicity of strain BC-212, BC-HB and strain BC-hn to adult was higher, the mortality rates was73.5%,69%,65%within8days respectively; the pathogenicity of six strains to pupae was poorer, not feather pupation ratio at around20%. The pathogenicity of strain BC-B1to eggs of melon fly was the highest, only39.5%within8days. The tested strains have lower pathogenicity for Tenebrio, Spodoptera litura and Aphids, and show some selectivity to host.5. The measured results of biological characteristics showed:(1)The most suitable medium of strain BC-212was Martin’s medium modified, the best carbon source was sucrose, the best nitrogen source was the protein peptone and the most suitable pH was6-7, the most suitable temperature was30℃-35℃.(2) The most suitable medium of strain BC-D-1was Martin medium modified, the best carbon source is maltose,the best nitrogen source was beef extract, the most suitable pH was7, the most suitable temperature was30℃～35℃(3) The most suitable medium of strain BC-22was Martin medium modified, the best carbon source is maltose, the best nitrogen source was peptone, the most suitable pH was5, the most suitable temperatur was30～35℃.(4)The most suitable medium of strain BC-Bi was PDAY medium, the best carbon source was glucose, the best nitrogen was beef extract, the most suitable pH was6-7, the most suitable temperature was20～25℃.