The Phytoseiid Mites And Evaluation Of Dominant Species In Inner Mongolia

Phytoseiid predators are important biological control agents of small phytophagous herbivores such as spider mites and received extensive application in the current biological control. The species of phytoseiid predators in Inner Mongolia were investigated and identificated in this paper, and then predation ability and potential ability to reproduce of three local native species such as Euseius utilis Liang et Ke, Paraseiulus soleiger Ribaga and Transius morii Ehara and four applied species such as Neoseiulus barkeri Hughes, Amblyseius swirskii Athias-Henriot, Amblyseius orientalis Ehara and Neoseiulus cucumeris Oudemans of phytoseiid mites fed on the spider mite Tetranychus truncatus were evaluated and compared in laboratory. The local native dominant species was also further studied in order to get better reservation and application. These studies will provide the basis for screening most effective phytoseiid species for controlling T. truncatus. The main results are as follows:1. The4genera and5species of phytoseiid mites in Inner Mongolia were newly discovered, including Neoseiulus barkeri Hughes, Transius morii Ehara, Euseius utilis Liang et Ke, Paraseiulus soleiger Ribaga and Typhlodromus yinchuanensis Liang et Hu, among which E. utilis and N. barkeri are the dominant species of phytoseiid mites.2. The predation amount of seven species of phytoseiid mites to the spider mite T. truncatus at the condition of25℃and80%RH indicated that a female mite of A. orientalis consumed the highest spider mite eggs up to21.86±0.14per day; while N. barkeri consumed the highest larvae up to14.61±0.22per day. A female mite of A. swirskii had the highest amount of predation on all stages of spider mite per day as well as the highest total amount of predation during adult period, which up to43.61±0.50and1324.60±51.98, respectively. Therefore, the predation ability of A. swirskii is stronger compared to other six species. 3. The results of life history of seven species of phytoseiid predators fed on larvae of T. truncatus indicated that the shortest developmental duration is9.16±0.34d and9.16±0.43d both for N. cucumeris and A. swirskii at25℃. P. soleiger and E. utilis had the shorter doubling time for population which was4.0235and4.2739, respectively. A. swirskii and E. utilis had the highest net reproductive rates which were38.3010and31.5412, respectively. P. soleiger and E. utilis had the biggest intrinsic rate of natural increase which was0.1723and0.1622, respectively. P. soleiger and E. utilis have relatively strong population growth potential.4. The results of life history of E. utilis fed on T. truncatus indicated that the developmental durations of various stages, longevity of female adults and longevity of male adults were all shortened as the temperature increased under five constant temperatures within the range of15-35℃, whereas the total egg production, the finite rate of increase and the intrinsic rate of increase were all the biggest at the temperature of25℃, which were44.05℃1.36,31.5412and0.1622, respectively. These results indicated that25℃was optimum temperature for the development of E. utilis. The developmental threshold temperature for egg of E. utilis was the highest up to15.90℃. and the effective accumulated temperature for generation period was97.96degree-day. Therefore, there will be25generations happened each year for E. utilis in Inner Mongolia according to the effective accumulated temperature more than10℃was2000-3000degree-day for whole year in Hohhot.5. The life table of Euseius utilis fed on different foods indicated that the developmental duration of Euseius utilis fed on Carpoglyphus lactis was shortest, was9.46±0.39d. The female average longevity and mean oviposition duration of Euseius utilis fed on Tetranychus truncates was longest, was36.85±0.89d,25.20±0.73d, respectively, and the finite rate of increase Ro, the intrinsic rate of increase rm is most, were31.5412,0.1622and1.1761. The result show that the Tetranychus truncatus is more suitable Euseius utilis developmental than Carpoglyphus lactis and Typha pollen.