[Relationships of bee population fluctuation and distribution with natural environment in Anhui province].

In 2002 to approximately 2004, an investigation was made on the bee population dynamics and its relationships with the ecological environment in four ecological regions of Anhui Province. The results indicated that in the mountainous areas of south and west Anhui, there were 46 and 37 species of nectariferous plants, and the distribution density of Apis cerena cerena population was 2.01 and 1.95 colony x km(-2), respectively. In Jianghuai area and Huaibei plain, there were 17 and 12 species of nectariferous plants, which had concentrated and short flowering period and fitted for Apis mellifera Ligustica oysterring and producing, and the distribution density of Apis cerena cerena population was 0. 06 and 0. 02 colony x km(-2), respectively. Bee population fluctuation and distribution was affected by wasp predation. The breeding proportion of Apis cerena cerena to local apis population was 41.5%, 36.8%, 3.1% and 1.1%, and that of Apis mellifera Ligustica was 58.5%, 63.2%, 96.9% and 98.9% in the mountainous areas of south and west Anhui, Jianghuai area, and Huaibei plain, respectively.

[Three-dimensional spatial distribution patterns of Monochamus alternatus and its natural enemy Dastarcus helophoroides].

In 2003 to approximately 2005, the Monochamus alternatus-infected Pinus thunbergii, P. massoniana and P. elliotii in pure and mixed forests were selected as attractants and dissected with one meter section manner, and five aggregation indices were used to analyze the spatial distribution patterns of M. alternatus and its natural enemy Dastarcus helophoroides. The results showed that M. alternatus and D. helophoroides had the horizontal distribution indices of diffused coefficient C > 1, diffused index I delta > 1, Kuno index C(A) > 0, clump intensity index I > 1, and swarm index Iw > 1 in the two stands, suggesting their aggregated horizontal distribution patterns, and except D. helophoroides on the P. massoniana in mixed forest appeared assemble vertical distribution, these two insects all had an even vertical distribution, with their C < 1, I delta < 1, C(A) < 0, Iw < 1, and I < 0. The spatial distribution patterns of M. alternatus and D. helophoroides were consistent, and the latter was spatially following the former.

[Structural characteristics of arthropod community in grapery].

By the method of principal component analysis, this paper analyzed the characteristic parameters of arthropod community and its phytophagous and predacious sub-communities in grapery. The results showed that in the first principal component, the contribution of arthropod community, phytophagous sub-community and predacious sub-community was 66.70%, 73.39% and 54.17%, respectively. For arthropod community, the absolute values of normalized regressive coefficients of individuals' number N, Hill diversity index N1, Hill diversity index N2 and McIntosh index D(mc) were larger, indicating their greater contribution on the community. For phytophagous sub-community, N, N1, N2, N and S (total species) had greater contribution; while for predacious sub-community, the greater contribution was made by N1, N2, Shannon-Wiener diversity index H' and abundance R. Synthetically, N2 and N1 had greater contribution on the arthropod community and its phytophagous and predacious sub-communities in grapery, comparing with other characteristic parameters.

[Community structure and its dynamics of predatory arthropod in different tobacco varieties fields].

With principal component analysis and using community structural characteristic indices, this paper studied the community structure and its dynamics of predatory arthropod in fields planted with tobacco varieties Nc89, Nc82 and K326. The results showed that in all test fields, spiders and predatory insects were the predominant components of the predatory arthropod community, and their relative abundances were 83.25%-86.87% and 13.13%-16.38%, respectively. There was a significant difference in the mean density (individuals per 8 plants) of the most common predatory arthropod groups between different tobacco varieties fields, which was the highest in K326 field, followed by Nc82, and Nc89 field. The individuals of both Linyphiidae and Coccinellidae played the dominant role in the community. There was a significant difference in the richness of predatory arthropod community between Nc89 and Nc82 fields, but the differences of other structural characteristic indices were not significant. The temporal dynamics of the richness and dominancy in all test fields had a trend of low-high-low, and those of the diversity and evenness index were high-low-high.

[Spatial structure of populations Myzus persicae and its predatory natural enemy Erigonidium graminicola].

In this paper, the spatial construction models of populations M. persicae and its predatory natural enemy E. graminicola during different periods were simulated by geostatistics, and their spatial relationships were analyzed. The spatial structure of M. persicae population was described by spherical model, showing an aggregated spatial arrangement. Its spatial dependence was 2.0252-4.1495 m, heterogeneity degree was 10,281.36-300,216.30, and sample variance was 12,176.81-303,433.70. The spatial structure of E . graminicola population was also simulated by spherical model, showing an aggregated spatial arrangement. Its spatial dependence was 3.7328-4.8983 m, heterogeneity degree was 1.4482-4.4134, and sample variance was 1.6941-5.8167. The results and methods could be applied to monitor the temporal and spatial dynamics of target insect pest population in tobacco field, and provide scientific basis for ecological control.

[Effects of imidacloprid on arthropod community structure in tobacco field].

The effects of imidacloprid on the structure of arthropod community and its sub-communities were analyzed. The results showed that after applied imidacloprid, the species number of arthropod community and its pest sub-community was influenced, but that of its natural insect enemy and spider sub-community was not influenced obviously. The individuals of arthropod community and its pest sub-community in both treatment plot (II) and control plot were decreased after the application of imidacloprid on May 23 to June 13, and the decline degree in treatment plot was larger than that in control plot. The individuals of arthropod community and its pest sub-community at treatment plots had a large decrease, and that in control plot had a large increase after imidacloprid application on June 14. Twice applications with imidacloprid did not reduce the number of the individuals of natural insect enemy and spider sub-community obviously. The individuals of tobacco aphids who were dominant in tobacco field decreased obviously within a period of time after application, and hence, the dominant concentration of arthropod community and its pest sub-community declined, and the diversity and stability increased.