浅谈本地寄生和捕食性生物在森林虫害防治策略中的作用

通过讨论和比较运用本地寄生和捕食性生物的可能性,估计本地寄生和捕食性生物对森林害虫的作用,提高本地寄生和捕食性生物种群的方法,以及保护本地寄生和捕食性生物,包括现行的方法和无效的保护策略可能被优化,所以我们应该详细研究种群生态知识,从而由短期保护为主转移至持续发展上。

黏细菌捕食生物学研究进展及其在农业领域的应用潜力

黏细菌(myxobacteria)是一类具有多细胞群体行为特征的捕食性微生物类群,能够以活的微生物细胞或者其他生物大分子作为食物获取营养,同时能够形成抗逆性强的子实体和黏孢子,从而使黏细菌具有良好的环境适应性。黏细菌对于植物病原真菌和细菌的捕食特性使其在植物病害防治方面具有重要的应用潜力,被视为是新的生防微生物类型。本文综述黏细菌对于微生物的捕食机制以及捕食行为的生态学功能,概述捕食性黏细菌作为一种新型的生防微生物在病害防治方面的应用潜力。在此基础上,也讨论目前黏细菌捕食生物学研究存在的问题,旨在为黏细菌捕食作用的深入研究及其在农业生产上的实际应用提供参考。

生物中的长矛和坚盾

自然界中有一场从未休止过的战争,那就是生物之间严酷而无止静的生存竞争。物种为了生存必须具备一系列结构上或行为上的特点——要么进攻,要么防御。在动物进攻性武器库中,牙齿是最引人注目的了。一些食肉动物,像狼、虎、狮、海豹等,都有四个大而犀利的犬齿,极适于捕捉和撕碎猎物。

Study on the Biological Diversity of Nematode-trapping Fungi in Erhai Lake

[Objective]The research aimed to investigate the biological diversity of nematode-trapping fungi in the sediment of Erhai Lake.[Method]616 pieces of sediments were collected from Erhai Lake.The traditional classification and identification methods were used to isolate,purify and identify.[Result]3 genera and 22 species of nematode-trapping fungi were isolated.Arthrobotrys oligospora,A.musiformis and Dactylella leptospora were the dominant species,and their detection rates were 28.05%,16.04% and 8.92% respectively.By analyzing the diversity of nematode-trapping fungi in four seasons,it was found that the biological diversity was richer in summer,spring and autumn,and the diversity indexes were 2.59,2.47 and 2.34 respectively.The diversity index in winter was 1.48 and was lower.Species forming the adhesive nets were predominant;positive rate was 41.00%.[Conclusion]The rich nematode-trapping fungi resource existed in Erhai Lake,and its biological diversity had the seasonal variation characteristic.The nematode-trapping fungi which formed the viscous net were the dominant species in Erhai Lake.

Studies of community structure and seasonal dynamics of planktonic copepods in saline-alkaline ponds

Species abundance and seasonal succession of copepods in saline-alkaline ponds were studied in Zhaodian Fish Farm, Gaoqing County, Shandong Province, from 5 April 1997 to 1 September 1998. The results indicated that in the conditions of salinity ranging from 1.36 to 20 g/L, total alkalinity changing from 2.4 to 7.2 mmol/L and pH 8–9, zooplankton in saline-alkaline ponds was composed of freshwater salt-tolerated species or halophile species, some of which are halobiont species and usually occurs in freshwater. In our study, copepods were predominant in many fish-culture ponds and all control ponds without fishes in spring, late autumn and early winter. Dominant species of copepods were Sinocalanus tenellus, Cyclops vicinus, Thermocyclops taiho- kuensis. The biomass of copepods in the control ponds without fishes was higher than that of the fish-culture ponds.

Nonlinear predator-prey singularly perturbed Robin Problems for reaction diffusion systems

The nonlinear predator-prey reaction diffusion systems for singularly perturbed Robin Problems are considered. Under suitable conditions, the theory of differential inequalities can be used to study the asymptotic behavior of the solution for initial boundary value problems.

No correlation between the diversity and productivity of assemblages: evidence from the phytophage and predator assemblages in various cotton agroecosystems

Biodiversity research has shown that primary productivity increases with plant species number,especially in many experimental grassland systems.Here,we assessed the correlation between productivity and diversity of phytophages and natural enemy assemblages associated with planting date and intercropping in four cotton agroecosystems.Twenty-one pairs of data were used to determine Pearson correlations between species richness,total number of individuals,diversity indices and productivity for each assemblage every five days from 5 June to 15 September 2012.At the same trophic level,the productivity exhibited a significant positive correlation with species richness of the phytophage or predator assemblage.A significant correlation was found between productivity and total number of individuals in most cotton fields.However,no significant correlations were observed between productivity and diversity indices(including indices of energy flow diversity and numerical diversity)in most cotton fields for either the phytophage or the predator assemblages.Species richness of phytophage assemblage and total individual numbers were significantly correlated with primary productivity.Also,species richness of natural enemy assemblage and total number of individuals correlated with phytophage assemblage productivity.A negative but not significant correlation occurred between the indices of numerical diversity and energy flow diversity and lower trophic-level productivity in the cotton-phytophage and phytophage-predator assemblages for most intercropped cotton agroecosystems.Our results clearly showed that there were no correlations between diversity indices and productivity within the same or lower trophic levels within the phytophage and predator assemblages in cotton agroecosystems,and inter-cropped cotton fields had a stronger ability to support the natural enemy assemblage and potentially to reduce phytophages.

Parameter uncertainty in biomathematical model described by one-prey two-predator system with mutualism

In this paper, a three-species system consisting of two predators which are in mutual- ism with each other and preying on the same single prey is considered. Also, the prey and first predator are harvested under optimal conditions. The values of the biological parameters depend on the collection of data from the experts as well as on the nature of the environment in which prey predator system are considered. So the biological para- meters are not precise in reality. This paper presents a different approach to study the prey-predator model with imprecise biological parameters. All the possible equilibrium points are identified and the local as well as global stability criteria under imprecise- ness are discussed. The possibility of existence of bionomic equilibrium is discussed. The optimal harvesting policy is studied using Pontryagin＇s maximum principle. Numerical examples are provided to support the proposed approach.