上海地区草坪害虫的发生为害初步调查

据作者初步调查 ,2种草坪害虫 :稻切叶野螟Psaralicarsisalis (Walker)和灰翅夜蛾Spodopteramauritia (Boisduval)在上海均以幼虫在土下越冬 ,1年发生 5代 ,后期存在世代重叠现象。灰翅夜蛾虫口密度一直到 7月份都较低 ,8月份虫口密度上升很快 ,所以在上海地区第 3 ,4代幼虫为害最严重 ;稻切叶野螟的幼虫发生期比灰翅夜蛾迟 1 0d左右 ,以 9～ 1 0月份虫口密度最高。在矮生百幕达草坪中稻切叶野螟虫口密度明显高于灰翅夜蛾 ;而在高羊茅、黑麦草等草坪中灰翅夜蛾的虫口密度则远远高于稻切叶野螟。     

应用马尔可夫链法预测晚稻稻飞虱发生程度

根据化州市 1 979～ 1 999年 2 1年晚稻稻飞虱主害代发生程度的时间序列资料 ,应用马尔可夫链预测法对该市 2 0 0 0年和 2 0 0 1年稻飞虱发生程度进行了预测 ,结果与大田实际发生情况完全一致。对1 985～ 1 999年的历史资料进行回检 ,符合率为 96.7%,可对晚稻稻飞虱的发生程度进行超长期预测。     

南美斑潜蝇在昭阳区烤烟上的发生及防治

南美斑潜蝇Liriomyza huidobrensis每年4～8月在云南省昭通市昭阳区的烤烟生育期间发生5～6代,世代重叠,4月上旬为始发期,5月中旬至6月上旬为发生高峰期。完成1代的历期为18～34d;该虫对各种烟乡(镇)的危害属轻度发生,年发生面积1500～3000hm^2,集中危害烟株下部的1～4个叶位叶片。同时提出了南美斑潜蝇的综合防治技术。     

甜菜夜蛾发生规律及其防治研究

甜菜夜蛾在福建漳州龙海每年发生9－10年,3月中下旬开始发生,4－10月份是该虫为害农作物的严重时期,其中8－9月份为全年发生危害的高峰期,通过田间药效试验,评价了不同类型的12种杀虫剂对甜菜夜蛾的防治效果,结果表明,除尽,菜喜以及米满对田间甜菜夜蛾具有较好的防效,锐颈特,杀虫单,敌杀死等药剂对田间甜菜夜蛾几乎失去防效。     

Soil Microfungi in Two Post-Mining Chronosequences with Different Vegetation Types

Soil microfungi were studied in the Sokolov (Czech Republic) post‐mining dumps afforested with Alnus glutinosa and in the Lusatian (Germany) post‐mining dumps afforested with Pinus sylvestris or P. nigra. Microfungi were isolated using the soil dilution plate method. Soil microfungi communities of two chronosequences were compared by species composition, frequency of species occurrence, and colony forming units of fungi (CFU‐counts). Differences in species occurrence were determined. More species of entomopathogenic microfungi were found from the Sokolov post‐mining area in comparison with the Cottbus post‐mining area. Absidia glauca, A. cylindrospora, Penicillium glabrum, and P. janthinellum were the most frequently isolated species from the Cottbus post‐mining area, while A. glauca, Geomyces pannorum, and Trichoderma koningii predominated at the Sokolov post‐mining area.     

Occurrence of Acremonium endophytes in wild populations of Lolium spp. in European countries and a relationship between level of infection and climate in France

Infection with endophytic fungi (Acremonium spp.) was detected in wild populations of Lolium spp. from 15 of 20 European countries. Of 523 populations examined, 38% contained no infection, 48% contained 1–50% infection and 14% contained 51–100% infection. Level of infection was slightly but significantly associated with abundance of Lolium in the sward. For data from France, significant correlations were obtained between level of infection and five climate variables; the highest correlations were with evapotranspiration (0.66, P < 0.001) and water supply deficit (-0.66, P < 0.001). A model established using multiple regression analysis and incorporating five climatic variables, accounted for 56% of total variation; water supply deficit alone accounted for 43%. These climatic variables were shown by geostatistical analysis to account for a spatial structure in infection level. Groups of Lolium populations with a high level of infection were located mostly in Mediterranean regions, where stress from summer drought is common.     

Environmental heterogeneity,dispersal mode,and co‐occurrence in stream macroinvertebrates

Both environmental heterogeneity and mode of dispersal may affect species co‐occurrence in metacommunities. Aquatic invertebrates were sampled in 20–30 streams in each of three drainage basins, differing considerably in environmental heterogeneity. Each drainage basin was further divided into two equally sized sets of sites, again differing profoundly in environmental heterogeneity. Benthic invertebrate data were divided into three groups of taxa based on overland dispersal modes: passive dispersers with aquatic adults, passive dispersers with terrestrial winged adults, and active dispersers with terrestrial winged adults. The co‐occurrence of taxa in each dispersal mode group, drainage basin, and heterogeneity site subset was measured using the C‐score and its standardized effect size. The probability of finding high levels of species segregation tended to increase with environmental heterogeneity across the drainage basins. These patterns were, however, contingent on both dispersal mode and drainage basin. It thus appears that environmental heterogeneity and dispersal mode interact in affecting co‐occurrence in metacommunities, with passive dispersers with aquatic adults showing random patterns irrespective of environmental heterogeneity, and active dispersers with terrestrial winged adults showing increasing segregation with increasing environmental heterogeneity.     

Local and regional rarity in a diverse tropical fish assemblage

Because most species in an ecological assemblage are rare, much of the species richness we value is due to taxa with few individuals or a restricted distribution. It has been apparent since the time of ecological pioneers such as Bates and Darwin that tropical systems have disproportionately large numbers of rare species, yet the distribution and abundance patterns of these species remain largely unknown. Here, we examine the diversity of freshwater fish in a series of lakes in the Amazonian várzea, and relate relative abundance, both as numbers of individuals and as biomass, to the occurrence of species in space and time. We find a bimodal relationship of occurrence that distinguishes temporally and spatially persistent species from those that are infrequent in both space and time. Logistic regression reveals that information on occurrence helps distinguish those species that are rare in this locality but abundant elsewhere, from those that are rare throughout the region. These results form a link between different approaches used to evaluate commonness and rarity. In doing so, they provide a tool for identifying species of high conservation priority in poorly documented but species rich localities.