Prior experience with eggs laid by non-nestmate queens induces egg acceptance errors in ant workers

We studied the effect of prior experience to eggs laid by nestmate and non-nestmate queens on the acceptance of queen-laid eggs by worker wood ants, Formica fusca. We transferred eggs from a non-nestmate queen into colonies during early spring, when their own queen was recommencing egg laying. A few weeks later, workers from these “experienced” colonies accepted eggs of both familiar (44% acceptance) and unfamiliar (40%) non-nestmate queens much more than workers from control colonies (2%) that had only had previous contact with their own queen’s eggs. Thus, prior exposure to eggs laid by a non-nestmate queen induces much greater acceptance of all non-nestmate queen-laid eggs. Mechanistically, we hypothesize that exposure to eggs from several queens may increase acceptance by causing a highly permissive acceptance threshold of non-nestmate queen-laid eggs rather than by widening the template for acceptable queen-laid eggs. These novel results show that egg-discrimination behaviour in F. fusca is flexible and that workers respond to the diversity of eggs experienced in their colony.     

Multiple mating increases the sperm stores of Atta colombica leafcutter ant queens

Multiple mating is likely to be costly for ant queens and yet it is common. Whether multiple mating brings benefits to queens that outweigh the costs has, therefore, received considerable theoretical attention. Empirical tests of hypotheses have been scarce and no clear evidence has been reported. We tested the “multiple-mating-for-more-sperm” hypothesis on individual young queens in a natural population of the leafcutter ant Atta colombica, a monogynous ant characterised by very large colonies and high colony longevity. We found that the number of sperm stored by queens was positively correlated with the number of mates per queen estimated through mother-offspring analysis with microsatellite DNA markers. Queen sperm stores increased on average by 30 million sperm for each additional mate. Life-history information for Atta indicate that the number of stored sperm observed is likely to constrain the reproductive lifespan of queens in nature. Multiple mating, despite costs, may therefore enhance the fitness of Atta queens because it enables them to store more sperm. Received: 19 September 1997 / Accepted after revision: 7 December 1997     

Levels of polycyclic aromatic hydrocarbons and dibenzothiophenes in wetland sediments and aquatic insects in the oil sands area of Northeastern Alberta, Canada

An immense volume of tailings and tailings water is accumulating in tailings ponds located on mine leases in the oil sands area of Alberta, Canada. Oil sands mining companies have proposed to use tailings- and tailings water-amended lakes and wetlands as part of their mine remediation plans. Polycyclic aromatic hydrocarbons (PAHs) are substances of concern in oil sands tailings and tailings water. In this study, we determined concentrations of PAHs in sediments, insect larvae and adult insects collected in or adjacent to three groups of wetlands: experimental wetlands to which tailings or tailings water had been purposely added, oil sands wetlands that were located on the mine leases but which had not been experimentally manipulated and reference wetlands located near the mine leases. Alkylated PAHs dominated the PAH profile in all types of samples in the three categories of wetlands. Median and maximum PAH concentrations, especially alkylated PAH concentrations, tended to be higher in sediments and insect larvae in experimental wetlands than in the other types of wetlands. Such was not the case for adult insects, which contained higher than expected levels of PAHs in the three types of ponds. Overlap in PAH concentrations in larvae among pond types suggests that any increase in PAH levels resulting from the addition of tailings and tailings water to wetlands would be modest. Biota-sediment accumulation factors were higher for alkylated PAHs than for their parent counterparts and were lower in experimental wetlands than in oil sands and reference wetlands. Research is needed to examine factors that affect the bioavailability of PAHs in oil sands tailings- or tailings water-amended wetlands.     

基于J2EE的城市森林病虫害专家系统研究

基于J2EE的城市森林病虫害专家系统将自然语言理解技术、数据库技术、网络技术以及领域专家的病虫害诊断经验和病虫害的预测与防治技术成果有机地结合起来,可以对城市森林常见病虫害进行预测、诊断和防治。本文讨论了城市森林病虫害的现状并介绍了基于J2EE的城市森林病虫害专家系统的主要应用技术、设计思路、系统功能和结构设计。     

Erosion control at construction sites on red clay soils

Five single-treatment methods used to stabilize seeded areas at urban and highway construction sites (asphalt-tacked straw, jute netting, mulch blanket, wood chips, excelsior blanket) were tested for their ability to control erosion of red clay soils by comparisons with exposed sites and multiple treatments. Sediment in runoff from experimental plots was characterized during low and high intensity precipitation from natural rainfall episodes during April, May, and June. Reductions in the total sediment concentration of runoff ranged from 28 percent (asphalt-tacked straw, 50 percent slope) to 90 percent (multiple treatments, 40 percent slope), with 85 percent of the eroded material composed of particles <0.04 mm in diameter. Larger size fractions were effectively reduced by all treatments tested regardless of slope (70 percent decrease). Established grass cover exceeded 90 percent on all plots after 60 days, but sediment release remained similar, attributable to high intensity rainfall, poor establishment of root systems, and piping on plots treated with tacked straw or jute netting. Results indicate that current stabilization methods shift sediment compostion toward a smaller particle size, causing single treatments to be minimally effective for controlling erosion of the major component of red clay soils. Because small particles have the greatest direct effect on aquatic biota, certain impacts of sedimentation may not be measurably lessened by single treatments in regions where red clays predominate even though the total sediment load is reduced by as much as 75 percent. Clearly, a multiple-treatment approach offers significantly greater control of erosion on red clay soils, however, current economic and construction policy represents a substantial deterrent to implementation.     

Test of a Model to Assess the Condition of Lodgepole Pine Stands

/ A predictive model for assessing stand condition as a function of suitability for achieving specified management objectives was originally developed using a data set for only 28 stands. In this study, we evaluate the model using an operational-sized data set composed of currently collected stand inventory data for 238 stands in the Snowy Range of the Medicine Bow National Forest in southern Wyoming. We compared its predictions of old growth suitability to results of a separate special old growth survey. Stands were characterized as profiles of variables derived from stand inventory data, and plotted as points in two-dimensional space where similarity between stands was reflected by the distance between their points. Results suggest the model is useful for classifying stand condition using relatively large sets of data currently collected during routine stand inventories.     

锌冶炼-氯碱复合污染区昆虫中的重金属

采集葫芦岛草地中14种昆虫（植食性、杂食性、肉食性）及蚯蚓,测定生物体内汞、镉、铅含量,研究生物体内重金属污染情况.植食性昆虫汞、镉、铅平均含量分别为0.168、 9.19、 12.58 mg·kg^-1;杂食性昆虫汞、镉、铅平均含量分别为0.375、 24.43、 17.71 mg·kg^-1;肉食性昆虫汞、镉、铅平均含量0.928、 29.78、 18.39 mg·kg^-1;蚯蚓平均汞含量为1.923 mg·kg^-1,葫芦岛生物体内重金属污染严重.不同种类昆虫对重金属的富集能力差异较大,蜗牛、蜻蜓对汞的富集能力较高;蜘蛛对镉、铅的富集能力较高.昆虫体内重金属含量顺序为汞<铅<镉.汞、镉、铅含量由低到高的顺序均为植食性昆虫<杂食性昆虫<肉食性肉昆虫,杂食性昆虫与肉食性昆虫平均镉、铅含量之间较为接近.昆虫体内镉、铅含量之间极显著相关,而汞与镉、汞与铅含量之间的相关性较差.表明昆虫体内镉铅具有同一来源,而汞的来源较为复杂.     

黄花忍冬夜间访花昆虫调查

采用夜间网捕、无味胶粘、固定捕网等方法对黄花忍冬夜间访花昆虫进行调查,根据对所收集标本分类得出该夜间访花昆虫的基本类群组成主要有夜蛾科占54%、螟蛾科占20%、卷蛾科占20%、豆象科占3%、叶蝉占3%等,其中以螟蛾科和夜蛾科所收集到数量最多,分别是9只和19只.其活动时间分析表明,在夜间19∶00~23∶00时间段内各种类活跃程度较高,对植物的到访较为频繁图1,表2,参12.     

Queen and worker policing in the tree wasp Dolichovespula sylvestris

Insect societies are sometimes exploited by workers who reproduce selfishly rather than help to rear the queens offspring. This causes a conflict-of-interest with the mother queen and, frequently, with the non-reproductive workers as well. One mechanism that can reduce conflict is policing, whereby either the queen or other workers aggress egg-laying workers or destroy worker-laid eggs. Here we present the first direct observations of queen and worker policing in natural, unmanipulated colonies of a social insect, the tree wasp Dolichovespula sylvestris. Worker reproduction was common, with workers producing 50% of all male eggs. However, most worker-laid eggs, 91%, were policed within 1 day, whereas most queen-laid eggs, 96%, remained unharmed. The workers were responsible for 51% of all policing events and the queen for 49%. The workers and mother queen also commonly aggressed ovipositing workers, and successfully prevented them from depositing eggs in 14% and 6% of all attempted ovipositions. Hence, both queen policing and worker policing occur and policing acts via two distinct mechanisms: selective destruction of worker-laid eggs and aggression of ovipositing workers. At a general level, our study shows that both centralized and decentralized control can act together to suppress conflict within social groups.Communicated by R. Page