Predicted taxonomic patterns in pheromone production by longhorned beetles

Males of five species of three tribes in the longhorned beetle subfamily Cerambycinae produce volatile pheromones that share a structural motif (hydroxyl or carbonyl groups at carbons two and three in straight-chains of six, eight, or ten carbons). Pheromone gland pores are present on the prothoraces of males, but are absent in females, suggesting that male-specific gland pores could provide a convenient morphological indication that a species uses volatile pheromones. In this article, we assess the taxonomic distribution of gland pores within the Cerambycinae by examining males and females of 65 species in 24 tribes using scanning electron microscopy. Gland pores were present in males and absent in females of 49 species, but absent in both sexes of the remaining 16 species. Pores were confined to indentations in the cuticle. Among the species that had male-specific gland pores were four species already known to produce volatile compounds consistent with the structural motif. These findings support the initial assumption that gland pores are associated with the production of pheromones by males. There were apparently no taxonomic patterns in the presence of gland pores. These findings suggest that volatile pheromones play an important role in reproduction for many species of the Cerambycinae, and that the trait is evolutionarily labile.     

Role of post-dispersal seed and seedling predation in establishment of dandelion (Taraxacum agg.) plants

Dandelion Taraxacum agg. (formerly Taraxacum officinale G.H. Weber ex Wiggers) is a common weed species associated with pastures, grasslands and no-tillage cropping systems throughout its native range in Europe, and more recently introduced into North America, Australasia and elsewhere. Following wind-dispersal from the parent plant, its seeds are subject to predation from a host of invertebrate predators. Similarly, seedling predation may also significantly limit dandelion recruitment. Although such post-dispersal mortality is central to our understanding of dandelion population dynamics and therefore weed control, the precise spatio-temporal role played by different putative seed and seedling predators is poorly understood. Here we studied how seed viability, and seed and seedling predation influenced dandelion recruitment at two contrasting sites in central Europe. The abundance in the field and seed and seedling consumption in the laboratory were determined for the main groups of predators—ground beetles (Coleoptera: Carabiade), terrestrial isopods (Isopoda: Oniscidea) and molluscs (Gastopoda: Pulmonata). At particular sites, seed viability and seedling predation were negatively correlated while the percentage of seeds that succumbed to seed predation was similar. Combined factors accounted for the death of 98% and 87% of exposed seeds. Ground beetles (particularly Amara spp.) and terrestrial isopods (Armadillidium vulgare) were efficient and dominant seed predators, while slugs (Arion lusitanicus) and isopods were important predators of seedlings. While there was no seasonal trend in the intensity of seed predation it decreased towards autumn in parallel with the feeding activity of the declining population of A. lusitanicus. The mortality factors thus varied in their importance, largely between sites and less with the course of the season. Although seed inviability, seed and seedling predation did not stop the recruitment of dandelion seedlings they are crucial factors limiting dandelion populations. Methods of increasing the efficiency of predation of seed as a means of managing weeds are worthy of further study, particularly in areas where dandelion is an invasive species.     

Defensive behavior of ants in a mutualistic relationship with aphids

Mutualistic relationships between ants and aphids are well studied but it is unknown if aphid-attending ants place a greater relative importance on defending aphids from aphid-predators or from competing ant colonies. We tested the hypothesis that aphid-attending ants defend their aphids against aphid-predators more aggressively than against ants from neighboring colonies. We conducted introduction trials by placing an individual non-predatory insect, an aphid-predator, or a foreign conspecific ant on the leaf of a resident ant. We found that ants did not attack non-predatory insects, but did attack competing ants and aphid-predators. When we presented resident ants with both the threats (i.e., predator and competitor) at the same time, residents always attacked potential competitors as opposed to aphid-predators. We suggest this behavior may reduce the likelihood of raids by neighboring colonies. Ants appear to balance both the energetic costs of making an attack and the costs associated with losing aphids to a predator, against the benefits of signaling their defensive ability to rivals and/or preventing rivals from gaining knowledge of a potential food resource.     

长白山阔叶红松林不同演替阶段地表甲虫组成和多样性(英文)

鞘翅目昆虫多样性的变化是森林演替过程的综合反映.于2007年6~8月采用陷阱诱捕法对长白山阔叶红松林带不同演替阶段地表甲虫物种组成和数量进行了调查,并分析了该地区不同演替阶段地表甲虫多样性的变化趋势及主要生境因子对地表甲虫群落的影响.结果显示,长白山阔叶红松林内共诱捕地表甲虫23种,共511头,隶属于10个科.其中个体数最多的为埋葬甲科,物种数最多的为步甲科,优势类群为步甲科和埋葬甲科.不同演替阶段中,次生白桦林地表甲虫物种数和个体数高于原始阔叶红松林和次生针阔混交林,3个生境内地表甲虫多样性无显著差别.地表甲虫高峰期为7月份.不同演替阶段的样地中物种统计数量都没有达到渐进线,次生白桦林样地中实际物种只占估计值的67%,其它2个生境实际物种数都在物种估计值的95%区间范围内,略低于平均值.3个生境的地表甲虫种-多度曲线无显著差异,符合对数分布.胸高断面积和土壤湿度对地表甲虫的分布有显著影响,它们可以解释99.2%的物种与环境之间的关系.     

Bicriteria decision model for farm management of the Colorado potato beetle: development and validation

This paper describes the development and testing of a deterministic simulation model for pest and resistance management of the Colorado potato beetle (CPB). Historically, CPB have developed resistance to new pesticides quickly. A potato farmer's pesticide application decisions trade off current crop yields and resistance development. The simulation incorporates major aspects of beetle life processes, pesticide resistance, and potato growth in order to predict the consequences of a pesticide application strategy over a ten-year planning horizon.     

三江平原湿地不同土地利用生境地表甲虫群落结构

2007年6月至9月,对三江平原湿地6种不同土地利用生境下地表甲虫群落结构的调查结果显示,所采集的1 646个地表甲虫标本隶属25科,其中步甲、隐翅虫和叩甲3科个体数量较多,分别占总数的52.9%、20.1%和10.8%,共同构成本研究区的优势类群。对该甲虫群落的物种丰富度、多样性指数、均匀度指数的分析结果表明,大豆田地表甲虫数量最多,松树林最少;物种丰富度以白桦-蒙古栎林最高,杨树林最低;多样性指数以田埂最高,杨树林最低;均匀度指数以田埂最高,杨树林最低。土地利用方式对地表甲虫数量、多样性有显著影响,对均匀度无显著影响;季节变化对地表甲虫数量无显著影响,但对地表甲虫多样性和均匀度有显著影响。     

HYDROLOGIC IMPACTS OF A LARGE-SCALE MOUNTAIN PINE BEETLE (DENDROCTONUS PONDEROSAE HOPKINS) EPIDEMIC1

The Jack Creek watershed, a 133 km² (51.5 mi²) drainage in southwestern Montana, was impacted by a mountain pine beetle (Dendroctonus ponderosae Hopkins) epidemic in 1975–1977 which killed an estimated 35 percent of its total timber. Analyses of USGS streamflow data for four years prior to and five years after mortality suggest a 15 percent post-epidemic increase in annual water yield, a two-to three-week advance in the annual hydrograph, a 10 percent increase in low flows and little increase of peak runoff.     

西苕溪中上游流域水生甲虫分布与环境的关系

水生甲虫(昆虫纲,鞘翅目)群落结构受多种环境因素的制约.西苕溪中上游流域38个样点共发现水生甲虫12科36个分类单元.优势属是长角泥甲科的Stenelmis属和扁泥甲科的Psephenoides属,出现频度分别为30和22,但有29属的出现频率不大于5.典范对应分析(CCA)表明,鞘翅目群落组成受荫蔽度、总氮、电导率和栖境质量影响最大.样点环境指标聚类结果与CCA结果一致,样点被分为3组.从第1组至第3组,水体中的总氮(2.80→3.52 mg/L)和化学需氧量(14.5→20.29 mg/L)明显上升,荫蔽度(18→6)明显降低.第1组(18个分类单元)和第3组(16个分类单元)的水生甲虫种类组成差异极显著(P＜0.01),第2组水生甲虫多样性最高(26个分类单元).Macronychus,Zaitzevia,Scirtes,Stenocolus,Berosus,Laccobius和Ectopria属可作为清洁水体指示生物,Hydrocassis和Ancyronyx属是重污染水体指示生物.图3表4参16     

A simple model for simulation of insect pheromone dispersion within forest canopies

Synthetic pheromones and other behavioral chemicals are used by land managers to prevent insect-caused tree mortality or crop failure in forest and agricultural systems. Currently, no method exists to continuously measure pheromone concentration or movement in real-time. To improve our understanding of pheromone fate and transport under different forest canopies, results from a set of surrogate pheromone (sulfur hexafluoride tracer) experimental trials were used to evaluate a simple, instantaneous, three-dimensional Lagrangian dispersion model. The model was designed to predict both instantaneous and time-averaged pheromone concentrations. Overall, the results from the model show simulated time-averaged arc maximum concentrations within a factor of two of the observed data. The model correctly matched the sharp peaks and narrow widths of the meandering plumes observed in the instantaneous data, however the magnitude of the instantaneous peaks was often under-estimated. This model and evaluation provide the basis for a tool that can be used to guide deployment of synthetic pheromones or other semiochemicals for monitoring, mass trapping, or disruption of mating or aggregation.     

Sexual contact influences orientation to plant attractant in Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae)

Chemical signals emitted by insects and their hosts are important for sexual communication and host selection. Plant volatiles facilitate the location of suitable hosts for feeding and oviposition, and may moderate responses to sex and aggregation pheromones. While mating has been shown to moderate behavioral responses to pheromones in a number of insects, little is known about the effects of mating on behavioral responses of insects to plant attractants, and even less is known about the mechanisms involved. In this study, mating was shown to decrease behavioral responses of the Colorado potato beetle to a host kairomone within 24 h, and attraction to the kairomone recovers only after 72 h. This decrease in responsiveness also occurs when only contact with the opposite sex is allowed; the effect is not observed with contact among individuals of the same sex. Peripheral olfactory responses to a component of the kairomone correlate with the observed behavioral responses and suggest involvement of antennal receptors in the behavioral change.