首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
采用山核桃产区的较长年份气候资料与病虫害资料,分析了气候变化与病虫害发生的关系,运用数学方法分析了山核桃病虫害发生与气候的相关性。结果表明:气候变化与山核桃病虫危害种类有明显的相关性,气候变暖病虫危害种类增加,危害面积扩大,危害程度加重。  相似文献   

2.
  • ? This review considers potential effects of atmospheric change and climate warming within the timberline ecotone of the Central European Alps. After focusing on the impacts of ozone (O3) and rising atmospheric CO2 concentration, effects of climate warming on the carbon and water balance of timberline trees and forests will be outlined towards conclusions about changes in tree growth and treeline dynamics.
  • ? Presently, ambient ground-level O3 concentrations do not exert crucial stress on adult conifers at the timberline of the Central European Alps. In response to elevated atmospheric CO2 Larix decidua showed growth increase, whereas no such response was found in Pinus uncinata. Overall climate warming appears as the factor responsible for the observed growth stimulation of timberline trees.
  • ? Increased seedling re-establishment in the Central European Alps however, resulted from invasion into potential habitats rather than upward migration due to climate change, although seedlings will only reach tree size upon successful coupling with the atmosphere and thus loosing the beneficial microclimate of low stature vegetation.
  • ? In conclusion, future climate extremes are more likely than the gradual temperature increase to control treeline dynamics in the Central European Alps.
    •   相似文献   

    3.
    Norway Spruce is the economically most important tree species in Europe and has been cultivated in plantations on a large-scale at low elevations, far outside its natural range. In the Bohemian Forest, it naturally occurs in pure stands above 1150 m a.s.l. and as a mixed tree species from 650 to 1150 m a.s.l. An understanding of natural distributions and the diversity along temperature gradients at various elevations is important for conservation, pest management, and predictions of future species assemblages by global warming. Here we investigated the species richness of canopy arthropods in spruce trees along a gradient from 300 to 1300 m a.s.l. using flight-interception traps. We analyzed species richness by combining diversity partitioning with a moving window approach after standardizing sample size per plot. Total richness decreased linearly as the elevation increased, which reflected declining temperatures and a declining regional species pool. Phytophages (herbivores excluding xylophages) were the most influenced. Richness did not peak at the transition zones of the three ecological elevation zones, neither for all species, nor for any of the separate functional groups. However, the proportion of both beetle and true bug spruce specialists significantly increased with elevation and actually doubled in richness above 1000 m a.s.l., where spruce is naturally dominating. Our results indicate that even planted spruce trees at lower elevations maintain high levels of species richness. Further climate warming will promote overall species richness, especially of phytophages, at all elevations. However, spruce specialists may be seriously threatened by global warming.  相似文献   

    4.
    Susceptibility of trees to herbivorous insects is often associated with the tree growth and phenology, both of which are sensitive to a warming climate. Therefore, changes in these traits may affect the intensity of herbivory on trees in the future. We grew silver birch (Betula pendula) populations differing in their growth and phenology in a common garden experiment, and studied the effect of these plant traits on the leaf herbivory, insect herbivore density and community composition of herbivores in two consecutive years, 2011 and 2012. Differences in size and the timing of growth cessation among the birch genotypes were related to differences in herbivore community compositions and herbivory. In 2011, the most intensive herbivore damage was observed on birch genotypes of small size, late bud burst and early growth cessation, and these genotypes originated from high-latitude populations. The differences among birch genotypes in their susceptibility to herbivore damage may lead to differences in their competitive abilities. While climate warming will affect phenology and growth of plants, our study shows, that it may indirectly affect herbivory and herbivore communities as well.  相似文献   

    5.
    In The Netherlands, insect pests on trees and shrubs are being monitored continuously since 1946. During these years, almost all insect pest populations showed marked changes, which may be the result of changes in forest management, shifts in forest composition, climate change and the arrival of new pests from the Mediterranean region or from other continents. In order to generate hypothesis about possible relationships between species ecology and environmental factors, we have analyzed 61 years of population development of the 98 most abundant species in the database while paying attention to life history traits and preferred host plants. The 22 species with infestations lasting a few years only were excluded from the analysis. Of the remaining 76 species, 18 were present over the entire observation period of 61 years. Of the other species, 27 showed a decline and 31 showed an increase. On coniferous trees most species showed decreasing populations. Increasing populations were found most on deciduous trees. Not directly climate-related factors such as changes in forest age, tree composition and forest management were identified as the most important causes for the fluctuations in pest insect populations. Climate change is a possible driver of the population increase in Thaumetopoea processionea, Haematoloma dorsatum and of the population decrease in Euproctis chrysorrhoea. The recently increasing exotic species Eupulvinaria hydrangeae and Pulvinaria regalis were exclusively found on trees in cities, presumably in relation to the higher temperatures of the urban habitat.  相似文献   

    6.
    We examined tree species responses under forest harvesting and an increased fire disturbance scenario due to climate warming in northern Wisconsin where northern hardwood and boreal forests are currently predominant. Individual species response at the ecosystem scale was simulated with a gap model, which integrates soil, climate and species data, stratified by ecoregions. Such responses were quantified as species establishment coefficients. These coefficients were used to parameterize a spatially explicit landscape model, LANDIS. Species response to climate warming at the landscape scale was simulated with LANDIS, which integrates ecosystem dynamics with spatial processes including seed dispersal, fire disturbance, and forest harvesting. Under a 5 °C annual temperature increase predicted by global climate models (GCM), our simulation results suggest that significant change in species composition and abundance could occur in the two ecoregions in the study area. In the glacial lake plain (lakeshore) ecoregion under warming conditions, boreal and northern hardwood species such as red oak, sugar maple, white pine, balsam fir, paper birch, yellow birch, and aspen decline gradually during and after climate warming. Southern species such as white ash, hickory, bur oak, black oak, and white oak, which are present in minor amounts before the warming, increase in abundance on the landscape. The transition of the northern hardwood and boreal forest to one dominated by southern species occurs around year 200. In the sand barrens ecoregion under warming conditions, red pine initially benefits from the decline of other northern hardwood species, and its abundance quickly increases. However, red pine and jack pine as well as new southern species are unable to reproduce, and the ecoregion could transform into a region with only grass and shrub species around 250 years under warming climate. Increased fire frequency can accelerate the decline of shade-tolerant species such as balsam fir and sugar maple and accelerate the northward migration of southern species. Forest harvesting accelerated the decline of northern hardwood and boreal tree species. This is especially obvious on the barrens ecoregion, where the intensive cutting regime contributed to the decline of red pine and jack pine already under stressed environments. Forest managers may instead consider a conservative cutting plan or protective management scenarios with limited forest harvesting. This could prolong the transformation of the barrens into prairie from one-half to one tree life cycle.  相似文献   

    7.
    Agroforestry trees are attacked by a wide spectrum of insects at all stages of their growth just like other annual and perennial crops. Pest management in agroforestry has not received much attention so far, but recent emphasis on producing high value tree products in agroforestry and using improved germplasm in traditional systems, and emergence of serious pest problems in some promising agroforestry systems have increased awareness on risks posed by pests. Insects may attack one or more species within a system and across systems in the landscape, so pest management strategies should depend on the nature of the insect and magnitude of its damage. Although greater plant diversity in agroforestry is expected to increase beneficial arthropods, diversity by itself may not reduce pests. Introduction of tree germplasm from a narrow genetic base and intensive use of trees may lead to pest outbreaks. In simultaneous agroforestry systems, a number of factors governing tree—crop—environment interactions, such as diversity of plant species, host range of the pests, microclimate, spatial arrangement and tree management modify pest infestations by affecting populations of both herbivores and natural enemies. Trees also affect pest infestations by acting as barriers to movement of insects, masking the odours emitted by other components of the system and sheltering herbivores and natural enemies. In sequential agroforestry systems, it is mostly the soil-borne and diapausing insects that cause and perpetuate damage to the common hosts in tree—crop rotations over seasons or years. An integrated approach combining host-plant resistance to pests, exploiting alternative tree species, measures that prevent pest build up but favour natural enemies and biological control is suggested for managing pests in agroforestry. Species substitution to avoid pests is feasible only if trees are grown for ecological services such as soil conservation and low value products such as fuelwood, but not for trees yielding specific and high value products. For exploiting biological control as a potent, low cost and environmentally safe tool for pest management in agroforestry, research should focus on understanding the influence of ecological and management factors on the dynamics of insect pest-natural enemy populations. Scientists and policy makers in national and international institutions, and donors are urged to pay more attention to pest problems in agroforestry to harness the potential benefits of agroforestry.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

    8.

    Key message

    Recent growth changes (1980–2007) in Western European forests strongly vary across tree species, and range from +42% in mountain contexts to ?17% in Mediterranean contexts. These changes reveal recent climate warming footprint and are structured by species' temperature (?) and precipitation (+) growing conditions.

    Context

    Unprecedented climate warming impacts forests extensively, questioning the respective roles of climatic habitats and tree species in forest growth responses. National forest inventories ensure a repeated and spatially systematic monitoring of forests and form a unique contributing data source.

    Aims

    A primary aim of this paper was to estimate recent growth changes in eight major European tree species, in natural contexts ranging from mountain to Mediterranean. A second aim was to explore their association with species’ climatic habitat and contemporary climate change.

    Methods

    Using >315,000 tree increments measured in >25,000 NFI plots, temporal changes in stand basal area increment (BAI) were modelled. Indicators of climate normals and of recent climatic change were correlated to species BAI changes.

    Results

    BAI changes spanned from ?17 to +42% over 1980–2007 across species. BAI strongly increased for mountain species, showed moderate/no increase for generalist and temperate lowland species and declined for Mediterranean species. BAI changes were greater in colder/wetter contexts than in warmer/drier ones where declines were observed. This suggested a role for climate warming, further found more intense in colder contexts and strongly correlated with species BAI changes.

    Conclusion

    The predominant role of climate warming and species climatic habitat in recent growth changes is highlighted in Western Europe. Concern is raised for Mediterranean species, showing growth decreases in a warmer climate with stable precipitation.
      相似文献   

    9.
    The subalpine coniferous forests on the eastern Qinghai-Tibet Plateau provide a natural laboratory for studying the effect of climate warming on terrestrial ecosystems. Research on differences between tree species in their responses to experimental warming can provide insights into their regeneration behavior and community composition under a future warmer climate. We used open-top chamber (OTC) to determine the short-term effect of two levels of air temperature (ambient and warmed) and light (full light and ca. 10% of full-light regimes) on the early growth and physiology of Betula albo-sinensis and Abies faxoniana seedlings. The OTC manipulation increased mean air temperature and soil surface temperature by 0.51 and 0.34°C, respectively, in a 60-year-old plantation and 0.69 and 0.41°C in forest openings, respectively. Warming generally increased plant growth, biomass accumulation, and advanced physiological processes for seedlings of both species. In response to warming, both tree species allocated relatively more biomass to foliage and had significantly decreased root/shoot ratios (R/S), which might provide the two species with an adaptive advantage when other environmental factors were not limiting. Warming may enhance photosynthesis in the two seedlings by increasing efficiency of PSII in terms of increases in F v/F m, photosynthetic pigment concentrations, and apparent quantum yield (Φ). However, the effects of warming on seedling growth and physiological performance varied by light conditions and species. For B. albo-sinensis seedlings, the effects of warming were pronounced only under full-light conditions, while the growth and physiological responses of A. faxoniana seedlings to warming were found only under low-light conditions. Competitive and adaptive relationships between the two species may be altered as a result of response differences to warming manipulation. The shortterm beneficial impact of warming on the early growth and development of the two species suggests that global warming may lead to changes in regeneration dynamics and species composition in subalpine coniferous forest ecosystems.  相似文献   

    10.
    An ecological risk assessment is described for determining the adaptation potential of the approximately 11 000 Swiss Forest Inventory points (FIP) to a hypothetically changing climate. The core of the study is a spatially explicit forest community model that generates estimates of the potential natural vegetation for the entire potential forest area of Switzerland under today's as well as under altered climate regimes. The model is based on the Bayes formula. The probabilities of the communities occurring along ecological gradients are derived from empirical data featuring the relationships between quasi-natural vegetation types and measured site variables. Bioclimatological input variables are the quotient between July temperature and annual precipitation (model version A) or mean annual temperature (model version B). Other site variables include aspect, acidity of top soil and, to account for continentality, geographical region. Climate change scenarios are defined as follows: ‘Moderate climate change’ implies an increase of the mean annual temperature of 4°C to 1.4°C depending on the region (model version B) or an increase of the July temperature of 1.5°C (model version A). ‘Strong climate change’ implies an increase of the mean annual temperature of 2°C to 2.8°C (model version B) or an increase of the July temperature of 3.0°C (model version A).

    The simulation experiment showed that the geographical distribution of 15 potential natural forest types (distinguished on the basis of floristic affinities) varies considerably with changing temperature. Under moderate warming 30–55% of the FIP change their potential natural vegetation type, whereas under strong climate change the values increase to 55–89% depending on the model version used. In the ecological risk assessment the existing tree species composition on any FIP was compared with the expected tree species composition under today's as well as under altered climate regimes. A major finding indicated that, under the current climate conditions, approximately 25–30% (depending on the model version used) of all FIP must be considered as poorly adapted, i.e. less than 20% of the actual basal area consists of tree species that are expected as dominating taxa. This definition applies for trees with a diameter at breast height (DBH) ≥ 12 cm. Moderate warming increases the percentage of poorly adapted FIP by 5–10% (relative to all FIP considered), strong warming leads to a 10–30% increase of poorly adapted FIP (relative to all FIP considered). If trees with a DBH < 12cm are considered, the percentage of FIP that have to be classified as poorly adapted is reduced significantly. There are strong regional differences as exhibited in risk maps of 10 km × 10 km resolution.  相似文献   


    11.
    We argue that the conclusions drawn from the paper “The potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest”, published in the Scandinavian Journal of Forest Research were not erroneous as stated by a letter published in the same journal by Björklund et al. (2015. Erroneous conclusions about current geographical distribution and future expansion of forest insects in Northern Sweden: Comments on Hof and Svahlin (2015). Scand. J. Forest Res)”, but cautious. We regret possible underestimations caused by lack of occurrence records for some species for some areas. However, basing predictions of the impact of future climate change on the distribution of species on current range maps likely leads to grave overestimations of future range predictions since current range maps assume species are homogenously distributed throughout the landscape, which is often not the case. We argue that underestimating the distribution range of pest species rather than overestimating their distribution pinpoints areas that may need extra attention in future better, and therefore chose to be cautious rather than bold. We further like to stress that one should always be aware of possible insect outbreaks throughout the region, not only because predictions may underestimate the future distribution of species but also since the location and likelihood of insect pest outbreaks is not only determined by climatic factors.  相似文献   

    12.
    The future of the endemic Taiwan spruce (Picea morrisonicola) under climate change is of great concern. It is the southernmost species of the genus and its current distribution is limited to high altitudes of Taiwan. As a first step toward assessing the impact of future temperature changes on the species, we quantified the effects of past monthly growing degree days (GDD) on the height growth of plantation Taiwan spruce based on nonlinear mixed-effects growth analysis. Our results showed that past GDD variations had both positive and negative effects on the height growth of the species. July of the preceding year had the greatest influence on current year height growth. An increase in the mean GDD level of the current May would also promote height growth. In contrast, a warmer previous November or current January had negative effects on height growth. If the established height growth–GDD relationship holds, the influences of climate change on Taiwan spruce height growth will depend on the timing of the temperature increases, as well as on the trees current growth stages. Our results suggested that a warmer climate would have a greater influence on trees that are still in the early stages along the height growth trajectory. The established height growth–GDD relationship will be a keystone for developing models assessing how Taiwan spruce responds to climate change.  相似文献   

    13.
    Outputs from the HadCM3 Global Climate Circulation Model according to scenarios A2 and B1 were used for climate change predictions in Lithuania. According to scenario A2, the annual temperature will increase by approximately 4.0 °C from 2061 to 2090, while scenario B1 predicts an increase of 2.0 °C. In contrast to scenario B1, scenario A2 predicts an annual increase in precipitation of 15–20 % at the end of the century. Based on the predicted climatic data for the two scenarios and climate maps by European Food Safety Authority for the EU, we created climate analogues for Lithuania for 2031–2060 and 2061–2090. These areas were overlain by the digital map of native tree species distributions in Europe, which was created from the European Forest Genetic Resources Programme database. If climate changes occur according to scenario B1, in 2031–2060, Lithuania’s climate will become suitable for approximately five to six alien species, such as Acer campestre, Acer pseudoplatanus, Fagus sylvatica, Populus nigra, and Prunus avium. In 2061–2090, these species will be joined by Sorbus domestica and Tilia platyphyllos. If climate changes occur according to scenario A2, at the end of the twenty-first century, Castanea sativa, Quercus pubescens, and Sorbus torminalis could expand this list. With respect to species dispersal rates, there is a high probability that the species A. campestre, A. pseudoplatanus, P. nigra, and P. avium will become immigrants to Lithuanian forests at the end of the twenty-first century. Approximately 20 new species native to Europe will be suitable for cultivation (scenario A2). Climate change will affect the distributions of native species too. An increase in the proportion of deciduous tree species (except Alnus incana) and some reduction in the proportion of conifers, Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), are expected in Lithuanian forests.  相似文献   

    14.
    The Siberian moth, Dendrolimus sibiricus, Tschtv. is the most harmful defoliator of coniferous forests in North Asia. The pest has already spread over the Urals and continues moving westwards. Recently, it has been recommended for quarantine in member countries by European and Mediterranean Plant Protection Organization (EPPO). The performances of the pest on coniferous species planted in Europe were assessed on a range of potted trees corresponding to the spectrum of economically important conifers in the EU: European larch Larix decidua, Norway spruce Picea abies, Scots pine Pinus sylvestris, European black pine Pinus nigra, and the North American species: Douglas fir Pseudotsuga menziesii and grand fir Abies grandis. Larvae showed a potential to survive and complete the development on all these host tree species. Favorable hosts were grand fir, European larch, and Douglas fir that allowed higher survival, better larval development, and as a result, yielded heavier pupae and adult moths with higher longevity. Black pine was a poor host but, however, could still support larval and pupal development. Norway spruce and Scots pine had an intermediate behavior. If accidentally introduced to Europe, the Siberian moth may become especially damaging in forest stands predominated by European larch and by the North American firs. Norway spruce and especially the two-needle pines will be less prone to intensive defoliation by this species. The fact that the pest may damage the range of economically important coniferous species should be taken into account in the pest risk assessment for Europe and also for North America where the Siberian moth occurrence is considered likely.  相似文献   

    15.
    Disturbance is a key factor affecting plant species richness and it has been hypothesized that species richness reaches a peak some time after disturbance occurs. Managed boreal forests are characterized by large scale disturbance in the form of clear-cuttings, which partly resembles natural disturbance regimes. The young stands however, which may be important to many plants, are often homogenous and dense compared to naturally regenerated stands. We examined previously unstudied effects of disturbance, succession and management practices on plant species richness in boreal forests. Survey data covering the northern and central parts of Sweden (4465 plots) were used to compare species richness and composition in four stand maturity classes—“cutting”, “young”, “pre-mature” and “mature”, and two fertility classes—“rich” and “poor”. In addition, the effect of thinning was examined in young and pre-mature forests.  相似文献   

    16.
    Forecasts of rapid climate change raise the question how quickly species can evolutionarily adapt to future climates. The adaptability of forest trees to environmental changes is generally promoted by high levels of genetic diversity and gene flow, but it can also be slowed down by long generation times and low mortality of established trees. Here, we investigate the adaptation of Scots pine (Pinus sylvestris) and Silver birch (Betula pendula) to climate change induced prolongation of the thermal growing season. We use quantitative genetic individual-based simulations to disentangle the relative roles of mortality, dispersal ability and maturation age for the speed of adaptation. The simulations predict that after 100 years of climate change, the genotypic growth period length of both species will lag more than 50% behind the climatically determined optimum. This lag is reduced by increased mortality of established trees, whereas earlier maturation and higher dispersal ability had comparatively minor effects. The evolutionary lag behind environmental change shown in our simulations stresses the importance of accounting for evolutionary processes in forecasts of the future dynamics and productivity of forests. Sensitivity of the adaptation speed to mortality suggests that species experiencing high mortality rates as well as populations subject to regular disturbances such as storms or fires might be the quickest to adapt to a warming climate.  相似文献   

    17.
    Monitoring populations of pests and their natural enemies under different management situations and seasonal weather parameters provides extremely useful information for taking preventive measures against pest outbreaks. The abundance, spatial and temporal distributions of herbivorous insects and arthropod natural enemies on Alnus species were monitored at four sites in Kabale district, Uganda between June 1999 and August 2000. Chewing insects, dominated by Coleoptera (75%), constituted the majority of insect herbivores sampled. Dominant and potentially serious pests of Alnus included Apion globulipenne, an unidentified Chrysomelidae (Coleopt. 27), Phymateus viridipes, Coloborrtics corticina and a Cacopsylla species (Homoptera: Psyllidae). Spiders were the predominant natural enemies accounting for 64% of the total natural enemies encountered, followed by parasitic Hymenoptera (30%). There were marked spatial and temporal variations in arthropod abundance. Among sites, mean abundance of total insect herbivores and total natural enemies on A. acuminata over 15 months ranged from 3.8–8.5 and 3.3–4.7 individuals per 1-m branch length respectively. Over the same period, mean number of total insect herbivores and total natural enemies on A. nepalensis that was studied at only one site were 11.9 herbivores and 4.2 natural enemies per 1-m branch length. Populations of most insect orders increased in the wet season although the greatest herbivore abundance was evident in the dry season. Further studies are necessary on the impact and management strategies of the potentially important insect pests and natural enemies on Alnus.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

    18.
    The future trajectory of forest ecosystems under climate change is heavily debated. Previous studies on the impacts of climate change on forest ecosystems have focused mainly on direct effects of altered climatic conditions, whereas interactions with disturbance events have been largely neglected. The aim of this study is to explore interactions of drought with fire disturbance and to assess their effects on tree species shifts in the European Central Alps. Tree recruitment after a stand replacing wildfire in the Rhone valley, Switzerland, was measured along an altitudinal temperature moisture gradient. Recruitment was more successful in pioneer species (Betula pendula, Populus tremula and Salix appendiculata) than in pre-fire stand forming (PFSF) species (Larix decidua, Picea abies and Pinus sylvestris). Seedling and sapling density was not related to fire intensity, but it correlated with the distance to the forest edge in PFSF species. The window of opportunity for seedling establishment was short (1–2 years), and moisture deficit was the main limiting factor for tree recruitment at lower altitudes. We suggest that prolonged drought periods, as projected under continued global warming, will further aggravate tree recruitment success after fire disturbance at low altitudes of the Central Alps and may eventually lead to a shift from PFSF species to either more drought-tolerant species or to forest-free vegetation.  相似文献   

    19.
    In northwestern Portugal, peasants have developed complex vineyard (Vitis vinifera) systems comprising agroforests composed of host trees, vines, annual crops and in some cases animals. Until recently these vineyards suffered very few pest problems and received relatively low pesticide loads. In the last few years, new policy and market forces have prompted the conversion of many of these systems to monoculture thereby decreasing the biodiversity inherent to traditional vineyards. Many scientists are concerned that with accelerating rates of vineyard simplification insect pest and disease problems may increase due to lack of habitat and resources for natural enemies or to a concentration of preferred host plants for specific pathogens and herbivores. During the growing seasons of 1997 and 1999 we conducted several farm surveys of traditional agroforestry and modernized, monoculture farms. We conducted field measurements to elucidate trends in insect pest and disease incidence in both types of vineyards. Our surveys revealed that monoculture vineyards exhibited lower number of species of predators and parasites and correspondingly higher densities of two grape herbivores (Lobesia botrana and Empoasca vitis) than diverse vineyard agroforests. Botrytis bunch rot seemed more prevalent in the monoculture systems, which also received increased fungicide applications when compared to the traditional vineyards. Although preliminary, our studies suggest that new vineyard designs may be more productive, but such gains occur at the expense of biodiversity and agricultural sustainability, reflected on higher pest vulnerability. Further agroecological studies are needed to account for the full ecological costs of the modernization of traditional vineyard agroforests.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

    20.
    Tropical insect species show year-round breeding activity due to favourable climatic conditions. However, most species also display seasonal reproductive peaks, but little is known about underlying causes of temporal density changes. We investigated population dynamics of the pest predator Rhynchium haemorrhoidale (F.) (Hymenoptera: Eumenidae) and its natural enemies in relation to season, climate and varying shade tree composition in cacao agroforestry systems in Central Sulawesi (Indonesia). Nesting of R. haemorrhoidale showed clear seasonality with highest densities in the wet season and lowest in the dry season, which was not related to changes in temperature. Wasp densities increased with land-use intensity, presumably because less-shaded areas offer more favourable climatic conditions and higher densities of the major prey, the cacao pest Agathodes caliginosalis (Lepidoptera: Pyralidae). Pupal body size was higher in June than in November indicating increasing intraspecific competition due to high wasp densities and food shortage at the beginning of the wet season. Body size between habitat types was similar, thus season appeared to be more important than habitat in terms of food supply. High wasp densities in the wet season were associated with high diversity of the altogether seven parasitoid species. In conclusion, we found a pronounced seasonality of the wasp R. haemorrhoidale and a preference for little shaded agroforestry, which may be due to enhanced temperature and density of its prey. Our data indicate a high potential for biological control of a major cacao pest by management of nesting sites of R. haemorrhoidale.  相似文献   

    设为首页 | 免责声明 | 关于勤云 | 加入收藏

    Copyright©北京勤云科技发展有限公司  京ICP备09084417号