Spatial distribution of Holcocerus hippophaecolus (Lepidoptera: Cossidae) pupae in a seabuckthorn (Hippophae rhamnoides) stand

The seabuckthorn carpenter moth, Holcocerus hippophaecolus, which has a generation time of four years, is recently becoming one of the major pests of the seabuckthorn (Hippophae rhamnoides) in Inner Mongolia, Liaoning, Shanxi, Ningxia and Shaanxi of China (Hua et al., 1990). The larvae of the H. hippophaecolus mainly damage the stems and roots of the seabuckthorn, and the mature larvae pupate in the soil. The spatial distribution of the pupae was analyzed by using biostatistics and geostatistics in order to effectively control the insect and further study the spatial distribution of the population. Results show that most of the pupae (90%) had an eclosion time span from early June to the end of July. The sex ratio of the pupae was nearly 1:1 in the woodland samples. In addition, 24.3% of the 971 trees investigated had pupae and it ranged from 0 to 4 per tree within a distance of 1.3 m from the base of the stem. 90% of the pupae were aggregated within a distance of 1 m from the base of the stem. The pupae show intense spatial aggregation in the sampled woodland which had an 11.1 m spatial dependence and a 90.7% intensity in the local spatial continuity. Moreover, the population presented an intensive spotted distribution and many aggregated spots were found in the woodlands. As for the relationship between grid size and variogram of the pupae, the variations in the range, the intensity of local spatial continuity and the sill were all very low or non-existent when the grid size was 5 m, 6 m or 7 m. Whereas, the value of the decisive coefficient was the biggest when the grid size was 5 m making it the ideal grid size. __________ Translated from Acta Ecologica Sinica, 2006, 26(10): 3232–3237 [译自: 生态学报]     

Spatial distribution of Holcocerus hippophaecolus (Lepidopetera: Cossidae) pupae in a seabuckthorn (Hippophae rhamnoides) stand.

The seabuckthorn carpenter moth,Holcocerus hippophaecolus,which has a generation time of four years,is recently becoming one of the major pests of the seabuckthorn (Hippophae rhamnoides) in Inner Mongolia,Liaoning,Shanxi,Ningxia and Shaanxi of China (Hua et al.,1990).The larvae of the H.hippophaecolus mainly damage the stems and roots of the seabuckthorn,and the mature larvae pupate in the soil.The spatial distribution of the pupae was analyzed by using biostatistics and geostatistics in order to effectively control the insect and further study the spatial distribution of the population.Results show that most of the pupae (90%) had an eclosion time span from early June to the end of July.The sex ratio of the pupae was nearly 1:1 in the woodland samples.In addition,24.3% of the 971 trees investigated had pupae and it ranged from 0 to 4 per tree within a distance of 1.3 m from the base of the stem.90% of the pupae were aggregated within a distance of 1 m from the base of the stem.The pupae show intense spatial aggregation in the sampled woodland which had an 11.1 m spatial dependence and a 90.7% intensity in the local spatial continuity.Moreover,the population presented an intensive spotted distribution and many aggregated spots were found in the woodlands.As for the relationship between grid size and variogram of the pupae,the variations in the range,the intensity of local spatial continuity and the sill were all very low or non-existent when the grid size was 5 m,6 m or 7 m.Whereas,the value of the decisive coefficient was the biggest when the grid size was 5 m making it the ideal grid size.     

沙棘木蠹蛾蛹的空间分布

沙棘木蠹蛾（Holcocerus hippophaecolus Hua, Chou , Fang et Chen）是近几年在内蒙古、辽宁、山西、宁夏和陕西等地大面积爆发的一种钻蛀性害虫,该虫约4a完成1代,主要以幼虫危害沙棘（Hippophae rhamnoidea）的根部和干部,老熟幼虫在土壤中化蛹.为了解种群的空间结构,从而有效控制其危害,应用生物学统计方法和地质统计学（Geostatistics）方法对沙棘木蠹蛾蛹的空间分布特性进行了分析研究.结果表明：约90%的蛹在6月初到7月末之间羽化,而7月份羽化的数量占总数的一半之多.在调查样地中,雌雄蛹的比例基本为1：1.每株沙棘树周围,蛹的数量为0～4个,有蛹株率仅为24.3%.蛹在距离根基部周围1.3m的范围内均有分布,不同分布区间内蛹的数量变化没有一定的规律性,但90%的蛹分布在距根基部1m的范围内.沙棘木蠹蛾蛹的种群呈现较明显的空间聚集状态,空间依赖范围大小为11.1m,局部空间连续性强度为90.7%,呈现较明显的斑块状分布,在整个区域内有很多聚集点.对不同样方大小的变异曲线图进行比较得知：样方边长分别为5、6、7m时,变程、空间局部连续性强度和基台值的变化幅度均很小,几乎相等,而样方边长为5m时的决定系数较大,此样方为最适样方大小.     

沙棘木蠹蛾卵和幼虫空间分布的地统计学分析

沙棘木蠹蛾(H olcocerushippophaecolus Hua,Chou ,Fang et Chen)是近几年在内蒙古、辽宁、山西、宁夏和陕西等地大面积爆发的一种钻蛀性害虫,其危害发生在幼虫期,主要危害沙棘(H ippophae rhamnoidea)的根干部。为了有效地控制其危害,深入了解种群的空间结构,利用地统计学方法分析了两种受害程度不同的林分内沙棘木蠹蛾幼虫种群和重度受害林分内卵块的空间分布特性。结果表明:两种受害程度不同的林分内,沙棘木蠹蛾的危害具有显著差异,轻度受害林分内无虫样本所占的比例较大,达70 % ,而重度受害林分内不到2 0 % ;虫口密度在轻度受害林分内超过6头/株的只有6 .9% ,而重度受害林分内高达31.9%。根据全方向的变异函数曲线图分析得知:重度受害林分和轻度受害林分内幼虫种群的空间依赖范围分别为7.3m和87.4 18m,而局部空间连续性强度分别为0 .914和0 .178。重度受害林分内幼虫表现较强的空间聚集性,而轻度受害林分则表现为随机分布。在重度受害林分中,单株沙棘树上沙棘木蠹蛾卵块数量最多的为11个,最少的为1个,有卵株率达72 %。分别采用四种不同的理论模型来拟合卵块的实际变异曲线图,得知其全方向的变异函数曲线为指数型,空间依赖范围大小为3.6 m,局部空间连续性强度为0 .876 ,卵块在重度受害林分中呈现较强     

褐梗天牛幼虫和成虫空间分布的地统计学研究

褐梗天牛(Arhopalus rusticus Linnaeus)是一种对松、杉、柏等林木危害非常严重的蛀干害虫,主要危害针叶树的衰弱木以及火灾后的枯立木,是继松褐天牛之后携带拟松材线虫能力最强的蛀干害虫。为了更好地控制其危害,深入地研究其种群空间格局,运用地统计学方法分析了3块受害程度不同的油松林内褐梗天牛幼虫和成虫的空间分布特性。结果表明:3种受害程度不同的林分内,褐梗天牛的危害具有显著差异,轻度受害林分内有虫株率为30.8%,中度受害林分内有虫株率为44.3%,而重度受害林分内高达78.3%。根据变异函数曲线图分析得知:轻度受害林、中度受害林和重度受害林内褐梗天牛幼虫种群空间分布最优拟合模型分别为高斯模型、高斯模型和指数模型,成虫的种群空间分布最优拟合模型均为线性模型。在3种林分中褐梗天牛幼虫数量具有明显的空间依赖性,轻度受害林、中度受害林和重度受害林内幼虫数量的空间依赖范围分别是19.10、11.97、61.98m,其空间连续性强度分别是0.646、0.784和0.500;成虫的空间依赖范围分别是43.08、43.23、44.17m,其空间连续性强度分别是0.044、0.021和0.171,但其成虫的数量在空间呈随机分布,没有表现出空间依赖性。根据垂直分布图分析得出:褐梗天牛幼虫和成虫在油松上主要集中聚集在某个高,然后随着高度增加密度降低,随着高度接近地面密度也降低。用Kriging插值法生成的空间分布图显示幼虫在空间分布上具有明显的聚集性,其聚集中心主要集中在林地中心,由林地中心株向整个林地扩散,而成虫则表现为随机分布。     

陕西省栎黄枯叶蛾蛹的空间分布

栎黄枯叶蛾(Trabala vishnou gigantina Yang)是近年来在陕西吴起沙棘林中大面积暴发的一种食叶害虫,为了解其种群空间结构,有效控制危害,利用地统计学等方法,对不同坡向和疏密度沙棘纯林中的栎黄枯叶蛾蛹的空间分布进行了研究。结果表明:栎黄枯叶蛾化蛹的高峰期为8月中旬,雄性幼虫较雌性幼虫平均早3.7 d化蛹;蛹在阴坡的东南向和阳坡的西、北两方向分布比例最大;在距沙棘树基部30.00—75.00 cm范围处分布密集。由全方向的变异函数曲线分析得知:阴坡密林、阴坡疏林、阳坡密林、阳坡疏林中,栎黄枯叶蛾蛹的空间依赖范围分别为95.609、47.379、79.238、42.415 m,空间变异值分别为0.760、0.561、0.649、0.407;且在阴阳两坡向的密林中均呈聚集分布,疏林中均呈随机分布。用Kriging插值方法生成的空间分布图显示蛹在空间分布上存在一定的边缘效应,且方向性较明显。     

不同林分白蜡树云斑白条天牛种群空间格局地统计学分析

云斑白条天牛是我国重要林业害虫,在黄河三角洲地区对白蜡树造成严重危害。利用地统计学方法,通过调查城市行道绿化林、庭院绿化林、公路林和片林4种不同林分类型的白蜡树林地,以产卵刻槽、排粪孔和羽化孔为调查指标,对危害白蜡云斑白条天牛种群卵、幼虫、成虫(蛹)的空间格局进行了研究。结果表明:除片林样点成虫(蛹)的半变异函数模型为指数模型外,危害白蜡云斑白条天牛种群卵、幼虫、成虫(蛹)在不同林分类型下的半变异函数模型均为球形模型,其指明空间分布均为聚集分布,种群的聚集分布习性与林分类型相关性不强。但不同林分类型云斑白条天牛种群的空间相关性地统计学参数存在差异,片林调查样点的卵、幼虫和成虫(蛹)的变程a、块金值C0和基台值C0+C均小于其他3种林分类型的统计值,片林样点成虫(蛹)的半变异函数模型不同于其他林分类型为指数模型。     

The spatial distribution of the wheat-bulb fly,Leptohylemyia coarctata (fall.) (Diptera: Anthomyiidae)

The spatial distribution of the eggs, larvae, pupae and adults of the wheat-bulb fly was investigated by fitting 42 sets of data comprising 1334 samples to the Poisson and negative binomial distributions, and by using the power law (S²=am^b). In general, the tests indicated that all stages were aggregated and fitted the negative binomial model.     

Spatial Distribution and Minimum Sample Size for Overwintering Larvae of the Rice Stem Borer Chilo suppressalis (Walker) in Paddy Fields

The rice stem borer, Chilo suppressalis (Walker), feeds almost exclusively in paddy fields in most regions of the world. The study of its spatial distribution is fundamental for designing correct control strategies, improving sampling procedures, and adopting precise agricultural techniques. Field experiments were conducted during 2011 and 2012 to estimate the spatial distribution pattern of the overwintering larvae. Data were analyzed using five distribution indices and two regression models (Taylor and Iwao). All of the indices and Taylor’s model indicated random spatial distribution pattern of the rice stem borer overwintering larvae. Iwao’s patchiness regression was inappropriate for our data as shown by the non-homogeneity of variance, whereas Taylor’s power law fitted the data well. The coefficients of Taylor’s power law for a combined 2 years of data were a?=??0.1118, b?=?0.9202?±?0.02, and r ²?=?96.81. Taylor’s power law parameters were used to compute minimum sample size needed to estimate populations at three fixed precision levels, 5, 10, and 25% at 0.05 probabilities. Results based on this equation parameters suggesting that minimum sample sizes needed for a precision level of 0.25 were 74 and 20 rice stubble for rice stem borer larvae when the average larvae is near 0.10 and 0.20 larvae per rice stubble, respectively.     

黑角直缘跳甲幼虫空间分布型及抽样技术的研究

通过运用二种回归方法和六种聚集度指标对黑角直缘跳甲幼虫的空间格局和抽样技术进行了研究。所有的指标表明黑角直缘跳甲幼虫在林间呈聚集分布,分布的基本成分是个体群,且个体间相互吸引。在空间分布型研究的基础上提出了理论抽样数和序贯抽样方案。通过不同抽样方式的精确度比较,表明对角线抽样方式最佳。     

油松毛虫幼虫,蛹种群聚集动态的分析

本文用灰色聚类分析、模糊聚类分析方法研究油松毛虫(Dendrolimustabulaeformis)幼虫、蛹种群的聚集动态。两种聚类分析方法综合分析结果表明:油松毛虫从越冬幼虫至蛹的种群聚集动态过程可分为:高度聚集,中等聚集程度和低聚集度三个阶段,它们各自相应的生物学阶段是:“刚刚上树期”,“上树后重新分布,扩散期(死亡率较高期)”,“取食盛期”以及蛹期,其中前二个阶段为“高聚集度”阶段。     

The arrangement of resources in patchy landscapes: effects on distribution, survival, and resource acquisition of chironomids

The spatial arrangement of resources in patchy habitats influences the distribution of individuals and their ability to acquire resources. We used Chironomus riparius, a ubiquitous aquatic insect that uses leaf particles as an important resource, to ask how the dispersion of resource patches influences the distribution and resource acquisition of mobile individuals in patchy landscapes. Two experiments were conducted in replicated laboratory landscapes (38×38 cm) created by arranging sand and leaf patches in a 5×5 grid so that the leaf patches were either aggregated or uniformly dispersed in the grid. One-day-old C. riparius larvae were introduced into the landscapes in one of three densities (low, medium, high). In experiment 1, we sampled larvae and pupae by coring each patch in each landscape 3, 6, 12, or 24 days after adding larvae. In experiment 2, emerging adults were collected daily for 42 days from each patch in each landscape. In aggregated landscapes, individuals were aggregated in one patch type or the other during a particular developmental stage, but the ”preferred” type changed depending on developmental stage and initial density. Adult emergence was lower by about 30% in all aggregated landscapes. In dispersed landscapes, individuals used both types of patch throughout their life cycles at all initial densities. Thus, patch arrangement influences the distribution of mobile individuals in landscapes, and it influences resource acquisition even when average resource abundance is identical among landscapes. Regardless of patch arrangement, high initial density caused accumulation of early instars in edge patches, 75% mortality of early instars, a 25% increase in development time, and a 60% reduction in adult emergence. Because mortality was extremely high among early-instar larvae in high-density treatments, we do not have direct evidence that the mechanism by which patch arrangement operates is density dependent. However, the results of our experiments strongly suggest that dispersion of resource patches across a landscape reduces local densities by making non-resource patches available for use, thereby reducing intraspecific competition. Received: 20 July 1999 / Accepted: 28 January 2000     

Distribution, Abundance and Molecular Analysis of Genus Barbadocladius Cranston & Krosch (Diptera, Chironomidae) in Tropical, High Altitude Andean Streams and Rivers

The distribution of the genus Barbadocladius Cranston & Krosch (Diptera: Chironomidae), previously reported from Chile to Bolivia, has extended northwards. Larvae, pupae and pupal exuviae of this genus have been found in the high mountain tropical streams of Peru to 9°22′56″, but are restricted to very high altitude streams (altitudes over 3,278 m asl) compared to the lower altitude streams (below 1,100 m asl) in which the genus is reported in Chile and Argentina. Based on morphological studies, both described species in the genus, Barbadocladius andinus Cranston & Krosch and Barbadocladius limay Cranston & Krosch, have been found in Peru as pupae or pupal exuviae. Morphological analysis of the larvae and pupae revealed no differences between the two described species from Patagonia and Peru, which are of similar size and with a similar armament of hooklets and spines in pupal tergites and sternites. However, molecular analysis of larvae and pupae revealed that in Peru, there are at least two different evolutionary lines, one distributed widely and another restricted to one site. Phylogenetic analysis (using cox1 mitochondrial sequences) of all available sequences of Barbadocladius shows that the Chilean and Argentinean material differs from that of Peru. Therefore, a total of four molecular segregates are identified, although morphologically, neither larvae nor the pupae may be differentiated.     

Dynamic tree aggregation patterns in a species‐poor temperate woodland disturbed by fire

Abstract. Question: How does fire affect the aggregation patterns of trees in a species‐poor oak woodland? Location: East‐central Minnesota, USA. Methods: More than 10 000 trees with DBH > 2 cm (comprising more than 11 000 stems) were monitored in a 16‐ha grid on an annual basis from 1995‐ 2001 in a species‐poor temperate woodland. Different portions of the grid experienced different frequencies of controlled burns. Aggregation indices were calculated for individual species and individual size classes within species. A community‐wide aggregation index was also calculated for different burn units. Spatial data were managed, and many of the aggregation indices calculated using a GIS ArcInfo? (ESRI). Results: Fire initially increased clumping, although repeated fires reduced it, a finding that suggests a corollary to the intermediate‐disturbance hypothesis, the corollary stating that intermediate levels of disturbance are expected to maximize community‐wide patterns of aggregation. Analyses also showed that all species are aggregated at small scales, that the degree of aggregation of a stem type (species or size) declines with distance from individual stems, that the degree of aggregation of large stems is usually less than that of small stems, and that rare species are more aggregated than common species. Findings from this study are consistent with those from similar studies in other temperate and tropical forests, woodlands, and savannas. Conclusion: The spatial patterns of trees in this woodland are dynamic, continually changing in response to the relative strengths of the often opposing forces of competition, which tends to reduce clumping, and disturbance, which, at low and intermediate frequencies, tends to increase it.     

Larval dispersal and cannibalism in a natural population of Zophobas atratus (Coleoptera: Tenebrionidae)

A natural population, of the tenebrionid beetle Zophobas atratus was studied in an attic in El Zamorano, Honduras. Larvae were living in bat guano and were, densest in the deepest part of the guano. No pupae or pharate pupae were found in the guano: they were always located a small distance away from the guano pile. Adults occurred on the guano surface and the beams and tiles of the roof. When larvae of three different ages and weights were marked and released in the guano, only the older, larger larvae were recaptured away from the guano, indicating a correlation between larval dispersal and increased weight and/or age. When 50 pharate pupae were exposed to a natural population of active larvae, only 4 (8%) survived after 5 days. This intense cannibalism of pharate pupae is consistent with the hypothesis that inhibition of pupation by crowding and the associated pre-pupal dispersal evolved, at least partly, in response to cannibalism.     

A resource-based conservation approach for an endangered ecotone species: the Ilex Hairstreak (Satyrium ilicis) in Flanders (north Belgium)

Ecotones are often species-rich and harbour specific resources and environmental conditions for invertebrates. Despite their functional significance for conservation, they are often not explicitly included in biotope typologies relevant to conservation policy and management (e.g., the European Habitats Directive). The Ilex Hairstreak (Satyrium ilicis) is a species of European conservation concern and a typical ecotone species inhabiting gradients from open (e.g., heathland, grassland) to closed vegetation (e.g., woodland). Here, we investigated its occurrence and habitat use at different spatial scales in Flanders (north Belgium). At a regional scale, species distribution modelling predicted 1,152 grid cells of 1 × 1 km² to be suitable of which 190 were presumed to occur within colonization capacity (±2.5 km). At a local scale, adult butterflies were more abundant on sites sheltered by bushes and small trees and with nectar sources in the vicinity of tall oak trees (mate locating sites). For egg-laying, females preferred oaks of intermediate height (50–150 cm) with many low branches at some distance from the nearest woodland edge (12 m). Additionally, Alder Buckthorn (Frangula alnus) was abundant as well as a herb layer of 10–15 cm. 73 % of the eggs were parasitized and parasitism occurred more often within sites where small oaks were very abundant. Making use of our results, we suggest conservation measures at different scales for this endangered ecotone species: policy measures at a regional level to delineate functional conservation units and local management measures using a resource-based approach.     

Susceptibility of preimaginal western cherry fruit fly, Rhagoletis indifferens (Diptera: Tephritidae) to Beauveria bassiana (Balsamo) Vuillemin Clavicipitaceae (Hypocreales)

Last-instar larvae of the western cherry fruit fly, Rhagoletis indifferens, were subjected to Beauveria bassiana GHA incorporated into sterile sand and non-sterile orchard soil. Mycosis in the pupal stage was observed in >20% of buried R. indifferens pupae and >80% of larvae entering sand treated with either of two B. bassiana isolates. When pre-pupal larvae burrowed into conidium-treated non-sterile cherry orchard soil, the incidence of mycosis, on both the puparia and internally developing pupae, increased with dose. Internal pupal tissues were found to contain B. bassiana. Increasing the soil moisture level from 20% to 35% water holding capacity did not have an effect on the percentage of mycosed pupae. This is the first evidence that the preimaginal stages of R. indifferens are susceptible to infection by B. bassiana.     

THE ECOLOGY OF ANISOPUS FENESTRALIS SCOP. (DIPTERA) IN SEWAGE BACTERIA BEDS

The assessment of populations of Anisopus fenestrate (Scopoli, 1763) in sewage bacteria beds by the trapping of adults at the surface has been previously proved to be unsatisfactory. Methods were therefore developed for determining the numbers of egg masses, larvae and pupae as well as the total organic matter in a unit volume of bed. The relative larval populations of three areas under investigation were related to the loading of the beds as measured by the sewage strength and rate of application. In the upper 2 ft. 6 in. the numbers of larvae and pupae per unit volume of bed decreased with depth. There was no evidence of any vertical migration of the larvae before pupation. The horizontal distribution of larvae was found to be affected by the method of distribution. In beds served with fixed spray jets larvae are more abundant nearer the jets than at some distance away. In beds served with travelling distributors the larvae are more abundant in the zones below the jets than in the drier intermediate zones. In both cases relatively higher percentages of pupae in the drier zones might indicate a horizontal migration of larvae before pupating or of the pupae themselves.
The incidence of the larvae throughout 1949 in all three beds showed recurring peaks. In the following year a more intensive investigation on one area showed that this was due to successive generations of the fly; the proximity of the peaks is determined mostly by temperature and their size by the amount of food available in the bed during the larval grazing phase.
In the area not treated with insecticide intraspecific competition during a period when food was limiting, due to depletion by the previous generation, resulted in a natural reduction in the population. In the area treated with insecticide the food was retained and this natural control was thereby delayed.     

Host-size preference of the parasitoidAnisopteromalus calandrae [Hym: Pteromalidae] onSitophilus zeamais (Col.: Curculionidae) larvae with a uniform age distribution

First generationAnisopteromalus calandrae (Howard) collected from commercial stored maize in South Carolina were exposed to a mixture of all sizes of immatureSitophilus zeamais Motschulsky, representative of a uniform age distribution, in shelled maize. Eighty-seven percent of parasitism is expected on larvae with tunnel diameters of 0.9 to 1.8 mm and 6% on prepupae and pupae, given this host-size distribution. Preference was greatest for large host larvae (1.6 mm diameter), intermediate for other larvae in the range 0.9 to 1.8 mm, and least for pupae and small larvae. Host-stage preference is discussed with respect to Chesson's (1983) parameters for preference, α_i, probability of parasitism, P_i, and electivity index, ?_i.     

Location,location, location: larvae position inside the nest is correlated with adult body size in worker bumble-bees (Bombus impatiens)

Social insects display task-related division of labour. In some species, division of labour is related to differences in body size, and worker caste members display morphological adaptations suited for particular tasks. Bumble-bee workers (Bombus spp.) can vary in mass by eight- to tenfold within a single colony, which previous work has linked to division of labour. However, little is known about the proximate mechanism behind the production of this wide range of size variation within the worker caste. Here, we quantify the larval feeding in Bombus impatiens in different nest zones of increasing distance from the centre. There was a significant difference in the number of feedings per larva across zones, with a significant decrease in feeding rates as one moved outwards from the centre of the nest. Likewise, the diameter of the pupae in the peripheral zones was significantly smaller than that of pupae in the centre. Therefore, we conclude that the differential feeding of larvae within a nest, which leads to the size variation within the worker caste, is based on the location of brood clumps. Our work is consistent with the hypothesis that some larvae are ‘forgotten’, providing a possible first mechanism for the creation of size polymorphism in B. impatiens.