Genetic diversity in a seed production population vs. natural populations of Sitka Spruce

Isozyme analysis was applied to estimate the level of variation and the genetic structure of a seed-production population (i.e., seed orchard) and 10 range-wide natural populations of Sitka spruce (Picea sitchensis (Bong.) Carr.). Gene diversity and heterozygosity estimates were comparatively high in both the seed orchard and the natural populations studied. The seed orchard population showed a significantly higher number of alleles per locus and percentage of polymorphic loci. Though not significant, mean heterozygosity of the seed orchard was higher than that observed for all natural populations. Genetic distance analysis indicated that the seed-orchard population was genetically similar to three natural populations from which the parent trees were selected. Parent trees sampling breadth has been identified as the major cause for the observed increased level. The impact of recurrent selection and seed orchard biology and management on maintaining the genetic diversity is discussed.     

龙眼和荔枝卷叶蛾类种群动态及其群落结构

调查结果显示,在广西南宁市和崇左市的部分龙眼和荔枝园中,危害龙眼和荔枝的卷叶蛾类有3科20种,其中龙眼园的卷叶蛾类有3科16种,荔枝园有2科17种,2类果园发生的种类有所不同。20种中,9种过去尚未见报道。龙眼园和荔枝园卷叶蛾类群落结构的均匀度指数较低,分别为0.298 2和0.406 3,说明在群落中有某种卷叶蛾的种群数量相当大,各种类数量分布不均一,有某个种群数量相当大。2类果园卷叶蛾类群落的多样性相比,荔枝园要高于龙眼园。龙眼园卷叶蛾类的优势种为三角新小卷蛾Olethreutes leucaspisMeyrick(优势度指数d=0.813 2),荔枝园分别为三角新小卷蛾(d=0.722 6)和灰白条小卷蛾Dudua aprobola(Meyrick)(d=0.102 8)。2类果园种群数量较大的种类均为三角新小卷蛾、灰白条小卷蛾和圆角卷蛾Ebodo cellerigeraMeyrick。各月份卷叶蛾类发生的总数量均以龙眼园高于荔枝园。     

不同生境中橘小实蝇种群动态及密度的差异

为揭示不同生境条件对橘小实蝇种群动态及密度的影响,通过设置橘小实蝇诱捕器,对2008-2009年福州地区不同生境条件下的橘小实蝇种群动态进行了监测。结果表明：（1）各寄主的转色成熟期是该果园橘小实蝇发生的高峰期。（2）在瓜果的成熟期,果园内橘小实蝇的种群数量要高于果园周边丛林的种群数量;成熟期过后,果园内部的种群数量小于果园周边丛林。（3）山谷生境橘小实蝇种群数量明显高于山脊生境,沿河生境则要明显高于非沿河生境。（4）城区的橘小实蝇的发生期早于乡村,且发生量要大于乡村。     

Evaluation of yellow sticky traps for monitoring the population of thrips (Thysanoptera) in a mango orchard

Populations of several thrips species were estimated using yellow sticky traps in an orchard planted with mango, Mangifera indica L. during the dry and wet seasons beginning in late 2008-2009 on Penang Island, Malaysia. To determine the efficacy of using sticky traps to monitor thrips populations, we compared weekly population estimates on yellow sticky traps with thrips population sizes that were determined (using a CO(2) method) directly from mango panicles. Dispersal distance and direction of thrips movement out of the orchard also were studied using yellow sticky traps placed at three distances from the edge of the orchard in four cardinal directions facing into the orchard. The number of thrips associated with the mango panicles was found to be correlated with the number of thrips collected using the sticky trap method. The number of thrips captured by the traps decreased with increasing distance from the mango orchard in all directions. Density of thrips leaving the orchard was related to the surrounding vegetation. Our results demonstrate that sticky traps have the potential to satisfactorily estimate thrips populations in mango orchards and thus they can be effectively employed as a useful tactic for sampling thrips.     

THE OCCURRENCE OF PHYTOSEIULUS PERSIMILIS ATHIAS-HENRIOT (ACARINA:PHYTOSEIIDAE) IN AN ORCHARD IN VICTORIA

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High numbers of the predatory mite, Phytoseiulus persimilis , were found on apple and nectarine trees in a commercial orchard at Werribee, Victoria in February 1981. In the following season, again it was not detected on trees or broad-leaved weeds in the orchard until late summer. Slide-dip tests on the Werribee population of P. persimilis and a population originating from strawberries in Sydney, New South Wales, showed that azinphos-methyl was equally toxic to the 2 strains and DDT was considerably less toxic to both.     

Population density of the predatory mite <Emphasis Type="Italic">Typhlodromus pyri</Emphasis> (Acari: Phytoseiidae) on various pear cultivars in organic and integrated orchards

During an experiment carried out in 2009–2010 we observed different population densities of Typhlodromus pyri in three monitored pear cultivars in Organic Pest Management (OPM) as well as Integrated Pest Management (IPM) orchards. In both years the population density of T. pyri was the highest in the cultivar Conference (organic orchard). The lowest population density was found in 2009 on the cultivar Dicolor (IPM orchard) and in 2010 on the cultivar Bohemica. Factors involved are discussed.     

Factors affecting orchard colonisation by the black-kneed capsid (Blepharidopterus angulatus (Hemiptera:Miridae)) from alder windbreaks

The colonisation of orchards by Blepharidopterus angulatus (the black-kneed capsid bug) from alder windbreaks was investigated, to determine its use as a biological control agent of orchard pests. The aphid Pterocallis alni provides an abundant and acceptable food for the capsid on alder. The key capsid mortality factor on windbreaks was the loss of adult females through migration. Clipping the windbreak prior to the aphid population peak resulted in male capsids migrating and females remaining, while clipping after the aphid population peak resulted in both sexes migrating to nearby orchards. Guidelines are given for windbreak management as part of a system of integrated orchard pest control.     

枇杷园蜘蛛混合种群空间分布型的动态分析

枇杷园蜘蛛混合种群的空间分布型在不同季节存在差异,其空间分布型主要由枇杷园蜘蛛本身的生殖水平、游猎型和定居型数量的多寡,主要目标害虫的数量及分布,气候环境的变化及其越冬生态习性,枇杷园蜘蛛的种群密度及其种间竞争程度决定。     

Cross-correlation analysis of fluctuations in local populations of pear psyllids and anthocorid bugs

1. To test whether predatory anthocorids migrate into pear orchards when populations of pear psyllids are building up, a cross-correlation analysis was carried out on their population numbers. Predator and prey population sizes were assessed weekly in 3 consecutive years (1991–93) by sampling pear leaves for eggs and nymphs of psyllids and pear tree branches for adult psyllids, as well as adults and nymphs of predatory anthocorids. The time-series consisted of numbers (per leaf or branch) averaged over preselected pear trees in an orchard and, in addition, over other trees selected along the hedgerows flanking the orchard. 2. The fluctuations in populations of adult and juvenile anthocorids showed strong cross-correlations with those of the eggs and nymphs of pear psyllids, but less correlation with adults of pear psyllids, as expected based on their increased ability to escape from predation. The psyllids always appeared first on the pear trees, resulting in positive phase shifts. The first peak of adult anthocorids on pear trees was always later than the first peak in the hedgerows, and the first peak of nymphal anthocorids on pear trees was always later than the first peak of adults on these pear trees. In each of the 3 years, anthocorids were rarely observed in the pear orchard during the first part of the growing season (April–June), but during the second half of the growing season (July–August) there was a strong numerical response of the anthocorid populations to increasing population densities of pear psyllids. 3. These results provide support for the hypothesis that the numerical response of the predators to prey density is caused initially by migration of anthocorids into the pear orchard and then by a reproductive response. The migrants originate from the hedgerows and other trees elsewhere, where they feed on aphids during the first part of the growing season.     

Life cycle of a non-diapausing population of the two-spotted spider mite,Tetranychus urticae Koch in a pear orchard

The life cycle of a non-diapausing T. urticae population was studied in a pear orchard in the southern part of Okayama Prefecture, western Honshû, Japan. The mites overwintered only on biennial weeds in the orchard without entering diapause, started to increase in number in early spring on them and then moved to other weeds as they emerged. The occurrence of the mites on pear began in early May several weeks after the unfolding of pear leaves and the population on pear was initiated by the migrants from the weeds around the base of pear trees. The population on pear showed two distinct peak occurrences, one in June and the other in mid-autumn. After pear leaves dropped in late autumn, the mites returned to biennial weeds for overwintering.     

Influence of weather on the moth catches of Helicoverpa armigera at various cotton-based agro-ecological sites

Pheromones are innate products, exploited for direct population manipulation in the trapping of precise pest density. They demonstrate feasibility and efficiency against Helicopverpa armigera at five different cotton-based agro-ecological sites: river site, vegetable farm, orchard, clean cultivation site, and forest. The data were recorded at 15–20 day intervals from 8 September 2004 to 1 December 2006. The Number of moths caught during the study period demonstrated that the vegetable farm showed the maximum population of moths per trap (0.54), followed by the orchard (0.29), forest (0.19), river (0.15), and clean cultivation site (0.12). During 2004, rainfall (in the orchard and clean cultivation site) and relative humidity (in the clean cultivation site) showed positive and significant correlation with the number of moths caught. During 2005, temperatures played a significant and positive role in population fluctuation of the pest almost at all the selected sites; the minimum temperature was recorded at the vegetable farm and the average temperature was found at the forest site. Rainfall also showed a significant and positive correlation with trapped moths in the vegetable farm, orchard, and clean cultivation site. During 2006, relative humidity showed a significant and negative correlation with the trapped population at all the sites except the river site. Rainfall showed a negative and significant correlation with the pest at the forest site. Relative humidity was the most important aspect at 8.93% causing variation in the trapped population followed by maximum temperature (5.7%), rainfall (1.63%), average temperature (0.74%), and minimum temperature (0.56%).     

Simultaneous estimation of pollen contamination and pollen fertilities of individual trees in conifer seed orchards using multilocus genetic data

Seed orchards of forest trees are established to produce genetically-improved seed for reforestation. Genetic efficiency requires seed orchards to be (1) reproductively isolated form surrounding trees, (2) that there be similar fertilities among all orchard trees, and (3) minimum inbreeding. Each aspect of seed orchard reproduction can be simultaneously estimated using the observed frequency of each multilocus gametic type contributed through fertilizing pollen and the expected multilocus gametic segregation frequencies of orchard tree and of the contaminating population. These genetic estimates are directly relevant to the genetics of the tree breeding program. The flexibility of sampling seed — the basic data for these techniques — allows great scope for hypothesis testing, including tests of the accuracy of predictions of biophysical models of pollen movement. A simple example and a white spruce seed orchard case study are presented to illustrate the estimation technique and to investigate its sensitivity.     

Effect of weather factors on populations of Helicoverpa armigera moths at cotton-based agro-ecological sites

Pheromone trapping was used to monitor populations of the moth Helicoverpa armigera at five cotton‐based agro‐ecological sites – river, vegetable, orchard, forest and clean cultivation (areas under only cotton cultivation) – in the Bahawalpur district, Pakistan. Three locations at each site were chosen and three pheromone traps at each location were installed in cotton fields. Moth catches were recorded at 15–20 day intervals from 24 October 2004 to 19 December 2006. In 2004, the river sites showed the maximum trapped population of H. armigera (0.22/trap) followed by 0.165 per trap at the vegetable sites. Orchard, clean cultivation and forest sites had zero moth catches. In 2005, the river sites again showed the highest trapped population (0.57/trap), followed by clean cultivation (0.45/trap), vegetable (0.44/trap), orchard (0.40/trap) and forest (0.29/trap). The moths appeared during July to December and March to May. In 2006, sites showed non‐significant difference, with a population range of 0.47 to 0.97 moths per trap. On average, river sites peaked at 0.49 per trap, followed by vegetable (0.38), clean cultivation (0.47), orchard (0.35) and forest (0.25) sites. The peak was observed on 3 April 2006, and moths appeared during February to July and October to December. The minimum temperature in river, forest and clean cultivation sites; the maximum temperature in orchard sites; and the average temperature in river, orchard, forest and clean cultivation sites showed significant positive correlations with trapped moth populations. Relative humidity showed significant negative correlation with population at the orchard sites in 2005. All weather factors during 2004 and 2006 showed non‐significant correlations with the moth populations. No model was found to be best fit by multiple linear regression analysis; however, relative humidity, minimum temperature, maximum temperature, minimum temperature and maximum temperature contributed 8.40, 10.23, 2.43, 4.53 and 2.53% to the population fluctuation of the moth at river, vegetable, orchard, forest and clean cultivation sites, respectively.     

Body size and the colonisation of cereal crops by the invasive slug Arion lusitanicus

The invasive slug Arion lusitanicus lives in undisturbed stands of grass or herbaceous plants from where it disperses into crops. Factors that determined the dispersal of slugs from a grassy orchard (O) into an adjacent cereal stand were investigated. Slug‐feeding activity, abundance and body weight were established along a 120 m transect across an orchard and a cereal crop. Slugs in the source population in the orchard were more abundant and lighter in 2008 than 2009. The slugs that left the orchard and moved into the cereal crop were heavier than those that remained in the orchard and the distance they travelled was positively correlated with their weight. The abundance of slugs in the cereal crop decreased with the increase in the distance from the source population, more so in 2008, when slugs were light in weight and accumulated near the edge of the orchard, than in 2009 when the slugs were heavier and distributed more evenly. The feeding activity of the slugs leaving the orchard and distance they dispersed also increased during the course of the season. Long distance dispersal is achieved by crawling, the speed of which increased with slug size. Seasonal and annual variation in body size thus affected the distribution of slugs in the cereal crop and the distance they dispersed.     

Trade-offs in responses to host plants within a population of a generalist herbivore,Christoneura rosaceana

Evolutionary constraints on the ability of herbivores to efficiently use a set of phytochemically similar hosts, while maintaining a high performance on phytochemically different hosts, are central in explaining the predominance of host specialization in phytophagous insects. Such feeding trade-offs could be manifested within insect populations as negative genetic correlations in fitness on different host species. We tested the hypothesis that feeding trade-offs were present within a population of the obliquebanded leafroller,Choristoneura rosaceana (Harris). Components of fitness were measured in families originating from an apple orchard that were fed on four host-plant species in the laboratory. Under the conditions of this experiment, all across-host genetic correlations were strongly positive, suggesting that this population comprised true generalists. With the exception of diapausing propensity, the heritability of the fitness components tended to be lower in caterpillars fed on apple leaves than in insects fed other hosts. This suggests a constraint on the selective response of the fitness components in the orchard environment.     

病原线虫对桔小实蝇种群的控制作用

通过室内和田间实验研究了昆虫病原线虫对桔小实蝇Bactrocera (Bactrocera) dorsalis (Hendel)的控制作用。室内实验结果表明,供试的3种线虫的4个品系（小卷蛾斯氏线虫Steinernema carpocapsae All品系与A24品系,夜蛾斯氏线虫Steinernema feltiae SN品系和嗜菌异小杆线虫Heterorhabditis bacteriophora H06品系）,以小卷蛾斯氏线虫All品系对桔小实蝇的侵染力最强,其3天的LD₅₀和LD₉₅分别为35.0和257.1条/cm²土壤。按300条/cm²土壤的量施用,小卷蛾斯氏线虫All品系对当代桔小实蝇的控制效果为86.3%。用以虫期作用因子组建的生命表方法评价了小卷蛾斯氏线虫All品系对田间桔小实蝇下代种群的控制作用,结果表明,按300条/cm²土壤的量施用线虫,对照杨桃园的桔小实蝇种群趋势指数为105.9,而处理杨桃园的桔小实蝇种群趋势指数下降为15.5;小卷蛾斯氏线虫All品系对桔小实蝇的干扰控制指数为0.146,即线虫处理果园的下代种群密度仅为对照果园的14.6%。     

Gene flow estimation with microsatellites in a Malagasy seed orchard of Eucalyptus grandis

Eucalyptus grandis has a mixed-mating reproductive system. Malagasy Eucalyptus seed orchards were established 15 years ago with two aims both based on panmixia: open-pollinated seed production and genetic improvement. The panmixia hypothesis has never been confirmed in the seed orchard. From a seedling seed-orchard stand comprising 349 trees and using data obtained with six selected microsatellite markers, paternity analysis was performed for 724 offspring collected on 30 adult trees. Paternity assignment, based on exclusion procedures and likelihood-ratio method, was achieved with high accuracy; the exclusion probability value was 0.997. The outcrossing rate was very high (96.7%). More than 50% of potential male trees (199 out of 349) in the seed orchard contributed to pollination for 440 offspring of 30 progenies (8.6% of the basic population). The pollination rate from outside the seed orchard was high (39.2%), but might be due to the small size of this seed orchard. This study showed that "panmixia-like pollination" can be assumed.     

Population dynamics of the citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae) in Japanese pear orchards

In spring a population of the citrus red mite (Panonychus citri),a non-diapausing species, migrated to a Japanese pear orchard, mainly from nearby Japanese holly trees, but in autumn most of the mites starved to death while the rest returned to the holly trees. In the Japanese holly trees, the population of mites reached their maximum density in late May1993 and in mid-June 1994 on overwintered leaves and moved to newly opened leaves in mid-June 1993 and late June 1994. The mites tended to disperse abruptly in early June or mid-June and again towards the end of June. The mites inhabiting the holly trees appeared to migrate to the Japanese pear trees in June but their densities on pear leaves remained low until mid-August. In the pear orchard, the mites initially tended to increase on pear leaves near the holly trees and then gradually spread to other leaves farther away from the holly trees. Their highest density in the pear orchard occurred in mid-October. When pear leaves were inoculated with two or five female adults at different times from May to September, the leaves inoculated before mid-August showed no increase in the number of mites. A possible cause for the suppression of the population increase on pear leaves from June to mid-August is discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

Principles of formation of the environment friendly program of management of arthropod pests and their enemies in an apple orchard agroecosystem in the North Caucasus

Ecological inefficiency of conventional IPM programs for apple orchard protection in the North Caucasus results from arbitrary use of compounds producing opposite ecological effects, i.e., broad-spectrum chemical insecticides after environment-friendly selective ones, which destroys the apple orchard agroecosystem. The investigation was aimed at developing an effective and ecologically acceptable program with alternation of environment-friendly compounds which act along the same vector to preserve the populations of natural enemies of the pests and thus to stabilize the apple orchard agroecosystem, i.e., create an ecological type of orchard. In this kind of orchards, broad-spectrum chemical pesticides are prohibited whereas selective biological compounds (including synthetic ones) and methods are welcomed. The test runs of the resulting pest and enemy management (PEM) programs based both on bioregulators (Insegar, Match, Dimilin) and bio-insecticides (Phytoverm™, Lepidocid™, etc.) in 2007 and 2009 demonstrated their high efficiency: the apple fruit damage by codling moth was 1.2% and 0.3%, respectively. The test of sticky bands fixed on apple tree trunks to prevent ants from getting to the crowns showed a significant increase in the abundance of predaceous bugs which sharply reduced the green apple aphid population.     

苹果园主要害虫生态调控体系的研究

通过在果园地面种植牧草或花生、油菜等覆盖作物,改善了生态环境,为天敌种群提供了良好的栖息条件和充足猎物,促进天敌群落的早期发展,在4－6月份使树上天敌总量增加60％,地面捕食性天敌增加20倍以上,不仅使苹果蚜、螨高峰期推迟,并使高峰值分别降低39％和1倍以上,使前中期害虫得很好控制。良好的果园生态环境也可促 使周围农田生态系中的天敌因季节性变动向果园迁移,并通过不同生态系之间的运动,扩大天敌种群,达到控制中后期害虫的效果,对优势天敌因季节性变动向果园迁移,并通过不同生态之间的运动,扩大天敌种群,达到控制中后期害虫的效果,对优势天敌在果园生态系中的作用亦做了研究和评价,认为在天敌－害虫相互作用系统中,天敌群落的综合功能是最重要的,针对不同害虫,小花蝽、草蛉、六点蓟马、赤眼蜂等也具有各自的重要作用。通过天敌的人工操纵和补充释放技术以及选择性药剂的筛选运用,在地面覆草,增强天敌功能的基础上,建立起果园主要害虫的生态调控体系,每年可使苹果园比通常减少用农药40％－50％,使果园生态逐步形成良性循环。