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1.
近年来,广东贺江暴发了由等足类寄生虫引起的严重的鱼类外寄生虫病,给当地网箱养殖和野生鱼类资源造成了严重危害.根据虫体的口器、触角、腹肢等形态学特征将其鉴定为等足目(Isopoda)、扇肢亚目(Flabellifera)、纺锤水虱科(Aegid ae)、海弯水虱属(Alitropus)的典型海弯水虱(Alitropus typus).为了弄清典型海弯水虱对贺江内野生鱼类资源的危害及其种群季节动态变化规律,作者从2006年5月份到2 007年4月份,用刺网定时定点捕获野生鲮鱼(Cirrhina molitorella),检查典型海弯水虱的寄生状况.结果发现:典型海弯水虱对鲮鱼的感染率、感染强度和平均密度均从20 06年5月份开始上升,至7月份达到高峰,然后逐渐下降,于次年的2月份达到最低点,从3月份开始有所回升.典型海弯水虱种群在不同月份及不同体长鲮鱼中均为聚集性分布,且聚集强度随着平均密度的增加而增加.典型海弯水虱种群在鲮鱼中的感染参数与水温呈显著的正相关,而与宿主的体长无明显的相关性.周年种群结构动态变化分析表明: 典型海弯水虱 1年只繁殖1次,繁殖受水温的影响,6、7月份是其繁殖高峰期 [动物学报 5 4(3):407-415,2008].  相似文献   

2.
In preparation for a study on population structure of the whale shark (Rhincodon typus), nine species-specific polymorphic microsatellite DNA markers were developed. An initial screening of 50 individuals from Holbox Island, Mexico found all nine loci to be polymorphic, with two to 17 alleles observed per locus. Observed and expected heterozygosity per locus ranged from 0.200 to 0.826 and from 0.213 to 0.857, respectively. Neither statistically significant deviations from Hardy-Weinberg expectations nor statistically significant linkage disequilibrium between loci were observed. These microsatellite loci appear suitable for examining population structure, kinship assessment and other applications.  相似文献   

3.
记述了喙尾琵甲Blaps rhynchopetera Fairmaire各虫态特征,观察了其生物学特性.实验种群1月下旬至12月上旬产卵,卵期为8~15 d;幼虫期141~213 d,共9~13龄,第9龄以后,龄期较长;蛹前期8~14 d;蛹期12~24 d.成虫羽化24~92 d后性成熟,开始交配产卵活动,成虫期超过18个月.自然种群在昆明和曲靖1年发生1~1.5代,世代重叠严重;以不同龄期幼虫和成虫越冬,越冬幼虫于次年4月上旬开始化蛹,新羽化成虫于4月下旬至12月上旬交配产卵,成虫全年都能活动、产卵.该虫为夜出型、暂栖性土壤昆虫,喜潮湿阴暗的环境.成虫具有夜出习性、防御性和群聚性.  相似文献   

4.
Abstract  Refining the process of selecting specialist herbivores that are used as biological control agents to maximise effects on the targets can diminish the risk to non-target species. While biotic factors (e.g. plant demography and agent–host interactions) have been explored for clues to improve the way we make agent selection decisions, recent ecological research indicates that abiotic factors related to the habitat (e.g. plant and soil nutrient composition, and soil characteristics) are important predictors of insect herbivore community composition. In this paper we explore the relevance of plant nutrient composition to aid in selecting agents for the invasive Eurasian perennial Euphorbia esula (leafy spurge) in Illinois, USA. We propose that an approach that compares such abiotic factors across the native and invaded ranges of plants in conjunction with the community composition of specialist herbivores in the native range may yield valuable clues in selecting agents that are most likely to establish and regulate populations of the target weed.  相似文献   

5.
Thamnurgus euphorbiae overwinters as adults in dry stems of Euphorbia characias until the end of March before exiting through circular holes cut with their mandibles. Females and males appeared in the field at the same time, and the first pairs were observed on 28 March on new stems of E. characias having the open‐flower at the beginning of its development. Throughout the rest of April it was possible to find and collect the fairly abundant adults. Mating occurs on new stems of the host plant and females walk up towards the top of the stem and start to mine the centre of it in order to penetrate. Oviposition occurs in new stems and eggs are laid singly along the interior of the stem; females laid 35–85 eggs. Upon hatching, larvae started feeding on vascular bundles and the inner cortex. There are three larval instars, and pupation occurred in the stem of the host plant; this insect is univoltine. Thamnurgus euphorbiae has been accepted by the Technical Advisory Group for Biological Control Agents of Weeds for release as a biological control agent of leafy spurge in the US. Prior to this study the biology of T. euphorbiae was unknown.  相似文献   

6.
描述了石榴巾夜蛾Paralleliastuposa的形态特征、生物学特性,建议用95%敌敌畏乳油500~800倍液防治石榴巾夜蛾,防治效果在938%以上。  相似文献   

7.
小火蚁Wasmannia auropunctata Roger被世界自然保护联盟(IUCN)列为最具危害性的100种入侵物种之一,已从其原产地南美洲扩散到除南极洲以外的每个大陆,近期被报道成功入侵中国。本文对小火蚁的分类学与形态特征进行了描述;简要探讨了小火蚁的原产地范围和在全球的扩散历史,进一步阐述其对农业生产、人类健康、生态系统等方面的影响;同时,介绍了小火蚁的监测与调查方法;最后就小火蚁的检疫、化学防治与生物防治等防控技术进行了归纳,以期提升大众对小火蚁的认识并为积极应对小火蚁的入侵提供参考。  相似文献   

8.
Under laboratory conditions, the nematodes Neoaplectana carpocapsae and Heterorhabditis heliothidis were able to infect and develop inside the hemocoel of terrestrial isopods belonging to the genus Porcellio. Armidillidium vulgare was also infected by N. carpocapsae, but this host was less susceptible than Porcellio. Results show that, under suitable ecological conditions, it would be feasible to utilize N. carpocapsae as a biological control agent of sowbugs (Porcellio spp.). This is the first report showing the ability of neoaplectanids and heterorhabditids to invade representatives of the Crustacea.  相似文献   

9.
For half a century, agriculture on Easter Island has been affected by an increasing number of accidentally introduced insect pests. Due to the absence of natural enemies and other factors, these have reached high density levels which claimed for intensive use of pesticides. A project supported by the National Funds for Regional Development (FNDR) was established in 1984 to develop a biological control program against these pest species. Presently, 60 beneficial species have been introduced to control agricultural pests and flies that affect cattle and humans. Some of the natural enemies have established and are reducing pest populations thereby decreasing the requirement for insecticidal treatments. Fly density has also decreased noticeably. This can be attributed to the activity of natural enemies and dung beetles which compete with larval fly for food.  相似文献   

10.
11.
Abstract  Melaleuca quinquenervia (Cav.) S.T. Blake, Australian broad-leaved paperbark, has become a serious weed in southern Florida. Poliopaschia lithochlora (Lower) is a promising candidate as a potential biological control agent, and this study describes laboratory and field observations of the life history of this moth. Eggs are laid in small batches, mainly on the surface of leaves, and larvae are voracious leaf feeders, concealed in tubes that are usually found in small colonies attached to leaves and stems. Larvae move from these tubes to feed on surrounding leaves, and saplings and suckers are frequently defoliated. Prepupae form sealed bulbs in the larval tubes in which they pupate. Adult females are mainly active and oviposit at night. Development from egg to adult occurs in approximately 80 d. Field populations appear to be regulated by several egg and larval parasites. Because this moth severely damages saplings and suckers of M .  quinquenervia , prefers low-lying humid sites, and can be successfully mass reared, it is rated highly for its potential as a biological control agent.  相似文献   

12.
Understanding how the biotic and abiotic factors influence pest-population dynamics is important to implement sound pest management strategies in biological control and integrated pest management (IPM) programmes. Coccus viridis (Green) is an important indirect pest of coffee plants, but very little has been done to understand the factors that contribute most for its biological control in the field. In the present study, we examined the critical life stage and the key factors associated with the mortality of C. viridis in coffee plantations in Brazil by conducting field-based life table studies. Predators, parasitoids, fungi, infested leaf abscission and rainfall were collectively responsible for a total C. viridis mortality of 96.08%. Predation by coccinellids was the key factor governing the mortality of C. viridis. The parasitism of early instars by parasitoids was the second most important factor contributing to C. viridis mortality. Unlike the parasitoids, the fungus Lecanicillium lecanii caused mortality of scales in more advanced life stages. The abscission of infested leaves from the trees, and rainfall also contributed to the mortality of C. viridis. The nymph stage was considered the critical stage for mortality of C. viridis in the field. The results suggest that predators (Coccinellidae) are the most important factors controlling C. viridis, and thus should be the target of conservation measures in coffee plantations infested with this pest.  相似文献   

13.
14.
Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae) is a major defoliator of regeneration eucalypt trees in Tasmania causing a significant reduction in height and diameter increment of trees which reduces wood volume per hectare. A study to conserve and enhance the efficiency of coccinellid species chieflyCleobora mellyi (Mulsant) (Coleoptera: Coccinellidae), and the cantharid,Chauliognathus pulchellus (Macleay) (Coleoptera: Cantharidae), for the biological control ofC. bimaculata was conducted in young regeneration forests in southern Tasmania from 1991–92. Cantharid adults and coccinellid adults and larvae feed onC. bimaculata eggs and, to a lesser extent, young larvae. The study found that coccinellids were more active throughout the egg and early (1st and 2nd) stage ofC. bimaculata. The cantharid, however was active only during the egg stage of the prey and then disappeared from the plantation. The coccinellids were therefore the most useful predators, but their population declined when the prey reached the 3rd and 4th stages. As shortage of food may account for this decline, supplementary food was provided in the form of sucrose sprays or sugar granules at a feeding station. This resulted in the retention of both predators and particularly the coccinellids and enhanced their efficacy.  相似文献   

15.
The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), is the most important pest of maize in many countries. Entomopathogenic viruses mainly Baculoviruses family are excellent biological control agents and therefore a viable alternative for managing this pest. The aim of this study was to determine the biological activity of eight native nucleopolyhedrovirus (NPVs) against FAW larvae. Additionally, two of the most virulent isolates (SfCH32 and SfCH15) were characterized biologically by bioassays to estimate their median lethal dose (LD50) and median lethal time (LT50), morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and molecularly by restriction enzymes. Three (SfCH15, SfCH18 and SfCH32) of the eight tested native nucleopolyhedrovirus isolates caused mortalities ˃98% at 168-hr post-inoculation (hpi) with a dose of 9.2 × 104 OBs/larva. SfCH15 and SfCH32 isolates showed occlusion bodies (OBs) of irregular shape and size (1.02–2.24 μm). The SfCH15 and SfCH32 isolates showed similar median lethal dose (5.6 × 102–6.4 × 102 OBs/larva). The lowest median lethal time (114.5 hpi) was observed with the SfCH15 isolate at the highest concentration (2.5 × 106 OBs/larva). The DNA restriction profiles for SfCH15 and SfCH32 were different, with their genome size being ~128,000 bp and 132,000 bp, respectively. SfCH15 and SfCH32 isolates showed similar morphological characteristics and the highest virulence against fall armyworm. This study showed that native isolates were highly virulent against S. frugiperda larvae, being similar to other reported strains; however, field studies are required to confirm their insecticidal effect.  相似文献   

16.
Opiine braconids are parasitoids of the immature stages of frugivorous tephritids. The female wasp lays her eggs into the eggs or larvae of the fruit fly host, where the immature wasp develops before emerging as a next-generation adult from the now dead host pupal case. In support of a new generation of Australian fruit fly parasitoid research, this paper comprehensively reviews what is known about the Australian fruit fly infesting opiines. Based on the most recent taxonomic revision 11 fruit fly infesting opiine species are documented to occur in Australia, but we consider as doubtful the record for Diachasmimorpha longicaudata and consider the record for Fopius illusorius to be tentative without further collections. We identify that the systematics and taxonomy of the Australian native fruit fly infesting opiines are in urgent need of further work. The history of fruit fly biological control in Australia is comprehensively reviewed, including the export of native Australian opiines for fruit fly control elsewhere in the world. Australia was actively involved in three major classical biological control programmes against fruit flies from the turn of the 1900s until the mid-1960s. Despite the introduction of 11 opiine species, plus numerous other natural enemies, only Fopius arisanus established in eastern Australia, where in South-east Queensland it can now cause between 30 and 40% mean parasitism. In addition to the exotic F. arisanus, the native species Diachasmimorpha kraussii and Diachasmimorpha tryoni also cause fruit fly parasitism in agriculturally important crops: both species have also been liberated widely outside of Australia for fruit fly control. Other Australian opiines have not been reared from flies infesting commercial crops and appear biologically restricted to the fruits and environs of Australian east-coast rainforests. The biology literature for D. tryoni and D. kraussii is comprehensively reviewed, while for F. arisanus, already reviewed elsewhere, key literature only is covered. Forward looking, we consider the potential for inoculative or inundative releases of opiines in areas where they do not currently occur to be good, while conservation biological control may help to increase the impacts of parasitoids in areas where they are already established.  相似文献   

17.
To identify a more effective and safe biological control agent against a common cabbage pest, Plutella xylostella (L.) (Lepidoptera: Plutellidae), the insecticidal effects of selected biological agents were evaluated. The highest insecticidal effects determined were 100, 73.5, 45.5, 47 and 55.3% using toxin HD‐1 (isolated from the Harry Dumagae strain of Bacillus thuringiensis), toxin BTS‐1 (isolated from the tenebrionis strain of B. thuringiensis), B. thuringiensis Berliner, B. thuringiensis israelensis and B. thuringiensis kurstaki, respectively.  相似文献   

18.
The efficiency of some commercial biological control agents (BCAs), Bio Zaid and Bio Arc, and resistance inducers chemicals (RICs) (salicylic acid and Bion) on management of cucumber powdery mildew, caused by Sphaerotheca fuliginea, was evaluated in vitro and in vivo. In vitro experiments revealed that application of the tested BCAs and RICs significantly reduced the disease severity, number of conidia per leaf area unit (cm) and reduced germination of conidiospores of the causal pathogen. Under field conditions, application of BCAs and RICs caused significant decrement in the disease severity with significant increment in the fruit yield compared with check treatments. On the average, application of Bion recorded the highest values, either in reducing the disease severity or in raising the average fruit yield followed by Bio Arc. On the other hand, applying salicylic acid (SA) recorded, on the average, the lowest efficiency in reducing disease severity and low values of fruit yield in both growing seasons.  相似文献   

19.
Abstract

Accelerating the mortality of stoats (Mustela erminea) using biological agents, or reducing their fertility using chemosterilants or biological agents, are increasingly seen as more sustainable and more humane than trapping and poisoning. Obligate delayed implantation in fertilised female stoats of all ages allows 10–11 months for an applied biological agent or chemosterilant to interfere with gestation. Two chemosterilants (cabergoline and mifepristone) disrupt pregnancy in some species and may be effective on stoats, although they are not species‐specific and are probably more expensive than poisoning. For the longer term, more recent fertility control research has explored potentially more species‐specific options for other species based on inducing an immune response to an animal's own reproductive hormones, gametes, or products from embryos. Conception will be difficult to disrupt in stoats because females are sexually mature and are mated in the nest during a short period before they are weaned. A large research effort will be required to determine which of the immunosterilants being developed could be suitable candidates for stoat control. There are fewer options apparent for using biological agents to increase stoat mortality, although species‐specific strains of canine distemper virus may be effective against stoats.

The greatest impediment to controlling stoat fertility will be effective delivery of sterilants. For the foreseeable future, it will probably be necessary to rely on baits, but they are unlikely to put all target stoats at risk, and will be incapable of delivery over larger scales than at present.

Before undertaking expensive field trials and development of anti‐fertility and biological agents, the effects of putative compensatory changes in demographics that may be associated with changes in stoat density should be modelled to see if the sterilisation and mortality rates that are required to achieve a given level of population control are realistic targets. Also, population control should be defined in terms of accrued benefit for wildlife by establishing the relationships between stoat densities and the viability of prey populations.

Biological control of fertility or mortality may never be suitable as stand‐alone control options for stoats, particularly when some native fauna survive only if stoats are reduced to very low densities. Biological control may have greater potential when integrated with conventional control.  相似文献   

20.
The host range of Leurocephala schinusae Davis & Mc Kay (Lepidoptera: Gracillariidae) was studied to assess its suitability as a biological control agent of Schinus terebinthifolius Raddi (Anacardiaceae), a serious environmental weed in the USA and elsewhere in the world. The host range was determined in the laboratory with adult no-choice oviposition (Argentina and USA) and larval development tests (USA). Seventeen plant species in ten genera were selected based on taxonomic relatedness to S. terebinthifolius, economic importance, and availability. Additional information was obtained by sampling foliage of S. terebinthifolius and six other South American native Anacardiaceae species in north-eastern Argentina. In the laboratory, except for Lithrea molleoides and Spondias mombin, all of the tested species were accepted for oviposition with a marked preference for Rhus aromatica. Incipient mines successfully developed into complete mines, pupae and adults on R. aromatica, Rhus copallinum, Schinus molle, Schinus lentiscifolius and S. terebinthifolius. In the field, although L. schinusae showed a clear preference for S. terebinthifolius, the host range, as determined by samples of host use in the native range, included three other Schinus species (S. lentiscifolius, Schinus longifolius, Schinus weinmannifolius) and one Astronium species (Astronium balansae). In conclusion, L. schinusae will not be considered for the biological control of S. terebinthifolius in continental US. However, the utilisation of this species in other infested areas such as Hawaii and Australia should be further discussed.  相似文献   

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