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1.
The life cycle of Rubenstrema opisthovitellinum So?tys, 1954, a parasite of shrews, is elucidated. The following developmental stages are described in detail: daughter sporocyst, cercaria, metacercaria, and adult. The freshwater snail Planorbarius corneus was found to be the first intermediate host in nature. The metacercariae were obtained from the larvae of mosquitoes Culex molestus and only exceptionally from snails Physa acuta. The adults were obtained from the small intestine of hamsters Mesocricetus auratus. The life cycle and the larval stages of R. opisthovitellinum are described for the first time. 相似文献
2.
Diplostomoid digenean metacercariae have caused widescale mortalities of channel catfish, Ictalurus punctatus (Rafinesque), at aquaculture farms in Louisiana, Mississippi and Arkansas, USA. Originally, based on a tentative diagnosis, the industry considered the primary harmful agent to be an introduced species from Europe, Bolbophorus confusus (Krause, 1914), frequently reported from the American white pelican, Pelecanus erythrorhynchos Gmelin. Our group has now shown, using ITS 1-2 plus three more-conservative gene fragments, that two sympatric species of Bolbophorus exist in the American white pelican. One, B. damnificus Overstreet et Curran, 2002, infects the musculature of catfish, and the other, probably not B. confusus, does not infect catfish. However, at least four other pathogenic diplostomoids and a clinostomoid infect the catfish, and they use at least four different snail hosts, including the planorbids Planorbella trivolvis (Say) and Gyraulus parvus (Say), the physid Physella gyrina (Say) and a lymnaeid. Two metacercariae, B. damnificus and Bursacetabulus pelecanus Dronen, Tehrany et Wardle, 1999, infect the catfish and mature in the pelican; two others, Austrodiplostomum compactum (Lutz, 1928) and Hysteromorpha cf. triloba (Rudolphi, 1819), mature in cormorants; one, Diplostomum sp., matures in seagulls and at least one, Clinostomum marginatum (Rudolphi, 1819), matures in herons, egrets and other wading birds. Consequently, management of catfish ponds relative to digenean infections requires considerable biological information on the fish, bird, and snail hosts as well as the parasites. 相似文献
3.
The steam-distilled fraction of the aerial parts of Erigeron speciosus (Lindl) DC was tested for activity against strawberry plant pathogenic fungi Botrytis cinerea Pers ex Fr, Colletotrichum acutatum Simmonds, C fragariae Brooks, C gloeosporioides (Penz) Penz & Sacc, and the intermediate host snail Planobdella trivolvis that harbors the trematode, Bolbophorus confusus, that infests and causes severe infections in pond-raised catfish in the Mississippi Delta region of the USA. Bioautography on silica TLC plates demonstrated antifungal activity in the steam distillate. Preliminary bioassays of the steam distillate indicated the presence of phytochemicals toxic to P trivolvis. The bioactive compounds methyl 2Z, 8Z-deca-2,8-diene-4,6-diynoate and its 2E, 8E isomer were isolated by bioassay-guided fractionation and chromatographic techniques and identified by 1H NMR spectroscopy. 相似文献
4.
The developmental cycle of the trematode Rubenstrema exasperatum (Rudolphi, 1819), a common parasite of insectivores of the family Soricidae, is described here for the first time. The first intermediate host in nature is the snail Planorbarius corneus. Metacercariae encysted experimentally in larvae of the mosquito Culex molestus; exceptionally, these were found encysted in daughter sporocysts. Adult specimens of R. exasperatum were found after experimental infections in the hamster Mesocricetus auratus. Daughter sporocysts, cercariae, metacercariae and adults are described in detail. 相似文献
5.
V Nasincová 《Folia parasitologica》1991,38(2):143-154
The life cycle of E. bolschewense, the species with 37 collar spines and closely related to E. revolutum, was experimentally studied. The following developmental stages are described: mother and daughter rediae, cercaria, metacercaria, and adult. The freshwater prosobranchiate snail Viviparus contectus was found to be the first intermediate host in nature. Under experimental conditions, the miracidia developed in V. contectus. They did not, however, penetrate into Bithynia tentaculata or into any of the pulmonate snails tested. The cercariae encysted in various Prosobranchia and Pulmonata. Adult worms were commonly obtained from hamsters (Mesocricetus auratus) and only exceptionally from chickens (Gallus gallus f. dom.). The species studied is considered to be conspecific with Cercaria bolschewensis described by Kotova (1939). 相似文献
6.
Euparyphium albuferensis and Echinostoma friedi cercarial infectivity to four species of sympatric snails was examined under single- or multiple-choice laboratory conditions to show the level of parasite-snail host compatibility. Radix peregra, Lymnaeafuscus, Physella acuta and Gyraulus chinensis act as second intermediate hosts of both parasite species although different cercarial transmission success (CTS) was observed. In single-host experiments, R. peregra and P. acuta showed a high degree of compatibility with E. albuferensis, while only P. acuta in the case of E. friedi. In two-choice snail communities, a snail with high CTS increased the values of another with low compatibility, in both parasite species. In multiple-choice snail communities, high CTS of some hosts decreased, while low CTS of other hosts increased. The degree of parasite-host compatibility of each snail species could be determined by the presence of other snails in the community. 相似文献
7.
Dolecková K Kasný M Mikes L Mutapi F Stack C Mountford AP Horák P 《Folia parasitologica》2007,54(2):94-98
Trichobilharzia regenti is a neurotropic bird schistosome,causing cercarial dermatitis in humans. In this study, ZAP cDNA expression library from Radix peregra s. lat. hepatopancreases containing intramolluscan stages of T. regenti was constructed and screened using PCR with specific and degenerate primers, designed according to previously described serine and cysteine peptidases of other parasite species. Full-length sequences of cathepsins B1 and L, and two serine peptidases, named RpSP1 and RpSP2, were obtained.The protein-protein BLAST analysis and parallel control reactions with template from hepatopancreases of T. regenti non-infected snails revealed that only cathepsin B1 was of parasite origin. The remaining sequences were derived from the snail intermediate host, which implies that the initial source of parasite mRNA was contaminated by snail tissue.Regardless of this contamination, the cDNA library remains an excellent molecular tool for detection and identification of bioactive molecules in T. regenti cercariae. 相似文献
8.
Preeti Singh 《Pesticide biochemistry and physiology》2008,92(3):120-124
Snail control is one of the important methods in the campaign to reduce the incidence of fascioliasis and schistosomiasis. In order to achieve this objective, the method of bait formulation containing an attractant and a molluscicide is an appropriate approach to lure the target snail population to the molluscicide. In the present study snail attractant pellets (SAP) were prepared from binary combination of carbohydrates (10 mM) and amino acids (20 mM) in 2% agar solution. These were tested on Lymnaea acuminata, an intermediate host of the digenean trematodes Fasciola hepatica and Fasciola gigantica. The behavioral responses of snails to these binary combination were examined. The fraction of snails that was in contact with the SAP at different times was used as a measure of attraction. Among all the binary combination of carbohydrates; (sucrose + starch)—72.9%, binary combination of amino acids; (proline + serine)—48.0% and binary combination of carbohydrates and amino acids; (sucrose + serine)—69.5%, emerged as the strongest attractant pellets. Toxicity of these SAP containing different concentrations of molluscicides were used as bait against the snail, L. acuminata. Thymol containing SAP emerged as the strongest bait formulation (96 h LC50 0.540%, 0.318% and 0.305%) against L. acuminata. 相似文献
9.
Vasconcellos ML Silva TM Camara CA Martins RM Lacerda KM Lopes HM Pereira VL de Souza RO Crespo LT 《Pest management science》2006,62(3):288-292
The molluscicidal activities of ten Baylis-Hillman adducts against Biomphalaria glabrata (Say) snails, the intermediate host of schistosomiasis, have been determined. Nine of these compounds showed significant molluscicidal activity against B. glabrata, falling below the threshold of 100 microg ml(-1) set for potential molluscicidal activity by the World Health Organisation. Among these compounds, 3-hydroxy-2-methylene-3-(4-nitrophenyl)propanenitrile had the highest activity, with LC(50) = 6.64 microg ml(-1). 相似文献
10.
为了明确螺虫乙酯大量使用后残留剂量对丽蚜小蜂寄生能力的亚致死效应,本研究在测定螺虫乙酯对丽蚜小蜂室内毒力的基础上,研究了不同浓度螺虫乙酯对丽蚜小蜂寄生功能反应的影响。结果表明LC10、LC30和LC50的螺虫乙酯均可降低丽蚜小蜂对烟粉虱若虫的瞬时攻击率。经LC50的螺虫乙酯处理后的丽蚜小蜂对烟粉虱若虫的处理时间延长,达0.13 d,寄生上限降低,寄生效能被抑制。经LC10的螺虫乙酯处理后的丽蚜小蜂对烟粉虱若虫的处理时间缩短,仅0.04 d,寄生上限提高,寄生效能被促进,但其平均寿命仅13.07 d;当烟粉虱若虫密度较高时,LC10的螺虫乙酯处理后的丽蚜小蜂对烟粉虱若虫的搜寻效应提高。LC50的螺虫乙酯可抑制丽蚜小蜂的寄生能力,而LC10的螺虫乙酯可刺激丽蚜小蜂,提升寄生效能,但缩短了成虫寿命。田间使用螺虫乙酯防治烟粉虱时,应注意其残留量对丽蚜小蜂寄生能力的亚致死效应。 相似文献
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12.
Microsporidia in mosquitoes can be divided into two categories based on their life cycles and host-parasite relationships. Some species of microsporidia exhibit simple life cycles with one spore type responsible for oral (horizontal) transmission. They affect only one generation of the mosquito and are not usually host or tissue specific. Brachiola algerae and Vavraia culicis are examples of species isolated from mosquitoes with relatively straightforward life cycles (one spore type) and simple host-parasite relationships. B. algerae and a close relative of V. culicis have also been isolated from a vertebrate (human) host but sources for these infections are unknown. In contrast to B. algerae and V. culicis, polymorphic (heterosporous) microsporidia in mosquitoes are characterized by complex life cycles involving multiple spore types responsible for horizontal and vertical transmission. They affect two generations of the mosquito and some involve an obligate intermediate host. These microsporidia are generally very host and tissue specific with complex developmental sequences comprised of unique stages and events. The microsporidium Edhazardia aedis is a pathogen of Aedes aegypti and does not require an intermediate host. The developmental cycle of E. aedis is characterized by four sporulation sequences, two in the parental host and two in the filial generation. Recent speculation relative to the source of B. algerae human infection have implicated infected mosquitoes and raised concerns about the safety of mosquito microsporidia in general. The subject of this review is to compare and contrast three species of microsporidia from mosquitoes, two with broad host ranges (B. algerae and V. culicis) and one specific to mosquitoes (E. aedis). This review describes features that distinguish mosquito-parasitic microsporidia with simple life cycles and broad host ranges from truly mosquito-specific microsporidian parasites with complex life cycles. 相似文献
13.
Momeana B. MahmoudWafaa L. Ibrahim Basma M. Abou-El-NourMohamed A. El-Emam Alaa A. Youssef 《Pesticide biochemistry and physiology》2011,99(1):96-104
Four plant species, as a dry powder of their leaves, were tested against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni. The bioassay tests revealed the plants Datura stramonium and Sesbania sesban to be more toxic to the snails than the other two ones. Therefore, they were tested against snails’ fecundity (Mx), reproduction rate (Ro) and their infection with S. mansoni miracidia. In addition, total protein concentration and the activities of the transaminases (AsT and AlT) and phosphatases (AcP and AkP) enzymes in hemolymph and tissues of snails treated with these plants were determined. As well, glucose concentration in snails’ hemolymph was evaluated.Exposure of snails for 4 weeks to LC10 and LC25 of the plants D. stramonium and S. sesban dry powder markly suppressed their Mx and Ro. The reduction rates of Ro for snails exposed to LC25 of these plants were 62.1% and 76.4%, respectively. As well, a considerable reduction in the infection rates of snails exposed to these plants either during, pre- or post-miracidial exposure was recorded. Thus, infection rates of snails treated during miracidial exposure with LC10 of D. stramonium and S. sesban were 41.7% and 52.2%, respectively, compared to 92.6% for control group (P < 0.01). These plants, also, reduced the duration of cercarial shedding and cercarial production/snail. So, snails exposed to LC25 of these plants shed 372.8 and 223.2 cercariae/snail, respectively, compared to 766.3 cercariae/infected control snail (P < 0.01).The results, also, revealed that glucose and total protein concentrations in hemolymph of snails treated with LC10 and LC25 of these plants were decreased, meanwhile, the activities of the enzymes AsT, AlT, AcP and AkP were elevated (P < 0.01). However, the activity of AcP in tissues of treated snails was decreased compared to that of control ones. It is concluded that LC25 of the plants D. stramonium and S. sesban negatively interferes with biological and physiological activities of B. alexandrina snails, consequently it could be effective in interrupting and minimizing the transmission of S. mansoni. 相似文献
14.
In Europe, the life cycle of the trematode N. sobolevi was studied for the first time. Following developmental stages are described in detail: daughter sporocysts, cercariae, metacercariae, adults. Snails Galba corvus and Lymnaea stagnalis were found to be the first intermediate hosts in nature. Metacercariae were obtained experimentally from larvae of the mosquitoes Culex pipiens molestus, adults from the intestine of hamsters (Mesocricetus auratus) and mice (Mus musculus). This is the first finding of this species in Czechoslovakia. The stability of taxonomically important features and comparison with closely related species is discussed. 相似文献
15.
在室内温度(25±2)℃,光周期L∥D=12h∥12h,相对湿度(75±10)%条件下,对蒲螨的寄生行为、其对寄主龄期的选择性、膨腹体的发育过程以及世代生活史进行观察。结果表明:在室内蒲螨能很好地找寻寄主并寄生。平均每头雌螨一生产雌43.31头,产雄4.82头,产子期14.06d,寿命为21.21d。蒲螨对椰心叶甲各龄期的选择性达极显著差异,最喜欢寄生蛹,选择寄生率达到96.67%;其次是5龄幼虫,寄生率为60.00%;1龄幼虫的寄生率最低,只有10.00%。 相似文献
16.
Robert H. Cowie 《国际虫害防治杂志》2013,59(1):23-40
The use of snails as biocontrol agents against other snails and against aquatic weeds is reviewed, evaluating their success and their impacts on non-target organisms. The predatory snail Euglandina rosea (and other species), although widely used against Achatina fulica (the giant African land snail) on Pacific and Indian Ocean islands, has not been shown to control A. fulica but has seriously impacted endemic island species. The facultative predator Rumina decollata , used in California against Helix aspersa (brown garden snail), is widely considered to be environmentally benign. However, evidence of its effectiveness is weak and it will also consume native snails. Ampullariid and thiarid freshwater snails have been used as competitors (and incidental predators) of snail vectors of human schistosomes, the parasites causing schistosomiasis (bilharzia). Successful control has been reported but impacts on native biotas have been essentially ignored. Ampullariids have been used in attempts to control aquatic weeds, sometimes successfully, but again with little consideration of impacts on native biota. Most snails have generalist feeding habits. Thus they are inappropriate biocontrol agents because of their potential nontarget effects. Rarely has adequate pre-release testing of snails been undertaken and post-release monitoring of non-target impacts has always been incidental. The use of non-native snails for biocontrol purposes is poorly regulated; many introductions are unofficial and sometimes illegal. Use of snails as biocontrol agents, if implemented, must be based on adequate pre-release testing, post-release monitoring and genuine concern for preservation of native biodiversity. 相似文献
17.
Rhabdovirus-like particles containing nucleoprotein in a helix with eight turns was demonstrated by transmission electron microscopy in subtegumental cells and syncytial layer of tegument in Brachylaimus fuscatus sporocyst. This is the first case of virus infection in trematodes. The possibility of transfer of the virus to intra-molluscan parasitic generations of the trematode is discussed with respect to the peculiarities of the life cycles of the family Brachylaimidae. 相似文献
18.
F Moravec 《Folia parasitologica》1992,39(2):133-144
From October 1985 until July 1987, the bionomy of the trematode Allocreadium isoporum (Looss, 1894) was studied in the Rokytná River (the Danube basin), Czechoslovakia. While clams of the genera Sphaerium Scopoli and Pisidium Pfeiffer apparently serve as its first intermediate hosts, mayfly larvae Ephemera danica Müll. were found (prevalence 8%, intensity 1-5 metacercariae per mayfly) to be the only second intermediate host of A. isoporum in the locality. The most important definitive host is chub, Leuciscus cephalus (L.), in which the seasonal dynamics of A. isoporum occurrence and maturation was followed. The parasite exhibits here a distinct seasonal cycle of maturation which is shown mainly by quantitative changes in the ratio of young to mature worms containing eggs. The trematodes containing eggs occur almost throughout the year, but mainly in the spring and early summer (maximum in May), and after the oviposition they leave the host. New infections are acquired by chub all the year round. This seasonal periodicity is determined by ecological factors, mainly the temperature regime in the locality. A isoporum infections in chub in this locality are dependent on the body size of host fishes; the highest degree of A. isoporum infection occurs in fishes 20-25 cm long, the prevalence decreasing somewhat in larger fishes; infection is associated with changes in the food composition of chub of different size groups. 相似文献
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20.
樟树叶水浸液对钉螺过氧化物酶等的影响 总被引：1，自引：0，他引：1
用1%~0.1%浓度梯度的新鲜樟树叶的水浸液处理血吸虫的唯一中间寄主———钉螺,设清水饲养为对照。结果表明:樟树叶水浸液处理4~5d后可达到100%的杀灭钉螺效果。采用聚丙稀酰胺电泳技术分离经浓度为1%~0.1%的樟树新鲜叶水浸液处理钉螺样品的过氧化物酶同工酶,经处理24h时样品的酶活高于对照组,而处理48h样品的酶活则大大减弱。由此在微观领域探究了樟树化感作用导致钉螺的病理变化等方面所表现出的杀伤钉螺的机理,获得强他感作用植物樟树灭螺的证据。 相似文献