Heavy Parasite Loads Research Articles

Histological findings associated with treatment response in cutaneous leishmaniasis: a clinicopathological correlation study.

Treatment responses to cutaneous leishmaniasis (CL) observed in Sri Lanka show variability, ranging from quick healing to delayed or failed responses to routine medication. The determinants of these differences in treatment response are not well defined. This study aimed to identify predictive features of treatment response and outcome in localized CL caused by Leishmania donovani, focusing on both clinical and histopathological findings in the patients. Tissue sections (n = 103) derived from 3 mm punch biopsies of parasitologically confirmed patients were assessed. Patients were followed up weekly until complete healing of skin lesions and were reviewed at the end of 6 months and 1 year. Healing required 7-21 weekly doses of intralesional sodium stibogluconate (IL-SSG) (mean = 12.2 ± 0.622). Twenty-nine (28.1%) patients were identified as delayed responders. None had recurred at the end of 1 year. The demographic or clinical features (age, gender, lesion type, size, location, and lesion duration) did not significantly influence the treatment response. A heavy parasite load and acanthosis were significant predictors of a delayed response to treatment (P < 0.001). Higher parasite loads were associated with inflammation of the entire dermis (P = 0.008), more intense infiltration of macrophages (p = 0.001), and epidermal atrophy (P = 0.033). Well-formed granulomas were inversely proportional to parasite loads. Histology findings proved to be better prognostic markers than clinical features for delayed responders to treatment and will aid in targeted patient management when tissue biopsies are performed in the initial diagnosis of CL.

Emerging insights on effects of sharks and other top predators on coral reefs.

Predation is ubiquitous on coral reefs. Among the most charismatic group of reef predators are the top predatory fishes, including sharks and large-bodied bony fishes. Despite the threat presented by top predators, data describing their realized effects on reef community structure and functioning are challenging to produce. Many innovative studies have capitalized on natural experimental conditions to explore predator effects on reefs. Gradients in predator density have been created by spatial patterning of fisheries management. Evidence of prey release has been observed across some reefs, namely that potential prey increase in density when predator density is reduced. While such studies search for evidence of prey release among broad groups or guilds of potential prey, a subset of studies have sought evidence of release at finer population levels. We find that some groups of fishes are particularly vulnerable to the effects of predators and more able to capitalize demographically when predator density is reduced. For example, territorial damselfish appear to realize reliable population expansion with the reduction in predator density, likely because their aggressive, defensive behavior makes them distinctly vulnerable to predation. Relatedly, individual fishes that suffer from debilitating conditions, such as heavy parasite loads, appear to realize relatively stronger levels of prey release with reduced predator density. Studying the effects of predators on coral reefs remains a timely pursuit, and we argue that efforts to focus on the specifics of vulnerability to predation among potential prey and other context-specific dimensions of mortality hold promise to expand our knowledge.

Biodiversity of Parasitic Trematode Allocreadium sp. Looss, 1894 (Digenea: Allocreadiidae): A Review

Although there are many heartening studies have been done on the parasitic helminthes of vertebrates but there are serious deficiencies in checklist of trematodes Allocreadium Looss (Digenea: Allocreadiidae). The present study based on the literature survey to tabulate biodiversity of Allocreadium Looss reported from various hosts in the India and worldwide so far. Allocreadium sp. is one of the most important parasitic digenean trematode with wide geographic distribution range across the world. The findings reflected that these trematodes infecting very wide range of hosts from invertebrates to vertebrates. About 104 Allocreadium sp. have been summarized in present review recovered from various hosts including 44 Indian species as well. As the aquaculture playing a key role in the food security and economy of country that is deteriorating due to heavy parasitic load in fishes. Therefore, awareness, knowledge of biodiversity and causes of parasites should be in the society at grassroots level. The authors wish to suppose that current review might be helpful in the strategic management of aquaculture for health, economy and sustainable development.

First molecular detection of the parasites Molicola uncinatus and Hepatoxylon trichiuri (Cestoda: Trypanorhyncha) infecting the silver scabbardfish Lepidopus caudatus from the Central Mediterranean Sea: Implications for the seafood quality and safety

Trypanorhynch tapeworms are marine heteroxenous parasites, involving sharks and rays as definitive hosts, invertebrates (i.e. crustaceans) as first intermediate hosts, and various teleost fishes as intermediate/paratenic ones. The massive presence of Trypanorhyncha larval forms in the flesh or body cavity of the fish hosts reduces their market value, making them unappealing to consumers, or causing discards of fish products.The identification of merocercoids (N = 100) of Molicola uncinatus and plerocercoids (N = 46) of Hepatoxylon trichiuri parasitizing the silver scabbardfish, Lepidopus caudatus, from the Central Mediterranean Sea (off Malta coast), was obtained, for the first time, by using sequences analysis of the complete small subunit (ssrDNA) and the partial large subunit (lsrDNA) ribosomal RNA gene loci. The Bayesian Inference from the concatenated sequences obtained at the two gene loci showed that the individuals of M. uncinatus and H. trichiuri clustered, respectively, in two well distinct and supported phylogenetic lineages, corresponding to the two cestode species. High prevalence (P) and mean abundance (MA) values were observed in the infection with merocercoids of M. uncinatus (P = 100%, A = 28.81), with the ventral musculature of the silver scabbardfish as the most parasitized site. Plerocercoids of H. trichiuri were found to infect only the mesenteries, attached to various fish tissues, with a mean abundance rate of 1.28.Even if harmless to humans, a heavy parasitic load with larval stages of Trypanorhyncha, particularly in the edible part of the silver scabbardfish (as here reported for merocercoids of M. uncinatus), can compromise the appearance of the fish-food, making it repugnant and unappealing for the final consumer. It has been also discussed that when managing the risk related to parasites affecting the fish quality and safety of fisheries products, the fishing ground where the life cycle of those parasites takes place should be also taken into account, as it would include the ecological drivers of the infection with those parasites. This wider ecological approach would be of help to the Food Business Operators (FBOs), gathering knowledge useful to manage fisheries in a wide “One-Health” perspective, aware of sustainability, quality and consumer safety aspects of sea-food production.

Immune response of channel catfish (Ictalurus punctatus) against Ichthyophthirius multifiliis post vaccination using DNA vaccines encoding immobilization antigens

The channel catfish (Ictalurus punctatus) immune response against Ichthyophthirius multifiliis (Ich) after vaccination using plasmid DNA vaccines pcDNA3.1-IAg52a and pcDNA3.1-IAg52b, encoding Ich immobilization antigen genes was studied. Parasite infection level, serum anti-Ich antibodies level, fish mortality after theront challenge, and immune-related gene expression were measured. After in vitro transfection of walking catfish gill cells (G1b) with both pcDNA3.1-IAg52a and pcDNA3.1-IAg52b, antigens IAG52A and IAG52B were detected. During the vaccination trial, 76-fold increase in the Iag52b gene expression was observed in the vaccinated fish group h4 post vaccination. Administration of DNA vaccines by IM injection induced significant gene up-regulation in the head kidney, including immunoglobulin M (IgM), cluster of differentiation 4 (CD4), major histocompatibility I (MHC I), and T cell receptor α (TcR-α) from h4 to d5 post immunization. Fish vaccinated with DNA vaccines or theronts showed increased gene expression of the cytokine interferon (IFN-γ), complement component 3 (C3), and toll-like receptor-1 (TLR-1). Anti-Ich antibodies were detected in fish received pcDNA3.1-IAg52a, pcDNA3.1-IAg52b and the combination of both vaccines d10 post vaccination. Fish vaccinated with pcDNA3.1-IAg52b showed mild parasite infection level, partial survival (20%) and longer mean day to death (MDD) after theront challenge. By contrast, a heavy parasite load, 0% survival and short MDD were observed in the sham vaccinated control fish that received pcDNA3.1 (plasmid without genes encoding Ich immobilization antigen). Further research is needed to improve DNA vaccines for Ich that can induce strong protective immunity in fish. Suggested studies include improved transfection efficiency, use of appropriate adjuvants and including additional parasite antigen genes in the plasmid.

Experimental infection of Phlebotomus perniciosus and Phlebotomus tobbi with different Leishmania tropica strains

Cutaneous leishmaniasis due to Leishmania tropica is increasingly documented in Europe and the Middle East. Besides its specific vector, Phlebotomus sergenti, permissive Phlebotomus sand flies are suspected as potential vectors of L. tropica. We investigated the susceptibility of two widely distributed species, Phlebotomus perniciosus and Phlebotomus tobbi. Laboratory-reared sand flies were infected experimentally with L. tropica strains differing in lipophosphoglycan epitopes, geographical distribution and epidemiology. High infection rates, heavy parasite loads and fully developed late-stage infections including colonization of the stomodeal valve were observed in all parasite-vector combinations. Our findings demonstrate that P. perniciosus and P. tobbi are susceptible to different L. tropica strains and may play a role in their circulation in endemic foci of Europe, the Middle East and North Africa.

A ReRAM-Based Nonvolatile Flip-Flop With Self-Write-Termination Scheme for Frequent-OFF Fast-Wake-Up Nonvolatile Processors

Nonvolatile flip-flops (nvFFs) enable frequent-off processors to achieve fast power-off and wake-up time while maintaining critical local computing states through parallel data movement between volatile FFs and local nonvolatile memory (NVM) devices. However, current nvFFs face challenges in large store energy ( $\text{E}_{\mathrm {S}}$ ) and long voltage stress time on the device ( $\text{T}_{\mathrm {STRESS}}$ ), due to wide distribution in the write time of NVM device as well as unnecessary writes. Moreover, heavy parasitic load on the power rail cause long wake-up time for restoring data from NVM to FFs. This paper proposes the resistive RAM (ReRAM)-based nvFF with self-write termination (SWT) and reduced loading on power rail to: 1) reduce 93+% waste of $\text{E}_{\mathrm {S}}$ from fast switching or matched cells; 2) suppress endurance and reliability degradation resulted from overprogramming and long $\text{T}_{\mathrm {STRESS}}$ ; and 3) achieve reliable and 26+ times faster restore operation compared with previous nvFFs. We have fabricated a nonvolatile processor and a test chip with SWT-nvFFs using logic-process ReRAM in a 65-nm CMOS process. Measured results show sub-2-ns termination response time and sub-20-ns chip-level restore time.

Low Prevalence but High Intensity of Infestation by Amblyceran Lice in Red-Necked Grebes (Podiceps grisegena) in Eastern Poland

Abstract. Patterns of louse infestation in waterbirds deserve attention due to potential impacts on host populations. Red-necked Grebes (Podiceps grisegena) were visually examined for the presence of amblyceran chewing lice during the 2000–2015 breeding seasons in eastern Poland. Only one species of lice (Pseudomenopon dolium) was recorded. Amblyceran prevalence was low; four young birds (2.7%) were found infested out of 147 banded individuals (66 adults and 81 chicks). However, all infested Red-necked Grebes bore heavy parasite loads. Negative consequences of infestation for physiological condition were indicated by low hemoglobin and total protein values when compared with same-age non-infested birds. The low infestation rate can be related to the biology of the host (a diving species undergoing molt at sea, solitary breeder) and the apparent high pathogenicity of P. dolium, which left numerous holes in feathers and bleeding bites in all parasitized birds.

Disseminated cysticercosis: clinical spectrum, Toll-like receptor-4 gene polymorphisms and role of albendazole: A prospective follow-up of 60 cases with a review of 56 published cases.

In this study, we describe clinical and imaging spectrum, and the natural course of patients with disseminated cysticercosis. How albendazole affects the course of disease has also been evaluated. We assessed the Toll-like receptor-4 gene polymorphisms, to know the reason for the apparently higher prevalence of disseminated cysticercosis in India.Sixty consecutive patients with disseminated cysticercosis were enrolled. Sixty age-and-sex-matched healthy controls were also enrolled for the purpose of genetic study. Twenty patients, who gave consent, were treated with albendazole along with corticosteroids. Forty patients did not give consent for antiparasitic therapy. Assessment for Toll-like receptor-4 gene polymorphisms (Asp299Gly and Thr399Ile genes) was done. Patients were followed for 6 months. We also performed a literature search of cases published in English language using PubMed electronic database and analyzed 56 cases thus available.There was an increased risk (6.63 fold and 4.61 fold) of disseminated cysticercosis in the presence of Asp299Gly and Thr399Ile polymorphisms in Toll-like receptor-4, respectively. The allelic frequency of Gly (11% vs. 3%, P = 0.024, odds ratio [OR] = 3.52) and Ile alleles (11% vs. 2%, P = 0.009, OR = 4.738) in disseminated cysticercosis was high. Albendazole resulted in complete disappearance of all cerebral lesions in 35% (7/20) patients and reduction in lesion load in remaining 65% (13/20) patients. No significant change in number of cysticercal lesion was noted in patients who did not receive albendazole. No major adverse reaction following antiparasitic treatment was noted. Three deaths were recorded in patients who did not receive antiparasitic treatment.Of the 56 cases reported in PubMed, 33 patients received antiparasitic treatment with follow-up data available for 31 patients. Most (24) of these patients received albendazole. A significant clinical and/or imaging improvements, on follow up, were observed in 27 patients. Of the 4 deaths recorded, 3 had a heavy parasitic load and died after praziquantel therapy.Toll-like receptor-4 gene polymorphisms are associated with an increased susceptibility to disseminated cysticercosis, in the Indian population. Albendazole treatment seems to reduce the lesion load and improve symptoms.

Hemiparasitism effect on Baccharis dracunculifolia DC. and consequences to its major galling herbivore

Mistletoes obtain nutrients and water from their hosts, with varying effects among those hosts. We assessed the factors that influence the colonization of the mistletoe Struthanthus flexicaulis on Baccharis dracunculifolia and the subsequent effects on host performance. We evaluated the incidence of S. flexicaulis according to size (height classes) and architecture of the host as well as its effects on various physiological parameters of the host. Furthermore, we assessed the occurrence of insect galls induced by Baccharopelma dracunculifoliae(Psyllidae), including the number of leaves infected, and the mortality of infected and non-infected branches. Taller hosts had a higher abundance of mistletoes (60%, p> 0.05). Physiological parameters of hosts were not affected by parasitism, although galling occurred more often (p 0.05) on infected branches. Taller individuals are more colonized by mistletoes and more architecturally complex hosts support a greater number of mistletoes. Mistletoe causes a top-down effect on host-associated organisms on parasitized branches. Mistletoes had a strong top-downeffect on B. dracunculifolia due to a reduction in the number of leaves on parasitized branches and the replacement of the bush crown, as well as an increased incidence of insect galls. Furthermore, the occurrence of a heavy parasite load increased the mortality rate of the host branches.

Mast cells promote malaria infection?

PurposeMalaria remains the most deadly human parasitic disease, mostly because of the mosquito-born protozoan parasite Plasmodium falciparum with ~627,000 deaths reported in 2012. Unfortunately, there is resistance to most drugs, and successful vaccines are still not developed. The role of the immune system is critical but poorly understood. MethodsOne specific publication that reported a new way through which the immune system may promote malaria pathogenesis is discussed. FindingsKenyan children with mild and severe malaria had increased plasma levels of the Flt3 ligand, a soluble cytokine released from the surface of mast cells (MCs). A positive correlation was found between disease severity and frequencies of circulating BDCA3+ dendritic cells. These human equivalents of the rodent CD8+ T cells migrate to tissues with a heavy parasite load and cause damage primarily through cytolysis. ImplicationsMalaria parasites may promote malaria pathogenesis by triggering MCs, which expand a unique class of dendritic cells with the subsequent activation of pathogenic CD8+ T cells. However, MCs may have additional regulatory functions. Selective inhibition of MC activation may serve as an adjuvant treatment.

Microfilaria in a thyroid nodule discovered by fine needle aspiration cytology

Filariasis is a major health problem in tropical countries, including India. The disease is endemic all over India, especially in Uttar Pradesh, Andhra Pradesh, Orissa, Bihar, Jharkhand, Tamil Nadu, Kerala, and Gujarat. A heavy parasitic load may appear in the blood, urine with chyle, and at times in scrotal aspirates. It is very unusual to find microfilaria in thyroid aspirate. Here, we present a rare case in which microfilaria was found during fine needle aspiration cytology of a solitary thyroid nodule.

Ascaris lumbricoides infection and parasite load are associated with asthma in children.

Association between Ascaris lumbricoides infection and asthma is a controversial subject that has been studied by several authors based on the hygiene theory. This work contributes to better understanding this issue. This was a cross-sectional study involving 1,004 children from a neighborhood of low socioeconomic status in Campina Grande, Paraíba, northeastern Brazil. Asthma was diagnosed using the International Study of Asthma and Allergy in Childhood (ISAAC) questionnaire. Intestinal parasitosis was diagnosed by parasitological examination (the Ritchie technique), and parasite load determined by the Kato-Katz technique. The statistical analysis was descriptive, and hypotheses were tested according to odds ratios. A total of 260 children were infected with A. lumbricoides, and 233 had asthma. Light parasite loads were significantly associated with asthma (wheezing more than three times per year); p = 0.003, OR = 0.41(IC 0.22 - 0.75), while the heavy parasite loads were not; p = 0.002, OR = 2.37(IC 1.35 - 4.18). Similar results were observed in almost all the symptoms of asthma. No association was found with maternal educational level. In children living in urban areas of low socioeconomic status, a light parasite load of A. lumbricoides is a protective factor against asthma and its symptoms. Meanwhile, heavy parasite load is a risk factor and contributes to the high prevalence of asthma and its symptoms among these children.

A rare case of microfilaria in thyroid aspirate

Filariasis is a major health problem in the Indian Subcontinent. Due to its nocturnal periodicity it may be difficult even to demonstrate in the blood. In heavy parasitic load they may appear in the blood, urine with chyle and at times in scrotal aspirates. It is very rare and unusual to find microfilaria in thyroid aspirate. This case report of presence of microfilaria in thyroid aspirate suggest that careful screening is important for thyroid lesions as patients may present with thyroid enlargement other than usual thyroid lesions.DOI: http://dx.doi.org/10.3329/bjms.v13i1.14217 Bangladesh Journal of Medical Science Vol. 13 No. 01 January2014: 99-100

Signal Transducer and Activator of Transcription Factor 6 Signaling Contributes to Control Host Lung Pathology but Favors Susceptibility againstToxocara canisInfection

Using STAT6−/− BALB/c mice, we have analyzed the role of STAT6-induced Th2 response in determining the outcome of experimental toxocariasis caused by embryonated eggs of the helminth parasite Toxocara canis. Following T. canis infection wild-type BALB/c mice developed a strong Th2-like response, produced high levels of IgG1, IgE, and IL-4, recruited alternatively activated macrophages, and displayed a moderate pathology in the lungs; however, they harbored heavy parasite loads in different tissues. In contrast, similarly infected STAT6−/− BALB/c mice mounted a weak Th2-like response, did not recruit alternatively activated macrophages, displayed a severe pathology in the lungs, but efficiently controlled T. canis infection. These findings demonstrate that Th2-like response induced via STAT6-mediated signaling pathway mediates susceptibility to larval stage of T. canis. Furthermore, they also indicate that unlike most gastrointestinal helminths, immunity against larvae of T. canis is not mediated by a Th2-dominant response.

Occurrence of partenites in mollusks and the influence that metacercaria of Apophallus muehlingi (Jagerskiold, 1898) and Posthodiplostomum cuticola (Nordmann, 1832) has on some biochemical parameters in fish

A heavy parasitic load from trematode partenites of Apophallus muehlingi (Jagerskiold, 1898) was observed in the mollusk population of Lithoglyphus naticoides (Pfeiffer) after its natural invasion into the Rybinsk Reservoir. An elevated concentration of glycogen was detected in the muscles of infected fish, both in the natural populations and under experimental conditions. Interspecific differences were found for the protein concentrations when elevated concentrations were observed in the muscles of the infected roach, and no differences were discovered for the goldfish (both infected and parasite-free). The ties between the biochemical parameters and motor activity are discussed for the infected fish.

Fish parasites in the Arctic deep-sea: Poor diversity in pelagic fish species vs. heavy parasite load in a demersal fish

A total of 219 deep-sea fishes belonging to five families were examined for the parasite fauna and stomach contents. The demersal fish Macrourus berglax, bathypelagic Bathylagus euryops, and mesopelagic Argentina silus, Borostomias antarcticus, Chauliodus sloani, and Lampanyctus macdonaldi were caught at 243–708 m trawling depth in the Greenland and the Irminger Sea in 2002. A total of 21 different parasite species, six Digenea, one Monogenea, two Cestoda, seven Nematoda, one Acanthocephala, and four Crustacea, were found. The parasite diversity in the meso- and bathypelagic environment was less diverse in comparison to the benthal. Macrourus berglax had the highest diversity (20 species), usually carrying 4–10 different parasite species (mean 7.1), whereas Bathylagus euryops harbored up to three and Argentina silus, Borostomias antarcticus, Chauliodus sloani and Lampanyctus macdonaldi each up to two species. Most Digenea, Cestoda, Nematoda, Acanthocephala, and Crustacea are known from a wide host range. Several of the encountered parasites occurred at a very low prevalence (<10%), indicating that the studied deep-sea fishes are most probably not instrumental to complete the parasite life cycles in the area of investigation. It is suggested that the lack of nutrients in the meso- and bathypelagial limits the abundance of potential first intermediate hosts of nematodes and cestodes, resulting in low infestation rates even of widely distributed, non-specific species. In contrast, the higher biomass in the benthic deep-sea environment increases the availability of potential intermediate hosts, such as molluscs for the digeneans, resulting in increased parasite diversity. Because many deep-sea fish have a generalistic feeding behavior, the observed different parasite diversity reflects a different depth range of the fish and not necessarily a specific fish feeding ecology.

Down-regulation of gp63 in Leishmania amazonensis reduces its early development in Lutzomyia longipalpis

The zinc protease (gp63) of promastigotes was found to play a role in the sand fly part of the Leishmania life cycle. Lutzomyia longipalpis females were fed with promastigotes (10 6 per ml) of a Leishmania amazonensis clone whose gp63 was up- and down-regulated by directional cloning into P6.5 for sense- and anti-sense transcription. Early development was found to differ significantly between the sense- and anti-sense transfectants 2 days post-feeding. The sense transfectants overexpressing gp63 were found similar to those with the vector alone: both developed in the gut at high rates of ~90–100% and at a high density with moderate to heavy parasite loads in >70% of the infected females. In contrast, the anti-sense transfectants with gp63 down-regulated developed at a lower rate (~70%) and, significantly, at a very low density, with moderate to heavy parasite loads only in ~30% of the infected females. On day 9 post-feeding, all three groups of transfectants developed at a similar rate of ~50% with comparable parasite loads. Thus, gp63 plays a role at the early stage of L. amazonensis establishment in L. longipalpis.

Invasion of the eastern Bay of Biscay by the nassariid gastropod Cyclope neritea: origin and effects on resident fauna

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 276:147-159 (2004) - doi:10.3354/meps276147 Invasion of the eastern Bay of Biscay by the nassariid gastropod Cyclope neritea: origin and effects on resident fauna Guy Bachelet1,*, Benoît Simon-Bouhet2,3, Céline Desclaux1, Pascale Garcia-Meunier2, Guillaume Mairesse1, Xavier de Montaudouin1, Hélène Raigné1, Karine Randriambao1, Pierre-Guy Sauriau4, Frédérique Viard3 1Laboratoire d¹Océanographie Biologique, UMR 5805 CNRS-Université Bordeaux 1, Station Marine d¹Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon, France 2Laboratoire de Biologie et Environnement Marins, EA 3168, Université de La Rochelle, 17000 La Rochelle, France 3Evolution et Génétique des Populations Marines, UMR 7127 CNRS, Station Biologique de Roscoff, BP 74, 29682 Roscoff cedex, France 4Centre de Recherche sur les Ecosystèmes Marins et Aquacoles, UMR 10 CNRS-IFREMER, Place du Séminaire, BP 5, 17137 L¹Houmeau, France *Email: g.bachelet@epoc.u-bordeaux1.fr Abstract: The distribution area of the nassariid gastropod Cyclope neritea (L.) includes the Mediterranean and the Black Sea, as well as the Atlantic coasts of the southern Iberian Peninsula. The species has spread north to the eastern Bay of Biscay (Arcachon Bay in 1976, Marennes-Oléron area and Morbihan Gulf in 1983-84). This spread might be explained either by (1) a natural spread favoured by environmental changes (e.g. an increase of temperature) or (2) a sudden range expansion due to the introduction of individuals from distant native populations. Molecular genetic analyses based on mitochondrial markers suggest that the present C. neritea population in Arcachon Bay has been introduced, probably unintentionally with oyster transfers, from several source populations, genetically similar to the populations analysed in this study, i.e. those in the western Mediterranean and in south Portugal. Within its new distribution area, C. neritea could potentially compete with the autochthonous nassariid Nassarius reticulatus, both species being scavengers. Although C. neritea tends to occur mainly in relatively clean sands in the intertidal and N. reticulatus in subtidal, organic rich sediments, the habitats of both species partially overlap. Laboratory experiments showed that in still water conditions C. neritea was more active and reached carrion faster than N. reticulatus, thereby having a competitive advantage over the latter; flow conditions ( ~1 cm s-1) appeared to stimulate the activity of N. reticulatus. Analysis of parasite load in both species in Arcachon Bay indicated that N. reticulatus was more heavily parasitized by digenean trematodes than C. neritea. This suggests that the spread and population dynamics of C. neritea along the French Atlantic coast has been favoured by the lack of parasites. Altogether, recurrent introduction, competitive ability and lack of heavy parasitic load might explain the successful settlement of C. neritea along the French Atlantic coast. KEY WORDS: Introduced species · Scavenging gastropods · Population genetics · Interspecific competition · Behaviour · Parasites Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 276. Online publication date: August 02, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

COWPEA YIELD GAIN FROM RESISTANCE TO STRIGA GESNERIOIDES PARASITISM IN SOUTHERN BÉNIN

Striga gesnerioides is a serious parasite of cowpea (Vigna unguiculata) on the Abomey plateau of southern Bénin. S. gesnerioides in southern Bénin has been characterized as a race that is different from those found in the dry savanna of West Africa. IITA breeding line IT93KZ-4-5-6-1-5 was used in a trial to study fertilizer response of cowpea on two farmers' fields in 1998. No emerged S. gesnerioides plants were observed on this breeding line while heavy parasite loads were observed on local cultivars growing in adjacent fields. In 1999, IT93KZ-4-5-6-1-5 was grown again on seven fields and no emerged S. gesnerioides plants were observed. In 2000 the same line was grown on 18 farmers' fields with local cowpea cultivars in adjacent control plots. The mean number of S. gesnerioides plants on the local cultivars was 0.92 per cowpea plant (s.d. 0.72) while the improved line carried none. The mean yield gain from the improved cowpea line was 156% and varied from 20 to 680 kg pods ha−1. Thus it appears that progress has been made in developing cowpea lines that are resistant to S. gesnerioides and the potential impact of adoption of resistant cowpea is high.