Nematicidal effect of volatile organic compounds (VOCs) on the plant-parasitic nematode Meloidogyne javanica

Previous studies have demonstrated that volatile organic compounds (VOCs), produced by the yeast Saccharomyces cerevisiae, were able to inhibit the development of phytopathogenic fungi. In this context, the nematicidal potential of the synthetic mixture of VOCs, constituted of alcohols and esters, was evaluated for the control of the root-knot nematode Meloidogyne javanica, which causes losses to crops of high economic value. The fumigation of substrate containing second-stage juveniles with VOCs exhibited nematicidal effect higher than 30% for the lowest concentration tested (33.3 µL g-1 substrate), whereas at 66.6 and 133.3 µL g-1 substrate, the nematode mortality was 100%. The present results stimulate other studies on VOCs for nematode management.

ESTIRIL-LACTONAS DE Cryptocarya aschersoniana Mez. (Lauraceae Juss.) COM ATIVIDADE CONTRA Meloidogyne spp. E INTERAÇÃO IN SILICO COM PROVÁVEL FUMARASE DEMeloidogyne hapla

In a previous study, substances with nematicidal properties were detected in the bark of Cryptocarya aschersoniana. Continuing such study, the methanol extract from this plant underwent fractionation guided by in vitro assays with the plant-parasitic nematode Meloidogyne exigua. Two active compounds were isolated and identified by spectroscopic methods as (E)-6-styrylpyran-2-one and (R)-goniothalamin. The latter compound was also active againstMeloidogyne incognita. In silico studies carried out with (R)-goniothalamin and the enzyme fumarate hydratase, which was extracted from the genome of Meloidogyne hapla and modeled using computational methods, suggested that this substance acts against nematodes by binding to a cavity close to the active site of the enzyme.

Differential responses of nematode communities to soybean genotypes resistant and susceptible to Heterodera glycines race 3

Heterodera glycines and Helicotylenchus dihystera were the two most abundant plant-parasitic nematodes found in two H. glycines race 3-infested fields, Chapadão do Céu, MS and Campo Alegre, MG. These fields had been planted with resistant (R) and susceptible (S) plants to cyst nematodes. In the first field, soybean (Glycine max) FT-Cristalina (S) was susceptible to H. glycines but resistant to H. dihystera, while GOBR93 122243 (R) was just the opposite. In the second field, M-Soy 8400 (R) was more resistant to the spiral nematode than M-Soy8411 (S), but the resistance to the cyst nematode was not different between the two genotypes. The total abundance of nematodes was not different between the susceptible and resistant plants in the two fields, suggesting that H. dihystera and/or bacterial feeders and other trophic groups replaced the reduced abundance of the cyst nematodes in resistant plants. Bacterial feeders acted as a compensatory factor to plant-parasitic nematodes in ecological function. The populations of fungal feeders were higher in GOBR93 122243 (R) than in susceptible FT-Cristalina (S) in Chapadão do Céu, but lower in M-Soy 8400 (R) than in M-Soy 8411 (S) in Campo Alegre. This is being attributed to the different periods of soil samplings that were made at the florescent period in the first field, and at the final growing cycle in the second field. Only four nematodes, H. glycines, H. dihystera, Acrobeles sp. and Panagrolaimus sp. dominated the nematode resistant community GOBR93 122243 (R) in Chapadão do Céu, but dominance was shared by ten genera in Campo Alegre, which explains why the five diversity indexes (S, d, Ds, H' and T) were higher in resistant plants than in susceptible plants in field two.

Management of crotalaria and pigeon pea for control of yam nematode diseases

Management of plant-parasitic nematodes with the use of nematicides has not been recommended for small farmers that grow yam in the Northeastern region of Brazil, due to its high cost and residue toxicity. The use of plants with antagonistic effect to nematodes and green manure which improves soil chemical, physical and biological characteristics can be a viable and low cost alternative to control parasitic nematodes. This work aimed to evaluate the effect of crotalaria (Crotalaria juncea) and pigeon pea (Cajanus cajan) plants on the control of yam nematodes. Three experiments were carried out. The first was conducted under in vitro conditions to evaluate the nematostatic and nematicide effect of extracts from fresh and dry matter of the above ground parts of crotalaria, pigeon pea, and the combination of both. The second experiment was carried out under greenhouse conditions to evaluate the effect of soil amendment with crotalaria, pigeon pea, and the combination of both in the infectivity of Scutellonema bradys, using tomato plants as the host plant. The third experiment was conducted under field conditions to evaluate the effect of crotalaria, pigeon pea, and the combination of both, cultivated between yam planting rows and incorporated to soil surface, on yam nematodes. The aqueous extract obtained form fresh matter of crotalaria had a nematicide effect of 100% for S. bradys. Extracts from dry matter of both crotalaria and pigeon pea did not have any nematicide effect, but had a nematostatic effect. Incorporation of crotalaria to soil inhibited infectivity of S. bradys in tomato seedlings. These results showed that planting crotalaria alone or in combination with pigeon pea, between the yam planting rows, is an efficient method for controlling S. bradys and Rotylenchulus reniformis associated with yams. Crotalaria can be used for controlling these plant-parasitic nematodes in soil.

Abdominal Angiostrongylosis in Southern Brazil - Prevalence and Parasitic Burden in Mollusc Intermediate Hosts from Eighteen Endemic Foci

Angiostrongylus costaricensis is a parasitic nematode of rodents and molluscs are the intermediate hosts. Nocturnal collection of molluscs and search for infective third stage larvae of A. costaricensis was carried out in 18 endemic foci identified by the notification of a confirmed diagnosis in human biopsies or surgical specimens. Molluscs were digested in acidic solution and isolation of larvae eventually present was done in a Baermann funnel. Larvae identified by the presence of a delicate groove in the tail were counted to assess the individual parasitic burden. Four species were found infected, with ranges of prevalence in parenthesis: Phyllocaulis variegatus (7% to 33.3%); Bradybaena similaris (11.7% to 24.1%); Belocaulus angustipes (8.3% ) and Phyllocaulis soleiformis (3.3% to 14.2%). Parasitic burden varied from 1 to 75 with P. variegatus, 1 to 98 with B. similaris, 1 to 13 with B. angustipes and 1 larvae in each of two specimens of P. soleiformis. P. variegatus was present in all sites and was found infected with the highest prevalence figures and the highest individual parasitic burdens. These data stress the importance of veronicellid slugs as intermediate hosts for A. costaricensis in the endemic areas in Rio Grande do Sul, Brazil

Immunolocalisation of secreted-excreted products of Meloidogyne spp. using polyclonal and monoclonal antibodies

Molecules expressed at the surface cuticle (SC) of plant parasitic nematodes represent the primary plant-nematode interface, and together with secreted-excreted (S-E) products are probably the first signals perceived by the host. These molecules, which are released into plant tissue, probably play important roles in the host-parasite interactions. Characterisation of these antigens will help in the identification of nematode targets useful for novel control strategies, which interfere with the nematode infection of plants. Three monoclonal (MAbs) and three polyclonal (PAbs) antibodies produced to S-E products of Meloidogyne spp. and Heterodera avenae were used to examine their reactivity towards M. incognita and/or M. arenaria second stage juveniles and adult females. The three PAbs showed cross-reactivity with M. incognita and M. arenaria. Antibody Roth-PC 373 strongly recognised molecules present in the SC, amphids and intestine, antibody Roth-PC 389 recognised the nematode amphids and metacorpus, while antibody Roth-PC 419 bound to molecules present in the subventral glands. Reactivity of the MAbs was only tested against M. arenaria. Monoclonal antibody Roth-MAb T116C1.1 showed intense reactivity with molecules present in the amphidial and phasmidial glands. Monoclonal antibodies Roth-MAb T46.2 and T42D.2 labeled the nematode amphids and molecules present in the nematode oesophagus (metacorpus), respectively.

dogs may be a reservoir host for Angiostrongylus costaricensis

Angiostrongylus costaricensis is a parasitic nematode of wild rodents. Several other vertebrate species including man may become infected by ingestion of the third stage larvae produced by the intermediate hosts, usually slugs from the family Veronicellidae. There is a report of the diagnosis of abdominal angiostrongyliasis in Canis familiaris with lesions resembling those found in human disease. As a preliminar evaluation of the adequacy of a canine model for pathogenetic studies, a dog was inoculated with 75 L3 of A. costaricensis. Infection was established and fist stage larvae were found in feces up to 88 days post infection, sometimes in very large numbers (9.5 x 10(4) L1/g). No clinical manifestations or significant lesions were detected. These are indications that dog may play a role as a reservoir host for A. costaricensis.

PARASITOLOGICAL AND MOLECULAR DIAGNOSIS IN EXPERIMENTAL Strongyloides venezuelensis INFECTION

Strongyloides venezuelensis is a parasitic nematode of rats which is frequently used as a model to study human and animal strongyloidiasis. The aim of this study was to evaluate the correlation between parasitological and molecular diagnosis in Strongyloides venezuelensis infection. PCR assays were used to detect S. venezuelensis DNA in fecal samples obtained from experimentally infected Rattus norvegicus. The results showed a higher sensitivity of the PCR assay in detecting the infection compared to parasitological methods.

MEMBRANE FRACTIONS FROM Strongyloides venezuelensis IN THE IMMUNODIAGNOSIS OF HUMAN STRONGYLOIDIASIS

Strongyloides venezuelensis is a parasitic nematode of rodents frequently used to obtain heterologous antigens for the immunological diagnosis of human strongyloidiasis. The aim of this study was to evaluate membrane fractions from S. venezuelensis for human strongyloidiasis immunodiagnosis. Soluble and membrane fractions were obtained in phosphate saline (SS and SM) and Tris-HCl (TS and TM) from filariform larvae of S. venezuelensis. Ninety-two serum samples (n = 92) were obtained from 20 strongyloidiasis patients (Group I), 32 from patients with other parasitic diseases (Group II), and 40 from healthy individuals (Group III), and were analyzed by enzyme-linked immunosorbent assay (ELISA). Soluble fractions (SS and TS) showed 90.0% sensitivity and 88.9% specificity, whereas the membrane fractions (SM and TM) showed 95.0% sensitivity and 94.4% specificity. The present results suggest the possible use of membrane fractions of S. venezuelensis as an alternative antigen for human strongyloidiasis immunodiagnosis.

Angiostrongylus costaricensis and the intermediate hosts: observations on elimination of L3 in the mucus and inoculation of L1 through the tegument of mollucs

Human accidental infection with Angiostrongylus costaricensis may result in abdominal disease of varied severity. Slugs from the Veronicellidae family are the main intermediate hosts for this parasitic nematode of rodents. Phyllocaulis variegatus, Phyllocaulis soleiformis and Phyllocaulis boraceiensis were experimentally infected to describe the kinetics of L3 elimination in the mucus secretions of those veronicelid species. A maximum of 2 L3/g/day was found in the mucus, while the number of L3 isolated from the fibromuscular tissues varied from 14 to 448. Productive infection was established by inoculations in the hyponotum or in the body cavity, through the tegument. Intra-cavity injection is a less complex procedure and permits a better control of inocula. A preliminary trial to titrate the infective dosis for P. variegatus indicated that inocula should range between 1000 and 5000 L1. The data also confirmed the importance of P. variegatus as an intermediate host of A. costaricensis.

Scanning Electron Microscopy of Lagochilascaris minor Leiper, 1909 (Nematoda: Ascarididae)

Lagochilascaris minor Leiper, 1909 is a parasitic nematode with its biological cycle still unknown, even though it was found in humans, domestic and silvatic animals. Adult worms, collected by surgical drainage from a human patient from the State of Pará, Brazil, were micrographed using a scanning electron microscope. Morphological aspects of males and females such as cephalic structures, caudal papillae and cuticular patterns were analyzed and compared with the previous descriptions adding new data for the identification of this species.

Ecological Data of Travassosnema travassosi travassosi (Dracunculoidea: Guyanemidae) from the Humour of the Eyes of Acestrorhynchus lacustris from Tibagi River, Paraná, Brazil

Data obtained between 1990 and 1995 provide, for the first time, ecological information of the parasitic nematode Travassosnema travassosi travassosi Costa, Moreira & Oliveira, 1991 from Acestrorhynchus lacustris (Characiformes: Acestrorhynchidae) collected in the Tibagi River, Sertanópolis, Paraná, Brazil. These nematode occurred with low prevalences (7.7% to 28.6%) and intensities (1 to 3) during almost the whole year. The observation of mature females throughout the year indicate that liberation of larvae can occur during all the year around. This is the first report on the occurrence of T. travassosi travassosi inside the eyes. These nematodes were mostly located in humour of the eyes (87% of cases), being less frequently detected in tissues behind the eyes (13% of cases).

Mortality in immatures of the floodwater mosquito Ochlerotatus albifasciatus (Diptera: Culicidae) and effects of parasitism by Strelkovimermis spiculatus (Nematoda: Mermithidae) in Buenos Aires Province, Argentina

Life tables were constructed for six cohorts of immature stages of the floodwater mosquito Ochlerotatus albifasciatus (Macquart) in a park in Buenos Aires, highlighting the mortality attributable to the parasitic nematode, Strelkovimermis spiculatus Poinar & Camino. Two cohorts were selected to compare parasite incidence in all mosquito stages when low and high parasitism occurred. Development time of Oc. albifasciatus from first instar to adult was 7.7-10 days in the spring, 6 days in the summer, and 10.9-21.9 days in the fall. Survival was estimated as 0-1.4% in the spring, 2% in the summer and 0.2-4.4% in the fall. The highest "K" value (Killing power) occurred during a fall cohort when prevalence of the parasite was 86.9%, and the lowest in a spring cohort. Parasitism occurred during all seasons, but S. spiculatus persisted to adult only in the summer and fall, when adult mosquitoes developed from parasitized third and fourth instars larvae. The abundance of S. spiculatus differed between old and young larvae only when parasite prevalence was the highest. Although pupae and adults of Oc. albifasciatus were parasitized, no pupal mortality attributable to parasitism was recorded. The proportion of parasitized adults ranged from 14.2% and 5.7% in the two cohorts compared. Pupal wet weight and adult wing lengths did not differ between parasitized and unparasitized individuals.

Spinitectus osorioi (Nematoda: Cystidicolidae) in the Mexican endemic fish Atherinella alvarezi (Atherinopsidae) from the Atlantic River drainage system in Chiapas, Southern Mexico

Specimens of Spinitectus osorioi Choudhury and Pérez-Ponce de León, an intestinal nematode species previously considered to be specific to Chirostoma spp and endemic to some lakes in the Pacific drainage in Michoacán, were collected from the freshwater fish Atherinella alvarezi (Díaz-Pardo) (Atherinopsidae) of the Michol River near Palenque, Chiapas, Southern Mexico, which belongs to the Atlantic drainage system. Studies using light and scanning electron microscopy revealed some taxonomically important, previously unreported or erroneously reported features of S. osorioi, such as the location of the vulva, the actual number and distribution of postanal papillae and phasmids and the presence of a short median cuticular ridge anterior to the cloacal opening (in addition to two long subventral ridges). The recorded somewhat shorter spicules (420-465 and 105-111 μm) and mostly smaller eggs (33-36 × 18-20 μm) as compared to the original species description may be due to a different type of host, geographical region or generally smaller body measurements of these specimens. These biometrical differences are considered to be within the limits of the intraspecific variability of S. osorioi. A key to species of Spinitectus parasitizing freshwater fishes in Mexico is provided.

Influence of mineral fertilization on edaphic fauna in Acacia auriculiformis (A. Cunn) plantations

Fertilization and/or the accumulation of organic matter from plant residues can influence the composition of soil and litter community. The goal of this study was to evaluate the effects of P and K fertilization on total faunal and nematode faunal composition and richness in plant litter and soil for 360 days in an area reforested with Acacia auriculiformis (A. Cunn), located in the municipality of Conceição de Macabu in the State of Rio de Janeiro. For each treatment (fertilized and unfertilized plots), samples of litter and soil (to a depth of 5 cm) were collected and transferred into a Berlese-Tüllgren funnels for the extraction of fauna. Mesofauna and macrofauna were quantified, and the major taxa identified. Nematodes were extracted by centrifugal flotation in sucrose solution and identified according to feeding habits. Density (number of individuals m-2) of total fauna, microphages, social insects and saprophages varied significantly per treatment and sampling time in both litter and soil. The total number of individuals collected was 5,127, and the total number of nematodes 894. Phosphorus and potassium fertilization resulted in an increase in total fauna density and richness in the litter due to an increased abundance of social insects, saprophages and herbivores. In the soil, fertilization increased the saprophage and predator densities. Saprophages were the predominant taxa in the litter, while social insects (Formicidae) prevailed in the soil. Litter nematode populations were favored by mineral fertilization. Bacteriophages were the predominant nematode group in both litter and soil.