Large Numbers Of Nematodes Research Articles

In Vitro Assessment of Aqueous Extracts of Castor Plant (Ricinus communis) against Root-Knot Nematodes (Genus Meloidogyne) Infecting Tomato

Root-knot nematodes represent a real problem for tomato cultivation throughout the world. The aim of this study was to develop a method of controlling root-knot nematodes with aqueous extracts of castor bean, and to evaluate the effect of these extracts on these agents. Firstly, a sampling which consisted of taking the roots presenting galls and the soil was carried out in a tomato plantation in the region of Tchologo (Côte d'Ivoire) more precisely at Camp Agropastoral Sika (CapSIKA). The analysis carried out showed that there is a significant difference between the number of nematodes in the soil and in the roots of the samples taken, (p-value0.05). A large number of nematodes were observed in the roots compared to the soil. Then, the extracted nematodes were used for a pathogenicity test to verify their involvement in the appearance of galls in tomato roots. Galls were observed on inoculated tomato plants following this test. Subsequently, the individuals were exposed to the aqueous extract of castor bean (Ricinus communis) at concentrations of 100, 75, 50 and 25%, the control group was not brought into contact with the aqueous extract of castor bean. Mortality and immobility rates were determined. A significant difference between the number of immobile and dead individuals in the extracts (P0.05) was obtained following the statistical analyses. The results made it possible to show the nematicidal nature of the aqueous extract of castor bean under controlled conditions (in vitro). This extract could be used for the control of Meloidogyne after testing its effectiveness in open fields.

Plant Parasitic Nematodes Associated with Okra in the Forest Savanna Transition and Semi-Deciduous Forest Agro-Ecologies of Ghana

Okra is an important vegetable crop in Ghana. Plant-parasitic nematodes infect okra, reducing the quality and quantity of fresh immature and dry fruits. This study was carried out to determine diversity, density and distribution of plant parasitic nematodes attacking okra in the Forest savanna transition and Semi-deciduous forest agro-ecologies of Ghana. In each agro-ecology, soils from okra rhizosphere were sampled from 15 farms for plant-parasitic nematodes assessment. Nematodes were extracted using the modified Baermann nematodes extraction method. Six nematode genera were identified; Meloidogyne, Pratylenchus, Xiphinema, Helicotylenchus, Rotylenchulus and Scutellonema. Meloidogyne occurred with 64.9% relative abundance and 100% frequency. Rotylenchulus, Pratylenchus, and Helicotylencus nematodes also occurred with 100% frequency. Xiphinema were the least abundant (0.05%) and the least frequent (15%). The findings have shown that a large number of nematodes exist on okra plants and therefore there is the need for educational campaigns to be stepped up by Agricultural Extension Services of the Ministry of Food and Agriculture on plant parasitic nematode infections in okra production.

Mortalidade causada por nematódeos gastrintestinais em bovinos de corte submetidos a protocolo sanitário inadequado

ABSTRACT: The aim of this study was to describe the epidemiological, clinical, and pathological findings of two outbreaks of gastrointestinal nematode infections in beef cattle kept under an inadequate sanitary protocol. An outbreak of trichostrongylosis occurred in Amambai, Mato Grosso do Sul (MS), from May to July 2016. The herd consisted of 3,000 Nellore cows, and of these, fifteen died after showing emaciation and diarrhea and remaining in recumbency. At necropsy, the abomasum showed edema in the folds, white, raised areas, multifocal to coalescent, and small ulcers. Histopathology showed larvae compatible with trichostrongylid nematodes were present inside the abomasum glands. Trichostrongylus axei was identify in the abomasum. The hemonchosis outbreak began in October 2018, in a breeding and finishing property in Santa Rita do Pardo, MS. Of 4,000 cattle aged 8 to 18 months, 673 became ill and 117 died. Clinical signs were emaciation, weakness, dehydration, submandibular edema, and soft stools. At necropsy, large numbers of nematodes were found in the abomasum; they were morphologically classified as Haemonchus placei. Both outbreaks were caused by failures in the parasite control protocol. However, in Outbreak I, frost and immune stress caused by lack of food may have contributed to the deaths. In Outbreak I, the main failure in the devermination protocol was the use of anthelmintics without carrying out an efficacy test. In Outbreak II, there was no parasite control protocol in the rearing and finishing property, and in the breeding property, there was resistance to the anthelmintic used (ivermectin). The two outbreaks highlight the importance of gastrointestinal nematode control protocols in cattle and demonstrate that infections by T. axei and H. placei can be lethal for this species.

A Mechanistic Approach To Assessing the Potential for Cover Crops To Serve as Trap Crops for the Soybean Cyst Nematode

The effects of cover crops on the biology of the soybean cyst nematode (SCN; Heterodera glycines) are not well established. It is possible that cover crops may reduce SCN population densities by acting as trap crops. Cover crops with potential to serve as trap crops may stimulate hatching and/or attract hatched SCN juveniles and also may be penetrated by large numbers of nematodes that cannot feed. Experiments were conducted to determine whether root exudates (REs) and soil leachates (SLs) from various cover crop plants affected SCN hatching and chemotaxis and if there were significant differences in SCN juvenile root penetration among different cover crop plant types. In 14-day-long hatching experiments, there was greater SCN hatching in crimson clover (Trifolium incarnatum) REs and SLs than in REs and SLs from all other cover crop treatments in the experiments. No other cover crop REs and SLs significantly affected hatching. In chemotaxis experiments, SCN juveniles were attracted to REs and SLs from annual ryegrass (Lolium multiflorum) and cereal rye (Secale cereale) after 24 h. In greenhouse experiments, significantly more SCN juveniles penetrated the roots of single cultivars of crimson clover, mustard (Brassica juncea), and rapeseed (B. napus) than 11 other cover crop species/cultivars evaluated in the experiment over the course of 20 days. Few SCN juveniles penetrated the roots of annual ryegrass and cereal rye. The results suggest that crimson clover, grown as a cover crop, has the most potential to act as a trap crop for SCN. Cover crop plants may affect SCN biology in ways other than the mechanisms investigated in these experiments.

Abortion in Captive Gray Brocket Deer (Mazama gouazoubira) Associated with Colloid Goiter, Hemonchosis and Necrotizing Rumenitis

Background: The gray brocket deer (Mazama gouazoubira) is a specie that shows great adaptability in different habitats and it is the most abundant deer specie in South America. The present work describes for the first time a case of abortion followed by death associated with colloid goiter, massive hemonchosis and necrotizing rumenitis in a captive female gray brocket deer. Case: A 4-year-old female gray brocket deer (M. gouazoubira) raised in captivity had a history of abortion during the last third of gestation. The animal was kept in an enclosure together with 3 other gray brockets deers, being 1 male of the same age and 2 juvenile brocket deer of approximately 1 and 2 years old. The animals were fed with concentrated used as cattle feed and dewormed annually with 1% Ivermectin. The animals' enclosure had vegetation cover formed by grasses and soil. The animals appeared healthy with no behavioral changes. The day after the stillbirth, the mother was found dead in the enclosure and sent to the animal pathology sector of the University of Vila Velha (UVV), Brazil. Necropsy revealed that thyroid lobules were highly increased in volume and histopathological findings were compatible with colloid goiter. A large number of nematodes were found in the abomasal content,totalizing 11,626 helminths, which were morphologically characterized as Haemonchus contortus. Grossly, the serous and ruminal mucosa exhibited an extensively reddish focal area with irregular contour, surface ulceration and a firm consistency. Microscopically, a severe necrotizing rumenitis was diagnosed. The liver showed pale multifocal areas on the subcapsular surface,friable to the touch which deepened when cut. Histopathological analysis revealed an accentuated multifocal panlobular coagulative necrosis, characterizing an acute liver necrosis.Discussion: Iodine is a mineral of great importance for thyroid hormones synthesis and your requirements are higher during pregnancy and lactation. Diets deficient in iodine causes a reduction in the basal activity of the hormones triiodothyronine (T3) and thyroxine (T4) and over-stimulation of the thyroid by thyroid stimulating hormone (TSH), resulting in goiter. In the present case, it is possible that the shortage of iodine in diet caused a goiter and, as a consequence, triggered the abortion. Haemonchus contortus is a pathogenic nematode of small ruminants, leading to decreased productivity and death in some cases as a result of anemia and hypoxia. The contact between domestic and wild animals, resulting in the emergence of infectious diseases and the spread of pathogens among species. In the present case, manual counting accounted for 11,626 H. contortus larvae, characterizing a massive infection and justifying the condition of severe anemia. The high parasitic load shown in this case points out this parasite's importance related to this species in captivity. In general, inflammatory lesions in the rumen are results of excessive intake of fermentable carbohydrates, which leads to a considerable decrease in ruminal pH and leads to a high proliferation of lactic acid bacteria. This lesion has been previously reported in cervids. This case of comorbidities demonstrates that failures in nutritional and health handling, may cause simultaneous multiple diseases leading to death. Preventive measures for helminth parasite control and a proper feeding management with an adequate diet must be provided in order to preserve the species in captivity. Keywords: colloid goiter, abortion, cervids, Haemonchus contortus.

ИДЕНТИФИКАЦИЯ ВОЗБУДИТЕЛЕЙ ЗООНОЗОВ У КАБАНА (SUS SCROFA, LINNAEUS, 1758) ПРИ ВЕТЕРИНАРНО-САНИТАРНОЙ ЭКСПЕРТИЗЕ ПРОДУКТОВ УБОЯ

The paper presents the results of a veterinary and sanitary study of meat and offal of wild boar (Sus scrofa). According to the results of our study, adult boars were infected with helminths, which are dangerous for humans: in two boars (14,3%) plerocercoids Spirometra sp. (sparganum) were found in the intermuscular connective tissue, in two samples (14,3%) microcysts of protozoa Sarcocystis sp. were detected, in one sample (7,1%) a large number of nematodes of the genus Metastrongylus were found in the lungs. Trichinosis, cysticercosis, echinococcosis, fascioliasis were not registered by us in the presented material.

Fatal Peritoneal Migration of Strongylus edentatus in a Foal

A 7-month-old female mixed breed foal with a 2-day history of recumbency and inability to open its mouth convulsed acutely and died and was submitted for necropsy examination. The foal was thin and large patches of haemorrhage were present throughout the peritoneal wall, the diaphragmatic surfaces and the retroperitoneum. Numerous nematode larvae were visible on the serosal surfaces and penetrated and embedded into the subserosa associated with the haemorrhages. The dorsal portion of the abdominal diaphragm had a partial tear and large numbers of nematodes were within the muscle fibres. Histologically, the larvae had a smooth cuticle, polymyarian/coelomyarian musculature and multinucleated intestinal cells, and were typically surrounded by haemorrhage, neutrophils, dense fibrovascular connective tissue and rare multinucleated giant cells. Parasitological examination identified the larvae as Strongylus edentatus based on the morphology of the buccal capsule. Additionally, there was severe muscle necrosis of the tongue and liver tissue analysis detected selenium deficiency. S. edentatus infections are uncommon in California, USA, and are typically non-lethal. In this case, the selenium deficiency may have led to immunosuppression, resulting in the hyperinfection with S. edentatus, and to the muscle damage and tear of the diaphragm. Although ivermectin treatment was indicated in the history, inadequate deworming or anthelmintic resistance may have played a role in the severity of infection.

Anthelmintic effect of herbicidal dinitroanilines on the nematode model Caenorhabditis elegans

Dinitroanilines are known herbicides that impair the polymerization of microtubules. This study investigated the effects of oryzalin and trifluralin on the viability, morphology, and ultrastructure of different life stages of Caenorhabditis elegans. Both drugs reduced the survival of the adult population in 50% after three days of treatment with concentrations of approximately 30 μM and 57 μM, respectively. The development of new adults was monitored for seven days and treatment with both drugs also showed a decrease in the adult population. 25 μM Oryzalin or trifluralin inhibited the hatching of eggs by nearly 100%. Both drugs showed remarkable larvicidal activity at 25 μM against the larvae at first and second stages (L1–L2) and at third and fourth stages (L3–L4) after 24 h. Treatment with dinitroanilines led to incomplete egg embryo development. The oryzalin and trifluralin treatments caused the detachment of cuticular layers of adults and larvae and the formation of a large number of intracellular membrane whirls and lipid bodies in the hypodermal cells and non-contractile muscles of adults. Both drugs also provoked the bagging process, which generated lesions in the uterus of the adults. In addition, trifluralin caused the detachment of certain areas of the cuticle adjacent to the hypodermis in a large number of nematodes. Our results suggest that dinitroanilines are a potentially new alternative for anthelmintic chemotherapy.

The white-tip nematode, Aphelenchoides besseyi, exhibits an auxin-orientated behaviour affecting its migration and propagation

Aphelenchoides besseyiis an obligate parasite that often causes white-tip symptoms in rice plants. The nematode exhibits ectoparasitic behaviour with its infection rate matching the development of rice plants. Few studies have analysed howA. besseyimigration is influenced by chemical and host factors. Here, we focused on the effects of auxins on nematode migration and propagation. Exposure ofA. besseyito an auxin gradient created by a Pluronic F-127 gel resulted in nematode aggregation at the highest auxin concentration tested, 100 μm. Inoculation on the susceptible cv. Ningjing1 produced more nematodes than on the resistant rice cv. Tetep, which correlated with their endogenous auxin levels. Young panicles treated with 1-naphthaleneacetic acid produced more grains and nematodes, whereas plants treated with the auxin transport inhibitor, 2,3,5-triiodobenzoic acid, led to fewer nematodes in the seeds. In addition,A. besseyirarely migrated and multiplied in the plants of the male sterile rice cv. Zhenshan97A, which had insufficient auxin level in pollen and thus could not generate any grains in most panicles. However, large numbers of nematodes were observed in seeds of cv. Zhenshan97A that had received pollens from the maintainer cv. Zhenshan97B. The results indicate that auxin might play a key role in the migration and propagation ofA. besseyi.

Estimations of Species Richness in The Complex Communities of Nematode Parasites Found in The Stomachs of Kangaroos and Wallabies (Family Macropodidae)

Kangaroos and wallabies harbour a diverse array of strongyloid nematodes in their sacculated forestomachs. Determining the number of nematode species present in complex communities such as these can be technically difficult due to the large size of the host organ, the large numbers of nematodes and the large number of closely related nematode species. This problem was investigated using species accumulation methods in 16 eastern grey kangaroos (Macropus giganteus), 15 red-necked wallabies (Macropus rufogriseus) and 6 swamp wallabies (Wallabia bicolor). Nematodes from a subsample of known size were identified individually to species and the number of nematodes which needed to be examined before all of the species in the subsample were found was determined. In M. giganteus (mean worm burden 20,500), between 27 and 92 (mean 57) nematodes had to be examined before all (13) species were recovered. In M. rufogriseus (mean worm burden 60,600), an examination of between 16 and 178 (mean 57) nematodes recovered all (8) species while in W. bicolor (mean worm burden 16,300), 16–196 (mean 67) nematodes needed to be examined to recover all (15) species present. It was concluded that examination of samples of 200 nematodes from each animal would have been sufficient to identify all parasite species present.

Levels of infection of gastric nematodes in a flock of great cormorants (Phalacrocorax carbo) from Lake Biwa, Japan

A high prevalence (86.7%) of various species of nematodes was observed in the stomach of great cormorants living in Lake Biwa, Japan. There were varying numbers of adults belonging to two common genera, Eustrongylides Jagerskiold 1909 (Nematoda: Dioctophymatidae) and Contracaecum Railliet & Henry 1912 (Nematoda: Anisakidae). The first included common adenophorean nematodes comprising a single species, Eustrongylides tubifex and the second comprised ascaroid nematodes that contained four named species: Contracaecum rudolphii Hartwich, 1964, Contracaecum microcephalum Yamaguti, 1961, Contracaecum multipapillatum Drasche, 1882 and Contracaecum chubutensis Garbin, 2008. After the prevalence and intensity of the infection had been noted, both types of nematodes were frequently observed to penetrate the mucosa and intrude into the wall of the glandular stomach, where they caused gross haemorrhage and ulceration. The Eustrongylides sp. was predominantly found in a nodular lesion of the proventricular wall, while Contracaecum spp. were observed either free in the lumen of the proventriculus or, on occasion, deeply penetrating its wall. Of the Contracaecum spp., C. rudolphii was the most prevalent. Grossly, large numbers of nematodes were present in infected stomachs (for C. rudolphii intensity was 1-34 and 3-57 nematodes in male birds and 1-21 and 1-32 in females; for C. microcephalum 1-2 and 1 in male birds and 1-2 in females; for C. multipapillatum 2 in male cormorants and no infection in females; for C. chubutensis 1-2 and 1 in male birds and 1-5 and 1 in females and for E. tubifex 1-5 nematodes in male birds and 2-8 in females). Ulcerative inflammation and hyperaemia were the most common pathological presentations, especially in areas that had been invaded by parasites. Microscopically, varying degrees of granulomatous inflammatory reactions were seen, in addition to degenerated nematodes which appeared to have deeply penetrated mucosal surfaces and were surrounded by fibrous connective tissues.

First report of the Hadjelia truncata infestation in pigeons of Iran

Summary Three adult pigeons (Columbia livia) belonging to a pigeon farm in Mashhad area were submitted to Poultry Clinic of School of Veterinary Medicine for post-mortem inspection. The farm had 150 adult pigeons and a number of them suffered from a chronic disease with body weight loss, diarrhoea and weakness. At necropsy, slight to extreme enlargement with distortion were observed in gizzards of all carcases. There was a large number of nematodes in or beneath the lining of the affected gizzards. The worms were removed from the lining of the rostral parts of the gizzards and cleared in lactophenol. Also, tissue blocks from various parts of the gizzards were processed by conventional methods for preparation of paraffin wax sections. Based on parasitological and pathological findings the Hadjelia truncata infestation was identified for the first time from Iran and this species is a pathogenic agent for pigeons.

The morphology of the filaroid nematodeSetaria tundra,the cause of peritonitis in reindeerRangifer tarandus

In Finland during 2003-2005, large numbers of nematodes, tentatively identified as Setaria sp., were observed in the peritoneal cavity of reindeer Rangifer tarandus during a peritonitis outbreak associated with poor body condition. The morphology of worms recovered from slaughtered reindeer is described based on light and scanning electron microscopy. Worms were confirmed as belonging to the superfamily Filarioidea by the presence of microfilariae-producing females and the size and the shape of the male spicules. Further classification to the genus Setaria was based on the location of worms in the peritoneal cavity and the morphology of spicules and the peribuccal crown. The present measurements correlate with those in the description of Setaria tundra by Rajewsky (1929) and only minor differences were present compared with descriptions of key parts of identification of S. yehi from the American white-tailed deer Odocoileus virginianus and mule deer O. hemionus. Current morphological findings support our earlier studies employing a polymerase chain reaction and confirm the occurrence S. tundra in reindeer in Finland.

Strong bottom-up and weak top-down effects in soil: nematode-parasitized insects and nematode-trapping fungi

The soils of the Bodega Marine Reserve (BMR, Sonoma County, California) contain many nematode-trapping fungi and many ghost moth larvae parasitized by entomopathogenic nematodes. The current study determined whether these nematode-parasitized moth larvae, which can produce very large numbers of nematodes, enhanced the population densities of nematode-trapping fungi and whether the fungi trapped substantial numbers of nematodes emerging and dispersing from moths. Wax moths were used in place of ghost moths because the former are easier to obtain. When nematode-parasitized moth larvae were added to laboratory microcosms containing BMR field soil, the population densities of four nematode-trapping fungi increased substantially. The greatest increase in population density was by Arthrobotrys oligospora, which uses adhesive networks to capture nematodes. A. oligospora population density increased about 10 times when the added moth larvae were parasitized by the nematode Heterorhabditis marelatus and about 100 times when added moth larvae were parasitized by the nematode Steinernema glaseri. Other trapping fungi endemic to the soil and enhanced by nematode-parasitized moth larvae included Myzocytium glutinosporum, Drechslerella brochopaga, and Gamsylella gephyropaga, which produce adhesive spores, constricting rings, and adhesive branches, respectively. The data suggest that the previously documented abundance and diversity of nematode-trapping fungi in BMR soil can be explained, at least in part, by nematode-parasitized insects, although that inference requires further studies with ghost moths. The strong bottom-up enhancement of nematode-trapping fungi was not matched by a strong top-down suppression of nematodes, i.e. the fungi trapped fewer than 30% of dispersing nematodes.

Wood, nematodes, and the nematode-trapping fungus Arthrobotrys oligospora

Researchers have proposed that Arthrobotrys oligospora and related fungi trap soil nematodes to obtain nitrogen and thereby compete saprophytically for carbon and energy in nitrogen-poor environments, including litter and wood. The current study tested two hypotheses concerning this model. The first was that wood decomposition would be enhanced if both large numbers of nematodes (a potential nitrogen supply) and A. oligospora (a cellulolytic organism that can use that N supply) were present. The second was that A. oligospora trapping activity would increase if large numbers of nematodes were added to soil containing abundant carbon (a wood dowel or chip). Although the first hypothesis was supported by an in vitro experiment on agar ( A. oligospora degraded much more wood when nematodes were present), neither hypothesis was supported by an experiment in vials containing field soil. In soil, wood decomposition was unaffected by the addition of A. oligospora or large numbers of nematodes. Whereas A. oligospora trapped virtually all nematodes added to agar cultures, it trapped few or no nematodes added to soil. Given that the fungal isolate was obtained from the same soil and that the fungus increased to large numbers (>1×10 3 propagules g −1 soil), the failure of A. oligospora to trap nematodes in soil is difficult to explain. Soil nitrate levels, however, were high (71 mg kg −1), and it is possible that with lower nitrate levels, trapping in soil might be stimulated by wood and nematodes.

RAPD characterization of single females of the root-knot nematodes, Meloidogyne spp.

Random amplified polymorphic DNA fingerprinting was performed on single females of root-knot nematodes, Meloidogyne spp., using a new procedure for DNA isolation. One-fourth of the total DNA amount isolated from a single female proved to be sufficient as a template in a polymerase chain reaction. Electrophoretic patterns of the amplified fragments were reproducible between replicates from a single female or sister females from the same progeny, and identical to those obtained with genomic DNA purified from a large number of nematodes. Moreover, a comparative analysis over three successive generations showed stability of the amplification patterns, thus demonstrating the utility of this procedure for epidemiological and ecological studies on root-knot nematodes.

Ascaridoid Nematodes from the Stomach of Harp Seals, Phoca groenlandica, from Newfoundland and Labrador

Stomachs of 488 harp seals, Phoca groenlandica, collected off Newfoundland and Labrador during 1984–88, contained four species of ascaridoid nematodes. Seals had high prevalences and abundances of Contracaecum osculatum B and Phocascaris sp. but were rarely infected with Anisakis simplex B or Pseudoterranova decipiens B (sealworm). Nematode abundance increased with age, and distribution of each species among seals was highly aggregated. Gastric lesions, often associated with clusters of nematodes, occurred in 13.8% of 405 seals. Female seals with large numbers of nematodes had a higher body condition index (sculp weight) than lightly infected females. Overall sex ratios of C. osculatum B and Phocascaris sp. were biased toward females, but sex ratios of adult nematodes among individual seals were heterogeneous. Most nematodes recovered were third- or fourth-stage larvae; adults of C. osculatum B and Phocascaris sp. were also common, but no mature females of A. simplex B or P. decipiens B were found. Harp seals are probably unimportant in the transmission of A. simplex but may be partly responsible for sealworm found in fish stocks off Newfoundland and Labrador. More information on other pinniped species is needed to assess more precisely the relative importance of harp seals in sealworm transmission.

Seasonal cycles of abundance of the flora and fauna associated withCladophora albida(Huds.) Kütz in rockpools

Seasonal data for one year on the flora and fauna associated with Cladophora albida (Huds.) Kutz from four rockpools (3 high-shore, 1 mid-shore) on Great Cumbrae Island, Firth of Clyde, Scotland are presented. A total of 131 858 animals was censussed. The mid-shore pool had a significantly lower annual mean density than the high-shore pools. Only at the most exposed site was a distinct seasonal trend apparent (lowest faunal density in spring, highest in summer). Species number showed no marked seasonal fluctuations neither did equitability. The lowest diversity was found in the mid-shore pool. Epiphytic cyanobacteria were present throughout the year. Diatoms were absent in the summer; possibly because of intense grazing by meiofaunal herbivores. The reduction in overall faunal density in the mid-shore pool was caused by the absence of large numbers of nematodes at this site related to the reduced availability of detritus and sand grains, perhaps reflecting greater wave scouring at this level on the shore....

Pathogenicity of canadian isolates of the Bursaphelenchus xylophilus (pinewood nematode) to provenances of Pinus sylvestris and Pinus contorta as grown in Finland: A greenhouse study

Seedlings of Scots pine (Pinus sylvestris L.) and lodgepole pine (P. contorta Dougl.) provenances, as grown in Finland, were inoculated with “m”; and “r”; “forms”; of the pinewood nematode (Bursaphelenchus xylophilus) from Canada, an m form isolate from France and an r form isolate from Missouri, USA. Scots pine was highly susceptible to an Alberta r form and a British Columbia m form isolate and moderately susceptible to two Quebec m form isolates. Lodgepole pine was higly susceptible to the two r form (Alberta and Missouri) isolates and moderately susceptible to the British Columbia m form and the two Quebec m form isolates. Mortality of both pines after inoculation with the French isolate was inconsistent. Mortality of both pines occurred more rapidly following inoculation with r form than with m form nematodes. Large numbers of nematodes were generally found in the tissues of both pines. Our results with seedlings need to be corroborated by inoculating larger field‐grown trees.

Efficacy of the Entomogenous Nematode Steinernema feltiae Against a Subterranean Termite, Reticulitermes tibialis (Isoptera: Rhinotermitidae)

The potential of the entomogenous nematode Steinernema feltiae Filipjev (=Neoaplectana carpocapsae Weiser), Breton strain, for control of a subterranean termite, Reticulitermes tibalis (Banks), was tested in laboratory and field trials. Termite workers were susceptible to nematodes in laboratory tests, but large numbers of nematodes were required for mortality. LD50 was estimated at 1.5 x 10(4) nematodes per termite in standard filter paper assays. Nematodes were applied to the soil directly beneath baited traps at a rate of 1 x 10(7) per m2 in field trials. There was a significant difference between treated and untreated traps in number of termites per trap, and protection was provided for a period of 2-3 wk. Termites attacking traps on treated sites entered traps at a corner or from the top, suggesting that termites may be avoiding contact with entomogenous nematodes. The reinvasion potential of termites shown in this study suggests that either nematode application should be made frequently or that the entire colony rather than only the feeding site must be treated.