Comparative efficacy of the nematode-trapping fungus Duddingtonia flagrans against Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis in goat faeces: influence of the duration and of the temperature of coproculture

Amongst the alternative strategies to the use of anthelmintics, the administration of Duddingtonia flagrans spores has already proved its efficacy in reducing the number of developing larvae of several nematode species in goat faeces. In this trial, the efficacy of this fungus against the larvae of the three major nematode species of goats was compared in various conditions of coproculture. Twelve strongyle free goats were experimentally infected with either Trichostrongylus colubriformis, Teladorsagia circumcincta or Haemonchus contortus larvae. Half of the animals received an oral dose of 5×10⁵ Duddingtonia chlamydospores/kg BW daily for 27 days, whereas the remaining was kept as control goats. From the 7th day of administration onwards, individual coproscopical examinations as well as coprocultures, which were incubated 4, 7, 10 or 14 days at 21 or 28°C, were performed. The reduction in developing larvae due to the activity of Duddingtonia ranged from 62.8 to 99.5% compared to control. The trapping efficacy depended on temperature (better activity of the fungus at 21 than at 28°C) and on duration (larval reductions lower after 4 days than after 7, 10 and 14 days of coproculture). Teladorsagia larvae were the least trapped, and Haemonchus larvae were the most trapped.     

Experimental cross-infections with gastrointestinal nematodes of sheep and cattle

Five parasite-free lambs and five parasite-free calves were infected experimentally with 20,000 third stage gastrointestinal nematode larvae cultured from faeces of sheep from five different farms. In the same way five lambs and five calves were infected with larvae cultured from faeces of calves from five different farms. Host specificity of the nematodes was determined using the following parameters: infection rate; number, size, and stage of the worms; their distribution within the gastrointestinal tract; and the onset, duration, and level of egg production. The conclusions with regard to the different species are:Almost exclusively in cattleSkrjabinagia lyrata Strongly adapted to cattleOstertagia ostertagi More adapted to cattle thanCooperia oncophora, C. surnabada to sheepC. punctata, Trichostrongylus longispicularis No special host preferenceT. axei, O. leptospicularis, S. kolchida More adapted to sheep thanC. curticei, T. vitrinus, T. colubriformis, to cattleO. trifurcata, Teladorsagia davtiani, Haemonchus contortus, Strongyloides papillosus Strongly adapted to sheepO. circumcincta, Oesophagostomum venulosum,Almost exclusively in sheepChabertia ovina     

Morphological variability,molecular phylogeny,and biological characteristics of the nematophagous fungus Duddingtonia flagrans

This study aims to investigate the molecular phylogenetic analysis, morphological variability, nematode‐capturing ability, and other biological properties of Chinese Duddingtonia flagrans isolates. We isolated 13 isolates of D. flagrans and found features that have never been reported before, such as two to three septa incluing club‐shaped conidia. Meanwhile, we conducted molecular phylogenetic analysis of the seven isolates and tested the radical growth of the isolates under different pH values, temperatures, and media. The capturing ability against infective larvae (L3) of Cooperia spp. in yak was detected in vitro. Finally, one isolate was selected for scanning electron microscopy (SEM) to investigate the trap formation process. The fungal sequence was obtained and submitted to GenBank (Accession no. KY288614.1, KU881774.1, KP257593.1, KY419119.1, MF488979.1, MF488980.1, and MF488981.1), and the tested isolates were identified as D. flagrans. Except for three isolates, the radial growth of the other isolates on 2% corn meal agar and 2% water agar exhibited faster growth than on other media. The fungus could not grow at 10 and 40°C but grew within 11 to 30°C. Moreover, it did not grow at pH 1–3 and 13–14, but instead at pH 4–12. In the in vitro experimental, L3s were reduced by 94.36%, 88.15%, and 91.04% for SDH035, DH055, and F088, respectively. SEM results showed that at 8 hr post addition of nematodes, some of the latter were captured. In the later stages of the interaction of the fungus with nematodes, a large number of chlamydospores were produced, especially on the predation trap. Results of the present study provided information about the molecular phylogenetic analysis, morphological variability, nematode‐capturing ability, and other biological properties of Chinese Arthrobotrys flagrans isolates before administering them for biocontrol.     

In vitro influence of temperature on the biological control activity of the fungus Duddingtonia flagrans against Haemonchus contortus in sheep

Recently, research for alternative methods to combat gastrointestinal parasites has increased, and the biological control activity of the fungus Duddingtonia flagrans stands out. In this study, the possible influence of temperature on the nematophagous activity of D. flagrans, after gastrointestinal passage, against Haemonchus contortus in sheep was analysed. Four female sheep, between 2 and 3 years of age and weighing between 40 and 50 kg, were used. Two sheep were parasitised with H. contortus, while two other sheep were dewormed. Before the collection of faeces, one of the dewormed animals received a dosage of 1?×?10⁶ chlamydospores of D. flagrans, lyophilised in gelatin capsules, for three consecutive days. The faeces were collected with collector bags, mixed, and then separated as samples with (fungus; 800 eggs per gram (EPG) of faeces) or without fungus (control; 900 EPG). Each sample (five replicates) was maintained in a biochemical oxygen demand incubator under different temperatures (5, 10, 15, 20, 25, 30, or 35 °C) for 21 days, followed by determination of the larval recovery. Compared to the control group, the best temperature for fungal action was 30 °C, while no larvae were recovered at 5 °C. At 10 °C, fungal action was detected, yet there was no significant difference in the percent larval reduction between all temperatures, demonstrating that larval presence seems to be the main factor affecting the nematophagous action of D. flagrans. Temperature does not appear to be a limiting factor in the biological control activity of D. flagrans against H. contortus, but larval presence, which was not observed at 5 °C, is mandatory. At low temperatures, which are typically suboptimal conditions for fungal and larval development, the lyophilised D. flagrans reduced the number of H. contortus larvae, which demonstrates the biological control potential and the potential use of D. flagrans in the subtropics.     

In vitro evaluation of physicochemical variables on the nematophagous fungus Duddingtonia flagrans

Duddingtonia flagrans is a biological alternative to the use of anthelmintic drugs in ruminants. This fungus must be ingested by the animal, pass through the cavities of the digestive tract and reach the feces where it develops traps that capture the nematodes. The severe conditions encountered in this process negatively affect the fungus, which is reflected in the low recovery rates compared to the amount administered. The aim of this study was to evaluate independently the in vitro effect of typical physical and chemical conditions of the gastrointestinal cavities of ruminants on the concentration, viability, and the in vitro nematode predatory ability of the chlamydospores of D. flagrans. The factors evaluated individually were pH (2, 6, and 8), temperature (28 ± 2°C and 39 ± 2°C), exposure to artificial saliva, and milling. The results showed that the concentration and viability of D. flagrans were not affected by the action of pH, temperature, milling, or exposure to artificial saliva. Regarding the in vitro nematode predatory ability, a reduction was observed after the milling process and the exposure for 24 h at different pH.     

Biological control of sheep gastrointestinal nematodiasis in a tropical region of the southeast of Brazil with the nematode predatory fungi Duddingtonia flagrans and Monacrosporium thaumasium

Formulations in matrix of sodium alginate (pellets) of the nematode predatory fungi Duddingtonia flagrans and Monacrosporium thaumasium were evaluated in the biological control of sheep gastrointestinal nematodiasis. Three groups (1, 2, and 3), each one with eight sheep of the Santa Inês breed, at the ages of 15–48 months, were placed in paddocks of Brachiaria decumbens for 5 months. In group 1, each animal received 1 g/10 kg of live weight (l.w.) of pellets of D. flagrans (0.2 g of fungus/10 kg l.w.). In group 2, each animal received 1 g/10 kg of l.w. of pellets of the fungus M. thaumasium (0.2 g of fungus/10 kg l.w.), twice a week, for 5 months. In group 3 (control), the animals received 1 g/10 kg of live weight of pellets without fungus. The monthly averages of the egg countings per gram of feces of the animals of groups 1 and 2 treated were 71.6% and 61.1% smaller, respectively, in comparison to the animals of group 3 (control). The treatment of sheep with pellets containing the nematophagous fungi D. flagrans and M. thaumasium may be used as an alternative for the control of sheep gastrointestinal nematodiasis.     

The efficacy of monepantel,an amino-acetonitrile derivative,against gastrointestinal nematodes of sheep in three countries of southern Latin America

The efficacy of the novel anthelmintic, monepantel (an amino-acetonitrile derivative), was investigated in sheep naturally infected with gastrointestinal nematodes in five studies in Argentina, Brazil, and Uruguay. Monepantel, administered at 2.5 mg/kg liveweight, was highly effective (>99.7%) against Haemonchus contortus, Teladorsagia (Ostertagia) circumcincta, Trichostrongylus axei, Trichostrongylus colubriformis, Cooperia curticei, Cooperia mcmasteri, Cooperia oncophora, Cooperia pectinata, Cooperia punctata, and Nematodirus spathiger, including strains resistant to the older broad-spectrum anthelmintics. Efficacy against C. mcmasteri, C. pectinata, and C. punctata is documented for the first time. The treatment with monepantel was well tolerated by the sheep.     

Persistent efficacy of topical eprinomectin against nematode parasites in cattle

Six studies were conducted to evaluate the persistent efficacy of eprinomectin pour-on against experimental challenges with infective nematode larvae in calves. In each study, calves were randomly assigned to one untreated group and up to four test groups, which were treated with eprinomectin at 500 μg/kg body weight at weekly intervals before single bolus challenge. The calves were necropsied approximately 4 weeks after challenge infection for nematode recovery. Eprinomectin pour-on provided ≥90% efficacy against challenge with Haemonchus placei, Trichostrongylus axei and T. colubriformis at 21 days after treatment and against Cooperia oncophora, C. punctata, C. surnabada, Dictyocaulus viviparus, Nematodirus helvetianus, Oesophagostomum radiatum and Ostertagia ostertagi at 28 days after treatment. Received: 14 April 2000 / Accepted: 18 May 2000     

The effect of sheep breed, age, and gender on the pharmacokinetics and efficacy of monepantel, an amino-acetonitrile derivative

This analysis investigated the influence of breed and gender on the pharmacokinetics of monepantel, and influence of breed, age, and gender on its efficacy against gastrointestinal nematodes of sheep. In a comparison of pharmacokinetic profiles from two studies, Merino lambs had significantly greater maximum concentrations of monepantel and monepantel sulfone, and faster times to reach these concentrations than Dorset cross lambs. Males had a statistically greater area under the curve (0–504 h) than females for monepantel sulfone. The biological relevance of these relatively small differences is unclear because efficacy was not evaluated in these studies. For efficacy, a breed effect existed for some nematodes when sheep were treated at a sub-optimum dose (1.25 mg/kg). There were no gender effects between sheep infected with adult parasites and treated at 1.25 mg/kg but there were differences between females and males treated at this dose when infected with fourth-stage larvae of Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis, and Cooperia curticei. There were no breed or gender differences for sheep treated at the recommended dose (2.5 mg/kg). There was a potential trend for declining efficacy with increasing animal age for fourth-stage Trichostrongylus axei. This analysis demonstrated that, similarly to what is observed with other anthelmintics, the pharmacokinetics and efficacy of monepantel can vary with factors like breed, age, and gender. Identifying these covariates is important for understanding inter-individual variability in drug response. While further investigation is warranted, correctly treating sheep at the recommended dose of 2.5 mg/kg appears to mitigate any associated risk.     

The efficacy of trichlorphon and naphthalophos against multiple anthelmintic-resistant nematodes of naturally infected sheep in Argentina

An anthelmintic efficacy trial was conducted in sheep harbouring anthelmintic-resistant worms in Argentina. Seventy lambs were selected from a flock that had been grazed on pastures infected with trichostrongyles previously shown to be resistant to the main anthelmintic groups. Lambs were allocated to comparable groups of ten animals each and treated with trichlorphon (50 mg/kg body weight (b.w.) orally); naphthalophos (50 mg/kg b.w. orally); ivermectin (0.2 mg/kg b.w. subcutaneously); fenbendazole (5 mg/kg b.w. orally); levamisole (8 mg/kg b.w. subcutaneously) and closantel (10 mg/kg b.w. orally). There was also an untreated group. The dose selection was based on manufacturer's recommendations.Faecal samples were collected 0 and 10 days post treatment to estimate efficacy (faecal egg count reduction). Six animals from each group were necropsied at day 10 for enumeration/identification of worms from the abomasum, small and large intestines to determine the absolute efficacy of each agent (controlled efficacy test). Trichlorphon and naphthalophos were effective (> 99 %) against Haemonchus contortus (p < 0.05).Naphthalophos also showed efficacy against Trichostrongylus axei (99.3 %), Teladorsagia circumcincta (97.8 %), Trichostrongylus colubriformis (99.2 %), Cooperia punctata/curticei/pectinata (90.4 %), Nematodirus spathiger (89.2 %) and Oesophagostomum venulosum/columbianum (93.7 %). Fenbendazole and levamisole showed efficacy (> 95 %) against all nematodes except T. colubriformis. The efficacy of ivermectin was low against H. contortus (23 %) and Cooperia spp. (46.3 %). Closantel showed low efficacy against T. axei (64.4 %), H. contortus (80.6 %) and T. colubriformis (59.5 %).When anthelmintic resistance is widespread, trichlorphon treatment is appropriate if H. contortus is present; however, naphthalophos represents an effective therapeutic alternative for incorporation into worm control programmes.     

Kinetics of capture and infection of infective larvae of trichostrongylides and free-living nematodes Panagrellus sp. by Duddingtonia flagrans

Duddingtonia flagrans, a nematode-trapping fungus, has been investigated as an agent for biological control against infective larvae of gastrointestinal nematode parasites of production animals. The initial process of nematode-trapping fungi infection is based on an interaction between the trap structure of the fungus and the surface of the nematode cuticle. This report investigates by light and scanning electron microscopy the kinetics of capture and infection during the interaction of D. flagrans with the infective larvae (L₃) of trichostrongylides and the free-living nematode Panagrellus sp. D. flagrans was cultivated for 7 days in a Petri dish containing agar–water. L₃ and Panagrellus sp. were inoculated in the Petri dishes and the samples consisting of agar–L₃–fungi and agar–Panagrellus sp.–fungi were collected after 10, 20, 30, 40, 50, 60, and 70 min and 3, 4, 5, 10, 15, 20, and 25 h of interaction. All samples were observed by light microscopy. The samples with 1, 5, 15, and 25 h of interaction were also analyzed by scanning electron microscopy. The interaction was monitored up to 25 h. An initial differentiation of predation structures was observed after 30 min of interaction. The presence of traps and of captured L₃ or Panagrellus sp. occurred after 70 min. The live captured nematodes were observed up to 3 h of interaction. However, after 4 h, all Panagrellus sp. were dead. It took 15 h of interaction for the fungus to invade the L₃, and the presence of hyphae inside the nematode near the region of penetration was evident. At this time, the hyphae had filled the whole body of Panagrellus sp. The complete occupation of the body of L₃ occurred at 20 h of interaction and with 25 h the nematode was completely damaged except for the cuticle. Although the double cuticle of L₃ slows the penetration of D. flagrans, it was possible to verify that the process of trap formation and capture occurs quickly when both nematodes were tested, suggesting that the organisms would eventually be killed once in contact with the fungi encouraging the use of the fungus as a biological control agent.     

Linear distribution of nematodes in the gastrointestinal tract of tracer lambs

Forty-eight tracer lambs were killed in 2004–2007. The abomasum, duodenum, small intestine (jejunum and ileum), colon and caecum were collected and processed for parasites enumeration and identification—mucosal scrapings of both abomasums and intestines were digested. Out of 48 gastrointestinal tracts examined, all were found to be positive for nematode infection. Seventeen species of gastrointestinal nematodes were recovered: Bunostomum trigonocephalum, Cooperia curticei, Haemonchus contortus, Chabertia ovina, Nematodirus battus, Nematodirus filicollis, Oesophagostomum venulosum, Teladorsagia circumcincta, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus vitrinus, Strongyloides papillosus, Trichuris ovis, Trichuris globulosa, Trichuris skrjabini and Skrjabinema ovis. All species were searched for in the entire gastrointestinal tract. Six species of nematodes were recovered from abnormal sites, naturally in small numbers of lambs as well as in small amounts: Nematodirus battus in the abomasums (6.67% of lambs), N. filicollis in the caecum and in the colon (%4 and 8%, respectively), T. axei in the colon (9.52%), T. colubriformis in the colon (13.89%), T. vitrinus in the caecum (16.67%), in the colon (20.00%) and in the abomasum (3.33%). T. ovis was found in one case in the small intestine.     

In vivo activities of the new anthelmintic depsipeptide PF 1022A

PF 1022A is a member of a new class of cyclic depsipeptides with antiparasitic activity. Following in vitro and laboratory animal studies it was tested for its anthelmintic efficacy in companion and livestock animals against a wide spectrum of intestinal nematodes and lungworms. Studies were carried out in rats, dogs, horses, sheep, and cattle. Animals were either naturally or experimentally infested. The efficacy of PF 1022A was investigated against the following parasite species: Strongyloides ratti and Nippostrongylus brasiliensis in rats, Ancylostoma caninum in dogs, small strongyles (cyathostomes) in horses, Trichostrongylus colubriformis and Haemonchus contortus in sheep, and Dictyocaulus viviparus in cattle. Doses varied from 1 to 10 mg/kg body weight for oral, subcutaneous or intravenous application in companion and livestock animals. High degrees of efficacy were found in all the above-cited examinations, and no clinical signs of intolerability were observed. Received: 24 September 1999 / Accepted: 5 October 1999     

Resistance of different fungal structures of Duddingtonia flagrans to the digestive process and predatory ability on larvae of Haemonchus contortus and Strongyloides papillosus in goat feces

The dynamics of the passage of conidia, chlamydospores, and mycelia of the fungus Duddingtonia flagrans through the digestive tracts of goats was evaluated. Four groups with five goats each were formed. In the group conidia, each animal received 1 × 10⁶ D. flagrans conidia per kilogram of live weight. In the group chlamydospore, each animal received 1 × 10⁶ chlamydospores per kilogram of live weight. In the group mycelia, each animal received 1 g of mycelium mass per kilogram of live weight. In the control group, the animals received no fungal structure. Feces were obtained 3 h before and 12, 24, 30, 36, 42, 48, 60, 72, 84, and 96 h after the inoculation. The feces were placed in Petri dishes containing water-agar. The Petri dishes were examined to detect the fungus and trapped nematodes. A second trial evaluated the effect of the fungal structures on the number of gastrointestinal larvae of Haemonchus contortus and Strongyloides papillosus harvested from the fecal cultures of the goats. The feces were obtained from the goats in the 12–24, 24–30, 30–36, 42–48, 60–72, 72–84, and 84–96 intervals after the inoculation. D. flagrans survived the digestive process of the goats and maintained its predatory activity, being observed from 12 to 96 h before inoculation in the animals that received chlamydospores and conidia.     

Differences in efficacy of monepantel,derquantel and abamectin against multi-resistant nematodes of sheep

Drug resistance has become a global phenomenon in gastrointestinal nematodes of sheep, particularly resistance to macrocyclic lactones. New anthelmintics are urgently needed for both the control of infections with multi-resistant nematodes in areas where classical anthelmintics are no longer effective, and the prevention of the spread of resistance in areas where the problem is not as severe. Recently, two new active ingredients became commercially available for the treatment of nematode infections in sheep, monepantel (Zolvix®) and derquantel, the latter used only in a formulated combination with the macrocyclic lactone, abamectin (Startect®). In order to assess the potential of the new actives for the control and prevention of spread of anthelmintic resistance, two characterized multi-resistant field isolates from Australia were used in a GLP (good laboratory practice) conducted efficacy study in sheep. Eight infected sheep in each group were treated orally according to the product labels with 2.5 mg/kg body weight monepantel, 0.2 mg/kg abamectin, or with the combination of 2.0 mg/kg derquantel and 0.2 mg/kg abamectin. The results demonstrate that monepantel was fully effective against multi-resistant species, Trichostrongylus colubriformis and Haemonchus contortus (99.9%). In contrast, the combination of derquantel and abamectin was effective against T. colubriformis (99.9%), but was not effective against larval stages of the barber's pole worm H. contortus (18.3%).     

Epidemiology and biology of nematodofauna affecting Testudo hermanni, Testudo graeca and Testudo marginata in Italy

Tortoises of the genus Testudo living in Italy are Testudo hermanni, Testudo graeca and Testudo marginata. Although a great deal of information has been acquired on the internal medicine and surgery on these animals, little is known of their parasitological fauna. A survey on the presence of gastro-intestinal parasitic nematodes in tortoises bred in Italy was carried out to acquire extensive epidemiological data. Stool samples of 62 tortoises (37 T. hermanni hermanni, 13 T. graeca, 6 T. hermanni boettgeri and 6 T. marginata) were macroscopically examined and subjected to qualitative (flotation and Baermann techniques) and quantitative (McMaster technique) microscopic examinations. Adult nematodes were identified using morphological keys. Eggs of oxyurids (species indistinguishable) and adults of Alaeuris numidica, Mehdiella microstoma, Mehdiella uncinata, Tachygonetria longicollis, Tachygonetria conica and Tachygonetria palearcticus (Oxyurida, Pharyngodonidae); larvae and adults of Atractis dactyluris (Ascaridida, Atractidae); and eggs and adults of Angusticaecum holopterum (Ascaridida, Ascarididae) were identified in all animals >1 year, whereas all tortoises <1 year of age were parasite-free. Moreover, this study reports for the first time A. numidica and M. microstoma in T. marginata. This work shows that nematodes affecting tortoises are diffused in Italy and highlights the need to investigate their epidemiology more in depth.     

Effects of single or concurrent infections with Eimeria alabamensis and gastrointestinal nematodes on the performance of calves on pasture

Twenty-four calves unexposed to pasture were allocated to four groups and inoculated with either two doses of 5 million Eimeria alabamensis oocysts at turn-out (E), 90,000 L3 of Ostertagia ostertagi and Cooperia oncophora divided on six occasions (N) or both oocysts and larvae as above (E + N). A control group was left uninoculated (C). For 10 weeks, the groups grazed in separate uniform paddocks not previously grazed by cattle. By day 5, most calves in groups E and E + N developed clinical coccidiosis that resulted in reduced weight gain compared to C and N. Mean trichostrongylid faecal egg counts in groups N and E + N never exceeded 300 eggs per gram of faeces, and average serum pepsinogen levels were less than 3.8 U tyrosine. This experiment demonstrates the potential impact of E. alabamensis on the performance of previously unexposed calves, whereas no aggravated effects were observed due to concurrent infections with gastrointestinal nematodes.     

Efficacy of Duddingtonia flagrans and Arthrobotrys robusta in controlling sheep parasitic gastroenteritis

The aim of this study was to evaluate the efficacy of formulations of sodium alginate matrix (pellets) of the nematode predatory fungi, Duddingtonia flagrans (AC001 isolate) and Arthrobotrys robusta (I-31 isolate), in the biological control of sheep gastrointestinal nematode infections. Thirty young Bergamacia ewes were allocated into three groups: In group 1 (control), the animals received 2 g/10 kg of live weight (l.w.) of pellets without fungus; in group 2, each animal received 2 g/10 kg of l.w. of pellets of D. flagrans (0.2 g of fungus/10 kg l.w.); and in group 3, each animal received 2 g/10 kg of l.w. of pellets of A. robusta (0.2 g of fungus/10 kg l.w.). The animals of each group were kept separately under rotational grazing. Pellets, with or without fungi, were mixed with 1 kg animal food and administered twice a week for 6 months. There was no significant difference in mean live weight and packed cell volume among groups (P > 0.05). Mean nematode fecal egg counts (FEC) did not significantly differ between the control and the remaining groups, except in one or two collections, when FEC was higher in the control group than in group 2 and group 3, respectively. The group that received A. robusta pellets needed less salvage anthelmintic treatments. Haemonchus contortus was the predominant species recovered from tracer lambs. The nematophagous fungi, D. flagrans and A. robusta, did not provide satisfactory results in the prophylaxis of parasitic gastroenteritis in sheep, under the conditions of the present study.     

Predatory activity of the fungus <Emphasis Type="Italic">Duddingtonia flagrans</Emphasis> in equine strongyle infective larvae on natural pasture in the Southern Region of Brazil

Biological control is an alternative method to reduce the population of parasites through natural predators. A promising option of biological control in the reduction of infective larvae on pasture is the use of nematophagous fungi. In this study, the efficacy of the nematophagous fungus Duddingtonia flagrans in controlling gastrointestinal nematode parasites in field-raised horses was tested. Ten foals with an average age of 12 months were divided in two groups: five males constituted the treated group and five females constituted the control group. Each group was introduced in a field of mixed pasture with approximately 5 ha. The treated group received the fungus D. flagrans at a concentration of 10⁶ chlamydospores per kilogramme of animal body weight daily, mixed with horse food for 5 months. The control group did not receive the fungus. Samples were collected to perform eggs per gramme (EPG) counts weekly. Coproculture and collection of pasture were done monthly for larvae counting. No significant difference was observed in the EPG counting and in the number of larvae recovered from coprocultures, where cyathostomines, Strongylus and Trichostrongylus spp. were found after monthly larvae counting. No significant difference was observed in the EPG counts, and Trichostrongylus sp. was identified. The number of recovered larvae on pasture was significantly lower in the treated group in the last month of treatment, showing a reduction of 73.5% (p < 0.05). As such, the fungus was able to reduce the number of infective larvae in the pasture. Nevertheless, this did not reflect in a decrease of parasitic infection during the 5-month study period.     

Genus-specific PCR for the differentiation of eggs or larvae from gastrointestinal nematodes of ruminants

Using sequences of the ribosomal second internal transcribed spacer (ITS2), PCR primers were designed for the differentiation of the gastrointestinal nematode genera Ostertagia, Cooperia, Nematodirus, Haemonchus and Trichostrongylus. Single eggs or larvae from faeces could be differentiated without previous DNA extraction. Quantification of the PCR result proved to be difficult because the DNA content between eggs from fresh or 24-h-old faeces varied considerably. Received: 12 February 1999 / Accepted: 2 May 1999