Impact of the nematophagous fungus Duddingtonia flagrans on Muellerius capillaris larvae in goat faeces

The small lungworm Muellerius capillaris is very prevalent in goats and causes production losses. Its control is particularly difficult. The nematophagous fungus Duddingtonia flagrans has been shown to be effective in trapping a large range of gastro-intestinal nematode larvae but its trapping activity against small lungworm remains to be assessed. The purpose of this work was firstly, to evaluate the ability of first-stage larvae of M. capillaris (L1) to induce trap formation in in vitro conditions and secondly, to determine the effect of D. flagrans on the L1 infectivity to snails. In experiments on agar, the presence of L1 failed to induce any D. flagrans traps whereas in the same conditions, gastro-intestinal third-stage larvae induced 44-135 traps/cm(2) depending on the species. Moreover, when the traps were pre-induced by Haemonchus contortus larvae, the L1 of M. capillaris were not trapped. For the in vivo trial, two goats naturally infected with M. capillaris received D. flagrans chlamydospores at the daily dose rate of 5x10(5) spores/kg BW for 8 days. Faeces were collected individually before, during and 11 days after spore administration. On each day of harvest, the initial larval output was determined. The remaining faeces were subjected to coproculture at 21 degrees C for 7 days. At the end of this period, L1 were collected and used to infect snails (30 snails per goat isolate each snail given 40 L1 by direct deposit of the larvae on the foot of the snail). These snails were artificially challenged in contrast to others that were exposed to natural infection by exposure to faeces carrying first-stage M. capillaris larvae. The natural infection used the same number of snails, i.e. 30 snails deposited on the faeces of each goat. After 3 weeks at room temperature, the infective larvae present in the snail foot were counted. There was no difference in the survival of the L1 in faeces after coproculture whether the faeces contained D. flagrans or not. The infectivity of the extracted larvae from the two goats before and after fungal administration was the same. The number of infective larvae per snail obtained after "natural" infection showed variations that were not related to the presence of D. flagrans mycelium in faeces. These trials clearly indicate that D. flagrans was unable to trap or to alter the infectivity of M. capillaris first-stage larvae and thus cannot be considered as a non-chemotherapeutic alternative approach to the control of the small lungworm in goats.     

Evaluation of Duddingtonia flagrans in reducing infective larvae of Haemonchus contortus in feces of sheep.

Consequences of nematode infections due to Haemonchus contortus are a serious constraint for the sheep industry worldwide. Development of anthelmintic resistance and increasing concern about the impact of anthelmintic use dictate the need of alternative control. Such an alternative is using the nematode trapping fungus Duddingtonia flagrans to reduce infective larvae levels on pasture. Two trials were conducted to determine the effect of D. flagrans in reducing infective larvae (predominantly H. contortus) in feces. The first trial determined the dose effect of D. flagrans in reducing infective larvae in feces. Eighteen ewes were dewormed to remove existing infections and randomly assigned to six treatment groups: 5 x 10(4), 1 x 10(5), 2.5 x 10(5), 5 x 10(5), 1 x 10(6) or no (control) spores of D. flagrans per kg of body weight mixed in their feed for 7 days. Fecal samples were collected daily from these and from infected donor ewes. Feces from individual-treated ewes were mixed with equal amounts of donor ewe feces, theoretically approximating oral dose spore concentrations of 2.5 x 10(4), 5 x 10(4), 1.25 x 10(5), 2.5 x 10(5), 5 x 10(5) and no spores, and were cultured. Across dosages and during the 7 days of fungus feeding, percent reduction of infective larvae ranged from 76.6 to 100.0%. The second trial determined the effect of D. flagrans at the dose of 10(5) spores per kg body weight on reducing infective larvae in feces from naturally infected lambs. Twenty lambs were randomly assigned to either treatment or control groups based on fecal egg count. Treatment lambs were fed spores mixed in feed for 7 days. Feces were collected daily and cultured. During the 7 days of fungus feeding, the percent reduction of infective larvae ranged from 82.8 to 99.7%. Results of these trials demonstrated that the nematode trapping fungus D. flagrans was highly effective in reducing infective larvae in sheep feces and should be considered as a biological control agent for integrated nematode control programs.     

Effect of different times of administration of the nematophagous fungus Duddingtonia flagrans on the transmission of ovine parasitic nematodes on pasture--a plot study

Investigations were made into the timing of administration of Duddingtonia flagrans as a biological control agent against ovine parasitic nematodes including stongylid and Nematodirus spp. Faeces from 3-4 months old male lambs were deposited onto pasture plots that had never been grazed by sheep. The trial was conducted over two consecutive years (1998 and 1999). For both years, the following three plot types were involved: Sim plots had faeces containing nematode eggs and Duddingtonia flagrans spores deposited simultaneously; Post plots had faeces containing nematode eggs followed 2 weeks later by faeces containing D. flagrans spores alone; Control plots had faeces containing only nematode eggs; Prior plots (included in 1999) had faeces containing D. flagrans spores alone followed 2 weeks later by faeces containing nematode eggs. In each year, two deposition periods were involved: July and August in 1998 and June and July in 1999. During the first year pasture samples were collected at 2, 4, 6, 8 and 12 weeks after initial deposition. In 1999, additional samples were collected at 10, 16 and 20 weeks. Larvae were extracted from the pasture samples and counts performed to estimate the number and species of infective third-stage (L(3), larvae) present. The number of third-stage strongylid larvae on pasture was significantly lower on Sim plots compared to the remaining plot types for both years at all deposition times (P<0.001). This was also the case for the number of Nematodirus infective larvae in August deposition plots in 1998 (P<0. 02). There was no significant difference between treatments in both deposition times in 1999 and July deposition plots in 1998 for the Nematodirus data. These results suggest that D. flagrans, if deposited at the same time as parasite eggs prevents transmission of third-stage larvae from the faecal deposit onto pasture, including occasionally Nematodirus species, but does not have an effect on third-stage parasitic nematode larvae in the surrounding soil.     

The potential of nematophagous fungi to control the free-living stages of nematode parasites of sheep: towards the development of a fungal controlled release device.

Studies showed that chlamydospores of the nematophagous fungus, Duddingtonia flagrans, are capable of surviving pressures of several tonnes when incorporated into matrices and pressed into tablets for the manufacture of prototype intraruminal controlled release devices (CRDs). They remain viable in this tabletted form for at least 9 months when stored at 4 degrees C. In vitro studies demonstrated that there was no effect on spore viability of prolonged exposure to either room or elevated temperature (40 degrees C) in air, or under an atmosphere of either of the major ruminal gases, carbon dioxide and methane. In vivo, studies showed that viable chlamydospores could be detected at the erosion surface of prototype CRDs recovered from the rumen and also in faeces of fistulated sheep, for up to 3 weeks after administration. Further studies have shown that chlamydospores released from such devices can substantially reduce the number of infective larvae that develop in cultures of faeces collected from sheep infected with the nematode parasite, Haemonchus contortus. This work demonstrates, in principle, that the deployment of chlamydospores of D. flagrans in intraruminal CRDs, is another possibility in the development of a range of methods for the biological control of parasites in livestock.     

Survey of nematophagous fungi in South Africa

Three hundred and eighty-four samples of leaf litter, soil, faeces from domestic and game animals, compost and aqueous cultures of infective nematode larvae contaminated with unidentified fungi were plated out on water agar, baited with pure infective larvae of Haemonchus contortus, incubated and examined for the presence of nematophagous fungi. Duddingtonia flagrans was isolated from five samples, and 73 samples were positive for other nematophagous fungi.     

Efficiency of feeding Duddingtonia flagrans chlamydospores to grazing ewes on reducing availability of parasitic nematode larvae on pasture

Gastrointestinal nematodes are of concern in sheep production because of production and economic losses. Control of these nematodes is primarily based on the use of anthelmintic treatment and pasture management. The almost exclusive use of anthelmintic treatment has resulted in development of anthelmintic resistance which has led to the need for other parasite control options to be explored. The blood sucking abomasal parasitic nematode Haemonchus contortus causes severe losses in small ruminant production in the warm, humid sub-tropic and tropics. This study evaluated the effectiveness of a nematode trapping fungus, Duddingtonia flagrans, in reducing availability of parasitic nematode larvae, specifically H. contortus, on pasture. Chlamydospores of D. flagrans were mixed with a supplement feed which was fed daily to a group of crossbred ewes for the duration of the summer grazing season. A control group was fed the same supplement feed without chlamydospores. A reduction in infective larval numbers was observed in fecal cultures of the fungus-fed group. Herbage samples from the pasture grazed by the fungus-fed group also showed a reduction in infective larvae. There were no significant (P > 0.05) differences in overall fecal egg count, packed cell volume or animal weight between fungus-fed and control groups. Tracer animals were placed on the study pastures at the end of the study to assess pasture infectivity. Although tracer animals were only two per group, those that grazed with the fungus-fed group had substantially reduced (96.8%) nematode burdens as compared to those from the control group pasture. Results demonstrated that the fungus did have activity against nematode larvae in the feces which reduced pasture infectivity and subsequently nematode burdens in tracer animals. This study showed that D. flagrans, fed daily to grazing ewes, was an effective biological control agent in reducing a predominantly H. contortus larval population on pasture.     

The efficacy of two isolates of the nematode-trapping fungus Duddingtonia flagrans against Dictyocaulus viviparus larvae in faeces.

A series of experiments was carried out to examine the effects of two different isolates of the nematode-trapping fungus Duddingtonia flagrans to reduce the number of free-living larvae of the bovine lungworm, Dictyocaulus viviparus. A laboratory dose-titration assay showed that isolates CI3 and Troll A of D. flagrans significantly reduced (P < 0.05 to P < 0.001) the number of infective D. viviparus larvae in cultures at dose-levels of 6250 and 12,500 chlamydospores/g of faeces. The larval reduction capacity was significantly higher for Troll A compared to CI3 when lungworm larvae were mixed in faecal cultures with eggs of Cooperia oncophora or Ostertagia ostertagi and treated with 6250 chlamydospores/g of faeces. Both fungal isolates showed a stronger effect on gastrointestinal larvae than on lungworm larvae. Two plot trials conducted in 1996 and 1997 involved deposition of artificial faecal pats containing free-living stages of D. viviparus and C. oncophora on grass plots. Herbage around the pats was collected at regular intervals and infective larvae recovered, counted and identified. These experiments showed that both D. flagrans isolates reduced the number of gastrointestinal as well as lungworm larvae in faecal pats. During both plot trials, the transmission of C. oncophora larvae, but not D. viviparus, from faecal pats to the surrounding herbage was clearly affected by climatic conditions. After collection of faecal pats from the grass plots one month after deposition, the wet and dry weight of pats as well as organic matter content were determined. No differences were found between the fungus-treated and non-treated control pats. This indicated that the rate of degradation of faeces was not affected by the addition of the fungus.     

Development and survival of free-living stages of equine strongyles under laboratory conditions

In a series of laboratory studies the optimum conditions for the development and survival of the free-living stages of strongyle parasites occurring in horses in tropical north Queensland were determined. No differences in behaviour were noted between the strongyle species. Development to the infective stage occurred only between 10 and 35 degrees C. The rate was affected by temperature, taking 15-24 days and 3 days, respectively, at the lowest and highest temperatures for the developing stages to reach the infective third stage. Yields of infective larvae were very low outside the range 20-33 degrees C, and were highest at 28 degrees C. Survival of infective larvae was good between 20 and 33 degrees C, and large numbers were recovered after 3 months in faeces incubated at 20-28 degrees C. At 33 and 37 degrees C larval survival was affected by the moisture content of the faeces, with infective larvae surviving better in dry than in moist faeces; even a residual moisture level of 40% significantly reduced the number of larvae recovered from faeces incubated at 37 degrees C for 1 month. Moisture also affected larval development, especially at the higher temperatures of 25-39 degrees C. When faecal moisture content fell to less than or equal to 20% by 3 days, larvae which had not yet reached the infective stage were still pre-infective at 7 days, while all larvae in faeces with adequate moisture had reached the infective third stage. It was not possible to determine the critical faecal moisture level below which larval development ceased, however, 28 degrees C (range 25-33 degrees C) was found to be the optimum temperature. Larval development was very rapid and yields of infective larvae highest at this temperature.     

Baermannization of Dictyocaulus spp. from faeces of cattle, sheep and donkeys

Faeces were collected per rectum from calves infected with Dictyocaulus viviparus (D.v.), from lambs infected with Dictyocaulus filaria (D.f.) and donkeys infected with Dictyocaulus arnfieldi (D.a.). In one experiment, the influence of storage temperature before Baermannization was investigated. Recovery rate for D.v. was approximately 80% after 24 h at 4 degrees C or 16 degrees C but only 40% at 20 degrees C. After two days at 20 degrees C the rate had fallen to 20%. Recovery rates for D.f. decreased so markedly during the first 12 h at 4, 16 and 20 degrees C that storage can not be recommended. Losses in the recovery rates of D.a. appeared insignificant after 48 h at 4 degrees C but not at 16 degrees C and 20 degrees C. In experiment II the time taken for larvae to emerge from a 10-g sample as well as the sedimentation time in Baermann tubes was investigated. The bulk of the D.v. larvae remained in the faeces for about 10 h whereas D.f. larvae emerged during the first few hours. D.a. larvae were intermediate in this respect. Sedimentation of the bulk of larvae from all three species took place within a few hours with the modified Baermann technique used.     

Observations of the sheath extension of the third stage, infective larvae of Trichostrongylus rugatus

The length of the sheath extension of third stage (L(3)), infective larvae of Trichostrongylus rugatus is reported. The total length and length of the sheath extension of L(3) recovered from the faeces of sheep originating from two localities in South Australia were measured. The total length of larvae was 615-722 microm and the length of the sheath extension was 46-56 microm (mean 51.5). The larvae of T. rugatus comprised up to 72% of the larvae recovered. Worm free sheep were infected with larvae from the two localities and L(3) were recovered following culture of faeces from these experimentally infected animals. L(3) measured 640-746 microm in total length with a sheath extension of 46-56 microm (mean 51.4). Adult nematodes recovered from gastro-intestinal tracts were identified as T. rugatus. The length of the sheath extension used in conjunction with the total length is a characteristic that enables confident differentiation of infective larvae of T. rugatus from other Trichostrongylus species infecting sheep in southern Australia and Haemonchus contortus.     

Administration of Duddingtonia flagrans chlamydospores to goats to control gastro-intestinal nematodes: dose trials

The ability of the nematophagous fungus Duddingtonia flagrans to reduce the number of infective nematode larvae in coproculture was investigated in goats using different doses of chlamydospores (0, 1.25 x 10(5), 2.5 x 10(5), 5 x 10(5) chlamydospores/kg BW/day) given by oral administration or by voluntary consumption in feed during natural or experimental infections with nematodes. The kinetics of excretion of D. flagrans chlamydospores in the faeces was also determined using a dose of 5 x 10(5) chlamydospores/kg BW/day for five days. For all the trials, the faecal nematode egg outputs were determined by a modified McMaster method and standard coprocultures were set up (14 days, 25 degrees C) to determine the number of larvae emerging from culture in fungus treated and control faeces. When chlamydospores were orally administered, the number of larvae were reduced by 50 to 97% when compared to control cultures. No difference in the level of larval emergence from the culture was seen for experimental or natural infections at the different chlamydospore dose rates. In contrast, when chlamydospores were distributed in the feed, a dose-dependent relationship was observed 10 days after the start of administration, the larval development being 2.0%, 14.0% and 86.9% for 5 x 10(5), 2.5 x 10(5) and 0 spores/kg BW/day, respectively. In addition, the kinetic study showed that the larval emergence from coproculture in the fungus group was statistically lower than in the control group from the second day of administration of the chlamydospores and remained lower until the second day after the last administration (p < 0.05). The results indicate that, for goats in farm conditions, a minimum daily dose of 5 x 10(5) chlamydospores/kg BW must be used to ensure a high treatment efficacy and that daily administration is preferable for maintenance of efficacy over time.     

Efficacy of the nematode-trapping fungus Duddingtonia flagrans against three species of gastro-intestinal nematodes in laboratory faecal cultures from sheep and goats

The ability of the nematode-killing fungus Duddingtonia flagrans to reduce number of infective larvae of three species of gastro-intestinal parasitic nematodes developing in dung was investigated in both goats and sheep. Groups of lambs and kids (12-20 weeks old) were given mono-specific infections of Haemonchus contortus, Ostertagia (Teladorsagia) circumcincta or Trichostrongylus colubriformis. Following patency of the infections (t1) faecal samples were collected for determination of faecal nematode egg count (FEC) and culture of parasite larvae. Groups of animals were then dosed on 2 consecutive days with one of the two dose rates of the fungus (250,000 or 500,000 spores/kg liveweight). One (t2) and 5 (t3) days after the second dose of fungus samples were again collected for FEC and culture. The number of larvae recovered from the faecal cultures at t1 and t3 were used as controls to assess the efficacy of the experimental treatment at t2. Average efficacy was 78% with group means ranging from 40 to 93%. Dose rate of fungus appeared to influence efficacy against O. circumcincta but not against H. contortus or T. colubriformis. Overall, there were no differences in the efficacy of the fungus against any of the parasite species or in either host animal. The results of this trial indicate the potential use of this fungus as a broad spectrum anti-parasite agent for use in both goats and sheep.     

Nematophagous fungi as a biological control agent for nematode parasites of small ruminants in Malaysia: a special emphasis on Duddingtonia flagrans

Approximately 2,800 fresh dung samples from animals, mainly ruminant livestock, were screened for the presence of nematophagous fungi in Malaysia. Arthrobotrys spp. was noted on numerous occasions, but only one isolate of Duddingtonia flagrans was made. For the purposes of producing sufficient quantities of this fungus for feeding trials in sheep, various, commonly available, cheap plant materials were tested as possible growth substrates. This showed that cereal grains (wheat, millet and rice) were the best media for fungal growth. Pen feeding trials were carried out using sheep, both naturally and experimentally infected with nematode parasites (predominantely Haemonchus contortus), to test the efficiency of D. flagrans when administered either in a grain supplement, or incorporated into a feed block. These showed that the fungus survived gut passage in sheep and that dose rates of approximately 1 x 10(6) D. flagrans spores / animal / day, reduced the percentage of infective larvae developing in faecal cultures by more than 90%. These results indicate that using D. flagrans as a biological control agent of nematode parasites, is a promising alternative to nematode parasite control of small ruminants in Malaysia, where anthelmintic resistance is now a major problem.     

Interaction between copper oxide wire particles and Duddingtonia flagrans in lambs

An experiment was completed to determine if copper oxide wire particles (COWP) had any effect on the activity of the nematode-trapping fungus Duddingtonia flagrans in growing lambs. COWP has been used recently as a dewormer in small ruminants because of nematode resistance to anthelmintics. D. flagrans has been used to control free-living stages of parasitic nematodes in livestock. Katahdin and Dorper lambs, 4 months of age, were administered no or 4 g COWP (n=24/dose) in early October 2003. Haemonchus contortus was the predominant gastrointestinal parasite during the trial, which was acquired naturally from pasture. Half the lambs from each COWP group were supplemented with corn/soybean meal with or without D. flagrans for 35 days. Fecal egg counts (FEC) and packed cell volume (PCV) were determined weekly between days 0 (day of COWP administration) and 35. Feces from lambs in each treatment group were pooled and three replicates per group were cultured for 14 days at room temperature. Larvae (L3) were identified and counted per gram of feces cultured. Treatment with COWP was effective in decreasing FEC, which remained low compared with FEC from lambs not treated with COWP. This led to an increase in PCV in these lambs (COWP x day, P<0.001). Number of larvae was decreased in feces from lambs treated with COWP and D. flagrans between days 14 and 35 compared to the other groups of lambs (COWP x D. flagrans x day, P<0.003). Percentage of larvae identified as H. contortus decreased in feces collected from lambs treated with COWP and D. flagrans between days 14 and 28 compared with other treatments (COWP x D. flagrans x day, P<0.05). Other trichostrongyles were present and remained less than 7% in feces collected from control lambs. There was no adverse effect of COWP on the ability of D. flagrans to trap residual larvae after COWP treatment. With fewer eggs being excreted due to the effect of copper on H. contortus, and the additional larval reducing effect exerted by the nematode destroying fungus D. flagrans, the expected result would be a much lower larval challenge on pasture when these two tools are used together in a sustainable control strategy.     

Effect of the nematophagous fungus,Duddingtonia flagrans,on the larval development of goat parasitic nematodes: a plot study

Effective alternatives to anthelmintic treatment against nematode parasites of goats are required because of the high prevalence of benzimidazole resistance. Towards this objective, the nematophagous fungus, Duddingtonia flagrans (Df), was used in a plot study against two main parasitic nematode species of goats, Teladorsagia circumcincta (Tcir) and Trichostrongylus colubriformis (Tcol). Worm-free, culled goats were experimentally infected with strains of Tcir and Tcol to constitute donors. Half of the animals were periodically given Df chlamydospores at a daily dose of 2.5 x 10(5) spores/kg BW while the remaining animals were kept as controls. At 5 time periods i.e. March, May, July, September and November 2001, corresponding to the main grazing season in France for goats, faeces were collected from the 6th day of fungus administration for the following 2 days to obtain approximately 1 kg of faeces from each group of animals: Tcir/Control, Tcol/Control, Tcir/Fungus, Tcol/Fungus. For each period and each group, the faeces were deposited on a 1 m2 grass plot and the grass was cut (3 replicates) on weeks 2, 4, 6, 8,12 after deposition, for infective larval recovery. Larvae were counted and the results were expressed as a ratio of larvae/eggs deposited. On the plots with the control faeces deposited in March, July and September, the grass infectivity due to Tcir and Tcol was similar and the maximum number occurred between 2 and 4 weeks post deposition. In May, the maximum numbers of larvae were not recorded until 8 weeks after deposition, due to high daily temperatures and dryness. In November, larval development took place only for Tcir. On the plots with the fungus treated faeces, a significant reduction in grass infectivity occurred for both nematodes and ranged from 50-60% in May, July and November deposits to 80-90% in the September deposit. On the contrary to these findings, no difference was recorded between the fungus and control plots for the March deposit. In conclusion, D. flagrans is suitable for reducing the number of infective larvae in the herbage during the main part of the grazing period for the most important digestive nematodes of goats.     

Production and characterization of a monoclonal antibody against recombinant fatty acid binding protein of Fasciola gigantica

Biological options for nematode parasite control are being sought, as the long-term efficacy of conventional anthelmintics comes increasingly under threat from drug-resistant parasites. Three biological methods with the potential to reduce pasture contamination by parasitic nematode larvae were examined: (a) killing of larvae developing in dung by nematophagous fungi; (b) removal of dung through earthworm ingestion; (c) burial of dung in soil as might occur through the action of dung beetles. Field trials with the test bio-control agents were carried out in autumn and spring by adding dung from sheep infected with Ostertagia (Teladorsagia) circumcincta to pots of ryegrass/white clover. The factorial treatment structure included five fungal treatments (individual applications of Duddingtonia flagrans, Monacrosporium gephyropagum and Harposporium helicoides, a combination of all the three fungi together and an untreated control), two dung burial treatments (dung buried or deposited on the soil surface) and two earthworm treatments (earthworms present or absent). D. flagrans and H. helicoides, individually or in combination, reduced recovery of infective stage larvae in experiment 1, while only H. helicoides reduced recovery in experiment 2. In both the experiments, dung burial increased the total number of larvae recovered, while the number of infective larvae were reduced by the action of earthworms. Increased recovery following burial, along with the fact that larvae moved rapidly from soil onto herbage, suggests that soil may provide a protective reservoir for infective larvae infesting herbage.     

Interaction between the nematode-destroying fungus Arthrobotrys robusta (Hyphomycetales) and Haemonchus contortus infective larvae in vitro.

In an in vitro trial, the effect of the nematode-destroying fungus Arthrobotrys robusta on Haemonchus contortus infective larvae was evaluated in petri dishes containing corn meal agar. After seven days incubation at 25 degrees C, 92.33% (+/- 4.1) predation was recorded.     

Spread of equine lungworm (Dictyocaulus arnfieldi) larvae from faeces by Pilobolus fungi

Between 10 and 25% of the Dictyocaulus arnfieldi larvae excreted in faeces from a naturally infected donkey were harvested as infective stages from faecal cultures by means of Pilobolus fungi. The faeces were collected between 24 and 56 hours after drenching the donor animal with Pilobolus spores and kept at 16 +/- 2 degrees C. Most larvae were collected between the 5th and the 8th day of culturing during which period fructification and sporangium discharge also peaked. The sporangia and the adhering larvae were collected in Petri dishes inserted between the faecal mass and a light source. All recovered larvae were viable. A mean larval length of 368 microns (range 312-440 microns) and width of 14.6 microns (range 12-20 microns) was recorded for the infective stage. The method was found suitable for the recovery of infective stages for experimental purposes. The authors suggest that the Pilobolus mechanism play an important part in the spread of equine lungworm infection under field conditions similar to the situation in bovine lungworm (Dictyocaulus viviparus) infection.     

Effect of temperature on development of the free-living stages of Ostertagia circumcincta

Hatching of the eggs of Ostertagia circumcincta was studied by recovering them from faeces and incubating them in distilled water at temperatures of 4, 16, 25 and 35 degrees C. Hatching occurred at all the temperatures. The rate of hatching increased with the rise in temperature. Development of larvae to the infective third stage (L3) was studied in faecal cultures incubated at 4, 16, 25, 30, 35, 40 and 45 degrees C. Except at 4 degrees C, L3 developed at all temperatures, the optimum temperature being 16 degrees C. The rate of development of L3 increased with the rise in temperature. This resulted in a corresponding decrease in the percentage recovery of larvae.     

Absence of obvious short-term impact of the nematode-trapping fungus Duddingtonia flagrans on survival and growth of the earthworm Aporrectodea longa

The nematode-trapping fungus Duddingtonia flagrans may be used in biological control of parasitic nematode larvae in faeces of domestic host animals after feeding the hosts with fungal chlamydospores. In this experiment a possible undesirable fungal impact on earthworms, of the species Aporrectodea longa, was investigated. As earthworms eat animal faeces, D. flagrans may come into contact with earthworms both in their alimentary tract and on their body surface. However during the experimental period of 20 days, when earthworms were living in soil and eating cattle faeces that were heavily infested with viable chlamydospores of D. flagrans there were no indications of internal or external mycosis among the earthworms.