In horses, the nematodes of the Strongylidae family are the most important due to their prevalence and pathogenicity. Sanitary plans include parasite control based on chemical anthelmintics. Among ...these, the benzimidazole compounds have been used since the 1960s to control the nematode
Strongylus vulgaris
. Its inappropriate use resulted in the development of resistance in parasites with a shorter biological cycle, such as the small strongyles. Currently, the genera that make up this group show widespread resistance to all chemical treatments available in veterinary medicine, except for macrocyclic lactones, where less effective action has been detected. The need to find alternative routes for its control is recognized. International organizations and markets are increasingly restrictive in the allowed levels of drugs in products of animal origin, so one of the drawbacks is the permanence of chemical compounds in tissues. Therefore, other tools not chemically based are proposed, such as the biological control of gastrointestinal nematodes. Various research groups around the world have carried out tests on the control capacity of the nematophagous fungus
Duddingtonia flagrans
against this group of parasites. The objective of this review is to compile the different tests that are available on biological control in this species, in in vivo and in vitro tests, and the possible incorporation of this tool as an alternative method of antiparasitic control in an integrated control scheme of parasites.
Ivermectin is one of the most widely used drugs for parasite control. Previous studies have shown a reduction in the abundance and diversity of “non-target” coprophilous organisms due to the presence ...of ivermectin (IVM) in bovine faecal matter (FM). Due to its breadth of behavioural habits,
Calliphora vicina
is a suitable dipteran species to evaluate the effects of IVM in FM. The aim of this work was to evaluate the effect of five concentrations of IVM in FM (3000, 300, 100, 30, and 3 ng/g) on the development of
C. vicina
. The following endpoints were evaluated: survival (between the first larval stage and emergence of new adults), larval development times to pupation and pupation times to adult, and adult emergence (% sex) and LC
50
. Sampling was performed from larval hatching at 60 and 120 min and at 3, 4, 5, and 12 h, and every 24 h specimens were weighed until pupae were observed. Data were analysed by ANOVA using a non-parametric Kruskal–Wallis test and as a function of elapsed development time and accumulated degree hours (ADH). Mortality at 3000 and 300 ng/g was 100% and 97%, respectively. There were statistically significant delays in adult emergence time (
p
= 0.0216) and in the ADH (
p
= 0.0431) between the control group (C) and 100 ng/g. The LC
50
was determined at 5.6 ng/g. These results demonstrate the lethal and sub-lethal effects of IVM on C.
vicina
, while highlighting the usefulness of this species as a bioindicator for ecotoxicological studies.
Duddingtonia flagrans is a natural strain of Nematophagous-Fungi isolated around the world. It has demonstrated efficacy and ease of use in laboratory as well as in field conditions. The fungus ...contributes to the prophylactic control of the worms by reducing the number of L3 on pasture. The aims of this study were to test and analyze the predatory effect of D. flagrans under sunny and shaded conditions on the L3 in the faeces, and to verify the reduction of translation to pasture during summer and winter seasons. Faecal Mass Units (FMUs) were assigned to two treated groups (groups treated with D. flagrans chlamydospores, TG) and two untreated groups (without D. flagrans chlamydospores, UG), in summer and winter, under sunny and shaded conditions. FMUs and herbage samples were taken for parasitological workup. Predatory activity of D. flagrans was evident under both conditions for the summer experiment but was not manifest for the winter experiment. In summer, an interaction between sunny and shaded conditions and predatory activity of D. flagrans was found. Environmental conditions on predatory activity should be considered when designing strategies for the implementation of D. flagrans in grazing systems to smooth the infectivity curve of L3.
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•The aim was to test Duddingtonia flagrans under different environmental conditions.•Predatory activity of Duddingtonia flagrans was evident in summer.•Predatory activity of Duddingtonia flagrans was not manifest in winter.•Predatory activity of D. flagrans was affected by the environment conditions.
Nematophagous fungi are a biological control tool used against gastrointestinal nematodes in livestock. These fungi prey on free-living larvae in faeces and could be affected by active drugs excreted ...post-treatment. This study aimed to determine in vitro and under environmental conditions the effect of the following anthelmintics on the fungus Duddingtonia flagrans: ivermectin, levamisole, albendazole, fenbendazole and ricobendazole. The in vitro effect of anthelmintics on fungal growth and predatory capacity was assessed in corn meal agar and coprocultures, respectively. Ivermectin (1, 2 and 10 ppm), fenbendazole (0.027, 0.054 and 1 ppm) and albendazole (1 ppm) significantly affected fungal development. The fungal efficacy against L3 was high in the control and levamisole coprocultures but decreased significantly in the presence of albendazole, fenbendazole, ricobendazole and ivermectin. The impact of levamisole on D. flagrans was further assessed under environmental conditions in autumn and winter; the fungal efficacy measured in faecal pats and the surrounding herbage was not affected by levamisole at any time. This study shows that using albendazole, fenbendazole, ricobendazole or ivermectin may compromise fungal activity, as these drugs affect the free-living stages of nematodes in faeces, but levamisole can be safely considered in parasite control strategies involving D. flagrans and anthelmintic treatments.
The purpose of using nematophagous fungi as biological control agents of gastrointestinal nematodes of livestock is to reduce the build-up of infective larvae on pasture and thus avoid clinical and ...subclinical disease. As the interaction of fungus-larval stages takes place in the environment, it is crucial to know how useful the fungal agents are throughout the seasons in areas where livestock graze all year-round. This study was designed to determine the predatory ability of the nematophagous fungus
against gastrointestinal nematodes of cattle during four experiments set up in different seasons. In each experiment, faeces containing eggs of gastrointestinal nematodes were mixed with 11,000 chlamydospores/g and deposited on pasture plots. A comparison between fungal-added faeces and control faeces without fungus were made with regard to pasture infectivity, larval presence in faecal pats, faecal cultures, faecal pat weight, and temperature inside the faecal mass. In three of the four experiments,
significantly reduced the population of infective larvae in cultures (68 to 97%), on herbage (80 to 100%), and inside the faecal pats (70 to 95%). The study demonstrated the possibility of counting on a biological control tool throughout most of the year in cattle regions with extensive grazing seasons.
Biological control of gastrointestinal nematodes of ruminants by use of nematophagous fungi would become part of any livestock parasite integral control system. Identifying autochthonous species that ...could then be selected for mass production is an important phase in the practical use of biological control.
To search for nematophagous fungi with potential use as biological control agents against gastrointestinal nematodes in Argentina.
Decomposing cattle faeces sampled in different locations were incubated in water agar 2% with Panagrellus sp. The developed nematophagous fungi were transferred to new water agar 2% plates and then to corn meal agar plates in order to carry out their identification. Fungal diversity and richness were also assessed.
Seventeen species from nine genera of nematophagous fungi were found. Twelve species were nematode-trapping fungi and three species plus two fungi identified to genus level corresponded to endoparasitic fungi. Arthrobotrys conoides, Arthrobotrys oligospora, Duddingtonia flagrans, Monacrosporium doedycoides, Arthrobotrys robusta and Drechmeria coniospora were the most frequently isolated species overall in the whole study (6.6%, 5.7%, 5.7%, 5.7%, 4.7% and 4.7%, respectively) although other species were more frequently recorded at local levels such as Arthrobotrys pyriformis (18.8%). Only A. conoides has been previously isolated from ruminant faecal samples in Argentina. Five nematode-trapping fungal species are mentioned for the first time in the Americas
D. flagrans and A. conoides, both identified in the present study, are among the most promising ones as biological control agents against gastrointestinal nematodes of ruminants.
The efficacy of the nematode-trapping fungus
Duddingtonia flagrans
incorporated into an energy block was evaluated for the control of gastrointestinal nematodes in sheep. Four naturally parasitised ...sheep with average nematode egg counts of 2,470 eggs per gram grazed by pairs on two similar parasite-free paddocks for 30 days. During that period, one pair of sheep (treated animals, T1) received an energy block containing chlamydospores of
D. flagrans
at a dose of 200,000 chlamydopores/kg bw/day, while the second pair (control animals, C1) received a fungus-free energy block. The animals in both groups were taken off the paddocks after contaminating the pastures for a month with either nematode eggs plus fungal chlamydospores (T1) or nematode eggs alone (C1). Twelve parasite-free sheep were divided into two groups of six animals each, the treated group (T2) was placed on the paddock previously contaminated with parasites and fungus, while the control group (C2) was placed on the parasite-only paddock. These two groups grazed on their respective paddocks during 30 days and were then housed for 15 days, after which period they were slaughtered in order to determine the parasite burden present in each animal. Results showed that animals in group T2 harboured significantly less nematodes than their counterpart in group C2. The efficacy of
D. flagrans
was 92% against the total parasite burden, 100% against
Haemonchus contortus
and
Teladorsagia circumcincta
, 89.9% against
Trichostrongylus colubriformis
, 87.5% against
Cooperia onchopora
, and 90% against
Trichostrongylus axei
. No efficacy was detected against
Nematodirus spathiger
,
Trichuris ovis
and
T. skrjabini
.
The large-scale production of nematophagous fungi as agents of biological control is one of the main challenges to be commercially used. In order to improve growth of microorganism in a culture ...medium, the addition of growth inducer is common. At the moment, the action of their addition in the mycelia growth and sporulation rate of nematophagous fungi is not known. The purpose of this trial was to evaluate the sporulation rate of
Duddingtonia flagrans
by adding two growth inducers,
meso
-inositol and Tween 80, both at 0.5 % in a traditional culture medium Sabouraud glucose agar (SGA) and also in a traditional culture medium enriched with wheat flour and milk powder. From a traditional sterile culture of
D
.
flagrans
, four groups were made: SGA; Sabouraud glucose agar–
meso
-inositol 0.5 %; Sabouraud glucose agar–Tween 80 0.5 %; and Sabouraud glucose agar-enriched (SGA-E). These media were placed at a constant temperature of 27 °C for 4 weeks. Following this, chlamydospores were gently rinsed off with sterile water and counted using a Neubauer haematocytometer to estimate the number of chlamydospores per millilitre of water. The addition of
meso
-inositol 0.5 % to SGA promoted a significant increase (
p
< 0.05) in chlamydospore production obtaining an average of 51,715,000 chlamydospores per Petri dish. The highest chlamydospore concentration was observed in the SGA-E in comparison with SGA (
p
< 0.01) obtaining an average of 208,760,000 chlamydospores. The aim of this study was to obtain basic knowledge regarding the effect of enriched culture medium and growth-inducing
meso
-inositol and Tween 80 on mycelial growth and production of chlamydospores.
The effect of ivermectin excreted in faeces of cattle treated in late winter on the arthropods and the degradation of faeces on pasture were evaluated. Four calves of similar age and weight were ...allocated to two groups, one group was treated subcutaneously with ivermectin and the other group remained as untreated control. From faeces collected from both groups at 3, 7, 14, 21 and 28 days post-treatment (dpt), three faecal pats of 1 kg each were made and deposited on a mixed paddock. One quarter of each faecal pat was removed at 10, 20, 30 and 60 days postdeposition (dpd) to determine the concentration of ivermectin, the organic matter content, and to collect colonising dung arthropods. Concentrations at days 3 and 7 pt were significantly higher than at the other dpt (
p
< 0.05). The highest ivermectin concentrations were found in samples from 3 dpt (
p
< 0.05). The organic matter percentage was not significantly different between treatments. An edaphic fauna characterised the colonisation of the faeces by organisms. Although arthropods’ abundance differences were not significant except for the 28 dpt at 30 dpd (
p
< 0.0003), fewer organisms were collected from the ivermectin group at all times.
The nematophagous fungus Duddingtonia flagrans, used for the biological control of gastrointestinal nematodes in livestock, is fed to infected animals so its chlamydospores and the parasite eggs are ...voided together with faeces where the fungus preys on nematode larvae, thus reducing pasture infectivity. The number of chlamydospores needed for the fungus to be efficient in the presence of a wide range in numbers of parasitic eggs is largely unknown and a matter of discussion. The aim of this study was to determine the fungal efficacy of four different chlamydospore concentrations against three different levels of cattle faecal egg counts. Fungal concentrations of 11000, 6250, 3000 and 1000 chlamydospores/gram of faeces (cpg) were added to cultures containing 840, 480 or 100 eggs/gram of faeces (epg). After 14 days of incubation, the efficacy of D. flagrans, in decreasing order of chlamydospore concentrations, ranged from 100% (P < 0.0001) to 77% (P > 0.0999) in the 100 epg groups; 100% (P < 0.0001) to 92% (P = 0.4625) in the 480 epg groups and 100% (P < 0.0001) to 96% (P = 0.7081) in the 840 epg groups. The results indicate that the numbers of eggs in cattle faeces were not a determining factor on the fungal efficacy against gastrointestinal nematodes.
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•Duddingtonia flagrans efficacy confirmed regardless of levels of faecal egg counts.•Fungal concentration is not crucial for high efficacy against cattle nematodes.•Nematode eggs:chlamydospores ratio is not relevant for fungal predatory activity.•Fungal ‘dose’ based on faecal egg counts does not need to be adjusted for cattle.
