Several studies have been conducted using fungi in the biological control of domestic animals and humans. In this respect, a large amount of research has been undertaken to understand the particularities of each fungus used. These fungi have been demonstrated to act on all classes of helminthes. Therefore, they should not only be called nematophagous but also helmintophagous. Evidence of enzymatic action has also revealed their mechanism of action, as well as potential metabolites that could be synthesized as bioactive molecules. Cultural barriers to the use of fungi should be broken down, since the impact on the environment is minimal. In this context, much is already known about the mechanism of interaction of these organisms with their 'targets'. Recent research has pointed to the search for substances derived from nematophagous fungi that have demonstrated their ovicidal and/or larvicidal activity, thus being a global premise to be studied further. Crude extracts derived from nematophagous fungi of predator and ovicidal groups reduce the amount of larvae of gastrointestinal nematodes and prevent the hatching of their eggs, since they have been demonstrated to act with extracellular proteases and other enzymes. Furthermore, the activity of these enzymes has begun to be explored regarding their possible interaction with the exoskeleton of arthropods, which could emerge as an alternative method of tick control. Finally, it should be clear that nematophagous fungi in general are 'old friends' that are ready to the 'fight with our old enemies', the gastrointestinal helminth parasites harmful to human and animal health.

RESUMO.-O controle biológico é um método desenvolvido para diminuir uma população de parasitas pela utilização de antagonista natural. A administração de fungos nematófagos aos animais domésticos é considerada uma promissora alternativa na profilaxia das helmintíases gastrintestinais parasitárias. Os fungos nematófagos desenvolvem estruturas em forma de armadilhas, responsáveis pela captura e destruição dos estágios infectantes dos nematóides. Os fungos dos gê-neros Arthrobotrys, Duddingtonia e Monacrosporium têm demonstrado eficácia em experimentos laboratoriais e no campo no controle de parasitos de bovinos, eqüinos, ovinos e suínos. Diversas formulações fúngicas têm sido avaliadas, no entanto, ainda não há nenhum produto comercial disponí-vel. A associação dos grupos de pesquisa e o envolvimento das indústrias poderão colaborar para o sucesso na implementação desta forma de controle. TERMOS DE INDEXAÇÃO:Controle biológico, helmintos gastrintestinais, profilaxia. INTRODUÇÃODentre os fatores que interferem no desenvolvimento pleno da atividade pecuária, as helmintíases gastrintestinais ocupam lugar de destaque (Macrae 1993). Os prejuízos estão relacionados ao retardo na produção, custos com tratamentos profilático e curativo e em casos extremos, a morte dos animais. Enquanto nos países desenvolvidos os gastos devidos aos custos com controle são significativos, nos países em desenvolvimento as doenças parasitárias causam prejuízos pela diminuição na produção e na restrição à criação de animais com reduzida susceptibilidade às parasitoses, porém com baixas performances produtivas. As raças de animais com melhores índices produtivos, quase sempre criadas nos paí-ses desenvolvidos, raramente se sobressaem em condições ambientais onde há grande disponibilidade de parasitos durante todo ano (Perry & Randolph 1999).O conhecimento sobre a epidemiologia dos parasitos e suas interações com os hospedeiros em um determinado ambiente e sistema produtivo são os requerimentos mais Biological control is a non-chemical alternative method with its main goal to reduce the amount of parasite population using natural antagonists. The administration of nematophagous fungi to animals has been considered an alternative in gastrointestinal helminthiasis prophylaxis. The nematophagous fungi produce trap-shaped structures, which are responsible for capturing and destroying the free-living stages of nematodes. The genera Arthrobotrys, Duddingtonia and Monacrosporium has been shown efficacy in laboratory and field experiments against cattle, equine, ovine and swine parasites. Several fungi formulations have been evaluated, but there is so far no commercial product available. The association of research groups with industry could improve the successful implementation of this control method.INDEX TERMS: Biological control, gastrointestinal helminths, prophylaxis.

The viability of a fungal formulation using the nematode-trapping fungus Duddingtonia flagrans was assessed for the biological control of horse cyathostomin. Two groups (fungus-treated and control without fungus treatment), consisting of eight crossbred mares (3-18 years of age) were fed on Cynodon sp. pasture naturally infected with equine cyathostome larvae. Each animal of the treated group received oral doses of sodium alginate mycelial pellets (1g/(10 kg live weight week)), during 6 months. Significant reduction (p<0.01) in the number of eggs per gram of feces and coprocultures was found for animals of the fungus-treated group compared with the control group. There was difference (p<0.01) of 78.5% reduction in herbage samples collected up to (0-20 cm) between the fungus-treated group and the control group, during the experimental period (May-October). Difference of 82.5% (p<0.01) was found between the fungus-treated group and the control group in the sampling distance (20-40 cm) from fecal pats. During the last 3 months of the experimental period (August, September and October), fungus-treated mares had significant weight gain (p<0.01) compared with the control group, an increment of 38 kg. The treatment with sodium alginate pellets containing the nematode-trapping fungus D. flagrans reduced cyathostomin in tropical southeastern Brazil and could be an effective tool for biological control of this parasitic nematode in horses.

Nematodes infections are responsible for debilitating conditions and economic losses in domestic animals as well as livestock and are considered an important public health problem due to the high prevalence in humans. The nematode resistance for drugs has been reported for livestock, highlighting the importance for development of new anthelmintic compounds. The aim of the current study was to apply and compare fluorimetric techniques using Sytox and propidium iodide for evaluating the viability of C. elegans larvae after treatment with anthelmintic drugs. These fluorescent markers were efficient to stain larvae treated with ivermectin and albendazole sulfoxide. We observed that densitometric values were proportional to the concentration of dead larvae stained with both markers. Furthermore, data on motility test presented an inverse correlation with fluorimetric data when ivermectin was used. Our results showed that lower concentrations of drugs were effective to interfere in the processes of cellular transport while higher drugs concentrations were necessary in order to result in any damage to cell integrity. The methodology described in this work might be useful for studies that aim to evaluate the viability of nematodes, particularly for testing of new anthelminthic compounds using an easy, economic, reproducible, and no time-consuming technique.

The in vitro action of the nematophagous fungi Duddingtonia flagrans, Monacrosporium thaumasium and Verticillium chlamydosporium on eggs of Ascaris lumbricoides was observed. After 7, 10 and 14 days of interaction, the fungus showing most promise for use in biologically control over Ascaris lumbricoides was Verticillium chlamydosporium (26-30%). The other fungi did not present satisfactory results.

The viability of a formulation of the fungus Monacrosporium thaumasium associated with ivermectin was evaluated for the biological control of bovine gastrointestinal nematode parasites. Four groups of five calves each were placed in pastures with a stocking rate of 1.6 animal/hectare. In group 1 (control), the calves did not receive any treatment. In group 2, each animal received 20g of pellets of M. thaumasium orally twice a week during a six-month period that began with the onset of the rainy season (October 23, 2000). In group 3, each animal received 20g of pellets of M. thaumasium orally twice a week during the same period as 2, as well as two strategic treatments with ivermectin (200 mcg/kg) on May 10, 2001 and July 5, 2001. In group 4, the animals were treated with ivermectin alone as described for group 3. EPG counts for group 1 were significantly greater (P< 0.01) than those for groups 2 and 3 and the difference at the end of the study period was near 100%. The EPGs of group 4 animals remained high until the first strategic treatment with ivermectin. Values for groups 1 and 4 differed significantly (P< 0.05) from those of groups 2 and 3 from December 2000 onwards. It was concluded that the use of this dose and periodicity of application of M. thaumasium pellets makes the application of anthelminthic treatments unnecessary.

The in vitro effect of four isolates of the nematophagous fungi Duddingtonia flagrans (AC 001), Monacrosporium sinense (SF 53), and Pochonia chlamydosporia (VC 1 and VC 4) on eggs of Ascaris suum was evaluated. One hundred thousand A. suum eggs were plated on 2% water-agar with the grown isolates and control without fungus. After 7, 14, and 21 days, 100 eggs were removed and classified according to the following parameters: type 1, lytic effect without morphological damage to eggshell; type 2, lytic effect with morphological alteration of embryo and eggshell; and type 3, lytic effect with morphological alteration of embryo and eggshell, besides hyphal penetration and internal egg colonization. P. chlamydosporia showed ovicidal activity (p < 0.01), mainly of the type 3 effect, on A. suum eggs in the studied intervals of 13.3% (isolate VC 1) and 17.3% (isolate VC 4), 13.9% (VC 1) and 17.7% (VC 4), and 19% (VC 1) and 20% (VC4), respectively, at 7, 14, and 21 days. The other fungi showed no type 3 effect. P. chlamydosporia is a potential biological control agent of A. suum eggs.

Angiostrongylus vasorum is a nematode that parasitizes domestic dogs and wild canids. We compared the predatory capacity of isolates from the predatory fungi Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34), Monacrosporium sinense (SF53) and Arthrobotrys robusta (I31) on first-stage larvae (L1) of A. vasorum under laboratory conditions. L1 A. vasorum were plated on 2% water-agar (WA) Petri dishes marked into 4 mm diameter fields with the four grown isolates and a control without fungus. Plates of treated groups contained each 1000 L1 A. vasorum and 1000 conidia of the fungal isolates AC001, NF34, SF53 and I31 on 2% WA. Plates of the control group (without fungus) contained only 1000 L1 A. vasorum on 2% WA. Ten random fields (4 mm diameter) were examined per plate of treated and control groups, every 24 h for 7 days. Nematophagous fungi were not observed in the control group during the experiment. There was no variation in the predatory capacity among the tested fungal isolates (P>0.05) during the 7 days of the experiment. There was a significant reduction (P < 0.05) of 80.3%, 74.5%, 74.2% and 71.8% in the means of A. vasorum L1 recovered from treatments with isolates AC001, NF34, SF53 and I31, respectively, compared to the control without fungi. In this study, the four isolates of predatory fungi were efficient in the in vitro capture and destruction of A. vasorum L1, confirming previous work on the efficiency of nematophagous fungi in the control of nematode parasites of dogs and as a possible alternative method of biological control.