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BACKGROUND: Geohelminths are parasites that stand out for their prevalence and wide distribution, depending on the soil for their transmission. AIMS: The aim of this work was to evaluate the predatory capacity of the fungal isolate of the genus Duddingtonia (CG768) on third stage larvae (L3) of Ancylostoma spp. in beach sand under laboratory conditions. METHODS: In the assay A five treatment groups and 1 control group were formed. The treatment groups contained 5000, 10,000, 15,000, 20,000 or 25,000 chlamydospores of the fungal isolate and 1000 Ancylostoma spp. L3 in pots containing 30g of sand. The control group (without fungus) contained only 1000 Ancylostoma spp. L3 and distilled water in pots with 30g of sand. RESULTS: Evidence of predatory activity was observed at the end of 15 days, where we observed the following percentages of reduction of L3: Group 1 (4.5%); Group 2 (24.5%); Group 3 (59.2%); Group 4 (58.8%); Group 5 (63%). However, difference was noted (p<0.01) only at concentrations 15,000, 20,000 and 25,000 in relation to control group. In the assay B two groups were formed in Petri dishes of 9cm in diameter containing agar water 2% medium. In the treated group, each Petri dish contained 500 Ancylostoma spp. L3 and 5g of sand containing the isolate CG 768 at a concentration of 25,000 chlamydospores/g of sand, and the control group (without fungus) contained only 500 L3. At the end of 7 days the non-predation L3 of Petri dishes using the method of Baermann were recovered. Difference (p<0.01) between groups on reducing the average number of Ancylostoma spp. L3 (percent reduction of 84%) was observed. CONCLUSIONS: The results of this study confirm earlier work on the efficiency of the Duddingtonia genus in the control of Ancylostoma spp. infective larvae.

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Viability and in vitro and in vivo activities of freeze-dried conidia of the predatory fungus Arthrobotrys robusta (I-31) were evaluated against infective larvae (L(3)) of Ancylostoma spp. in dogs. A. robusta conidia were lyophilized and stored at 4°C for a month. Freeze-dried conidia were diluted to 1×10(3)conidia/ml and tested in vivo. The treated group consisted of a solution containing conidia (1ml) and 1000 Ancylostoma spp. (L(3)) placed on Petri dishes plated with 2% water-agar (2% WA), at 25°C, in the dark for 10 days. The control group consisted of 1000 Ancylostoma spp. L(3), plated on 2% WA. After 10 days, Ancylostoma spp. L(3) from both the treated and the control groups were recovered and counted. The in vivo test was performed on two dogs by administering a single oral dose of freeze-dried conidia (1.5×10(5)) in aqueous solution to one animal and only water to the other. Fecal samples were collected at 12, 24 and 48h after the treatments, plated 2% WA plates and incubated at 25°C for 15 days. A thousand Ancylostoma spp. L(3) larvae were spread on these plates. At day 15, infective L(3) recovered from the treated and control groups were counted. In the in vitro test, A. robusta was able to survive the freeze-drying process, grow in the plates, form traps and capture Ancylostoma spp. L(3). There was a 75.38% decrease in the number of infective larvae recovered from the treated group. The in vivo test showed that freeze-dried A. robusta conidia survived the passage through the gastrointestinal tract of the treated dog, was able to grow in the plates and capture Ancylostoma spp. L(3), reducing the number of recovered L(3) (p<0.01). Freeze-drying can be an alternative method for conservation of conidia of nematophagous fungi.

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The potential role of companion animals as reservoirs for zoonotic diseases has been recognised as a significant public health problem worldwide. Ancylostoma ceylanicum is the only ancylostomatidae species known for infecting human beings. This article aimed to compare the predatory capacity of predatory fungi isolates Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34), Monacrosporium sinense (SF53) and Arthrobotrys robusta (I31) on A. ceylanicum infectious larvae (L(3)) in a 2% water-agar plate. There was no predatory capacity variation among the fungi tested (P>0.05) over the 7-day period experimental assay. When compared to the control (without fungi), there was a significant reduction (P<0.05) of 95.6%, 85.1%, 87.4% and 90.2% on the A. ceylanicum L(3) mean recovered from treatments with isolates AC001, NF34, SF53 and I31, respectively. Regarding linear regression coefficients, negative values were noted for treatments, therefore indicating A. ceylanicum non-predated larvae reduction over 7 days. In this work, all predatory fungi isolates were efficient at capturing and destroying in vitro the A. ceylanicum L(3); therefore being able to be used as biological controllers of such nematode.

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The interaction between the nematode-trapping fungus Duddingtonia flagrans (isolate CG768) against Ancylostoma spp. dog infective larvae (L(3)) was evaluated by means of scanning electron microscopy. Adhesive network trap formation was observed 6h after the beginning of the interaction, and the capture of Ancylostoma spp. L(3) was observed 8h after the inoculation these larvae on the cellulose membranes colonized by the fungus. Scanning electron micrographs were taken at 0, 12, 24, 36 and 48 h, where 0 is the time when Ancylostoma spp. L(3) was first captured by the fungus. Details of the capture structure formed by the fungus were described. Nematophagous Fungus Helper Bacteria (NHB) were found at interactions points between the D. flagrans and Ancylostoma spp. L(3). The cuticle penetration by the differentiated fungal hyphae with the exit of nematode internal contents was observed 36 h after the capture. Ancylostoma spp. L(3) were completely destroyed after 48 h of interaction with the fungus. The scanning electron microscopy technique was efficient on the study of this interaction, showing that the nematode-trapping fungus D. flagrans (isolate CG768) is a potential exterminator of Ancylostoma spp. L(3).

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In the present work, it was evaluated the in vitro effect of 12 isolates from the fungal species Arthrobotrys, Duddingtonia, Nematoctonus and Monacrosporium genera in different conidial concentrations on the capture of Ancylostoma spp. dog infective larvae (L(3)), on 2% water-agar medium at 25 degrees C, at the end of a period of 7 days. The concentrations used for each nematophagous fungus were 1000, 5000, 10,000, 15,000 and 20,000conidia/Petri dish plated with 1000 Ancylostoma spp. L(3). All nematode-trapping fungi isolates tested reduced the averages of the uncaptured Ancylostoma spp. L(3) recovered, with the increase of the fungal inoculum concentration, in comparison to the fungus-free control (p<0.05). The adhesive network producing species were better predators than the constricting ring or adhesive knob producing species. Duddingtonia flagrans (Isolate CG768) was the most effective, reducing the averages of the uncaptured Ancylostoma spp. L(3) recovered in 92.8%, 96.3%, 97.5%, 98.3% and 98.9%, respectively in five fungal inoculum concentrations established. Other effective nematophagous fungi were Arthrobotrys robusta (Isolate I31), which reduced the averages of the uncaptured Ancylostoma spp. L(3) recovered in 85.4%, 88.3%, 90.7%, 92.5% and 95.2%, and Arthrobotrys oligospora (Isolate A183), with reductions of 66.6%, 79.8%, 86.8%, 89.5% and 90.8%, respectively for both, in the five fungal inoculum concentrations established. No difference was found between Isolates A183 and I31 in the conidial concentrations of 15,000/Petri dish. Nematoctonus robustus (Isolate D1) and Arthrobotrys bronchophaga (Isolate AB) had the smallest percentages of reduction among the tested isolates and showed the lowest predacious activity. The Isolates CG768, I31 and A183 were considered potential biological control agents of Ancylostoma spp. dog free-living stages, being directly influenced by the fungal inoculum concentration.

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The predatory capacity of nematophagous fungi Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34a), M. appendiculatum (CGI), M. sinense (SF53), Arthrobotrys conoides (I-40), A. cladodes (CG719) and A. robusta (I-31) on infective Ancylostoma sp. larvae (L3) was evaluated. Compared with the control without fungi there was a significant reduction (P < 0.05) of 87.02%, 82.74%, 47.93%, 60.49%, 76.89%, 71.33% and 86.02% in the mean number of Ancylostoma sp. (L3) recovered from treatments with the isolates AC001, NF34a, CGI, SF53, I-40, CG719 and I-31, respectively. Isolates AC001, I-31 and NF34a were more effective in capturing L3 during the in vitro assay. Isolates were then in vivo evaluated for the capacity to remain viable after passing through the gastrointestinal tract of dogs, while still maintaining their predatory activity against L3. Fungal isolates survived the passage and showed efficient predation 48 h after fungal administration to the dogs (P < 0.05). After this time, only the isolate NF34a remained effective up to 96 h after administration (P < 0.05). Monacrosporium thaumasium, D. flagrans and A. robusta are potential biological control agents of Ancylostoma sp. in dogs.

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