Viability and nematophagous activity of the freeze-dried fungus Arthrobotrys robusta against Ancylostoma spp. infective larvae in dogs

Viability and in vitro and in vivo activities of freeze-dried conidia of the predatory fungus Arthrobotrys robusta (1-31) were evaluated against infective larvae (L-3) of Ancylostoma spp. in dogs. A. robusta conidia were lyophilized and stored at 4 degrees C for a month. Freeze-dried conidia were diluted to 1 x 10(3) conidia/ml and tested in vivo. The treated group consisted of a solution containing conidia (1 ml) and 1000 Ancylostoma spp. (L-3) placed on Petri dishes plated with 2% water-agar (2% WA), at 25 degrees 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 x 10(5)) in aqueous solution to one animal and only water to the other. Fecal samples were collected at 12, 24 and 48 h after the treatments, plated 2% WA plates and incubated at 25 degrees 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. (C) 2010 Elsevier B.V. All rights reserved.