Butlerius butleri (Nematoda: Diplogasteridae) Feeds on Haemonchus contortus (Nematoda: Trichostrongylidae) Infective Larvae and Free-Living Nematodes in Sheep Faecal Cultures Under Laboratory Conditions: Preliminary Report

Aim This study assessed the feeding activity of the predatory nematode Butlerius butleri on the infective larvae of the sheep parasitic nematode Haemonchus contortus ( Hc-L 3 ) and on two free-living nematodes Panagrellus redivivus ( Pr ) and Rhabditis sp. ( R ) in sterile sheep faecal cultures. Materials and Methods A bioassay was carried out in sheep faecal cultures, where predatory and prey nematodes were put together to assess the predatory behaviour on the different nematodes. Faecal cultures ( n = 9) were set up in different treatments as follows: Treatments 1, 2 and 3 contained 20 specimens of B. butleri and 2000 Hc-L 3 , Pr and R , respectively; treatments 4, 5 and 6, contained only 2000 Hc-L 3 , Pr and R, respectively, as control groups. Treatment 7 contained 20 B. butleri as control. All treatments were incubated at room temperature for 30 days. The average number of nematodes recovered from each treatment was obtained and the reduction rate with respect to their corresponding control was estimated. Data were analysed using an ANOVA test using a completely randomised design in the SAS programme. Results Butlerius butleri reduced the Hc-L 3 , population by 91.8%, whereas its population increased 131.6 times. The interactions between B. butleri and Pr and R resulted in 80.9% and 62.5% nematode reduction and B. butleri increased its populations 268.3 and 82.7 times, respectively. This experiment was performed only once, so this can be considered a preliminary report at this time. Conclusion This study provides evidence for the first time that B. butleri feeds on one of the most economically important nematodes of small ruminants, Hc-L 3 . Graphic Abstract