Isolamento, caracterização e eficácia de fungos nematófagos autóctones do Rio Grande do Sul no controle de nematóides gastrintestinais de ovinos

Abstract

The biocontrol with nematophagous fungi has been a promising alternative for use against gastrointestinal nematodiosis of sheep, due to the adversities that suppressive use of chemical molecules has occasioned. This study aimed to isolate and characterize fungi with nematophagic potential from soil samples from the municipalities of Rio Grande do Sul. The isolates were tested for nematophagic efficiency against the nematode Panagrellus redivivus being one of the fungi elected for in vitro and in vivo testing. The tests consisted of evaluation of the activity of the isolated on infective larvae in ideal conditions (bacteriological oven) and adverse conditions (field) from oral administrations of the fungus in corn substrate at three different doses in sheep naturally infected with gastrointestinal nematodes. Rates of physical integrity and viability of the related fungus were also evaluated after passage through the digestive tract of these animals. The results demonstrated the existence of fungi with nematophagic potential in the state. There has been the isolation of Duddingtonia flagrans nematophagous fungi, considered one of the most efficient due to its large-scale production of chlamydospores, which was used in the tests was isolated. D. flagrans demonstrated integrity and viability after crossing the gastrointestinal tract of sheep and the results in both environment such as controlled and adverse , demonstrated a decrease in the number of larvae when compared to the control group. Given the above, Rio Grande do Sul has fungi with nematophagic potential and D. flagrans when challenged, attested its nematocide efficacy being therefore likely its usage as a biological controller of gastrointestinal sheep larvae.