Avaliação da atividade larvicida dos fungos Duddingtonia flagrans e Monacrosporium sinense associados ou não a ivermectina e sulfóxido de albendazol sobre larvas de Heterakis gallinarum

Abstract

The nematode Heterakis gallinarum parasitizes the cecum of birds and holds significant importance in poultry farming due to its role in the transmission of histomoniasis. The principal current treatment employs broad-spectrum anthelmintics, especially fenbendazole; however, their excessive use combined with improper management has led to the emergence of parasitic resistance. Biological control has shown promise, particularly through the use of helminthophagous fungi, but there are no studies determining the efficacy of these fungi against nematodes of the genus H. gallinarum. Therefore, the objective of this research was to evaluate the larvicidal activity of the fungi Duddingtonia flagrans and Monacrosporium sinense, either alone or in combination with 1% ivermectin and 15% albendazole sulfoxide, against H. gallinarum. Eggs of H. gallinarum were recovered directly from adult females located in the intestines of domestic hens by means of necropsy, in a commercial farm located in Espírito Santo; subsequently, larvae were obtained by rupturing the eggshells. The experimental groups were established as follows: Group G1 (nematodes + D. flagrans); Group G2 (nematodes + M. sinense); Group G3 (nematodes + M. sinense + D. flagrans); Group G4 (nematodes + D. flagrans + 1% ivermectin); Group G5 (nematodes + D. flagrans + 15% albendazole sulfoxide); Group G6 (nematodes + M. sinense + 1% ivermectin); Group G7 (nematodes + M. sinense + 15% albendazole sulfoxide); Group G8 (nematodes + 1% ivermectin + albendazole sulfoxide); Group G9 (nematodes + 1% ivermectin); and Group G10 (nematodes + 15% albendazole sulfoxide). Group G11 served as the negative control, comprising nematodes + H₂O. The results demonstrated that Groups G1 (AC001) and G2 (SF53), treated solely with conidia, exhibited a mean reduction of 88.9% and 30.9% in larval numbers, respectively, with a significant difference (P < 0.05) for G1 compared to G11. Light microscopy also revealed greater predatory activity on larvae in Group G1. It was further observed that the combination of AC001 and SF53 conidia in Group G3 resulted in an 80.2% reduction in L3 numbers at the end of the experimental period. In Groups G4 and G5, the incorporation of 1% ivermectin and 15% albendazole sulfoxide resulted in a 100% reduction in larval numbers in both groups; the same result was obtained in Groups G6 and G7, where SF53 conidia received the incorporation of 1% ivermectin and 15% albendazole sulfoxide. In Groups G8, G9, and G10, composed solely of 1% ivermectin, 15% albendazole sulfoxide, or their combination, a 100% reduction was observed. In the negative control group (G11), live H. gallinarum were observed throughout the entire experimental period. It is concluded from the observed results that the fungi AC001 and SF53 exhibited activity both in association with and without ivermectin and albendazole sulfoxide.