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Nematophagous fungi (NF) form part of the soil microbiota and are natural enemies of nematodes, helping to regulate nematode populations. A verticillate NF isolated from soil from Tepalcingo, Mexico, was morphologically and molecularly characterised. This fungus was cultured in two different liquid media—Czapek-Dox broth (CzDoxB) and sweet potato dextrose broth (SPDB)—for 21 days. The ovicidal (OA) and larvicidal (LA) activities of fungal liquid culture filtrates (LCFs) were assessed in 96-well microtitre plates at different concentrations against Haemonchus contortus after 48 h. The morphological and molecular identification revealed the presence of Lecanicillium psalliotae. Additionally, the groups of compounds associated with nematocidal activity were determined from a qualitative chemical profile (QCP) using different reagents. The highest OA of the LCFs was obtained at 25 mg/mL from SPDB and CzDoxB and amounted to 97.2 and 99.06%, respectively. Meanwhile, the highest LA recorded with these LCFs at 100 mg/mL was 54.27% and 96.8%, respectively. The QCP revealed the presence of alkaloids and tannins in both LCFs that have previously been associated with nematocidal activity. Lecanicillium psalliotae exerted an important effect on H. contortus and could be of significance in future studies focused on the control and prevention of haemonchosis in small ruminants. [ABSTRACT FROM AUTHOR]

Aquaculture represents the fastest growing food‐producing sector worldwide. However, the intensification of fish farms has led to environmental, health, and welfare challenges. The monogenean ectoparasite Gyrodactylus spp. has been considered one of the most pathogenic ectoparasites affecting fish, and no specific control strategies besides formalin baths have been established. The use of bioactive plants has been recently proposed as an alternative method to control gyrodactylid infections. Leucaena leucocephala is a tropical legume that has been found with anthelmintic activity against both internal and external parasites of cattle. Therefore, the objective of this study was to assess the anthelmintic‐like activity of L. leucocephala aqueous extract against Gyrodactylus spp. in hybrid tilapia Oreochromis spp. fingerlings and its effect on host health through histopathological analysis. Five concentrations of L. leucocephala aqueous extract were employed (2.00, 1.00, 0.50, 0.25, and 0.125 mg/mL) to estimate the mean effective concentration (EC50). Distilled water and formalin (1:4,000) were used as negative and positive controls, respectively. The aqueous extract of L. leucocephala showed a dose‐dependent behavior, with an EC50 of 0.228 mg/mL. Quercetin was identified as the main phytochemical present in the extract. Postmortem analysis of fingerlings exposed to the plant extract had no treatment‐associated pathological findings, thus indicating that the use of L. leucocephala baths had no negative impact that could jeopardize the lives of treated animals. After the in vivo assessment, the aqueous extract of L. leucocephala appears to be a promising alternative to control gyrodactylid infection in tilapia. [ABSTRACT FROM AUTHOR]

Bioactive plants might represent an alternative for Cooperia punctata control in grazing cattle. The objectives of this study were (1) to assess the ovicidal activity of extracts from 4 plant species against C. punctata, (2) to determine the role of the polyphenols in the plants' anthelmintic (AH) activity, and (3) to evaluate the best plant extraction procedure when searching for ovicidal activity. The egg hatch assay was used with different extraction procedures, aqueous (AQ), acetone:water (AW) and acetonic (AC), to evaluate the ovicidal activity of Leucaena leucocephala, Gliricidia sepium, Guazuma ulmifolia and Cratylia argentea. Eggs of C. punctata were exposed in quadruplicate to 0.6, 1.2, 2.4, 4.8 and 9.6 mg mL-1 of each plant extract. The roles of the polyphenols were assessed using polyethylene glycol (PEG). The 12 plant extracts inhibited egg hatching in a dose-dependent manner. Best-fit LC50 values were 1.03 ± 0.17 and 7.90 ± 1.19 mg mL-1 for G. sepium-AC and L. leucocephala-AQ, respectively. Differences in AH activity were found among the extraction procedures (P < 0.05). At the highest concentration, L. leucocephala- AQ inhibited more than 50% of C. punctata hatching. The G. sepium-AC extract fully inhibited egg hatching. The addition of polyethylene glycol revealed the role of the polyphenols in the bioactivity of most plant extracts; however, for G. sepium-AC, the polyphenols were not the main bioactive compounds. Overall, acetone:water extraction represented the best extraction procedure to obtain both ovicidal activity and higher yield. The inhibition rates suggested that L. leucocephala and G. sepium should be evaluated as a means of reducing larval density in pastures. [ABSTRACT FROM AUTHOR]

This study is an evaluation of resistance to natural infection by Cooperia spp. in Zebu x Holstein crossbreed calves in the tropics. Fourteen four-month-old calves were dewormed and moved to pastures naturally infested with gastrointestinal nematodes under sub-humid tropical conditions. Fecal samples were collected from each animal every seven days for three months to quantify the number of eggs per gram of feces (EPG), and nematode species identified with end-point PCR. Hair samples were collected for genotyping using the GeneSeek Genomic Profiler HD-V3 panel, which contains 139,376 SNP markers. Variation in EPG per individual ranged from a minimum of 7+7 to a maximum of 4,657+1,886 EPG. The PCR identified breed differences between the Zebu x Holstein crossbreeds. Genome-wide association studies detected five statistically significant haplotypes (P<0.001). The haplotype in chromosome 2 includes four markers, that in chromosome 10 includes three, that in chromosome 15 includes two, that in chromosome 23 includes four and chromosome X includes three. Of these regions only chromosome 23 was found to be associated with parasite resistance, measured as EPG phenotypes. The remaining chromosomes exhibited no association in the studied animals. These regions could be sequenced and tested for gene expression against Cooperia and other gastrointestinal nematodes. [ABSTRACT FROM AUTHOR]