Detection of anthelmintic resistance in nematodes infecting dairy heifers in Puerto Rico

The efficacy of the anthelmintic albendazole (ALB), doramectin (DOR) and ivermectin (IVM) were evaluated in Holstein and Holstein crossbreed dairy heifers using the fecal egg count reduction test (FECRT). Dairy heifers (n=420; ~6 months of age; BW = 149 ± 39.6 kg) were evaluated in 21 dairy farms. All heifers were required to be on pasture and not have been exposed to anthelmintic treatment for a minimum of 3 months. At each dairy farm, a priori, groups of at least 18 heifers were randomly divided to be treated with IVM, or DOR, or ALB following manufacturer's instructions. Fecal samples were collected directly from the rectum 7 days before anthelmintic treatment (d-7), at the time of the treatment (d0), and 14 days after treatment (d14). Only heifers that had an average FEC ³ 100 eggs per gram of feces (average of FEC from day d-7 and d0) were considered in the FECRT. The FECRT was determined by the modified McMaster technique. Of the three-anthelmintic used, ALB (n=142) proved to be the most effective (P < 0.0005) with an efficacy of 67.47% ± 8.43. The efficacy of DOR and IVM did not differ (P = 0.8713). While DOR (n = 130) exhibited a efficacy of 25.50% ± 18.00, IVM (n = 148) exhibited a efficacy of -8.13% ± 19.89 due to an increase in FEC after treatment. Dairy farmers should implement integrated methods of nematode control to preserve the effectiveness of currently available anthelmintics.

Humic acid – a potential bioresource for nematode control

Summary There is a growing interest in the use of natural products for crop production and protection. Humic acid is a well-known bioresource that intensifies soil functions and improves crop productivity. This review article provides a synopsis of the humic acid-plant-nematode association and the prospects for using humic acid as an alternative to chemical control of nematodes. Humic acid is known to have toxic and antagonistic effects against many plant-parasitic nematodes, including Meloidogyne spp., Rotylenchulus reniformis, Radopholus similis and Helicotylenchus multicinctus. The required dose for getting significant nematode control ranges from 0.04 to 2.0% concentration. Delivery methods like soil application or drenching, seedling root dip treatment and foliar spray on leaves are effective for nematode control. Humic acid controls plant-parasitic nematodes through various mechanisms including killing juveniles, inhibiting hatching, reducing nematode infectivity and reproduction, and inducing systemic resistance. Humic acid is compatible with bio-inoculants such as Azospirillum spp., phosphobacterium, Bacillus megaterium, Pseudomonas fluorescens, Trichoderma viride, Glomus spp., Pochonia chlamydosporia, Purpureocillium lilacinum and T. asperellum. These attributes of humic acid show a promising potential for use in nematode control. However, further work on bio-efficacy against a broad spectrum of plant-parasitic nematodes is needed.

Review on Control Methods against Plant Parasitic Nematodes Applied in Southern Member States (C Zone) of the European Union

The European legislative on the use of different control strategies against plant-parasitic nematodes, with particular reference to pesticides, is constantly evolving, sometimes causing confusion in the sector operators. This article highlights the nematode control management allowed in the C Zone of the European Union, which includes the use of chemical nematicides (both fumigant and non-fumigant), agronomic control strategies (crop rotations, biofumigation, cover crops, soil amendments), the physical method of soil solarization, the application of biopesticides (fungi, bacteria and their derivatives) and plant-derived formulations. The authors analyze the use of these strategies and substances in organic agriculture as well as in Integrated Pest Management (IPM) programs.

Efficacy of a Chitin-Based Water-Soluble Derivative in Inducing Purpureocillium lilacinum against Nematode Disease (Meloidogyne incognita)

Plant-parasitic nematodes cause severe economic losses annually which has been a persistent problem worldwide. As current nematicides are highly toxic, prone to drug resistance, and have poor stability, there is an urgent need to develop safe, efficient, and green strategies. Natural active polysaccharides such as chitin and chitosan with good biocompatibility and biodegradability and inducing plant disease resistance have attracted much attention, but their application is limited due to their poor solubility. Here, we prepared 6-oxychitin with good water solubility by introducing carboxylic acid groups based on retaining the original skeleton of chitin and evaluated its potential for nematode control. The results showed that 6-oxychitin is a better promoter of the nematicidal potential of Purpureocillium lilacinum than other water-soluble chitin derivatives. After treatment, the movement of J2s and egg hatching were obviously inhibited. Further plant experiments found that it can destroy the accumulation and invasion of nematodes, and has a growth-promoting effect. Therefore, 6-oxychitin has great application potential in the nematode control area.

Transcriptomic insights into the effects of CytCo, a novel nematotoxic protein, on the pine wood nematode Bursaphelenchus xylophilus

Background The pine wood nematode Bursaphelenchus xylophilus is a destructive pest of Pinus trees worldwide and lacks effective control measures. Screening for nematotoxic proteins has been undertaken to develop new strategies for nematode control. Results The results of the present study provided initial insights into the responses of B. xylophilus exposed to a nematotoxic cytolytic-like protein (CytCo) based on transcriptome profiling. A large set of differentially expressed genes (DEGs = 1265) was found to be related to nematode development, reproduction, metabolism, motion, and immune system. In response to the toxic protein, B. xylophilus upregulated DEGs encoding cuticle collagens, transporters, and cytochrome P450. In addition, many DEGs related to cell death, lipid metabolism, major sperm proteins, proteinases/peptidases, phosphatases, kinases, virulence factors, and transthyretin-like proteins were downregulated. Gene Ontology enrichment analysis showed that the CytCo treatment substantially affected DEGs involved in muscle contraction, lipid localization, and the mitogen-activated protein kinase cascade. The pathway richness of the Kyoto Encyclopedia of Genes and Genomes showed that the DEGs were concentrated in lysosomes and involved in fatty acid degradation. Weighted co-expression network analysis indicated that the hub genes affected by CytCo were associated with the nematode cuticular collagen. Conclusions These results showed that CytCo toxin interferes with gene expression to exert multiple nematotoxic effects, thereby providing insights into its potential use in pine wood nematode control.