The Predation Behaviour of Fictor composticola on Parasitic Nematodes of Button Mushroom, Agaricus bisporus

In this study, the predation behaviour of male and female predatory nematode, Fictor composticola, was studied on five prey nematode species, Aphelenchus avenae, Aphelenchoides swarupi, Ditylenchus myceliophagus, Bursilla sp. and Panagrolaimus sp., found in the white button mushroom compost. The period of the study is of six months. The data recorded on number of encounters, part of the body of prey attacked, stage of the prey attacked, duration of feeding etc. The strike rate and prey susceptibility were calculated. The average number of encounters on all the five preys done by female F. composticola was 3.0 and that of the male was 6.0. Male F. composticola had more number of encounters on the prey nematode species than the females. Both the sexes preferred juvenile stages over adults as prey. The most attacked part by both females and males predator, was the posterior part of the prey body. In 80% of cases, female predators fed on the first encountered prey while males attacked the first encountered prey in 30% of cases only. The strike rate of female F. composticola was more (78.6%) than the male (48.2%). Mycophagous nematodes were more susceptible to predator’s attack than the microbivorous nematodes. The strike rate of the predator on different prey nematode species was found more on mycophagous nematodes than on microbivorous nematodes and minimum on Panagrolaimus sp. The average feeding duration of female F. composticola was 8 min and 31 sec and in the case of males it was 4 min and 11 sec.

The Aphelenchus avenae genome highlights evolutionary adaptation to desiccation

Some organisms can withstand complete body water loss (losing up to 99% of body water) and stay in ametabolic state for decades until rehydration, which is known as anhydrobiosis. Few multicellular eukaryotes on their adult stage can withstand life without water. We still have an incomplete understanding of the mechanism for metazoan survival of anhydrobiosis. Here we report the 255-Mb genome of Aphelenchus avenae, which can endure relative zero humidity for years. Gene duplications arose genome-wide and contributed to the expansion and diversification of 763 kinases, which represents the second largest metazoan kinome to date. Transcriptome analyses of ametabolic state of A. avenae indicate the elevation of ATP level for global recycling of macromolecules and enhancement of autophagy in the early stage of anhydrobiosis. We catalogue 74 species-specific intrinsically disordered proteins, which may facilitate A. avenae to survive through desiccation stress. Our findings refine a molecular basis evolving for survival in extreme water loss and open the way for discovering new anti-desiccation strategies.

Cytoplasmic Lipases—A Novel Class of Fungal Defense Proteins Against Nematodes

Fungi are an attractive food source for predators such as fungivorous nematodes. Several fungal defense proteins and their protective mechanisms against nematodes have been described. Many of these proteins are lectins which are stored in the cytoplasm of the fungal cells and bind to specific glycan epitopes in the digestive tract of the nematode upon ingestion. Here, we studied two novel nematotoxic proteins with lipase domains from the model mushroom Coprinopsis cinerea. These cytoplasmically localized proteins were found to be induced in the vegetative mycelium of C. cinerea upon challenge with fungivorous nematode Aphelenchus avenae. The proteins showed nematotoxicity when heterologously expressed in E. coli and fed to several bacterivorous nematodes. Site-specific mutagenesis of predicted catalytic residues eliminated the in-vitro lipase activity of the proteins and significantly reduced their nematotoxicity, indicating the importance of the lipase activity for the nematotoxicity of these proteins. Our results suggest that cytoplasmic lipases constitute a novel class of fungal defense proteins against predatory nematodes. These findings improve our understanding of fungal defense mechanisms against predators and may find applications in the control of parasitic nematodes in agriculture and medicine.

METHODOLOGICAL INSTRUCTIONS “METHODOLOGY FOR IN VITRO SCREENING OF STRAINS, ISOLATES OF BACTERIA WITH PARASITIC AND NONMATICIDAL PROPERTIES”

The aim of this work was to develop a sequence for in vitro screening of isolates and strains of bacteria with similar activity on nematodes of various ecological groups, respectively, differing in the degree of cuticle permeability and having a different structure of the stoma, which is fundamental for the penetration of bacterial spores and toxins. The objects of screening were the saprobic nematode Caenorhabditis elegans, vinegar eel (Turbatrix aceti), mycohelminths Aphelenchus avenae, Aphelenchoides saprophilus, Paraphelenchus, migrating phytohelminths Ditylenchus destructor, larvae of gall nematodes of the genus Meloidyne. The proposed screening scheme makes it possible to comprehensively assess the effect of various strains and isolates on nematodes of various ecological groups. Strains, bacterial isolates that cause immobilization or death of nematodes, are reevaluated in vitro for other nematode species. In the case when the maximum mortality is observed in the variant with the undiluted isolate suspension, and when the suspension is diluted from minimum to maximum, there is a decrease in mortality to a minimum or does not differ statistically from the control, then a nematicidal effect of the metabolite products of the tested bacteria can be assumed. With a well-organized microbiological part, this algorithm can provide significant material for identifying bacteria with the desired properties, which in the future could serve as the basis for creating new drugs for protecting plants from nematodes and other pathogenic organisms.

Influence of Asclepias syriaca on soil nematode communities

The main goal of this study was to evaluate the impact of the invasive common milkweed (Asclepias syriaca L.) on soil nematode communities. The research was carried out in 2018 and 2019 in an ecosystem of permanent grassland in the basin of the Laborec River in land registries of Drahňov, a Vojany village in southeastern Slovakia. The ecosystem contained a total of 64 species of free-living and parasitic nematodes. The most prevalent trophic groups were bacterial feeders (Acrobeloides nanus), followed by plant parasites (Helicotylenchus digonicus and Pratylenchus pratensis), fungal feeders (Aphelenchus avenae), and omnivores (Eudorylaimus carteri). The number of nematode species, the composition of trophic groups and the structure of communities in areas with invasive plants were similar to those in areas with native vegetation during the two years of observation.

Populations of parasitic nematodes colonizing Jerusalem artichoke (Helianthus tuberosus L.)

The populations of parasitic nematodes colonizing the rhizosphere of <em>Helianthus tuberosus</em> L. grown in Polish plantations were studied in the summer of 2016 and the spring of 2017. A total of 35 nematode species were identified: <em>Paratrichodorus pachydermus</em>, <em>Trichodorus cylindricus</em>, <em>T. viruliferus</em>, <em>Longidorus attenuatus</em>, <em>L. elongatus</em>, <em>L. leptocephalus</em>, <em>Criconema annuliferum</em>, <em>Criconemoides informis</em>, <em>Mesocriconema rusticum</em>, <em>M. solivagum</em>, <em>M. xenoplax</em>, <em>Paratylenchus nanus</em>, <em>P. neoamblycephalus</em>, <em>P. projectus</em>, <em>Bitylenchus dubius</em>, <em>B. maximus</em>, <em>Merlinius brevidens</em>, <em>M. nothus</em>, <em>Scutylenchus quadrifer</em>, <em>S. tartuensis</em>, <em>Helicotylenchus digonicus</em>, <em>H. pseudorobustus</em>, <em>H. vulgaris</em>, <em>Rotylenchus pumilus</em>, <em>R. robustus</em>, <em>Pratylenchus crenatus</em>, <em>P. fallax</em>, <em>P. neglectus</em>, <em>Hirschmanniella gracilis</em>, <em>Aphelenchoides fragariae</em>, <em>Aphelenchus avenae</em>, <em>A. eremitus</em>, <em>Ditylenchus dipsaci</em>, and <em>D. medicaginis</em>. <em>Aphelenchoides fragariae</em> and <em>Ditylenchus dipsaci</em> could be foliar pathogens of <em>H. tuberosus</em> L. This is the first study to demonstrate the presence of <em>A. fragariae</em> on the leaves of the Jerusalem artichoke in Poland. The frequencies of occurrence and population densities of the 35 nematode species were determined.