Wood ants produce a potent antimicrobial agent by applying formic acid on tree-collected resin.

Wood ants fight pathogens by incorporating tree resin with antimicrobial properties into their nests. They also produce large quantities of formic acid in their venom gland, which they readily spray to defend or disinfect their nest. Mixing chemicals to produce powerful antibiotics is common practice in human medicine, yet evidence for the use of such "defensive cocktails" by animals remains scant. Here, we test the hypothesis that wood ants enhance the antifungal activity of tree resin by treating it with formic acid. In a series of experiments, we document that (i) tree resin had much higher inhibitory activity against the common entomopathogenic fungus Metarhizium brunneum after having been in contact with ants, while no such effect was detected for other nest materials; (ii) wood ants applied significant amounts of endogenous formic and succinic acid on resin and other nest materials; and (iii) the application of synthetic formic acid greatly increased the antifungal activity of resin, but had no such effect when applied to inert glass material. Together, these results demonstrate that wood ants obtain an effective protection against a detrimental microorganism by mixing endogenous and plant-acquired chemical defenses. In conclusion, the ability to synergistically combine antimicrobial substances of diverse origins is not restricted to humans and may play an important role in insect societies

Antiretroviral-naive and -treated HIV-1 patients can harbour more resistant viruses in CSF than in plasma

Objectives The neurological disorders in HIV-1-infected patients remain prevalent. The HIV-1 resistance in plasma and CSF was compared in patients with neurological disorders in a multicentre study. Methods Blood and CSF samples were collected at time of neurological disorders for 244 patients. The viral loads were >50 copies/mL in both compartments and bulk genotypic tests were realized. Results On 244 patients, 89 and 155 were antiretroviral (ARV) naive and ARV treated, respectively. In ARV-naive patients, detection of mutations in CSF and not in plasma were reported for the reverse transcriptase (RT) gene in 2/89 patients (2.2%) and for the protease gene in 1/89 patients (1.1%). In ARV-treated patients, 19/152 (12.5%) patients had HIV-1 mutations only in the CSF for the RT gene and 30/151 (19.8%) for the protease gene. Two mutations appeared statistically more prevalent in the CSF than in plasma: M41L (P = 0.0455) and T215Y (P = 0.0455). Conclusions In most cases, resistance mutations were present and similar in both studied compartments. However, in 3.4% of ARV-naive and 8.8% of ARV-treated patients, the virus was more resistant in CSF than in plasma. These results support the need for genotypic resistance testing when lumbar puncture is performe

Identification of ant deterrents emitted by entomopathogenic nematode-infected insect cadavers

Trabajo presentado en el 34th annual meeting of the International Society of Chemical Ecology, celebrado en Budapest (Hungría), del 12 al 18 de agosto de 2018Peer reviewe

The lure of hidden death: Attractive volatile organic compounds to attract wireworms towards entomopathogenic nematodes

Trabajo presentado en el 52nd Annual Meeting of the Society for Invertebrate Pathology y 17th Meeting of the IOBC‐WPRS Working Group “Microbial and Nematode Control of Invertebrate Pests”, celebrado en Valencia (España), del 28 de julio al 1 de agosto de 201

The lure of hidden death: volatile organic compounds to attract wireworms towards entomopathogenic nematodes

Trabajo presentado en el 35th Meeting of the International Society of Chemical Ecology, celebrado en Georgia (Estados Unidos), del 2 al 7 de junio de 2019Wireworms (Coleoptera: Elateridae) ae) are common polyphagous soil pests. One strategy to control these pest insects could be an attract-and-kill system combining volatile organic compounds (VOCs), as attractants, and entomopathogenic nematodes as biocontrol agents

Efficiency of an attract-and-kill system with entomopathogenic nematodes against wireworms (Coleoptera: Elateridae)

Trabajo presentado en el 52nd Annual Meeting of the Society for Invertebrate Pathology y 17th Meeting of the IOBC‐WPRS Working Group “Microbial and Nematode Control of Invertebrate Pests”, celebrado en Valencia (España), del 28 de julio al 1 de agosto de 2019This study aimed at contributing to the development of an attract-and-kill strategy combining plant natural extracts with entomopathogenic nematodes (EPNs). We first compared the efficiency of two EPN strains through classical screening laboratory assays (contact application of EPNs) and found 8.3 and 16.7% of mortality after 10 days for Steinernema carpocapsae B14 and Heterorhabditis bacteriophora, respectively. Then, we encapsulated EPNs with potato extracts (acting as attractant and feeding stimulant) in alginate beads and the results showed higher mortality rates: 16.7% and 41.7% for S. carpocapsae and H. bacteriophora, respectively. In absence of attractants in the beads, the mortality dropped to 0% (S. carpocapsae) and 8.3% (H. bacteriophora). We conclude that the ingestion of EPN lead to increased mortality, compared to contact application of EPNs. The association of volatiles organic compounds as attractants and EPNs as biological agents represent a promising alternative to pesticides that remains to be evaluated in the field.D. la Forgia is supported by a PhD grant from Coordinated Integrated Pest Management in Europe (C-IPM), project ElatPro and a FNRS mobility grant. R. Campos-Herrera is awarded with a Ramón y Cajal contract (RYC-2016-19939

Molecular detection and quantification of slug parasitic nematodes from the soil and their hosts

Terrestrial gastropod molluscs are widely distributed and are well known as pests of many types of plants that are notoriously difficult to control. Many species of nematodes are able to parasitize land snails and slugs, but few of them are lethal to their host. Species and/or populations of mollusc-parasitic nematodes (MPNs) that kill their hosts are promising for biological control purposes. The recent discovery of new nematode species of the genus Phasmarhabditis in Europe and the associations between Alloionema spp. and slugs are expanding the possibilities of using MPNs as control agents. However, very little is known about the distribution and ecology of these species. Using molecular techniques based on qPCR methods for quick identification and quantification of various species of MPN isolated directly from the soil or from infected hosts can assist in providing information on their presence and persistence, as well as the composition of natural assemblages. Here, we developed new primers and probes for five species of the genus Phasmarhabditis and one species of the genus Alloionema. We employed these novel molecular techniques and implemented a published molecular set to detect MPN presence in soil samples coming from natural and agricultural areas in Switzerland. We also developed a method that allows the detection and quantification of Phasmarhabditis hermaphrodita directly from the tissues of their slug host in a laboratory experiment. The new molecular approaches were optimized to a satisfactory limit of detection of the species, with only few cross-amplifications with closely related species in late cycles (>32). Using these tools, we detected MPNs in 7.5% of sampled sites, corresponding to forest areas (P. hermaphrodita and Alloionema appendiculatum) and wheat-oriented agricultural areas (Phasmarhabditis bohemica). Moreover, we confirmed that the method can be used to detect the presence of P. hermaphrodita inside slug hosts, with more detections in the susceptible slug Deroceras larvae compared to the resistant Arion vulgaris. These primers/probe sets provide a novel and quick tool to identify MPNs from soil samples and infected slugs without having to culture and retrieve all nematode life stages, as well as a new tool to unravel the ecology of nematode-slug complexes.This work was funded by the Swiss National Science Foundation: Grants NRP68 and SNSF Div. I-III, reference 166632. The Government of Spain supports RCH with a Ramón y Cajal contract award: RYC-2016-19939.Peer reviewe

The evaluation of entomopathogenic nematode soil food web assemblages across Switzerland reveals major differences among agricultural, grassland and forest ecosystems

Entomopathogenic nematodes (EPNs) occur in natural and agricultural soils and contribute to the control of soil dwelling insect pests. Ecosystems differ in their soil parameters (pH, moisture, texture, etc.) and microhabitat conditions (presence of roots, plant cover, belowground fauna, etc.), which can affect the EPN soil food web assemblage in an unpredictable manner. By comparing soils that represent different ecological scenarios, we can link the natural distribution of the EPN to abiotic and biotic factors that shape the assemblages of soil food web to unravel the factors that determine EPN abundance and activity. We hypothesized that the EPN soil food web assemblages are affected by agricultural management practices and that this should be reflected when compared to natural ecosystems, such as forests and grasslands. By combining traditional and state-of-the-art molecular tools, we targeted 25 soil organisms to explore EPN food web in 40 Swiss georeferenced sites that can be categorized as “agricultural area”, “forest”, and “grassland”. EPNs abundance, richness and diversity did not vary among the different ecosystems. However, EPN activity (capability to kill insects) was higher in grasslands. Similarly, the free-living nematodes (FLNs) that compete with EPN for the cadavers were much more abundant in grassland, while reduced in the forest soils, suggesting contrasting conditions between these two natural areas. Nematophagous fungi (NF) were more diverse and present in agricultural areas, suggesting that the abiotic conditions in the agricultural areas may favor NF presence. Six soil properties and environmental factors shaped the EPN soil food web in Swiss soils (pH, elevation, clay content, soil water content, temperature, and rainfall), which explained 54% of the community variation in multivariate analysis. These observations were consistent with the key abiotic variables described for subtropical and Mediterranean regions. Identifying the links between the abiotic and biotic factors in very distinct areas can be the basis for predicting EPN soil food web assemblages. Such information can be of value for developing strategies to favour EPN resilience in a changing environment and enhance their capacity as biocontrol agents.This work was supported by an economic stimulus grant (51NF40-144621) and by the National Research Program 68 (NRP68) grant (406840_143065) from the Swiss National Science Foundation. GJ was supported by an assistantship from the University of Neuchâtel and XC was supported by a PhD fellowship from the Commission Fédérale des Bourses pour Etudiants Etrangères CFBE (Confédération Suisse). RCH was supported by The Government of Portugal (Investigator Program award, IF/00552/2014).Peer reviewe