Gilles San Martin

Walloon Agricultural Research Centre CRA-W · Department of Life Sciences (D1)

To evaluate the risks of pesticides for pollinators, we must not only evaluate their toxicity but also understand how pollinators are exposed to these xenobiotics in the field. We focused on this last point and modeled honey bee exposure to pesticides at the landscape level. Pollen pellet samples (n = 60) from 40 Belgian apiaries were collected fro...

The harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is native to Asia but has been intentionally introduced to many countries as a biological control agent of pest insects. In numerous countries, however, it has been introduced unintentionally. The dramatic spread of H. axyridis within many countries has been met with co...

As in many other locations in the world, honeybee colony losses and disorders have increased in Belgium. Some of the symptoms observed rest unspecific and their causes remain unknown. The present study aims to determine the role of both pesticide exposure and virus load on the appraisal of unexplained honeybee colony disorders in field conditions....

1. Red Lists assess the extinction risk of species and are an important tool to prioritise species conservation and management measures. Worldwide, quantitative IUCN criteria are used to estimate the threat status of species at the regional level. 2. In Flanders (north Belgium), about 70 000 distribution records of ladybirds were collected in 36% o...

The number of non-native invasive pests and pathogens has increased dramatically in recent years, with disastrous consequences for the health of forests worldwide. Multiple studies have shown that mixed forests may suffer less damage from insect pests than single species forest. This “associational resistance” can be notably explained by the fact t...

This article presents managed honey bee colony loss rates over winter 2019/20 resulting from using the standardised COLOSS questionnaire in 37 countries. Six countries were from outside Europe, including, for the first time in this series of articles, New Zealand. The 30,491 beekeepers outside New Zealand reported 4.5% of colonies with unsolvable q...

Background The DNA metabarcoding approach has become one of the most used techniques to study the taxa composition of various sample types. To deal with the high amount of data generated by the high-throughput sequencing process, a bioinformatics workflow is required and the QIIME2 platform has emerged as one of the most reliable and commonly used....

The spruce bark beetle, Ips typographus , is causing severe economic losses during epidemic phases triggered by droughts and/or windstorms. Sanitation felling and salvage logging are usually the most recommended strategies to limit the damages. However, any additional control method to limit the economic impact of an outbreak would be welcome. In t...

This article presents managed honey bee colony loss rates over winter 2019/20 resulting from using the standardised COLOSS questionnaire in 37 countries. Six countries were from outside Europe, including, for the first time in this series of articles, New Zealand. The 30,491 beekeepers outside New Zealand reported 4.5% of colonies with unsolvable q...

Unraveling the origin of molecular pathways underlying the evolution of adaptive traits is essential for understanding how new lineages emerge, including the relative contribution of conserved ancestral traits and newly evolved derived traits. Here, we investigated the evolutionary divergence of sex pheromone communication from moths (mostly noctur...

Forest diseases caused by invasive fungal pathogens are becoming more common, sometimes with dramatic consequences to forest ecosystems. The development of early detection systems is necessary for efficient surveillance and to mitigate the impact of invasive pathogens. Windborne spores are an important pathway for introduction of fungal pathogens i...

The recent identification of Douglas fir needle midge (Contarinia pseudotsugae Condrashoff) (Diptera: Cecidomyiidae; Genus Contarinia) in Western Europe represents a new and previously unrecognised threat to the Douglas fir resource in the United Kingdom and Ireland. This article provides an overview of Douglas fir needle midge, its morphology, eco...

Unraveling the origin of molecular pathways underlying the evolution of adaptive traits is essential for understanding how new lineages emerge, including the relative contribution of conserved, ancestral traits, and newly evolved, derived traits. Here, we investigated the evolutionary divergence of sex pheromone communication from moths (mostly noc...

This article presents managed honey bee colony loss rates over winter 2018/19 resulting from using the standardised COLOSS questionnaire in 35 countries (31 in Europe). In total, 28,629 beekeepers supplying valid loss data wintered 738,233 colonies, and reported 29,912 (4.1%, 95% confidence interval (CI) 4.0–4.1%) colonies with unsolvable queen pro...

The Japanese flower thrips, Thrips setosus , is a polyphagous insect which in Europe has mainly been observed on hydrangeas ( Hydrangea spp.). The first report of T. setosus in the EPPO region was in the Netherlands (2014). Since then it has been observed in four other countries inside the EPPO region: Germany (2015), the United Kingdom (2016), Fra...

The orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a common pest of wheat that is frequently parasitized by Macroglenes penetrans (Kirby) (Hymenoptera: Pteromalidae). Both species need to be detected and quantified using a reliable monitoring system to assess the risk for wheat crops and, if necessary, deter...

Nous présentons les premières observations en Belgique du Bupreste Anthaxia candens (Panzer, 1793) dans le Hainaut et la province de Namur. We present the first observations in Belgium of the Jewel beetle Anthaxia candens (Panzer, 1793) in the Hainaut and Namur provinces.

Summary of the COLOSS survey results about honey bees winter mortalities in Belgium (in Franch)

Phenotypic variation is the raw material for selection that is ubiquitous for most traits in natural populations, yet the processes underlying phenotypic evolution or stasis often remain unclear. Here, we report phenotypic evolution in a mutant line of the butterfly Bicyclus anynana after outcrossing with the genetically polymorphic wild type popul...

Three species of cecidomyiid midges (Diptera: Cecidomyiidae), whose larvae overwinter in the soil, can cause significant yield losses on wheat in Europe: the orange wheat blossom midge, Sitodiplosis mosellana (Géhin), the yellow wheat blossom midge, Contarinia tritici (Kirby), and the saddle gall midge, Haplodiplosis marginata (von Roser). The biol...

Synthetic fungicides are pesticides widely used in agriculture to control phytopathogenic fungi. The systemicity, persistency and intense application of some of these fungicides, such as boscalid, leads to long periods of exposure for honeybees via contaminated water, pollen and nectar. We exposed adult honeybees in the lab to food contaminated wit...

The harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) has rapidly spread in several continents over the past 30 years and is considered an invasive alien species. The success of H. axyridis as an invader is often attributed to weak control by natural enemies. In this paper, we provide an overview of current knowledge on predators and...

General audience paper about winter colony losses of honey bees (Apis mellifica) in Belgium during the winter 2016-2017 based on the COLOSS survey(text in french)

Measures of fitness such as reproductive performance are considered reliable indicators of habitat quality for a species. Such measures are, however, only available in a restricted number of sites, which prevents them from being used to quantify habitat quality across landscapes or regions. Alternatively, species presence records can be used along...

The interaction between mutational (i.e. genetic) robustness, cryptic genetic variation and epistasis is currently under much debate, as is the question whether mutational robustness evolved under direct selection or as a by-product of environmental robustness. Here we report that mutational robustness was restored in a mutant line of the butterfly...

General audience chapter about the biodiversity of insects in forest ecosystems in Belgium (text in French).

The Multicolored Asian Ladybird, Harmonia axyridis, is an extremely successful invasive species. Here we suggest that, in addition to many other traits, the dorsal spines of its larvae contribute to their success, as suggested by behavioral observations of agonistic interactions between H. axyridis and European coccinellids. In coccinellids, the ro...

Bees are key participators to the fertility of plants and yet they are suffering from losses and disorders. In other studies, double the amount of fungicides were found in colonies showing disorders than in healthy ones, with boscalid among the most frequently detected residues. Boscalid was mainly found in bee bread, main ingredient of larvae food...

Measures of fitness such as reproductive performance are considered reliable indicators of habitat quality for a species. Such measures are, however, only available in a restricted number of sites, which prevents them from being used to quantify habitat quality across landscapes or regions. Alternatively, species presence records can be used along...

Invasive alien predators are a serious threat to biodiversity worldwide. However, there is no generic method for assessing which local species are most at risk following the invasion of a new predator. The harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is an alien in Europe and many other parts of the world where it aff...

Ash dieback, caused by the fungus Hymenoscyphus fraxineus, has been observed in Europe for several years. In Belgium, the disease was first reported in 2010. Besides crown defoliation and dieback, collar lesions have sometimes been reported. To evaluate the prevalence and the progression of collar lesions and crown defoliation in ash dieback-affect...

Bryological composition, water chemistry, and environmental factors were characterized on 67 Belgian travertines. We explore the relationship between these environmental factors and the community composition, species richness, or presence of individual species using Redundancy Analysis with Hellinger’s transformation (tb-RDA) or Generalized Linear...

In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences...

Up‐to‐date knowledge on species distribution is needed for efficient biodiversity conservation and management decision‐making. Implementing efficient sampling strategies to identify previously unknown locations of species of conservation‐concern is therefore a key challenge. Both structured expert judgement and habitat suitability models may help t...

The molecular mechanisms controlling sex pheromone production in moths have been studied extensively both at molecular and biochemical level. The production of sex pheromones in females of many moth species is tightly regulated by a photoperiodic cue initiated with the release of the pheromone biosynthesis activating neuropeptide (PBAN) to the hemo...

Since 2010, there has been a resurgence of the saddle gall midge, Haplodiplosis marginata (von Roser), in Belgium and several other European countries, with this pest sometimes causing severe damage in cereals. In 2012 and 2013, field trials were conducted in heavily infested fields to assess its impact on winter wheat crops and to determine effici...

The orange wheat blossom midge, Sitadiplosis mosellano (Géhin) (Diptera: Cecidomyiidae), can cause severe losses in wheat grain yield and quality. This pest is known to be susceptible to many insecticides, but various field observations have suggested that some fungicides could also significantly affect S. mosellana. In order to confirm these field...

Harmonia + and Pandora + : risk screening tools for potentially invasive plants, animals and their pathogens Bram D'hondt • Sonia Vanderhoeven • Sophie Roelandt • François Mayer Abstract Given the large number of alien species that may potentially develop into invasives, there is a clear need for robust schemes that allow to screen species for such...

Une équipe belge a évalué la nuisibilité de la cécidomyie Haplodiplosis marginata et en tire des conseils pour la protection du blé tendre d’hiver. Le tout est valable en France aussi !

Table S2. Environmental variables calculated in the 1-km resolution squares and used to identify the environmental strata in Luxembourg

Table S1. Red-backed shrike territories recorded during the period 2000–2009 in Luxembourg and used as a common source of basic information to design the expertbased and model-based sampling strategies. Geographical coordinates (XY) are given using the Luxembourg 1930 Gauss coordinate system. The spatial precision of each record is provided in mete...

Appendix S1. Further explanation about expert selection and qualification

Depuis quelques années, la cécidomyie équestre, Haplodiplosis marginata (von Roser) connaît une recrudescence dans plusieurs pays d'Europe, et inflige quelquefois de sévères dégâts aux céréales. Des essais ont été menés dans des champs fortement infestés afin d'évaluer la nuisibilité du ravageur envers le blé tendre d'hiver. A cette fin, des schéma...

Red Lists assess the extinction risk of species and are an important tool to prioritise species conservation and management measures. Worldwide, quantitative IUCN criteria are used to estimate the threat status of species at the regional level. In Flanders (north Belgium), about 70.000 distribution records of ladybirds were collected in 36% of all...

Background In 2012 and 2013, Sitodiplosis mosellana (Géhin) flights occurred during the susceptible phase of wheat development in Belgium. The protection against this midge afforded by various insecticides was assessed in infested fields on four winter wheat cultivars (susceptible or resistant, and early or late heading).ResultsThe insecticides spr...

A large scale field trial was performed in spring 2013 to assess the effects of Plenum (pymetrozine), Mavrik 2F (tau-fluvalinate), Biscaya (thiacloprid), Boravi WG (Phosmet) and Pyrinex (Chlorpyriphos-ethyl) used to control the pollen beetle Meligethes aeneus (F.) (Col.; Nitidulidae) on pest and beneficial arthropods' populations in winter oilseed...

Historically, Neuroptera received a lot of attention in Belgium by entomologists such as WESMAEL, DE SELYS-LONGCHAMPS, LAMEERE and NAVAS. However, since more than a century, no updated checklist has been published. Recently, only the family Chrysopidae has been studied, while the other families belonging to the Neuroptera hardly received any attent...

The saddle gall midge, Haplodiplosis marginata (von Roser, 1840) is a univoltine pest of cereals which occurs in Europe. The larvae feed on stems and attractive saddle-shaped depressions, driving to important yield losses when the galls are numerous. After 40 years without any reporting, large populations of H. marginata and important damage have b...

Rates of global extinction are accelerating and show no sign of slowing (Millenium Ecosystem Assessment 2005). Invasive alien species (IAS) are recognised as major drivers of biodiversity loss (Winter et al. 2009). IAS afford a unique opportunity to accurately assess threats to biodiversity because the time at which an IAS arrives within an ecosyst...

Aim Invasive alien species (IAS) are recognized as major drivers of biodiversity loss, but few causal relationships between IAS and species declines have been documented. In this study, we compare the distribution (Belgium and Britain) and abundance (Belgium, Britain and Switzerland) of formerly common and widespread native ladybirds before and aft...

Urbanization alters environmental conditions in multiple ways and offers an ecological or evolutionary challenge for organisms to cope with. Urban areas typically have a warmer climate and strongly fragmented herbaceous vegetation; the urban landscape matrix is often assumed to be hostile for many organisms. Here, we addressed the issue of evolutio...

Dispersal distance is understudied although the evolution of dispersal distance affects the distribution of genetic diversity through space. Using the two-spotted spider mite, Tetranychus urticae, we tested the conditions under which dispersal distance could evolve. To this aim, we performed artificial selection based on dispersal distance by choos...

In human-altered environments, organisms may preferentially settle in poor-quality habitats where fitness returns are lower relative to available higher-quality habitats. Such ecological trapping is due to a mismatch between the cues used during habitat selection and the habitat quality. Maladaptive settlement decisions may occur when organisms are...

Over a period of less than 5years, Belgium was thoroughly invaded by the multicolored Asian coccinellid, Harmonia axyridis. At the same time, a decline of some native coccinellid species was observed in tree habitats. One hypothesis about the cause of this decline was that it might have been due to intraguild predation (IGP) by H. axyridis. In natu...

House dust mites (Dermatophagoides pteronyssinus) are widespread in the furniture and mattresses of homes throughout Eurasia. Because human occupation induces wide diurnal fluctuations in temperature and relative humidity, the most favourable locations for mites change constantly and they must migrate repeatedly. Here, we triggered and studied mite...

Since the publication of the first red lists in 2000, the Belgian grasshopper and cricket fauna has changed considerably. As this group has now been studied quite intensively for about two decades, the detected trends have also become more reliable. Unfortunately, Stenobothrus lineatus has become extinct in Flanders. Luckily, no other species are c...