Experimental simulation of environmental warming selects against pigmented morphs of land snails

H-R.K. and R.T. were gratefully hosted by INRA-PACA, Avignon, France, during the time of fieldwork in 2017. We gratefully acknowledge assistance in the field and with the open-top chamber experiments by Nik Triebskorn and Tim Triebskorn. The 35 field sites were sampled within the 2018 European Theba survey initiated by H-R.K and Thomas Knigge, Le Havre University, France. We also thank Menno Schilthuizen, Leiden University, the Netherlands, and another anonymous reviewer for constructive remarks on a previous manuscript version. Open access funding enabled and organized by ProjektDEAL.In terrestrial snails, thermal selection acts on shell coloration. However, the biological relevance of small differences in the intensity of shell pigmentation and the associated thermodynamic, physiological, and evolutionary consequences for snail diversity within the course of environmental warming are still insufficiently understood. To relate temperature‐driven internal heating, protein and membrane integrity impairment, escape behavior, place of residence selection, water loss, and mortality, we used experimentally warmed open‐top chambers and field observations with a total of >11,000 naturally or experimentally colored individuals of the highly polymorphic species Theba pisana (O.F. MÜLLER, 1774). We show that solar radiation in their natural Mediterranean habitat in Southern France poses intensifying thermal stress on increasingly pigmented snails that cannot be compensated for by behavioral responses. Individuals of all morphs acted neither jointly nor actively competed in climbing behavior, but acted similarly regardless of neighbor pigmentation intensity. Consequently, dark morphs progressively suffered from high internal temperatures, oxidative stress, and a breakdown of the chaperone system. Concomitant with increasing water loss, mortality increased with more intense pigmentation under simulated global warming conditions. In parallel with an increase in mean ambient temperature of 1.34°C over the past 30 years, the mortality rate of pigmented individuals in the field is, currently, about 50% higher than that of white morphs. A further increase of 1.12°C, as experimentally simulated in our study, would elevate this rate by another 26%. For 34 T. pisana populations from locations that are up to 2.7°C warmer than our experimental site, we show that both the frequency of pigmented morphs and overall pigmentation intensity decrease with an increase in average summer temperatures. We therefore predict a continuing strong decline in the frequency of pigmented morphs and a decrease in overall pigmentation intensity with ongoing global change in areas with strong solar radiation.ProjektDEA

Turkozelotes (Araneae, Gnaphosidae), un nouveau genre pour la France et description de Turkozelotes noname n. sp.

International audienc

Impact des pratiques de protection sur les organismes utiles du sol et du verger

Impact des pratiques de protection sur les organismes utiles du sol et du verger. Séminaire BioREc

Exposure to spinosad affects orb-web spider (Agalenatea redii) survival, web construction and prey capture under laboratory conditions

Spinosad is a neurotoxic pesticide, which is currently used in IPM and organic agriculture. It can affect the survival and ecological function of spiders, which are natural enemies of important agricultural pests. In the laboratory, we carried out tests to determine lethal and sublethal effects of spinosad on mortality, web building, and web characteristics of Agalenatea redii. Spinosad has a lethal effect at the normal application rate (NAR, i.e., 96 g ha(-1)) causing 35 % mortality (vs 0 % for control) after 4 days and 62 % mortality (vs 14 % for control) after 30 days. For the sublethal effects, web building was affected and fewer spiders built webs when exposed to spinosad (10/37 at NAR and 28/39 at half the NAR vs 35/37 for control group). No delay in web building was observed following exposure. Spider webs showed irregularities in the spiral-thread spacing (parallelism) when exposed to higher doses of spinosad (NAR and half of the NAR). Spinosad also affected prey capture: spiders exposed to spinosad (NAR) showed decreased prey capture efficiency (32 vs 73 % for control). These results showed that spinosad affects the spider predatory behavior (agriculture auxiliaries), which could modify their role in pest biocontrol

Pellenes seriatus (Thorell, 1875), découverte pour la France et redescription de l’espèc

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Temporal activity of spiders and earwigs during winter in apple trees under a Mediterranean climate

International audienceIt is well known that spiders are present in high numbers in orchards and may contribute to biocontrol. Some recent studies in central Europe further showed that some spiders are active year-round and consume pests even in winter. Using cardboard traps laid every two weeks, we carried out a survey to determine which spider and earwig species are active from September to May in an experimental, pesticide-free, apple orchard under a Mediterranean climate. We observed that spider activity was never completely absent. The structure of the spider communities showed a marked seasonality in three periods (so-called 'autumn', 'winter' and 'spring'). Only two spider genera, Philodromus and Trachelas, were highly active in winter (percentage of catches during this season above 40%) and six others (Lathys, Clubiona, Gnaphosa, Theridion, Phrurolithus) had moderate activity (between 20 and 40%). The two earwig species had different patterns of winter activity with Forficula auricularia almost absent whereas F. pubescens was moderately active on trees. Spider community abundance, diversity and evenness significantly decreased between autumn and winter and remained low in the following spring probably because the attractiveness of the traps is much lower at this time of year due to mild temperatures and the presence of leaves on the trees. Winter-active spiders could contribute to pest biocontrol during the cold season and we advocate that the use of broad-spectrum pesticides at the end of winter, as classically applied in orchards, may be counter-productive for pest control. ARTICLE HISTOR

Erratum: Neurological diseases and bullous pemphigoid: A case-control study in Iranian patients

National audienc

Application des techniques de microrespirométrie pour la caractérisation écotoxique microbienne (traits physiologiques et PICT) de sols contaminés par des métaux lourds

National audienc

Use of the MicroRespTM method to assess Pollution-Induced Community Tolerance to metals and ecophysiological traits for soil microbial communities.

International audienc