Biology subjects

Thiery, D.

Publications and source records attributed to Thiery, D..

5 recordsLinked to original sources

bioRxiv2025

Vineyard footprint revealed by honey bees used as sentinels for organic and inorganic pollutants in contrasted environments

The contamination of non-target organisms by elements and pesticides can adversely affect biodiversity and key ecosystem services such as pollination. In this study, we used honey bee colonies as sentinels of environmental contamination in four distinct habitats - urban, suburban, forest, and vineyard - and collected bees every three weeks from May to November. Pesticide residues were extracted using an adapted QuEChERS method and analyzed by LC-MS/MS, while inorganic major and trace elements were measured by ICP-MS and ICP-AES. Our results show that land-use and seasonal changes shape contaminant profiles in bees. Bees from vineyards exhibited the highest contaminant diversity and loads, indicating a particularly intense contamination profile in this environment. This reflects exposure to multiple pesticide inputs - such as copper - which can accumulate over time to potentially harmful levels. Pollinators like honey bees provide effective indicators of environmental risk, as their contaminant loads may affect honey bee health and can reveal broader ecological impacts.

ecology↗

bioRxiv2025

Social attraction mediates collective foraging decisions in invasive hornets

Group-living animals commonly use social information to better locate and exploit resources. In many insects, birds, fish and mammals, this can lead to collective foraging decisions by which animals share a single food source among alternatives of equal qualities. Here, we report collective foraging decisions in a social wasp, the yellow-legged hornet Vespa velutina nigrithorax, a major predator of bees and other terrestrial invertebrates invasive across Asia, Europe and North America. When given a choice between two identical liquid food sources (feeders or traps containing sugar solutions), wild hornets distributed asymmetrically on the two options, and this phenomenon was more frequent as group size increased. Priming one of the food sources with dead hornets predictably biased the collective choices towards this particular option, irrespective of whether the dead insects were conspecifics or hornets from a closely related species. Inter-attraction in yellow-legged hornets is thus a passive and non-specific mechanism, possibly mediated by visual or chemical cues displayed by dead hornets. This collective behaviour may provide important foraging advantages to hornets invading new territories and bring new perspectives for population control.

animal behavior and cognition↗

bioRxiv2024

Invasive Vespa velutina nigrithorax hornets are more susceptible to entomopathogenic fungus than two other hymenopteran species, the wasp Vespa vulgaris and the bumblebee Bombus terrestris.

Entomopathogenic fungi are commonly used as biological control agents. Recently, a strain of Metarhizium robertsii (Sorokin, 1883) (Hypocreales: Clavicipitaceae) collected in France was identified as a good candidate for controlling invasive populations of yellow-legged hornet, Vespa velutina nigrithorax (Buysson, 1905) (Hymenoptera: Vespidae) in Europe. Since M. robertsii is generalist, its use as bioagent could be damaging for non-targeted species. Here, we compared the lethal effects of three concentrations of this M. robertsii strain on the invasive hornet and two non-targeted species commonly found in Europe, the common wasp Vespa vulgaris (Linnaeus, 1758) (Hymenoptera: Vespidae) and the buff-tailed bumblebee Bombus terrestris (Linnaeus, 1758) (Hymenoptera: Apidae). Exposure to M. robertsii spores altered the survival of all three species but at different degrees. Hornets had consistently lower survival, even under low concentrations of spores, when compared to wasps and bumblebees. Such lower susceptibility of beneficial Hymenoptera is encouraging in the perspectives of using M. robertsii as biocontrol agent against invasive hornets.

animal behavior and cognition↗

bioRxiv2023

Flexible visual learning and memory in nectar foraging hornets

Pollinators, such as bees, develop flexible memories of colours, patterns and shapes, for efficient flower recognition. Here we tested whether other insects facing the same foraging problem have evolved similar cognitive abilities for flexible learning. We trained wild hornets from two species commonly found in Europe (Vespa velutina nigrithorax and Vespa crabro) to associate sucrose solution rewards to colour stimuli in a Y maze. Hornets of both species succeeded in differential and reversal learning, and developed short and long-term memories of the learnt associations. Thus, just like bees, hornet foragers can learn various visual cue-reward associations and remember them over several hours or days for selecting flowers. Our study in non-model species illustrates how standard conditioning approaches can be used to explore and compare the cognitive abilities of animals with similar foraging ecology.

animal behavior and cognition↗

bioRxiv2019

Organic farming expansion drives natural enemy abundance not diversity in agricultural landscapes

O_LIOrganic farming is seen as a prototype of ecological intensification able to conciliate crop productivity and biodiversity conservation in agricultural landscapes. However, how natural enemies, an important functional group supporting pest control services, respond to organic farming at different scales and in different landscape contexts remain unclear.\nC_LIO_LIUsing a hierarchical design within a vineyard-dominated region located in southwestern France, we examine the independent effects of organic farming and semi-natural habitats at the local and landscape scales on natural enemies.\nC_LIO_LIWe show that the proportion of organic farming is a stronger driver of species abundance than the proportion of semi-natural habitats and is an important facet of landscape heterogeneity shaping natural enemy assemblages. Although our study highlight a strong taxonomic group-dependency about the effect of organic farming, organic farming benefits to dominant species while rare species occur at the same frequency in the two farming systems.\nC_LIO_LIIndependently of farming systems, enhancing field age, reducing crop productivity, soil tillage intensity and pesticide use are key management options to increase natural enemy biodiversity.\nC_LIO_LISynthesis and Applications. Our study indicates that policies promoting the expansion of organic farming will benefit more to ecological intensification strategies seeking to enhance ecosystem services than to biodiversity conservation.\nC_LI

ecology↗