Biology subjects

Colinet, H.

Publications and source records attributed to Colinet, H..

6 recordsLinked to original sources

bioRxiv2026

Using thermal death time models to analyze cold stress resistance across Drosophila species

O_LIChill-susceptible insects such as Drosophila are vulnerable to progressive disruption of ion and water homeostasis during cold stress, and low temperature exposure is a key factor affecting their physiology and distribution. Comparative studies of cold tolerance traditionally use simple or single-condition assays for interspecific comparisons, but the emergence of thermal death time (TDT) models offers a comprehensive framework to assess cold tolerance across different stress intensities and durations. C_LIO_LIHere we construct TDT curves for six Drosophila species, spanning boreal to tropical habitats, using Lt50 estimates across a range of stressful low temperatures (Lt50 ranging from [~] 20 min to 2 days). For all species, the TDT curves provided good fits to the log(Lt50) vs. temperature data (R2 = 0.87 - 0.99). C_LIO_LITDT curves from all species had steep slopes demonstrating that cold injury rate has a high thermal sensitivity such that small changes in temperature have profound effects on survival duration. The interspecific similarity of TDT slopes indicates that a conserved physiological dysfunction underlies cold injury across species. Further, additive accumulation of cold-induced injury in split-dose experiments suggests that acute and moderate cold damage represent the same underlying physiological dysfunction occurring at different rates. C_LIO_LIThe TDT curve intercepts (species-specific tolerance thresholds) differed markedly between boreal, temperate, and tropical species and correlated strongly with their habitat temperature. Data from the present study and meta-analysis of published data find that the inherent species cold tolerance decreases by [~] 0.45 {degrees}C for each {degrees}C colder the winter environment of the species is. When also considering the cold acclimation cues in cold climates we argue the experienced level of cold stress intensity is similar across environments inhabited by the Drosophila genus. This suggests that cold tolerance is important in shaping the fundamental niche of both boreal and tropical species. C_LIO_LIOverall, the TDT analysis of Drosophila at low temperature provides a powerful and predictive tool for quantifying insect cold tolerance. This approach enables detailed cross-species comparisons that allows for both ecological and physiological inference. Thus, TDT curves offer relevant approximations of insect cold resistance that could help predict insect responses to climatic change. C_LI

ecology↗

bioRxiv2025

Parallel clines of chromosomal inversion in seaweed flies associated with thermal variation

Chromosomal inversion supergenes, which form blocks of linked genes, are increasingly recognized for their role in maintaining intra-specific diversity. They are predicted to be relevant genetic architectures for local adaptation in the face of gene flow. However, pinpointing the underlying traits and functional mechanisms under selection remains challenging. The seaweed fly Coelopa frigida harbors several large polymorphic inversions, of which the Cf-Inv(4.1) inversion displays a latitudinal cline of frequencies along the North American Atlantic Coast, suggesting a putative role in adaptation along the eco-climatic gradient. To investigate this hypothesis, we designed a molecular marker for karyotyping and studied natural and experimental populations from North America and Europe. We confirmed that this inversion is also polymorphic in Europe, and displays parallel latitudinal clines across continents, providing strong indirect support that Cf-Inv(4.1) is under natural selection along similar environmental gradients. We found that Cf-Inv(4.1) had a significant impact on egg-to-adult survival and fecundity under different thermal conditions. However, no effect on cold tolerance could be determined using supercooling point and chill coma recovery time. We speculate that fitness associated with Cf-Inv(4.1) is shaped by subtle life-history differences whose relative advantage depends on climate. While our experimental approaches provided insights into genotype-phenotype associations, it is worth noting that selection acts on the overall fitness, involving complex sets of traits. This is especially relevant for inversions linking hundreds of genes. This multi-gene property also explains why inversions are frequently involved in repeated parallel adaptation to environmental gradients, as demonstrated here in the seaweed fly.

evolutionary biology↗

bioRxiv2023

First record of Zaprionus tuberculatus (Diptera: Drosophilidae) in mainland France

BACKGROUNDAs most drosophilid species are not considered as primary pest, studies of the whole drosophilid communities, including other genera than Drosophila, with standardized surveys are relatively sparse. However, the spotted wing drosophila Drosophila suzukii (Matsumura, 1931) and its rapid expansion through the world led to the implementation of many monitoring programs in various countries. As part of a research project on D. suzukii, we set up in 2022 an annual fly monitoring in 16 fruits farms to understand populations dynamics of D. suzukii and to survey drosophilid communities. RESULTSWe report here the first observation of Zaprionus tuberculatus Malloch, 1932 (Diptera: Drosophilidae) in mainland France. Over the whole monitoring, we trapped a total of 111 specimens in a fig orchard located in southern France (Salses-le-Chateau), both in fig trees and nearby hedgerows. The first detection of Z. tuberculatus occurred in July 2022 in the hedgerow and captures continued until January 2023 with an interruption in November and December. In addition, in this orchard we collected overripe figs in September 2023 from which over 15 Z. tuberculatus have emerged in the following two weeks. CONCLUSIONThe pest status of Z. tuberculatus and its potential risk for agriculture is not clear, but the pest behavior of the close-relative species Zaprionus indianus, especially on figs, should be a warning point for the entry of Z. tuberculatus into the EU and France, as they may have similar nutritional ecology. The pest status, the establishment and the future spread of Z. tuberculatus should thus be monitored to assess possible damages to fruits productions.

ecology↗

bioRxiv2022

The transcriptomic signature of physiological trade-offs caused by larval overcrowding in Drosophila melanogaster

Intraspecific competition at the larval stage is an important ecological factor affecting life-history, adaptation and evolutionary trajectory in holometabolous insects. However, the molecular pathways and physiological trade-offs underpinning these ecological processes are poorly characterised. We reared Drosophila melanogaster at three egg densities (5, 60 and 300 eggs/ml) and sequenced the transcriptomes of pooled third-instar larvae. We also examined emergence time, egg-to-adult viability, adult mass and adult sex-ratio at each density. Medium crowding had minor detrimental effects on adult phenotypes compared to low density and yielded 24 differentially expressed genes (DEGs) including several chitinase enzymes. In contrast, high crowding had substantial detrimental effects on adult phenotypes and yielded 2107 DEGs. Among these, upregulated gene sets were enriched in sugar, steroid and amino acid metabolism as well as DNA replication pathways, whereas downregulated gene sets were enriched in ABC transporters, Taurine, Toll/Imd signalling and P450 xenobiotics metabolism pathways. Overall, our findings show that larval overcrowding has a large consistent effect on several molecular pathways (i.e., core responses) with few pathways displaying density-specific regulation (i.e., idiosyncratic responses). This provides important insights into how holometabolous insects respond to intraspecific competition during development.

ecology↗

bioRxiv2021

Biogeographic position and body size jointly set lower thermal limits of wandering spiders

Most species encounter large variations in abiotic conditions along their distribution range. Climate, and in particular temperature, varies along clinal gradients, which determines phenotypic plasticity, local adaptations and associated physiological responses of most terrestrial ectotherms, such as insects and spiders. This study aimed to determine how the biogeographic position of populations and the body size of two wandering spiders set their limits of cold (freezing) resistance. Using an ad-hoc design, we sampled relatively large numbers of individuals from four populations of Dolomedes fimbriatus and one population of the sister species Dolomedes plantarius originating from contrasting climatic areas (temperate and continental climate), and compared their supercooling ability as an indicator of cold resistance. Results indicated that spiders from northern (continental) populations had higher cold resistance than spiders from a southern (temperate) populations. Larger spiders had a lower supercooling ability in northern populations. The red-listed and rarest D. plantarius was slightly less cold-tolerant than the more common D. fimbriatus, and this might be of importance in a context of climate change that could imply colder overwintering habitats in the north due to reduced snow cover protection.

physiology↗

bioRxiv2020

The discovery, distribution and diversity of DNA viruses associated with Drosophila melanogaster in Europe

Drosophila melanogaster is an important model for antiviral immunity in arthropods, but very few DNA viruses have been described from the family Drosophilidae. This deficiency limits our opportunity to use natural host-pathogen combinations in experimental studies, and may bias our understanding of the Drosophila virome. Here we report fourteen DNA viruses detected in a metagenomic analysis of approximately 6500 pool-sequenced Drosophila, sampled from 47 European locations between 2014 and 2016. These include three new Nudiviruses, a new and divergent Entomopox virus, a virus related to Leptopilina boulardi filamentous virus, and a virus related to Musca domestica salivary gland hypertrophy virus. We also find an endogenous genomic copy of Galbut virus, a dsRNA Partitivirus, segregating at very low frequency. Remarkably, we find that Drosophila Vesanto virus, a small DNA virus previously described as a Bidnavirus, may be composed of up to 12 segments and represent a new lineage of segmented DNA viruses. Two of the DNA viruses, Drosophila Kallithea nudivirus and Drosophila Vesanto virus are relatively common, found in 2% or more of wild flies. The others are rare, with many likely to be represented by a single infected fly. We find that virus prevalence in Europe reflects the prevalence seen in publicly-available datasets, with Drosophila Kallithea nudivirus and Drosophila Vesanto virus the only ones commonly detectable in public data from wild-caught flies and large population cages, and the other viruses being rare or absent. These analyses suggest that DNA viruses are at lower prevalence than RNA viruses in D. melanogaster, and may be less likely to persist in laboratory cultures. Our findings go some way to redressing an earlier bias toward RNA virus studies in Drosophila, and lay the foundation needed to harness the power of Drosophila as a model system for the study of DNA viruses.

microbiology↗