Biology subjects

Guertin, C.

Publications and source records attributed to Guertin, C..

6 recordsLinked to original sources

bioRxiv2026

A Closer Look at the White Pine Cone Beetle

Conophthorus coniperda (Coleoptera: Curculionidae; Schwarz), known as the white pine cone beetle, is a pest in white pine seed orchards. The insect was primarily studied in the United States of America during the late 1960s to 1992. No contemporary studies have been performed since, despite the devastating damage the beetle causes to white pine seed orchards, and the seeds they produce for reforestation purposes. To help future research on potential biological control, this work revisits the ontogeny of the white pine cone beetle. The biology of the insect was studied over two years in 2022 and 2023 in a seed orchard (Quebec, Canada). Observations were complemented with data collected from the same orchard and other sites in 2009 and in 2012. Except in 2022, the emergence of the insect occurred around 53.6 {+/-} 1.98 {degrees}C.d above a threshold of 6.5 {degrees}C. A shorter developmental cycle was observed compared with the ones described in 1965 and 1976. The relationship between cone size and the number of insects per cone was statistically significant but explained only a small proportion of the variance and showed high variability. These results will help improve survey timing and sampling strategies for this species.

ecology↗

bioRxiv2021

Quantification of breeding sites parameters in shaping bacterial communities in Aedes aegypti (Diptera: Culicidae).

Studies have demonstrated the importance of breeding site, few had disentangled the role of microbiome, physico-chemical and biological factors of water as well as landuse on larval microbial communities and their recruitment in mosquito. A quantitative exploration of the interplay of multiple factors on mosquito microbiome was performed using a dataset obtained through a field survey undertaken in French Guiana. Two complementary hypotheses were tested (i) the most dissimilar larval microbiome structures in breeding sites displayed the most contrasting water properties and land-use, (ii) a higher specificity level of environmental parameters have an incidence on larval microbiome. Variance partitioning approach validated the two hypothesis by providing evidence that water bacterial community is a most significant driver shaping the structure of the bacteriome in mosquito than other environmental parameters from the breeding sites. However, land-use does not play such important role to explain variance. Our results consolidate and complement the knowledge shaping mosquito microbiota but also highlighted the large unknown in understanding the ecology of the recruitment into host.

ecology↗

bioRxiv2021

The biological sink of atmospheric H2 is more sensitive to spatial variation of microbial diversity than N2O and CO2 emissions in an agroecosystem

The relationship between soil microbial diversity and agroecosystem functioning is controversial due to the elevated diversity level and the functional redundancy of microorganisms. A field trial was established to test the hypothesis that enhanced crop diversity with the integration of winter cover crops (WCC) in a conventional maize-soy rotation promotes microbial diversity and the biological sink of H2 in soil, while reducing N2O emissions to the atmosphere. Vicia villosa (hairy vetch), Avena sativa (oat), and Raphanus sativus (Daikon radish) were cultivated alone or in combinations and flux measurements were performed throughout two subsequent growing seasons. Soil acted as a net sink for H2 and as a net source for CO2 and N2O. CO2 flux was the most sensitive to WCC whereas a significant spatial variation was observed for H2 flux with soil uptake rates observed in the most productive area two-fold greater than the baseline level. Sequencing and quantification of taxonomic and functional genes were integrated to explain variation in trace gas fluxes with compositional changes in soil microbial communities. Fungal communities were the most sensitive to WCC, but neither community abundance nor beta diversity were found to be indicative of fluxes. The alpha diversity of taxonomic and functional genes, expressed as the number of effective species, was integrated into composite variables extracted from multivariate analyses. Only the composite variable computed with the inverse Simpsons concentration index displayed a reproducible pattern throughout both growing seasons, with functional genes and bacterial 16S rRNA gene defining the two most contrasting gradients. The composite variable was decoupled from WCC treatment and explained 19-20% spatial variation of H2 fluxes. Sensitivity of the trace gas exchange process to soil properties at the local scale was inconsistent among H2, N2O and CO2, with the former being the most related to microbial diversity distribution pattern.

ecology↗

bioRxiv2019

Horizontal transmission of the entomopathogenic fungal isolate INRS-242 of Beauveria bassiana in emerald ash borer, Agrilus planipennis Fairmaire

Emerald ash borer (EAB), Agrilus planipennis Fairmaire, is an invasive and destructive beetle that causes extensive damages to ash trees in North America. The entomopathogenic fungus Beauveria bassiana is considered as an effective biological control agent for EAB adult populations. Using an assisted autodissemination with the fungal isolate INRS-242 of B. bassiana, our research aims to investigate the possibility of horizontal transmission of the fungal disease from infected to uninfected EAB adults during mating. Results show that the efficiency of fungal transmission is significantly related to the sex of EAB carrying the pathogen. EAB males are the promising vector to transmit INRS-242 isolate of B. bassiana to their partners during mating. Results strengthen the potential of the fungal autodissemination device as a powerful biological strategy to control EAB populations.

microbiology↗

bioRxiv2018

The symbiotic complex of Dendroctonus simplex: implications in the beetle attack and its life cycle

The eastern larch beetle (Dendroctonus simplex Le Conte) is recognized as a serious destructive forest pest in the upper part of North America. Under epidemic conditions, this beetle can attack healthy trees, causing severe damages to larch stands. Dendroctonus species are considered as holobionts, as they engage in multipartite interactions with microorganisms, such as bacteria, filamentous fungi, and yeasts, which are implicated in physiological processes of the insect, such as nutrition. They also play a key role in the beetles attack, as they are responsible for the detoxification of the subcortical environment and weaken the trees defense mechanisms. The eastern larch beetle is associated with bacteria and fungi, but their implication in the success of the beetle remains unknown. Here, we investigated the bacterial and fungal microbiota of this beetle pest throughout its ontogeny (pioneer adults, larvae and pupae) by high-throughput sequencing. A successional microbial assemblage was identified throughout the beetle developmental stages, reflecting the beetles requirements. These results indicate that a symbiotic association between the eastern larch beetle and some of these microorganisms takes place and that this D. simplex symbiotic complex is helping the insect to colonize its host tree and survive the conditions encountered.

ecology↗

bioRxiv2017

Fungal communities associated with the eastern larch beetle: diversity and variation within developmental stages

Bacterial and fungal communities associated with bark beetles, especially some Dendroctonus species, mediate challenging aspects of the subcortical habitat for their hosts. Filamentous fungi and yeasts are important in various metabolic processes of certain bark beetles, with involvement in nutrition, protection and detoxification of plant defense compounds. The eastern larch beetle, Dendroctonus simplex, is recognized as a serious forest pest in the upper part of North America. Although D. simplex is well studied, the fungal communities and their ecological role remain to be investigated. Here, using 18S rRNA gene pyrosequencing, we provide a comprehensive overview of the yeasts and filamentous fungi associated with the eastern larch beetle and compare fungal communities between different developmental stages and microenvironments. Fungal mycobiome associated with the galleries was also investigated. Our study has unveiled an unexpected fungal diversity associated with the developmental stages. Significant differences in species richness between the developmental stages were determined. Yeasts were found to be predominant in the adult and larval stages, whereas filamentous fungi were most prevalent in the pupae. Our results indicate a possible implication of yeasts in the eastern larch beetle nutrition.

microbiology↗