Biology subjects

Bras, A.

Publications and source records attributed to Bras, A..

3 recordsLinked to original sources

bioRxiv2026

Flight performance of the highly invasive box tree moth Cydalima perspectalis (Lepidoptera: Crambidae)

The multivoltine non-native box tree moth, Cydalima perspectalis (Lepidoptera: Crambidae), was accidentally introduced in several continents and exhibited a very rapid expansion in its invaded ranges, colonising around 40 countries in less than twenty years. Initially observed in urban areas, it quickly spread to forest stands, causing significant damage to boxwood trees. If the role of the ornamental plant trade in its fast invasion has been investigated, the insects flight capabilities has thus far been overlooked, limiting estimations of its natural dispersal. In this context, we assessed the flight performance of the adults and investigated potential effects of sex, age and generation using computer-monitored flight mills. Under these controled conditions, we estimated the distance flown per night and over the adults lifespan in both sexes for each generation. The adults were able to fly on average 18 km within their lifespan, even though distances flown were highly variable, including several females capable of performing long-distance flights (up to 150 km). The distances covered were partly correlated with the age and body mass of the adults. Mated females flew longer distances than virgin ones, but long dispersal seemed to limit their fecundity. Finally, the overwintering generation presented the highest flight capabilities with individuals able to cover 22 km on average while the late summer generation covered only 10 km. The box tree moth showed good dispersal abilities that likely played a significant role in its rapid local expansion, while human-mediated dispersal favoured its long-distance dispersal.

ecology↗

bioRxiv2024

Relative Effects of Habitat Amount and Fragmentation Per Se on the Genetic Diversity of The Glanville Fritillary Butterfly

Habitat loss and fragmentation are considered the key drivers of biodiversity loss. Understanding their relative roles is difficult as habitat loss and fragmentation tend to co-occur. It has been proposed that the total habitat amount available in the local landscape mainly drives species richness while fragmentation per se - the breaking apart of habitat independent of habitat amount - has negligible or even a positive effect on biodiversity. Several studies support this at the species richness level. Yet, the potential effects of fragmentation per se on genetic diversity at the landscape scale are understudied. Using the Glanville fritillary butterfly metapopulation in the [A]land islands, we tested the effects of fragmentation per se on genetic diversity using a landscape-based approach and 2,610 individuals genotyped at 40 neutral SNP markers. We assessed the independent effect of habitat amount and fragmentation (i.e. number of patches) within the local landscape on the focal patch genetic diversity. The amount of habitat in the local landscape had a positive effect on genetic diversity, while fragmentation per se had a more negligible impact on the genetic diversity. Our results thus highlight that all fragments, even the small ones, likely contribute to the maintenance of genetic diversity of the focal population.

evolutionary biology↗

bioRxiv2020

Diapause regulation in newly invaded environments: termination timing allows matching novel climatic constraints in the box tree moth, Cydalima perspectalis (Lepidoptera: Crambidae)

The association between indirect environmental cues that modulate insect diapause and the actual stressors is by no means granted when a species encounters new environments. The box tree moth, Cydalima perspectalis, is an Asian pest whose rapid invasion in Europe cause considerable economic and ecological impacts. Larvae enter a winter diapause induced by photoperiod in both native and invaded ranges, but factors that trigger the return to an active phase are still unknown. Yet, identifying them is crucial to understand how diapause end synchronizes with the end of the winter stress encountered in Europe. To test whether activity resumption is regulated by thermal and/or photoperiodic thresholds, or additive effects between these factors often involved in diapause termination, diapausing caterpillars from an invaded area were exposed to crossed treatments at the laboratory. The evolution of diapause rate was monitored over time and compared to that of nearby field sites invaded. A strong positive effect of increasing temperature was found on the rate and dynamics of diapause termination, whereas no compelling effect of photoperiod appeared. Resuming development directly when main stressors fade, not in response to indirect photoperiodic cues that could be mismatched outside native areas, likely contributes to the good match observed between diapause and the new climates this pest encountered in the invaded range.

zoology↗