Pesticide resistance development is an example of rapid contemporary evolution that poses immense challenges for agriculture. It typically evolves due to the strong directional selection that pesticide treatments exert on herbivorous arthropods. However, recent research suggests that some species are more prone to evolve pesticide resistance than others due to their evolutionary history and standing genetic variation. Generalist species might develop pesticide resistance especially rapidly due to pre‐adaptation to handle a wide array of plant allelochemicals. Moreover, research has shown that adaptation to novel host plants could lead to increased pesticide resistance. Exploring such cross‐resistance between host plant range evolution and pesticide resistance development from an ecological perspective is needed to understand its causes and consequences better. Much research has, however, been devoted to the molecular mechanisms underlying pesticide resistance while both the ecological contexts that could facilitate resistance evolution and the ecological consequences of cross‐resistance have been under‐studied. Here, we take an eco‐evolutionary approach and discuss circumstances that may facilitate cross‐resistance in arthropods and the consequences cross‐resistance may have for plant–arthropod interactions in both target and non‐target species and species interactions. Furthermore, we suggest future research avenues and practical implications of an increased ecological understanding of pesticide resistance evolution.

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 causes considerable economic and ecological impacts. Larvae enter a winter diapause induced by the 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 that this pest encountered in the invaded range.

Identifying the invasion routes of non-native species is crucial to understanding invasions and customizing management strategies. The box tree moth,Cydalima perspectalis, is native to Asia and was recently accidentally introduced into Europe as a result of the ornamental plant trade. Over the last 15 years, it has spread across the continent and has reached the Caucasus and Iran. It is threateningBuxustrees in both urban areas and forests. To investigate the species’ invasion routes, native and invasive box tree moth populations were sampled, and moth’s genetic diversity and structure were compared using microsatellite markers. Our approximate Bayesian computation analyses strongly suggest that invasion pathways were complex. Primary introductions originating from eastern China probably occurred independently twice in Germany and once in the Netherlands. There were also possibly bridgehead effects, where at least three invasive populations may have served as sources for other invasive populations within Europe, with indication of admixture between the two primary invasive populations. The bridgehead populations were likely those in the countries that play a major role in the ornamental plant trade in Europe, notably Germany, the Netherlands, and Italy. All these invasion processes likely facilitated its fast expansion across Europe and illustrate the role played by the ornamental plant trade not only in the moth’s introduction from China but also in the species’ spread across Europe, leading to an invasion with a complex pattern.

Habitat loss and fragmentation are considered 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 a 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 Åland islands, we tested the effects of fragmentation on genetic diversity using a landscape‐based approach and 2610 individuals genotyped at 40 neutral SNP markers. We assessed the independent effect of habitat amount and fragmentation (i.e., number of patches, habitat aggregation) within the local landscape on focal patch genetic diversity. The amount of habitat in the local landscape had a positive effect on genetic diversity. Fragmentation measured as the number of patches within the landscape had a negligible impact on genetic diversity, whereas habitat aggregation had a negative effect on genetic diversity when the available amount of habitat in the landscape was low. Focal patch size increased genetic diversity, whereas focal patch structural connectivity had no impact. Our results highlight that all fragments are important to contribute to the total amount of habitat available, and that the impact of habitat fragmentation matters more when the total amount of habitat available is low.

The Western conifer seed bug, Leptoglossus occidentalis, is native to North America and has already been considered a significant pest in several European countries since its first observation in Italy in 1999. In Spain and Portugal, it was recorded for the first time in 2003 and 2010, respectively, and its impact on Stone Pine (Pinus pinea) is of major concern. Before developing control measures for this insect pest, it is paramount to clarify its spatiotemporal dynamics of invasion. Therefore, in this study, we aimed to (a) characterise the genetic structure and diversity and (b) invasion pathways of L. occidentalis populations in the Iberian Peninsula. To do so, specimens of L. occidentalis were collected at fourteen sites widely distributed within the Iberian Peninsula. We used mtDNA sequences of Cytochrome b and eleven microsatellite markers to characterise the genetic diversity and the population structure in the Iberian Peninsula. Our genetic results combined with the observational dates strongly support a stratified expansion of L. occidentalis invasion in the Iberian Peninsula proceeding from multiple introductions, including at least one in Barcelona, one in Valencia, and one in the west coast or in the Southeastern region.