Transcriptome analysis reveals gene expression differences in Liriomyza trifolii exposed to combined heat and abamectin exposure

The development of abamectin resistance in Liriomyza trifolii and its contribution to thermotolerance

BACKGROUND

Liriomyza trifolii is an economically significant, invasive pest of horticultural and vegetable crops. The larvae form tunnels in foliage and hasten senescence and death. Outbreaks of L. trifolii often erupt in hot weather and are driven by thermotolerance; furthermore, the poor effectiveness of pesticides has made outbreaks more severe. But it is still unclear whether the development of insecticide tolerance will contribute to thermotolerance in L. trifolii.

RESULTS

To explore potential synergistic relationships between insecticide exposure and thermotolerance in L. trifolii, we first generated an abamectin-resistant (AB-R) strain. Knockdown behavior, eclosion and survival rates, and expression levels of genes encoding heat shock proteins (Hsps) in L. trifolii were then examined in AB-R and abamectin-susceptible (AB-S) strains. Our results demonstrated that long-term selection pressure for abamectin resistance made L. trifolii more prone to develop cross-resistance to other insecticides containing similar ingredients. Furthermore, the AB-R strain exhibited enhanced thermotolerance and possessed an elevated critical thermal maximum temperature, and upregulated expression levels of Hsps during heat stress.

CONCLUSION

Collectively, our results indicate that thermal adaptation in L. trifolii was accompanied by emerging abamectin resistance. This study provides a theoretical basis for investigating the synergistic or cross-adaptive mechanisms that insects use to cope with adversity and demonstrates the complexity of insect adaptation to environmental and chemical stress. © 2023 Society of Chemical Industry.

Effects of common artificial sweeteners at environmentally relevant concentrations on soil springtails and their gut microbiota

Artificial sweeteners (AS) are extensively utilized as sugar substitutes and have been recognized as emerging environmental contaminants. While the effect of AS on aquatic organisms has garnered recent attention, their effects on soil invertebrates and gut microbial communities remain unclear. To address this knowledge gap, we exposed springtails (Folsomia candida) to both single and combined treatments of four typical AS (sucralose [SUC], saccharin [SAC], cyclamate [CYC], and acesulfame [ACE]) at environmentally relevant concentrations of 0.01, 0.1 and 1 mg kg-1 in soil. Following the first-generational exposure, the reproduction of juveniles showed a significant increase under all the AS treatments of 0.1 mg kg-1. The transcriptomic analysis revealed significant enrichment of several Kyoto Encyclopedia of Gene and Genome pathways (e.g., glycolysis/gluconeogenesis, pentose and glucuronate interconversions, amino sugar, and nucleotide sugar metabolism, ribosome, and lysosome) in springtails under all AS treatments. Analysis of gut bacterial microbiota indicated that three AS (SUC, CYC, and ACE) significantly decreased alpha diversity, and all AS treatments increased the abundance of the genus Achromobacter. After the sixth-generational exposure to CYC, weight increased, but reproduction was inhibited. The pathways that changed significantly (e.g., extracellular matrix-receptor interaction, amino sugar and nucleotide sugar metabolism, lysosome) were generally similar to those altered in first-generational exposure, but with opposite regulation directions. Furthermore, the effect on the alpha diversity of gut microbiota was contrary to that after first-generational exposure, and more noticeable disturbances in microbiota composition were observed. These findings underscore the ecological risk of AS in soils and improve our understanding of the toxicity effects of AS on living organisms.

Cross-protection interactions in insect pests: Implications for pest management in a changing climate

Agricultural insect pests display an exceptional ability to adapt quickly to natural and anthropogenic stressors. Emerging evidence suggests that frequent and varied sources of stress play an important role in driving protective physiological responses; therefore, intensively managed agroecosystems combined with climatic shifts might be an ideal crucible for stress adaptation. Cross-protection, where responses to one stressor offers protection against another type of stressor, has been well documented in many insect species, yet the molecular and epigenetic underpinnings that drive overlapping protective responses in insect pests remain unclear. In this perspective, we discuss cross-protection mechanisms and provide an argument for its potential role in increasing tolerance to a wide range of natural and anthropogenic stressors in agricultural insect pests. By drawing from existing literature on single and multiple stressor studies, we outline the processes that facilitate cross-protective interactions, including epigenetic modifications, which are understudied in insect stress responses. Finally, we discuss the implications of cross-protection for insect pest management, focusing on the consequences of cross-protection between insecticides and elevated temperatures associated with climate change. Given the multiple ways that insect pests are intensively managed in agroecosystems, we suggest that examining the role of multiple stressors can be important in understanding the wide adaptability of agricultural insect pests. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.