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

Abstract

BACKGROUNDLiriomyza 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 the thermotolerance in L. trifolii.RESULTSTo explore potential synergistic relationships between insecticide exposure and thermotolerance in L. trifolii, we firstly generated an abamectin‐resistant (AB‐R) strain. Then knockdown behavior, eclosion and survival rates and expression levels of genes encoding heat shock proteins (Hsps) in L. trifolii were examined in abamectin‐resistant (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.CONCLUSIONCollectively, our results indicate that thermal adaption 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.This article is protected by copyright. All rights reserved.

Life Table Study of Liriomyza trifolii and Its Contribution to Thermotolerance: Responding to Long-Term Selection Pressure for Abamectin Resistance

“…In the context of global warming, the negative effects of pesticides on insects might be reduced through thermal adaptation and increased degradation rates [ 24 , 25 , 26 ]. Our previous research supports the argument that L. trifolii displays adaptive cross-tolerance to insecticides and elevated temperatures, and the evolution of thermal adaption coincides with enhanced insecticide tolerance [ 20 ]. Heat shock proteins (HSPs) are stress-responsive proteins in insects that safeguard host proteins from diverse stressors, and their expression is modulated by thermal changes [ 27 , 28 ].…”

“…The abamectin-resistant derivative of L. trifolii (AB-R strain) used in this study was derived from the S strain, and the resistance ratio was 33.912-fold, as described previously [ 20 ]. The selection process for resistance was accomplished using 3% abamectin EC (Anhui Sida Pesticide Chemical Co., Ltd., Hefei, China).…”

“…The selection process for resistance was accomplished using 3% abamectin EC (Anhui Sida Pesticide Chemical Co., Ltd., Hefei, China). A leaf-dip method was developed to assay insecticide toxicity in L. trifolii larvae, as described before [ 20 ], and DPS version 9.01 software (DPS, Hangzhou, China) was used to calculate the median lethal concentrations (LC 50 ) with 95% confidence intervals (CIs). Bean leaves infested by 3-day-old larvae of L. trifolii were treated daily with the LC 50 dosage of abamectin until pupation.…”

“…The knockdown assessment of individuals was conducted in 24-well plexiglass plates placed in a customized incubator (JM-CXG-32, Jiangsu Jiamei Instrument Manufacturing Co., Ltd., Changzhou, China) equipped with a monitoring camera and a sensor for real-time temperature recording. Knockdown was declared when adult leafminers dropped from the interior walls to the well bottom and were unable to climb back up, irrespective of movement [ 20 ]. Each strain included 30 pairs of adults, with individuals showing no discernible behaviors being excluded from the analysis.…”

“…In response to different stresses, insects undergo self-optimization and adaptation, affecting various processes, such as metabolic rate, feeding, digestion, growth, assimilation, and development [ 18 , 19 ]. Previously, we developed a strain of L. trifolii resistant to abamectin (AB-R) [ 20 ], demonstrating that the species was prone to develop cross-resistance to other insecticides with similar ingredients, such as a 0.2% w / w microemulsion of abamectin + 19.8% monosultap (also known as ‘Banqianjing’). This targeted process of domestication may result in insects focusing on the development of a specific adaptive response, but this always comes with a fitness cost [ 21 ].…”