张蕊 张东霞 朱兴秋 郑卫锋 李娅 郭艳琼 庾琴 摘 要：【目的】明確阿维菌素致死中浓度（LC50）连续处理对梨小食心虫（Grapholita molesta）的抗性风险及其交互抗性。【方法】在室内条件下，采用浸果法测定阿维菌素对梨小食心虫田间种群（F）初孵幼虫的LC50值；以F种群为基础，建立梨小食心虫对阿维菌素相对敏感品系（SS）、F种群连续6代接触LC50浓度阿维菌素的田间抗性品系（FR）和6代未接触阿维菌素的田间对照品系（FS），测定阿维菌素对不同品系梨小食心虫初孵幼虫的毒力，计算其抗性水平；测定高效氯氟氰菊酯、吡虫啉和氯虫苯甲酰胺对不同品系的毒 力，分析不同品系与其交互抗性。【结果】，敏感性降低；阿维菌素致死中浓度汰选2代后，梨小食心虫对阿维菌素抗性为低水平，汰选4代后升至中等水平，；未接触阿维菌素的梨小食心虫从第4代降为敏感，第6代时敏感性进一步恢复。抗性品系抗性现实遗传力h2=，在致死率50%～90%选择压力下，梨小食心虫对阿维菌素抗性增加10倍，预计需汰选4～9代。，有交互抗性；对吡虫啉和氯虫苯甲酰胺无交互抗性。对照品系对高效氯氟氰菊酯、吡虫啉和氯虫苯甲酰胺均无交互抗性。【结论】梨小食心虫对阿维菌素存在快速产生抗性的风险，中抗品系与高效氯氟氰菊酯有交互抗性，低敏感品系与3种药剂均无交互抗性。田间使用阿维菌素时可通过间隔用药或与无交互抗性药剂轮换使用来减缓抗性发展。 Key：梨小食心虫；阿维菌素；初孵幼虫；抗性风险评估；交互抗性 ：； 文献标志码：A ：1009-9980（2024）03-0525-08 Resistance risk assessment and the cross-resistance of Grapholita molesta to avermectin ZHANG Rui1， ZHANG Dongxia2， ZHU Xingqiu1， ZHENG Weifeng2， LI Ya1， GUO Yanqiong1， YU Qin1* （1College of Plant Protection， Shanxi Agricultural University， Taiyuan 030031， Shanxi， China; 2Shanxi Provincial Plant Protection and Quarantine Station， Taiyuan 030801， Shanxi， China） Abstract： 【Objective】 Grapholita molesta is a major pest of many kinds of fruit crops in the world and China. Due to its characteristics of boring， hiding and generations overlapping， G. molesta is difficult to control. With the climate warming， and the change of cultivation mode and management technology in pear orchards， the damage of G. molesta has been increasing year by year in several major fruit species in China， including peaches， pears and apples. Currently， chemical pesticides are still one of the most effective measure to control G. molesta. Long-term frequent and non-standard use of pesticides has led to a gradual decline in the effectiveness of chemical control to G. molesta， and G. molesta has developed varying degrees of resistance to some pesticides in pear orchards. Avermectin， a high efficiency and low toxicity pesticide used in pear orchards frequently， was used for 5-7 times in a year to control many kinds of pests， such as G. molesta， Aphis citricola Van der Goot， Tetranychus viennensis Zacher， and so on. Over the past 20 years， the application concentration of avermectin has increased by 40 times in pear orchards due to its high dose and exceessive usage times. Studies on avermectin mainly focus on its toxicity， control efficacy， management and efficience in pear orchards. The change patterns of resistance and sensitiveness were studied with lethal concentration of 50% of avermectin to G. molesta in this paper. By studying the resistance and sensitivity changes， it is expected to obtain change patterns of resistance， development speed， resistance heritability of G. molesta to avermectin， and its interaction resistance with other pesticides that were also used in pear orchards， such as imidacloprid， chlorphenicol benzamide， lambda-cyhalothrin and so on. The objective of this experiment was to obtain theoretical basis for reasonable use avermectin to delay the development of its resistance in pear orchards. 【Methods】 In order to measure control efficiency of avermectin to G. molesta neonate larvae， the survival rate and damage rate of G. molesta neonate larvae were measured with fruitlets as the sample. The G. molesta neonate larvae and larvae were fed in an artificial intelligence incubator under the following conditions： （25±1） ℃， 70%-80% relative humidity， 3000-4000 lx illumination and 15 h//9 h （L/D） photoperiod. The test agent was % avermectin， % Lambda-cyhalothrin， 96% imidacloprid and 96% chlorantraniliprole. Fruit dipping method was used to measure the resistance development of G. molesta to avermectin. These methods included： （1） the young fruits of apple with same variety， consistent size， and good appearance were wash with pure water， dried in air， and soaked in the pesticide solution for 10 seconds. （2） The young fruits were taken out from pesticide solution， excessive pesticide solution was absorbed with a filter paper， and they were placed on a plastic container with a wet filter paper and a lid at the bottom. （3） The paper containing 50 G. molesta ready-to-hatch eggs was placed on the young fruit gently， then the egg was managed to contact the fruit， and the relative humidity in the container was maintained above 90%. （4） Tween-80 aqueous solution with a mass fraction of % was taken as the control. Each process was repeated for three times. （5） The survival rate of G. molesta neonate larvae was surveyed in 78 h after laying eggs. Survey method was determined by observing carefully pest morphological characteristic and damage symptoms of G. molesta neonate larvae on apple and damage rate in 78 h. According to mortality of G. molesta neonate larvae， the toxicity equation and LC50 were calculated with SPPS. Two strains of G. molesta neonate larvae were obtained from field populations， which were resistance-selection by LC50 of avermectin. The field population was collected from pear orchards in Yanhu District， Yuncheng City， Shanxi province in 2022. Two strains were field resistant strain and field control strain. Field resistant strain was selected with LC50 of avermectin， and the toxicity of earlier generation of G. molesta neonate larvae was measured for six times. Field control strain was fed with apples， which were not touched by any pesticides. The comparative strain G. molesta was susceptible strain that was reared 100 generations continuously in the lab. The toxicity of different strains of G. molesta was measured in 2 generations， 4 generations and 6 generations， respectively. The resistance ratio （RR） and sensitivity level of different strains G. molesta were calculated with resistance multiple formulas. In order to obtain cross-resistance of different strains of G. molesta， Lambda-cyhalothrin， imidacloprid and chlorflubenzamide that were used frequently in pear orchards were selected to assess the cross-resistance to field resistant strain and field control strain of G. molesta. Experimental data were analyzed with Duncans new multiple range test （p＜）. 【Results】 The LC50 of avermectin of field population of G. molesta was mg·L-1， and its resistance ratio was times higher than the susceptible strain， with low sensitivity. The resistance level of field population selected with LC50 avermectin at second generation was up to low resistance from low sensitivity. The LC50 of field population increased continuously with the increase of selection generations when the resistance ratios were and times at fourth generation and sixth generation respectively， which increased to the medium resistance level. The sensitivity of the field population without exposure to avermectin increased gradually. The resistance ratio of the field population decreased to times at fourth generations， which was sensitivity. The toxicity of the field population of G. molesta without exposure to avermectin decreased from first generation to sixth generation and its sensitivity was further improved. The results also showed that the continuous use of avermectin in field populations of G. molesta caused a rapid increase in the level of resistance to avermectin. The sensitivity of strains of G. molesta without continued exposure to avermectin increased sensitivity to avermectin. The field population of G. molesta was selected with LC50 avermectin for 6 generations， and its actual heritability of resistance was h2 = . The actual heritability of F0-F2 and F4-F6 selection stage was and ， respectively. In the case of resistance heritability of ， the resistance of G. molesta to avermectin increased by 10 times in about 4-9 generations. The resistance ratio of the 6th generation resistant strain of G. molesta to lambda-cyhalothrin was ， which was a cross-resistance between them. The resistance ratio to chlorantraniliprole was ， and its resistance ratio also increased. The resistance ratio to imidacloprid was with no cross-resistance. The resistance ratios of the field population control strain to lambda-cyhalothrin， imidacloprid and chlorantraniliprole were ， and ， respectively， and there was no cross-resistance among them. 【Conclusion】 G. molesta could develop resistance to avermectin rapidly. The low-sensitive field population of G. molesta could decrease sensitiveness with no exposure to avermectin. The medium-resistant strain had cross-resistance to lambda-cyhalothrin， and the low-sensitive strain had no cross-resistance to lambda-cyhalothrin， imidacloprid and chlorantraniliprole. The development of resistance of G. molesta to avermectin can be slowed down by interval medication or rotative application of avermectin and its non-cross-resistance pesticides in pear orchards. Therefore， avermectin should be used in pear orchards with an interval， and growers should reduce or limit the use frequency of lambda-cyhalothrin and chlorantraniliprole to avoid or delay the emergence and development of resistance， and ensure the control efficacy of avermectin and other pesticides， which were used in pear orchards frequently. Key words： Grapholita molesta; Avermectin; Neonate larvae; Resistance risk assessment; Cross-resistance 梨小食心虫（Grapholita molesta）为世界和中国重大果树害虫，因其钻蛀性、隐蔽性、世代重叠严重等特点，其防治较为困难[1-3]。目前梨小食心虫多采用化学药剂防控，药剂主要包括阿维菌素、氯虫苯甲酰胺、高效氯氟氰菊酯、毒死蜱等，化学药剂长期频繁不规范使用已导致害虫产生了不同程度的抗性[4]，其化学防治效果逐年下降[5-6]，阿维菌素为生物源类杀虫剂，生产上主要用于防治多种害虫[7-9]。因其杀虫活性强、杀虫谱广，在梨园中常用于防治梨小食心虫、梨木虱、黄粉蚜和山楂叶螨等多种害虫[10-12]，年使用次数
