抗吡虫啉棉蚜种群对啶虫脒和噻虫胺的交互抗性及相关酶学机理

【目的】通过对乙酰胆碱受体β1亚基突变后的抗吡虫啉棉蚜Aphis gossypii (Glover)种群的继续筛选, 明确该种群的抗性发展规律以及对其他新烟碱类杀虫剂啶虫脒和噻虫胺的交互抗性及相关酶学机理。【方法】采用浸渍法连续对抗吡虫啉棉蚜进行室内筛选、 测定噻虫胺和啶虫脒对抗吡虫啉棉蚜种群的毒力; 选择LC₂₀剂量吡虫啉、 啶虫脒和噻虫胺处理抗性棉蚜, 采用生化分析法测定其体内羧酸酯酶、 谷胱甘肽-S-转移酶和乙酰胆碱酯酶的活性变化, 并观察其生物学特性的变化。【结果】本研究对抗性棉蚜突变种群用吡虫啉继续筛选至75代, 抗性倍数达到72.6倍, RF75停止用药筛选12代（RF₇₅₊₁₂）, 抗性仍达72.0倍。且RF₇₅₊₁₂对噻虫胺和啶虫脒的交互抗性可分别达11.9倍和20.1倍。噻虫胺对抗吡虫啉棉蚜的蜜露分泌和体重的抑制作用均大于吡虫啉和啶虫脒。噻虫胺对RF₇₅₊₁₂的羧酸酯酶、 谷胱甘肽-S-转移酶和乙酰胆碱酯酶均具有明显的抑制作用, 而啶虫脒的抑制作用较小。【结论】结果表明乙酰胆碱受体基因突变棉蚜种群对吡虫啉的抗性水平不仅升高, 且停止用药后其抗性可稳定遗传; 第二代新烟碱类的噻虫胺在抗吡虫啉棉蚜靶标突变种群的治理中具有较大的应用价值。     

抗吡虫啉棉蚜种群对吡蚜酮等药剂的交互抗性及施药对其生物学特性的影响

为了明确吡蚜酮对抗吡虫啉棉蚜Aphis gossypii种群的防治效果,提出抗吡虫啉棉蚜的治理策略,利用抗吡虫啉棉蚜种群(RF₂₇)、敏感种群(SS)和夏津田间种群(XJ),分别采用浸渍法、微量点滴法、生化测定法和系统观察法研究了棉蚜无翅成蚜对吡蚜酮等药剂的交互抗性及施药对其生物学特性的影响。结果表明: 吡蚜酮对RF₂₇,XJ和SS的LD₅₀分别为1.213×10^-5,8.506×10^-5和5.140×10^-5 μg/头,RF₂₇对吡蚜酮表现出明显的负交互抗性现象。RF₂₇对啶虫脒、烯啶虫胺和噻嗪酮分别产生2.35,2.98和1.71倍的抗性。RF₂₇的羧酸酯酶和谷胱甘肽-S-转移酶的比活力较SS分别高2.73和1.57倍,说明羧酸酯酶和谷胱甘肽-S-转移酶比活力的提高是引起棉蚜对吡虫啉产生抗性的重要原因之一。吡蚜酮分别处理RF₂₇,XJ和SS,其羧酸酯酶和谷胱甘肽-S-转移酶均受到显著抑制。吡蚜酮以低剂量处理RF₂₇成蚜,对其生长发育有显著的不利影响,表现为若蚜存活率降低(64.60%),净生殖率降低（10.39）,内禀增长率和周限增长率显著降低(分别为0.21和1.23),世代历期延长（10.87 d）,相对适合度较小（仅为0.70）。这些结果表明吡蚜酮在棉蚜防治中具有很高的应用价值。     

棉蚜啶虫脒抗性种群交互抗性和增效剂增效作用的研究

【目的】明确棉蚜Aphis gossypii Glover啶虫脒抗性品系与其它杀虫剂的交互抗性现状以及增效剂的增效作用,为延缓和治理棉蚜对啶虫脒的抗性提供依据。【方法】采用单头反选育和群体汰选的方式,获得了棉蚜啶虫脒敏感和抗性品系;采用叶片药膜法测定了13种杀虫剂对啶虫脒的交互抗性以及增效剂对啶虫脒的增效作用。【结果】经过室内棉蚜敏感和抗性品系的筛选,获得了相对抗性倍数为82.33倍的棉蚜啶虫脒抗性品系。棉蚜啶虫脒抗性品系的交互抗性谱的研究表明,交互抗性倍数小于5的药剂为:吡蚜酮,甲基阿维菌素;交互抗性倍数在5~10倍的药剂为:噻虫嗪,联苯菊酯,毒死蜱,马拉硫磷,丙溴磷,辛硫磷;交互抗性倍数在10~15倍的药剂为:硫丹,阿维菌素,高效氯氰菊酯,三唑磷,氧化乐果;交互抗性倍数大于1 5倍的药剂为:吡虫啉。增效剂实验表明,TPP和PBO在啶虫脒敏感品系中增效作用不明显,但在抗性品系中增效作用显著。在啶虫脒抗性品系中的增效比为1.77、1.61,在啶虫脒敏感品系中的增效比为1.02、1.03。DEM在啶虫脒抗性、敏感品系中的增效作用均不明显,增效比为1.04、1.02。TPP和PBO对啶虫脒有很好的增效作用。以室内棉蚜敏感品系(LC_(50)为0.180 mg/L)为基础,对新疆各主要棉区的棉蚜种群进行了啶虫脒药剂的抗性调查,结果表明新疆各主要棉区棉蚜对啶虫脒的相对抗性倍数为6.1~22.0倍。【结论】由此说明新疆主要棉区棉蚜对啶虫脒具有一定的抗性风险,生产中可以利用无交互抗性的吡蚜酮和甲基阿维菌素来治理抗性棉蚜种群。     

我国棉花主产区棉蚜对吡虫啉的抗性监测及抗性机理

【目的】由于生长周期短、繁殖率高,棉蚜Aphis gossypii容易对杀虫剂产生抗药性。本研究旨在明确我国棉花主产区棉蚜对吡虫啉的抗性水平及抗性机理。【方法】采用浸叶法测定了北京海淀,河北廊坊和邯郸,山东德州,河南许昌,以及新疆奎屯和阿克苏地区棉蚜对吡虫啉的抗性水平;测定了不同种群棉蚜3种解毒酶（多功能氧化酶、羧酸酯酶、谷胱甘肽S-转移酶）及乙酰胆碱酯酶的活性;并对靶标基因烟碱型乙酰胆碱受体（nAChR）β1亚基基因进行了突变检测。【结果】北京海淀、河南许昌和河北邯郸的棉蚜对吡虫啉敏感;河北廊坊、新疆阿克苏、山东德州及新疆奎屯地区的棉蚜对吡虫啉的抗性倍数(resistance ratio, RR)分别为22.6, 26.3,53.5和61.1倍,为中等水平抗性。酶活力对比研究发现,阿克苏和奎屯地区的棉蚜多功能氧化酶的比活力分别是敏感种群(北京种群)的1.7和1.8倍,羧酸酯酶的比活力分别是敏感种群的1.6和1.7倍,谷胱甘肽S-转移酶的比活力均是敏感种群的1.5倍,但是乙酰胆碱酯酶比活力在棉蚜种群间差异不显著。靶标基因突变检测表明,河北廊坊、新疆阿克苏、山东德州及新疆奎屯棉蚜种群nAChR β1亚基均存在与吡虫啉抗性相关的精氨酸到苏氨酸（R81T）突变。【结论】结果提示,多功能氧化酶、羧酸酯酶和谷胱甘肽S-转移酶活力升高以及nAChR β1亚基R81T突变与棉蚜对吡虫啉的抗性形成相关。     

棉蚜对有机磷杀虫剂抗性的生化机理

本文对有机磷抗性和感性棉蚜Aphis gossypii三个种群抗性生化机制进行了讲究.首先用解毒酶的抑制剂测定药剂的解毒途径.进一步测定乙酰胆碱酯酶活力及其敏感性和多功能氧化酶、谷胱甘肽s-转移酶、α-乙酸萘酯酶和α-乙酸萘酯羧酸酯酶等解毒酶的活力.结果表明,体内条件下,多功能氧化酶与抗性有关,但在离体条件下,在棉蚜匀浆液中有内源抑制剂存在.α-乙酸萘酯酶和α-乙酸萘酯羧酸酯酶活力的增加,乙酰胆碱酯酶对杀虫剂敏感性的降低也是造成棉蚜对有机磷产生抗性的原因.     

棉蚜抗吡虫啉品系和敏感品系主要解毒酶活性比较

通过生物测定和生物化学方法比较了棉蚜 Aphis gossypii 对吡虫啉抗性（约为7倍）和敏感品系几种主要解毒酶的活性。结果表明：氧化胡椒基丁醚对两个品系均无明显增效作用。抗性品系中羧酸酯酶和谷胱甘肽S-转移酶的比活力均明显高于敏感品系,抗性品系中羧酸酯酶的K_m值也显著高于敏感品系,说明抗性品系羧酸酯酶与底物的亲和力明显高于敏感品系。上述结果证明羧酸酯酶和谷胱甘肽S-转移酶活力增强在棉蚜对吡虫啉的抗性中起重要作用。     

广东稻区褐飞虱对烯啶虫胺和呋虫胺的敏感性测定

为了科学用药和抗性治理提供理论依据,在室内采用稻茎浸渍法测定了采自广东省广州、南雄、雷州、连州、海丰、怀集和大埔等7个地方田间褐飞虱种群对烯啶虫胺、呋虫胺的敏感性。试验结果表明:广东地区褐飞虱种群对烯啶虫胺的敏感性LC_(50)值为2.3187-7.1489mg/L,抗性倍数分别为4.93-15.21倍,南雄地区褐飞虱种群对烯啶虫胺仍处于敏感阶段;广州、海丰和雷州等3个地区褐飞虱对烯啶虫胺已产生低水平抗性,大埔、连州和怀集等3个地方褐飞虱已对烯啶虫胺产生中等水平抗性。广东地区褐飞虱种群对呋虫胺的敏感性LC_(50)值为3.6696-11.8093 mg/L,抗性倍数为26.21-84.35倍,表明广东省不同地区褐飞虱种群对呋虫胺均产生中等水平抗性。建议在防治褐飞虱时,对于低水平抗性的烯啶虫胺应轮用、混用,对中等水平抗性的呋虫胺应限制使用。     

西花蓟马抗辛硫磷种群的抗性机制及交互抗性

为明确西花蓟马对辛硫磷的抗性风险,研究了西花蓟马抗辛硫磷种群对其他杀虫剂的交互抗性及其对辛硫磷的抗性机制.交互抗性测定结果表明,西花蓟马抗辛硫磷种群对辛硫磷与毒死蜱、高效氯氟氰菊酯和灭多威存在中等水平的交互抗性,对溴虫腈、吡虫啉、甲维盐和多杀菌素存在低水平交互抗性,对啶虫脒和阿维菌素不存在交互抗性.酶抑制剂与辛硫磷的增效剂测定结果表明,胡椒基丁醚(PBO)、三丁基三硫磷酸酯(DEF)和磷酸三苯酯(TPP)对西花蓟马抗辛硫磷种群(XK)、田间种群(BJ)和敏感种群(S)均起到了显著的增效作用(P＜0.05),马来酸二乙酯对西花蓟马抗辛硫磷种群和敏感种群增效作用均不显著,但对田间种群增效作用显著(P＜0.05).生化测定发现:除田间种群西花蓟马乙酰胆碱酯酶活性提高不显著外,西花蓟马抗辛硫磷种群和田间种群的细胞色素P450含量(2.79和1.48倍)、细胞色素b5含量(2.88和1.88倍)及O-脱甲基酶活性(2.60和1.68倍)、羧酸酯酶活性(2.02和1.61倍)和乙酰胆碱酯酶活性(3.10倍)均显著高于敏感种群(P＜0.05);谷胱甘肽-S-转移酶酶活性也有一定程度提高(1.11和1.20倍),但不显著(P＞0.05).表明其体内解毒代谢酶和靶标酶活性提高是西花蓟马对辛硫磷产生抗性的重要原因.     

西花蓟马对烯啶虫胺、噻虫胺和噻虫嗪的抗性风险和抗性稳定性

为明确使用新烟碱类杀虫剂烯啶虫胺、噻虫胺和噻虫嗪防治入侵害虫西花蓟马的抗性风险及抗性稳定性,本研究采用芸豆浸药法对西花蓟马敏感种群初羽化雌成虫进行连续筛选获得抗性种群,根据抗性现实遗传力计算公式分析西花蓟马对上述3种杀虫剂的抗性风险,预测其抗性发展速度,并测定抗性稳定性。结果表明: 经过30代抗性筛选,西花蓟马对烯啶虫胺、噻虫胺和噻虫嗪均达到高水平抗性(44.7、45.5和32.7倍)。西花蓟马对噻虫胺、烯啶虫胺和噻虫嗪的抗性发展速度依次降低,抗性现实遗传力分别为0.1503、0.1336和0.1258。对抗性种群在无选择压力下继续饲养10代,西花蓟马对烯啶虫胺、噻虫胺和噻虫嗪的抗性水平均出现一定程度的下降,但均未能恢复到敏感性水平。抗性选育后,西花蓟马若虫与成虫对杀虫剂的敏感性差异显著缩小,西花蓟马敏感种群及抗性种群若虫对上述3种杀虫剂的敏感性显著高于成虫。西花蓟马对烯啶虫胺、噻虫胺和噻虫嗪均存在高抗风险,噻虫嗪的抗性上升速度较慢且抗性稳定性最低。因此,在西花蓟马若虫期使用噻虫嗪有利于西花蓟马防治。     

西花蓟马抗噻虫胺种群对杀虫剂的交互抗性及机制

噻虫胺是具有内吸和触杀等多种作用方式的新烟碱类杀虫剂,常用于防治入侵害虫西花蓟马。为明确抗性风险,本文研究了西花蓟马抗噻虫胺种群对多种杀虫剂的交互抗性及其机制。经过45代筛选,西花蓟马对噻虫胺产生了高水平抗性(56.8倍)。生物测定结果表明: 西花蓟马高抗噻虫胺种群与噻虫嗪、吡虫啉、毒死蜱、三氟氯氰菊酯、甲维盐存在中等水平交互抗性(18.6>RR₅₀>11.3),对辛硫磷及灭多威具有低水平交互抗性,与溴虫腈和多杀菌素不存在交互抗性。胡椒基丁醚(PBO)与磷酸三苯酯(TPP)对杀灭西花蓟马抗噻虫胺种群(CL)、云南田间种群(YN)和敏感种群(S)均有显著增效作用。西花蓟马抗噻虫胺种群细胞色素P₄₅₀含量(3.6倍)、细胞色素b₅含量(2.9倍)及O-脱甲基酶活性(4.9倍)和羧酸酯酶活性(2.5倍)均显著高于敏感种群,表明多功能氧化酶及羧酸酯酶活性增强是西花蓟马对噻虫胺产生抗性的重要机制。     

Assessment of cross-resistance potential to neonicotinoid insecticides in Bemisia tabaci (Hemiptera: Aleyrodidae)

Laboratory bioassays were carried out with four neonicotinoid insecticides on multiple strains of Bemisia tabaci (Gennadius) to evaluate resistance and cross-resistance patterns. Three imidacloprid-resistant strains and field populations from three different locations in the southwestern USA were compared in systemic uptake bioassays with acetamiprid, dinotefuran, imidacloprid and thiamethoxam. An imidacloprid-resistant strain (IM-R) with 120-fold resistance originally collected from Imperial Valley, California, did not show cross-resistance to acetamiprid, dinotefuran or thiamethoxam. The Guatemala-resistant strain (GU-R) that was also highly resistant to imidacloprid (RR=109-fold) showed low levels of cross-resistance when bioassayed with acetamiprid and thiamethoxam. However, dinotefuran was more toxic than either imidacloprid or thiamethoxam to both IM-R and GU-R strains as indicated by low LC50s. By contrast, a Q-biotype Spanish-resistant strain (SQ-R) of B. tabaci highly resistant to imidacloprid demonstrated high cross-resistance to the two related neonicotinoids. Field populations from Imperial Valley (California), Maricopa and Yuma (Arizona), showed variable susceptibility to imidacloprid (LC50s ranging from 3.39 to 115 microg ml(-1)) but did not exhibit cross-resistance to the three neonicotinoids suggesting that all three compounds would be effective in managing whiteflies. Yuma populations were the most susceptible to imidacloprid. Dinotefuran was the most toxic of the four neonicotinoids against field populations. Although differences in binding at the target site and metabolic pathways may influence the variability in cross-resistance patterns among whitefly populations, comparison of whitefly responses from various geographic regions to the four neonicotinoids indicates the importance of ecological and operational factors on development of cross-resistance to the neonicotinoids.     

DDT resistance in Drosophila correlates with Cyp6g1 over-expression and confers cross-resistance to the neonicotinoid imidacloprid

Mutagenesis can be used as a means of predicting likely mechanisms of resistance to novel classes of insecticides. We used chemical mutagenesis in Drosophila to screen for mutants that had become resistant to imidacloprid, a neonicotinoid insecticide. Here we report the isolation of two new dominant imidacloprid-resistant mutants. By recombinational mapping we show that these map to the same location as Rst(2)DDT. Furthermore, we show that pre-existing Rst(2)DDT alleles in turn confer cross-resistance to imidacloprid. In order to localize the Rst(2)DDT gene more precisely, we mapped resistance to both DDT and imidacloprid with respect to P-element markers whose genomic location is known. By screening for recombinants between these P-elements and resistance we localized the gene between 48D5-6 and 48F3-6 on the polytene chromosome map. The genomic sequence in this interval shows a cluster of cytochrome P450 genes, one of which, Cyp6g1, is over-expressed in all resistant strains examined. We are now testing the hypothesis that resistance to both compounds is associated with over-expression of this P450 gene.     

Resistance of aphis gossypii (Homoptera: Aphididae) to fenvalerate and imidacloprid and activities of detoxification enzymes on cotton and cucumber

Resistance of two strains of cotton aphid, Aphis gossypii Glover, to fenvalerate and imidacloprid were determined on cotton (Gossypium hirsutum L.) and cucumber (Cucumis sativa L.) after resistance selection of one strain to fenvalerate for 16 consecutive generations, and of a second strain to imidacloprid for 12 consecutive generations on cotton in greenhouses. Dose-response and activities of detoxication enzymes of the fenvalerate-resistant strain (R-fenvalerate), the imidacloprid-resistant strain (R-imidacloprid), and a susceptible strain (S) were determined. After 16 consecutive generations of selection, resistance of A. gossypii to fenvalerate increased >29,000-fold and to imidacloprid 8.1-fold. On cucumber. resistance of the R-fenvalerate strain to fenvalerate increased 700-fold and to imidacloprid 3.6-fold. However, the most significant finding in this study was that the R-imidacloprid strain exhibited cross-resistance to fenvalerate, with a resistance ratio of 108.9-fold on cotton and 3:3.5-fold on cucumber, whereas the R-fenvalerate strain did not show significant cross-resistance to imidacloprid on either plant species. Both resistant strains of A. gossypii were more resistant to fenvalerate on cotton than on cucumber, whereas their susceptibility to imidacloprid on otton and cucumber were not significantly different. The response of the S strain to fenvalerate and imidacloprid were similar on cotton and Cucumber. Activities of acetylcholinesterase (AChE) and alpha-naphthylacetate (alpha-NA) esterases of A. gossypii were significantly different among the three strains, with the R-fenvalerate strains having the highest, followed by the R-imidacloprid strain, and the S strain the lowest. The activities of the AChE and alpha-NA esterases for all three strains were also significantly higher on cotton than on cucumber. The resistance mechanism and resistance management strategies for the R-fenvalerate and R-imidacloprid strains of A. gossypii to fenvalerate and imidacloprid on cotton and cucumber are discussed.     

Biorational insecticides: mechanism and cross-resistance

Potency and cross-resistance of various biorational insecticides, exemplified by the whitefly Bemisia tabaci, have been studied. Bemisia tabaci were exposed to the juvenile hormone mimic pyriproxyfen for the past 12 years resulting in an over 2,000-fold resistance, but there was no appreciable cross-resistance with the benzoylphenyl urea novaluron. Similarly, no cross-resistance was found between pyriproxyfen and the two neonicotinoids, acetamiprid and imidacloprid. On the other hand, a slight cross-resistance of 5-13-fold was observed with another neonicotinoid thiamethoxam. Among the neonicotinoids, a resistant strain of B. tabaci to thiamethoxam (approximately 100-fold) showed no appreciable cross-resistance to either acetamiprid or imidacloprid, while another strain 500-fold resistant to thiamethoxam resulted in a mild of 4-6-fold resistance to acetamiprid and imidacloprid. In other assays, B. tabaci strain resistant to thiamethoxam (approximately 100-fold) had no cross-resistance to pyriproxyfen. Our findings indicate that no appreciable cross-resistance was observed between the benzoylphenyl urea novaluron, the juvenile hormone mimic pyriproxyfen, and the neonicotinoids acetamiprid and imidacloprid. Hence, these compounds could be used as components in insecticide resistance management programs.     

Genetic diversity of the cotton aphid Aphis gossypii in the unstable environment of a cotton growing area

1 Spatial and temporal habitat heterogeneity represented by annual crops is a major factor influencing population dynamics of phytophagous insect pests such as the cotton aphid Aphis gossypii Glover. We studied the effects of instability of the cotton agroecosystem resulting from the temporary availability of the plant resource and the repeated use of insecticides on the genetic variability of the cotton aphids.
2 Samples of A. gossypii were collected in cotton plots, treated or not with insecticides and from vegetable crops (Malvaceae, Cucurbitaceae and Solanaceae) within the cotton growing area of northern Cameroon. The genetic structure of the samples was assessed using eight microsatellite markers. Insecticide resistance was estimated through the detection of two mutations in the ace -1 gene that are associated with insensitivity of acetylcholinesterase to carbamate and organophosphate insecticides.
3 The results obtained show that both host plants and insecticides act in genetic structuring of A. gossypii . Ninety-three percent of aphids collected on cotton were characterized by the same microsatellite multilocus genotype, Burk1 , which also displays the insecticide resistant alleles.
4 During the dry season, the cotton crop season after, the genotype Burk1 was principally found on two other malvaceous cultivated plants, rosella and okra, acting as suitable reservoir plants. The ability of the cotton aphid to move among asynchronous suitable habitats in response to changes in resource availability enables the pest to exploit unstable cropping systems. An understanding of the cotton aphid life system may aid to improve strategies for integrated resistance management.     

Resistance of insect pests to neonicotinoid insecticides: current status and future prospects

The first neonicotinoid insecticide introduced to the market was imidacloprid in 1991 followed by several others belonging to the same chemical class and with the same mode of action. The development of neonicotinoid insecticides has provided growers with invaluable new tools for managing some of the world's most destructive crop pests, primarily those of the order Hemiptera (aphids, whiteflies, and planthoppers) and Coleoptera (beetles), including species with a long history of resistance to earlier-used products. To date, neonicotinoids have proved relatively resilient to the development of resistance, especially when considering aphids such as Myzus persicae and Phorodon humuli. Although the susceptibility of M. persicae may vary up to 20-fold between populations, this does not appear to compromise the field performance of neonicotinoids. Stronger resistance has been confirmed in some populations of the whitefly, Bemisia tabaci, and the Colorado potato beetle, Leptinotarsa decemlineata. Resistance in B- and Q-type B. tabaci appears to be linked to enhanced oxidative detoxification of neonicotinoids due to overexpression of monooxygenases. No evidence for target-site resistance has been found in whiteflies, whereas the possibility of target-site resistance in L. decemlineata is being investigated further. Strategies to combat neonicotinoid resistance must take account of the cross-resistance characteristics of these mechanisms, the ecology of target pests on different host plants, and the implications of increasing diversification of the neonicotinoid market due to a continuing introduction of new molecules.     

八种新烟碱类杀虫剂对地熊蜂工蜂的毒性及风险评估

【目的】评价新烟碱类杀虫剂对地熊蜂Bombus terrestris工蜂的毒性和生态风险性,为温室施用新烟碱类杀虫剂提供科学依据。【方法】分别采用饲喂法和接触法测定了噻虫嗪、噻虫胺、啶虫脒、吡虫啉、烯啶虫胺、呋虫胺、噻虫啉和氟吡呋喃酮8种新烟碱类杀虫剂对地熊蜂成年工蜂的急性经口和急性接触毒性。同时评估了8种新烟碱类杀虫剂对地熊蜂工蜂的生态风险性。【结果】8种杀虫剂经饲喂法测定,噻虫胺对地熊蜂成年工蜂的毒性最高,24 h和48 h的LD 50值分别为0.0433和0.0330μg a.i./蜂;氟吡呋喃酮毒性最低,24 h和48 h的LD 50值分别为72.4119和67.9079μg a.i./蜂。接触法测定的毒性与饲喂法测得的结果一致,噻虫胺的毒性最高,24 h和48 h的LD 50值分别为0.0220和0.0192μg a.i./蜂;氟吡呋喃酮的毒性最低,24 h和48 h的LD 50值分别为141.7641和130.3062μg a.i./蜂。生态风险评估表明,啶虫脒、噻虫啉和氟吡呋喃酮对地熊蜂成年工蜂的经口毒性和接触毒性均表现为低风险,吡虫啉、烯啶虫胺和呋虫胺的毒性表现为中等风险。噻虫嗪和噻虫胺对地熊蜂成年工蜂的经口毒性表现为中等风险,而接触毒性则表现为高风险。【结论】检测的8种新烟碱类杀虫剂中啶虫脒、噻虫啉与氟吡呋喃酮对地熊蜂成年工蜂的毒性为低毒,而噻虫嗪、噻虫胺、吡虫啉、烯啶虫胺、呋虫胺这5种杀虫剂均为高毒。在设施蔬菜花期使用地熊蜂授粉时,建议禁用这5种中、高风险的新烟碱类杀虫剂,以避免对熊蜂授粉的危害,而另3种低风险药剂可根据田间试验情况合理施用。     

可降解新烟碱类杀虫剂微生物及其代谢途径的研究进展

新烟碱类化合物基于烟碱结构改造修饰制备,相较菊酯、含磷类等杀虫剂,因其选择性毒力被认为是一类对人类和生态无害的农药。然而,近年来由于新烟碱类杀虫剂(neonicotinoid insecticides)过度施用,其残余或转化的物质通过在土壤与水体中累积,影响昆虫甚至哺乳动物及其生理与行为,导致了一系列生态环境问题和继发危害。本文聚焦新烟碱类杀虫剂的产业现状,面向生物降解新烟碱类杀虫剂这一迫切需求,围绕新烟碱类杀虫剂的微生物菌株资源,重点阐述微生物降解新烟碱类杀虫剂的代谢机制及其多样性。通过梳理新烟碱类杀虫剂生物降解及其应用转化的关键问题和前沿进展,旨在为借助合成生物学和宏基因组学手段建立或筛选安全可控的新烟碱类杀虫剂的高效转化体系提供参考。