不同茶园灰茶尺蠖和茶尺蠖对5种杀虫剂的抗药性监测

为了明确茶园暴食性害虫灰茶尺蠖Ectropis grisescens和茶尺蠖E. obliqua抗药性现状，制定有效的防治措施，本研究采用浸叶法分别测定了5种茶园常用杀虫剂对5个地理种群灰茶尺蠖和2个地理种群茶尺蠖的抗药性。结果表明，不同茶园灰茶尺蠖和茶尺蠖对供试药剂的抗性水平存在差异：浙江兰溪、浙江金华、河南南阳地区的灰茶尺蠖种群和浙江杭州、浙江安吉的茶尺蠖种群对联苯菊酯产生了中高等抗性；浙江杭州的茶尺蠖种群对苦参碱的抗性达到中等水平，其余供试种群对苦参碱抗性处于敏感水平；所有供试种群对虫螨腈、甲氨基阿维菌素苯甲酸盐和茚虫威这3种药剂的抗性均处于敏感水平。从化学防治的角度来看，目前茶园灰茶尺蠖和茶尺蠖对虫螨腈、甲氨基阿维菌素苯甲酸盐和茚虫威敏感性高，抗性低，推荐合理科学使用，并避免长期使用单一农药。     

Evaluating the efficacy of insecticides to control Sceliodes cordalis (Doubleday) (Lepidoptera: Crambidae) in eggplant

The efficacy of insecticides in controlling Sceliodes cordalis , eggfruit caterpillar, in eggplant was tested in four small plot trials because there has been a very limited range of insecticides available to manage this pest. Weekly applications of bifenthrin, flubendiamide, methoxyfenozide, chlorantraniliprole and spinosad and twice weekly applications of methomyl provided control as measured by a percentage of damaged fruit significantly lower than that in an untreated control. Twice weekly applications of methoxyfenozide, chlorantraniliprole or spinosad were not significantly more effective than weekly applications. Bacillus thuringiensis kurstaki , emamectin benzoate, indoxacarb, methomyl and pyridalyl applied weekly were ineffective, with percentages of damaged fruit not significantly different from the untreated control. These trials have identified a number of insecticides that could be used to manage S. cordalis , including several that would be compatible with integrated pest management programs in eggplant.     

溴虫腈、茚虫威与氟啶脲混配对小菜蛾毒力最佳配比筛选及田间防效研究

为了延缓小菜蛾Plutella xylostella(L.)抗药性的产生和发展,本研究选用常用的3种化学杀虫剂,即氟啶脲、溴虫腈、茚虫威,采用交互测定法进行了最佳配比的筛选,并根据孙云沛法计算其共毒系数,最后筛选出具增效作用的混配配方,氟啶脲∶溴虫腈(有效成分含量为13.20∶1.72),共毒系数为241;氟啶脲∶茚虫威(有效成分含量为2.20∶3.60),共毒系数为142。田间试验结果表明氟啶脲与溴虫腈混配2000倍液药后7d校正防效为84.24%,与其他处理的校正防效具有极显著差异;氟啶脲与茚虫威混配1000倍液药后7d校正防效为85.08%,与其他处理的校正防效有显著性差异。     

Toxicity of seven termiticides on the formosan and eastern subterranean termites

Using both topical application and substrate (sand) treatments the toxicities of seven new generation soil termiticides were evaluated to determine the LD50 and LC50 against two economically important subterranean termite species, eastern subterranean termite, Reticulitermes flavipes (Kollar), and Formosan subterranean termite, Coptotermes formosanus Shiraki. The lethal dose toxicity (LD50) rankings for R. flavipes from highest to lowest were: fipronil > bifenthrin > chlorantraniliprole > cyantraniliprole > imidacloprid > chlorfenapyr > indoxacarb; the rankings for C. formosanus were fipronil > imidacloprid > chlorantraniliprole > cyanthraniliprole> bifenthrin > chlorfenapyr > indoxacarb. The respective lethal concentration toxicity (LC50) rankings were fipronil > bifenthrin > chlorfenapyr > indoxacarb > cyantraniliprole > chlorantraniliprole > imidacloprid for R. flavipes; and fipronil > chlorfenapyr > bifenthrin >imidacloprid > cyantraniliprole > chlorantraniliprole > indoxacarb for C. formosanus. The study provides an opportunity to directly compare toxicity, action speed, and bioavailability among this group of newer generation soil termiticides.     

氰氟虫腙对草地贪夜蛾的毒力与田间防效

【目的】本研究旨在明确氰氟虫腙对草地贪夜蛾Spodoptera frugiperda幼虫的毒力水平和田间防治效果,为科学使用氰氟虫腙防治草地贪夜蛾提供参考依据。【方法】采用饲料混毒法在室内测定了氰氟虫腙与4种常用杀虫剂甲维盐、氯虫苯甲酰胺、虱螨脲和茚虫威对草地贪夜蛾3和6龄幼虫的致死中浓度(LC₅₀)及LC₉₀值,以及LC₉₀浓度的这些杀虫剂对3龄幼虫的致死中时(medium lethal time, LT₅₀)值。采用人工喷雾方法测定了玉米田中22%氰氟虫腙悬浮剂(6.6 g/667 m²)、22%氰氟虫腙悬浮剂(17.6 g/667 m²)、5.7%甲维盐水分散剂(1 g/667 m²)和150 g/L茚虫威悬浮剂(2 g/667 m²)对草地贪夜蛾幼虫的防效。【结果】室内生测结果显示,供试的5种杀虫剂中氰氟虫腙对草地贪夜蛾3和6龄幼虫均具有较高的毒力,其LC₅₀值分别为2.64和4.3...     

Could resistance to insecticides in Plutella xylostella (Lep., Plutellidae) be overcome by insecticide mixtures?

Abstract: To investigate if synergism occurs between pyrethroids, organophosphates and new insecticides, we tested representatives of these compounds (bifenthrin, chlorpyrifos, spinosad, indoxacarb and emamectin) against the diamondback moth (Plutella xylostella). Larvicidal activity of these insecticides was assessed separately and together on a susceptible strain (Lab‐UK) of P. xylostella as well as a field population collected from Multan. The field population showed significant resistance to chlorpyrifos (331 100‐fold), bifenthrin (45 200‐fold), emamectin (1800‐fold), spinosad (11‐fold) and indoxacarb (5600‐fold) when compared with the Lab‐UK population. When insecticides were mixed based on LC₅₀ and tested at serial concentrations against Lab‐UK, significant synergy (CI < 1) occurred between bifenthrin, spinosad and emamectin. In contrast, the interaction between bifenthrin and indoxacarb was additive (CI = 1). The toxicity of bifenthrin against the field population increased significantly (P < 0.01) when combined with spinosad, emamectin and indoxacarb. Synergistic effects could be attributed to the complementary modes of action by these insecticide classes acting on different components of nerve impulse transmission (which are not identical for bifenthrin and indoxacarb either). However, chlorpyrifos/bifenthrin mixture was not significantly different either from bifenthrin or chlorpyrifos alone, indicating an additive affect. In combination with spinosad and emamectin, tested against the resistant field population, the toxicity of chlorpyrifos increased significantly and even more so with indoxacarb. Mixtures could also give rise to multiple resistance that may extend across other chemical classes and thus become difficult to manage. Therefore, alternative strategies such as mosaics or rotations should be considered. That is, though synergistic effects have been found, this should not be followed up as a strategy to manage resistant field populations.     

草地贪夜蛾幼虫对常用杀虫剂相对敏感基线的建立

【目的】本研究旨在建立草地贪夜蛾Spodoptera frugiperda对常用杀虫剂的相对敏感基线,为我国草地贪夜蛾的抗药性系统性监测提供依据。【方法】从玉米田采集草地贪夜蛾在室内不接触任何杀虫剂连续饲养5~7代,采用浸叶法和点滴法测定了草地贪夜蛾3龄幼虫以及采用饲料药膜法测定了草地贪夜蛾2龄幼虫对6大类共7种常用杀虫剂(甲维盐、乙基多杀菌素、虫螨腈、茚虫威、四氯虫酰胺、虱螨脲和氯虫苯甲酰胺)的敏感性,并据此建立了草地贪夜蛾幼虫对这7种杀虫剂的相对敏感基线。【结果】浸叶法测得上述7种药剂对草地贪夜蛾幼虫的LC₅₀值在0.054~12.131 mg/L之间;点滴法测得上述6种药剂(不含虱螨脲)对草地贪夜蛾幼虫的LD₅₀值在0.355~4.707 μg/g之间;饲料药膜法测得上述7种药剂对草地贪夜蛾幼虫的LC₅₀值在0.003~0.238 μg/cm²之间。【结论】采用3种生测方法建立了草地贪夜蛾幼虫对几种常用杀虫剂的相对敏感基线,为我国草地贪夜蛾的抗药性监测和化学防治提供了依据。     

Toxicity of seventeen insecticides to Camponotus sericeus (Hymenoptera: Formicidae)

The success of chemical control depends on toxicity of insecticides against insect pests. Camponotus sericeus is an important urban pest with the ability to cause substantial damage to wooden structures, but there is a lack of information on toxicity of insecticides against C. sericeus. To determine the insecticide toxicity, workers of C. sericeus were exposed to 17 insecticides from different classes: carbamate (methomyl, bendiocarb), organophosphate (chlorpyrifos, profenofos, temephos), pyrethroid (bifenthrin, deltamethrin, permethrin), neonicotinoid (acetamiprid, imidacloprid, thiamethoxam), avermectin (abamectin, emamectin), pyrrole (chlorfenapyr), phenylpyrazole (fipronil), and spinosyn (spinosad and spinetoram), via residual bioassay method. The LC₅₀ ranged from: 0.15 to 0.20 µg/vial for carbamates, 0.09 to 0.27 µg/vial for organophosphates, 0.09 to 0.44 µg/vial for pyrethroids, 0.02 to 0.67 µg/vial for neonicotinoids, 0.54 to 0.82 µg/vial for avermectins, 0.78 µg/vial for pyrrole, 0.62 µg/vial for phenylpyrazole, and 1.96 to 2.05 µg/vial for spinosyns. Overall, acetamiprid was the most toxic one among the tested insecticides followed by permethrin, temephos, profenofos, bendiocarb and methomyl, while spinosad and spinetoram were the least toxic insecticides. Considering the potential toxicity of different insecticides against C. sericeus, future studies could investigate the practical application of these insecticides in order to design an effective management plan.     

新疆和云南番茄潜叶蛾种群对六种杀虫剂的敏感性及其与解毒酶活性的关系

【目的】番茄潜叶蛾Tuta absoluta 是新入侵我国的对番茄具有毁灭性危害的入侵害虫,目前入侵我国的番茄潜叶蛾种群对杀虫剂的抗性尚无报道。本研究旨在明确新疆和云南番茄潜叶蛾田间种群对6种常用杀虫剂的敏感性及其与解毒酶活性的关系。【方法】采用浸叶法测定6种常用杀虫剂对番茄潜叶蛾新疆和云南种群2龄幼虫的室内毒力。通过对2龄幼虫的生物测定确定3种增效剂［CYP450抑制剂胡椒基丁醚(PBO)、酯酶抑制剂磷酸三苯酯(TPP)和GST抑制剂丁烯二酸二乙酯(DEM)］对氯虫苯甲酰胺的增效作用。采用酶活性分析测定室内敏感种群和田间抗性种群(新疆种群) 2龄幼虫体内解毒酶［细胞色素P450酶(CYP450)、谷胱甘肽S-转移酶(GST)和羧酸酯酶(CarE)］活性,以确定杀虫剂抗性与解毒酶活性的关系。【结果】番茄潜叶蛾云南种群对6种杀虫剂的敏感性由高到低依次为甲维盐、溴虫腈、多杀菌素、茚虫威、氯虫苯甲酰胺和高效氯氰菊酯。新疆种群对6种杀虫剂的敏感性由高到低依次为甲维盐、溴虫腈、氯虫苯甲酰胺、多杀菌素、茚虫威和高效氯氰菊酯。与室内敏感种群相比,云南和新疆种群对氯虫苯甲酰胺的抗性水平最高,抗性倍数分别为212.7和169.3倍。生物测定结果表明,3种增效剂PBO, TPP和DEM均对氯虫苯甲酰胺无明显增效作用。酶活性测定结果表明,番茄潜叶蛾室内敏感种群和田间抗性种群之间2龄幼虫中CYP450, GST和CarE活性无显著差异。【结论】番茄潜叶蛾新疆和云南种群对测试的6种杀虫剂产生不同程度的抗性,对氯虫苯甲酰胺的抗性最高,番茄潜叶蛾对杀虫剂的抗性与解毒酶活性无关。本研究的结果对番茄潜叶蛾的田间防治和杀虫剂抗性治理具有指导意义。     

Insecticide Mixtures Could Enhance the Toxicity of Insecticides in a Resistant Dairy Population of Musca domestica L

House flies, Musca domestica L., are important pests of dairy operations worldwide, with the ability to adapt wide range of environmental conditions. There are a number of insecticides used for their management, but development of resistance is a serious problem. Insecticide mixtures could enhance the toxicity of insecticides in resistant insect pests, thus resulting as a potential resistance management tool. The toxicity of bifenthrin, cypermethrin, deltamethrin, chlorpyrifos, profenofos, emamectin benzoate and fipronil were assessed separately, and in mixtures against house flies. A field-collected population was significantly resistant to all the insecticides under investigation when compared with a laboratory susceptible strain. Most of the insecticide mixtures like one pyrethroid with other compounds evaluated under two conditions (1∶1-“A” and LC₅₀: LC₅₀-“B”) significantly increased the toxicity of pyrethroids in the field population. Under both conditions, the combination indices of pyrethroids with other compounds, in most of the cases, were significantly below 1, suggesting synergism. The enzyme inhibitors, PBO and DEF, when used in combination with insecticides against the resistant population, toxicities of bifenthrin, cypermethrin, deltamethrin and emamectin were significantly increased, suggesting esterase and monooxygenase based resistance mechanism. The toxicities of bifenthrin, cypermethrin and deltamethrin in the resistant population of house flies could be enhanced by the combination with chlorpyrifos, profenofos, emamectin and fipronil. The findings of the present study might have practical significance for resistance management in house flies.     

斜纹夜蛾抗药性监测及茚虫威对其解毒代谢酶的影响

【目的】斜纹夜蛾Spodoptera litura (Fabricius)是主要的农业害虫之一。本研究旨在明确该害虫在湖南省5个主要蔬菜种植区的抗药性水平,并探讨该害虫对茚虫威的抗性与解毒代谢酶活性之间的关系,为斜纹夜蛾有效防控及抗性治理提供依据。【方法】采用浸叶法测定了2014-2016年湖南5地斜纹夜蛾田间种群对10种杀虫剂的抗性水平;将斜纹夜蛾敏感种群3龄幼虫在死亡率40%~70%的选择压下用茚虫威进行汰选,比较了斜纹夜蛾敏感种群和抗茚虫威种群的羧酸酯酶、谷胱甘肽S-转移酶和多功能氧化酶对硝基苯甲醚O-脱甲基活性。【结果】湖南5地斜纹夜蛾田间种群对有机磷类杀虫剂产生了26.9~220.2倍的抗性,对氨基甲酸酯类杀虫剂产生了68.3~890.8倍的抗性,对拟除虫菊酯类杀虫剂产生了21.0~267.2倍的抗性,对相对较新型杀虫剂（甲维盐、阿维菌素、茚虫威和溴虫腈）产生了5.2~53.4倍的抗性。经茚虫威汰选后第14代[抗性倍数(resistance ratio, RR)=26.43]斜纹夜蛾羧酸酯酶、谷胱甘肽S-转移酶和对硝基苯甲醚O-脱甲基酶活性分别上升2.86, 1.01和1.83倍。【结论】斜纹夜蛾对多种药剂产生了不同水平的抗性,斜纹夜蛾幼虫羧酸酯酶和对硝基苯甲醚O-脱甲基活性增强可能是斜纹夜蛾对茚虫威的抗性上升的重要因素。     

Evaluation of resistance to different insecticides in field strains of Helicoverpa armigera (Lepidoptera: Noctuidae) in Punjab, Pakistan

Susceptibility of field populations of Helicoverpa armigera (Lepidoptera: Noctuidae) from Punjab, Pakistan to selected insecticides was evaluated using the leaf dip method. The resistance factors varied between populations. The general trends were low to moderate resistance to endosulfan; very low to low resistance to chlorpyrifos and profenofos; very low resistance to spinosad, indoxacarb and thiodicarb; moderate to high resistance to bifenthrin; high to very high resistance to cypermethrin; and very high resistance to lambda-cyhalothrin. Integrated pest management strategies aimed at reducing pesticide application, such as rotating the conventional insecticides having low resistance with newly developed synthetic insecticides and conserving natural enemies, are recommended.     

Evidence for resistance to pyrethroids and organophosphates in Plutella xylostella (Lepidoptera: Plutellidae) from Pakistan

The susceptibility of representative pyrethroid (cypermethrin, deltamethrin, lambdacyhalothrin, bifenthrin), organophosphate (chlorpyriphos, triazophos, profenophos) and new chemistry insecticides (spinosad, indoxacarb and emamectin) was investigated for 18 field populations of Plutella xylostella (Linnaeus) from three different zones in Pakistan. The LC(50) (mg ml(-1); 48 h) values of pyrethroids for various populations ranged from 0.19-1.88 for cypermethrin, 0.31-2.64 for deltamethrin, 0.08-1.16 for lambdacyhalothrin and 0.07-0.88 for bifenthrin. The LC(50) (mg ml(-1); 48 h) of organophosphates ranged from 0.52-5.67 for chlorpyriphos, 0.37-4.14 for triazophos and 0.03-2.65 for profenophos. The most probable reason for low toxicity of organophosphates and pyrethroids is the evolution of multiple resistance mechanisms; however, further studies are required to establish these mechanisms. When these same products were tested against a susceptible laboratory population (Lab-Pak), the new chemistry compounds were significantly more toxic than pyrethroids and organophosphates. The results are discussed in relation to integrated pest management and insecticide resistance management strategies for P. xylostella.     

Assessment of insecticide resistance in five insect pests attacking field and vegetable crops in Nicaragua

Field populations of Hypothenemus hampei (Ferrari), Plutella xylostella (L.), Spodoptera exigua (Hübner), Helicoverpa zea (Boddie) and Bemisia tabaci (Gennadius) were tested for resistance to several insecticides commonly used in Nicariagua. Assays were conducted to estimate the LD50s or LC50s and the corresponding resistance ratios. A diagnostic concentration was used to discriminate between susceptible and resistant strains of H. hampei. The tests with >6,000 H. hampei adults collected from six different sites indicate the absence of resistance to endosulfan. Resistance to cypermethrin, deltamethrin, chlorfluazuron, thiocyclam, and methamidophos was documented in six field populations of P. xylostella. High levels of resistance to cypermethrin and deltamethrin, but moderate levels of resistance to chlorpyriphos and methomyl, were also documented in two field populations of S. exigua. Moderate levels of resistance to cypermethrin, deltamethrin and chlorpyriphos were also documented in three field populations of H. zea. Moderate to high levels of resistance to bifenthrin, methamidophos and endosulfan were documented in four field populations of B. tabaci. The presence of significant correlations between LD50s or LC50s suggests the occurrence of cross-resistance or simultaneous selection for resistance by different insecticides with different modes of action. Our data could not differentiate between these two possibilities. Because insecticides will continue being used in Nicaragua, a resistance management program is urgently needed. The implementation of integrated pest management tactics must be accompanied by specific regulations for pesticide registration. In the future, pesticide registration regulations in Nicaragua should include periodic resistance monitoring. The mechanisms to cover the costs of resistance monitoring and resistance management should also be established.     

Functional and genetic characteristics of Chlorantraniliprole resistance in the diamondback moth,Plutella xylostella (Lepidoptera: Plutellidae)

The diamondback moth (Plutella xylostella) is a globally distributed and important economic pest, and it has developed resistance to all conventional insecticide classes used in the field. Chlorantraniliprole is a new chemical class of insecticide that acts as a conformation‐sensitive activator of the insect ryanodine receptor (RyR). In the present study, a field strain (16.3‐fold resistance to chlorantraniliprole) was collected in Korea and lab‐selected with chlorantraniliprole for more than one year. The resulting strain presented 2,157‐fold resistance to chlorantraniliprole. A point mutation (G4946E) in the RyR gene was observed at a high frequency in the resistant strain. Enzyme assays indicated that glutathione S‐transferase (GST) and P450 activity in the resistant strain were 2.4‐ and 1.96‐times higher than that of the susceptible strain, respectively. The expression of the RyR, GST (sigma, omega, and zeta) and CYP321E1 gene was higher in the resistant strain than in the susceptible strain. The F₁ progeny resulting from reciprocal crosses did not reveal maternal effects or a diamide‐susceptible phenotype, which suggests an autosomal nearly recessive mode of inheritance. In addition, we surveyed the susceptibility to 13 insecticides (3 diamides, 2 synthetic pyrethroids, 2 spinosyns, 1 organophosphate, 1 oxadiazine, 1 avermectin, and 3 others) in the chlorantraniliprole‐resistant strain. The resistant strain exhibited high cross‐resistance to flubendiamide (5,910 fold) and showed no cross‐resistance to spinetoram, spinosad, indoxacarb, and metaflumizone. These results can serve as an important basis for guiding the use of insecticides in the field.     

Comparative efficacy of different pesticides against mango bark beetle Hypocryphalus mangiferae Stebbing (Coleoptera: Scolytidae)

Hypocryphalus mangiferae Stebbing is one of the most destructive insect pests of mango trees and is found to be associated with the transmission of causal organisms of mango sudden death disease. The present study was carried out to evaluate the toxicity of deltamethrin, bifenthrin, chlorpyrifos, emamectin benzoate, imidacloprid and spinosad in laboratory and field trials. Bioassay results showed that the toxicity of chlorpyrifos was significantly higher than deltamethrin but similar to bifenthrin. Deltamethrin and bifenthrin toxicity, however, increased significantly (P < 0.01) from day 1 to day 3. Spinosad was the least toxic compound while emamectin was the most toxic among new chemical insecticides tested, but its toxicity increased significantly from day 1 to day 5. Comparison of the efficacies of the insecticides using lethal times to produce 50% mortality (LT₅₀) and 90% mortality (LT₉₀) showed that the relative potencies of chlorpyrifos, emamectin, imidacloprid and spinosad were greater than bifenthrin and deltamethrin. The results of field trials showed the highest number of beetles emerged from the control twigs while significantly fewer beetles emerged from the twigs treated with bifenthrin (P < 0.05), which accounted for 12% for bifenthrin compared to that of the control. The present study demonstrated increased toxicities of systemic insecticides and chlorpyrifos compared to toxicities of deltamethrin and bifenthrin, suggesting these insecticides could be an alternative tool in a comprehensive H. mangiferae management program to eradicate the beetles from mango orchards.     

Resistance,its stability and reversion rate of resistance to imidacloprid,indoxacarb and chlorfenapyr in a field population of green lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae)

Abstract

Green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is a valuable bio-control agent that predates over various insect pests with high efficacy. It has developed considerable resistance to different classes of insecticides. This study was planned to investigate resistance level, stability and reversion rate against some new chemical insecticides using a field collected population of C. carnea. Field collected strain of C. carnea showed 313.44-fold, 216.50-fold and 276.83-fold resistance to imidacloprid, indoxacarb and chlorfenapyr compared to susceptible population, respectively. Baseline susceptibility values of C. carnea to imidacloprid, indoxacarb and chlorfenapyr were 2627.31, 502.10 and 581.89?ppm, while the insecticide resistance decrease rate was ?0.039, ?0.048 and ?0.040, respectively. Rotation of these insecticides requires quality measures maintaining survival of C. carnea in an intense environment where repeated applications are required to avoid economic damage by pests.     

A field study investigating the insecticidal efficacy against Diaphorina citri Kuwayama on Kinnow mandarin,Citrus reticulata Blanco trees

Asian citrus psyllid is a most damaging insect pest of citrus. In this field study, the efficacy of seven insecticides (emamectin benzoate, bifenthrin, chlorfenapyr, fipronil, imidacloprid, pyriproxyfen and thiamethoxam) was evaluated against Diaphorina citri Kuwayama in the citrus orchard of Kinnow mandarin, Citrus reticulata Blanco. The insecticides revealed a differential and substantial relative efficacy against D. citri compared to the untreated plants. The insecticidal effect attributed as percent reduction in insect population was more prominent after three days of spray: highest reduction values were recorded with thiamethoxam (50.89%), imidacloprid (44.27%) and bifenthrin (42.94%) after first spray, and thiamethoxam (83.36%), imidacloprid (73.20%) and bifenthrin (72.66%) after second spray. Thus, neonicotinoids (thiamethoxam and imidacloprid) and pyrethroid (bifenthrin) resulted as highly effective against D. citri at three days after both sprays. At seven days, imidacloprid (63.53%) and fipronil (62.47%) presented relatively higher population reduction after first spray, and thiamethoxam (92.66%) and chlorfenapyr (89.59%) after second spray. At 12 days, the insecticidal effect on insect population became significantly at par after each spray except chlorfenapyr that reflected high population reduction (93.17%) only after second spray. It is also obvious from the data that there is need of regular monitoring to suppress the psyllids population below threshold level by timely application of the second insecticidal spray.     

马尾松毛虫抗阿维菌素种群的抗性机制及交互抗性

为探讨阿维菌素防治马尾松毛虫的抗性风险和抗性机制,本研究采用叶片浸药法测定了马尾松毛虫抗阿维菌素种群(AV)对多种杀虫剂的交互抗性及增效剂胡椒基丁醚(PBO)、磷酸三苯酯(TPP)和顺丁烯二酸二乙酯(DEM)对马尾松毛虫AV种群、秦岭接官亭种群(JGT)和敏感种群(S)的增效作用,并使用分光光度计测定了AV、JGT和S种群的羧酸酯酶(CarE)、谷胱甘肽转移酶(GST)和多功能氧化酶系(MFOs)活性。结果表明: 马尾松毛虫AV种群与甲氨基阿维菌素苯甲酸盐(抗性倍数RR₅₀=25.0)、毒死蜱(RR₅₀=19.0)和高效氯氟氰菊酯(RR₅₀=15.4)存在中等水平交互抗性,与溴虫腈存在低水平交互抗性(RR₅₀=8.1),与乙基多杀菌素、多杀菌素和氯虫苯甲酰胺不存在交互抗性。增效剂PBO与TPP对马尾松毛虫AV、JGT和S种群均有显著增效作用,DEM对马尾松毛虫AV、JGT和S种群均无显著增效作用。马尾松毛虫AV种群MFOs中细胞色素P₄₅₀含量(3.5倍)、细胞色素b₅含量(3.1倍)、O-脱甲基酶活性(4.1倍)和CarE活性(2.2倍)均显著高于S种群,AV种群GST活性与S种群不存在显著性差异。MFOs及CarE活性增强是马尾松毛虫对阿维菌素产生抗性的重要生化机制,推荐乙基多杀菌素、多杀菌素和氯虫苯甲酰胺与阿维菌素轮换使用防治马尾松毛虫。     

滇西菜区小菜蛾发生规律及抗药性监测

掌握滇西菜区小菜蛾Plutella xylostella种群发生规律和抗药性水平,对提出区域性防控策略具有重要意义。2009-2015年,采用诱集法和浸叶法监测了滇西菜区小菜蛾种群发生动态及其对常用杀虫剂的抗药性。结果表明：滇西菜区小菜蛾全年发生,为害期有9个月,春夏季为害重,3-6月为发生高峰期,2009-2015年最高诱蛾量为290~905头/7 d,小菜蛾种群对化学杀虫剂均产生了不同水平的抗药性,其中对阿维菌素和高效氯氰菊酯的抗药性最高,达到高水平抗药性,对多杀菌素、茚虫威和溴虫腈维持在中等水平抗药性,2011年对氯虫苯甲酰胺产生了28倍的抗药性,后恢复敏感,3年后又出现抗药性的上升趋势。可见,3-6月是滇西菜区小菜蛾防控的重要时期,可选择Bt、多杀菌素、茚虫威和溴虫腈等药剂轮换使用,减少氯虫苯甲酰胺使用次数,建议停用阿维菌素和高效氯氰菊酯。