Cross-resistance, genetics and stability of resistance to deltamethrin in a population of Chrysoperla carnea from Multan, Pakistan

Broad-spectrum insecticides are still widely being used. Chrysoperla carnea has been shown to develop resistance to the insecticides in the field. Knowledge of the evolution and genetics of resistance to insecticides in natural enemies could enable to explain how effectively natural enemies can be implemented in different IPM systems. To examine this, a population of C. carnea from Multan Pakistan was collected and was subjected to deltamethrin selection in the laboratory. Bioassays at generation G₁ gave resistance ratios of 47, 86, 137, 76 and 110 for deltamethrin, alphamethrin lambdacyhalothrin, chlorpyrifos and profenofos respectively compared with susceptible Lab-PK. Bioassays at G₄ with a deltamethrin-selected population (Delta-SEL) showed that selection gave resistance ratios of 896 and 30 for deltamethrin compared with the Lab-PK and UNSEL, respectively. Cross-resistance to other insecticides tested was observed in the selected population. A notable feature of the Delta-SEL strain was that resistance to deltamethrin, alphamethrin, lambdacyhalothrin, chlorpyrifos and profenofos did not decline over the course of four generations. Synergism tests with microsomal oxidase (MO) and esterase-specific inhibitors indicated that the deltamethrin resistance was associated with MO and, possibly, esterase activity. Reciprocal crosses between the Delta-SEL and Lab-PK strains indicated that resistance was autosomal and incompletely dominant. A direct test of monogenic inheritance suggested that resistance to deltamethrin was controlled by more than one locus. The broad spectrum of resistance, cross resistance, incompletely dominant mode of inheritance and stability of resistance to insecticides suggest that Delta-SEL population of C. carnea could be compatible with most spray programs.     

Patterns of resistance to organophosphate insecticides in field populations of Helicoverpa armigera in Pakistan

The pattern of organophosphate resistance in field populations of Helicoverpa armigera (Hübner) was monitored in Pakistan from 1994 through 1997 using an IRAC leaf-dip method. Generally, moderate to high resistance was found to an orthophosphorate, monocrotophos and to a dithiophosphorate, ethion. Resistance to the commonly used thiophosphorates, chlorpyrifos and profenofos, was very low during 1994 and 1995 but showed an upward trend during 1996 and 1997. Resistance factors to the other thiophosphorates such as quinalphos, parathion-methyl, methamidophos and triazophos remained very low. Baseline lethal concentrations for ethion, methamidophos and triazophos were at least four to five times higher than those for the other organophosphates tested, suggesting their low intrinsic efficacy against H armigera. © 1999 Society of Chemical Industry     

Efficacy of insecticide mixtures against pyrethroid‐ and organophosphate‐resistant populations of Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND: Spodoptera litura (F.) is an important pest worldwide, with over 112 host plants, and is exposed to insecticides throughout the year, resulting in the rapid development of resistance. Insecticide mixtures can delay the development of resistance more effectively than sequences or rotations. Cypermethrin, deltamethrin, profenofos, chlorpyrifos and fipronil were assessed separately and in mixtures against laboratory susceptible S. litura and two field‐collected populations. RESULTS: The field‐collected population from Khanewal (KWL) was significantly more resistant to cypermethrin, deltamethrin, chlorpyrifos and profenofos than one collected from Muzaffar Garh (MGH). Mixtures of cypermethrin + chlorpyrifos or profenofos and of deltamethrin + chlorpyrifos or profenofos at 1:1, 1:10 and 1:20 ratios significantly increased (P < 0.01) toxicity to cypermethrin and deltamethrin in field populations. The combination indices of cypermethrin + chlorpyrifos at 1:1 and 1:10 ratios and cypermethrin + fipronil at 1:1, 1:10 and 1:20 ratios for the KWL strain and of cypermethrin + profenofos or fipronil at 1:1, 1:10 and 1:20 ratios for MGH were significantly below 1, suggesting synergistic interactions. The inhibitors DEF and PBO largely overcame resistance to deltamethrin, cypermethrin and profenofos, suggesting that resistance to the insecticides was associated with esterase and monooxygenase detoxification respectively. CONCLUSION: Chlorpyrifos, profenofos and fipronil could be used in mixtures to restore cypermethrin and deltamethrin susceptibility. These findings may have considerable practical implications for S. litura resistance management. Copyright © 2008 Society of Chemical Industry     

Using synergists to detect multiple insecticide resistance in field populations of rice stem borer

The rice stem borer, Chilo suppressalis (Walker), an important insect pest of rice in China, has developed resistances to several classes of insecticides in field. In order to investigate multiple resistance mechanisms, synergistic tests were conducted with the Ruian (RA) population and Lianyungang (LYG) population, two representative populations to different insecticides. Results showed that diethyl maleate (DEM), S,S,S-tributyl phosphorotrithioate (DEF) and piperonyl butoxide (PBO), had no significant synergistic or inhibitory effect on the high level of resistance to monosultap (313.4-fold) and moderate level to chlorpyrifos (36.9-fold) in Ruian field population from the year 2011 (RA11). DEF significantly synergized the activity of triazophos in RA11 population (536.8-fold), with synergism ratio of 1.92. DEF and PBO significantly suppressed 43.3% and 40.4% of resistance to fipronil in RA11 population (48.4-fold), respectively, with the synergistic ratios of 1.76 and 1.69. When pretreated with PBO, the activity of deltamethrin against RA11 population were significantly synergized, with synergism ratio of 9.57, and with reducing resistance levels from 152.5- to 15.9-fold. The results of this study indicated that resistance to several classes of insecticide among the field populations of C. suppressalis might be provided by the combination of the multiple resistance mechanisms. Metabolic resistance mechanism might be the major reason for the evolution for resistance to deltamethrin and fipronil, while resistance to monosultap, triazophos and chlorpyrifos is not associated with metabolic resistance.     

Effect of foliar applications of some insecticides onBemisia tabaci, predators and parasitoids: Implications in its management in Pakistan

Three experiments were carried out during three consecutive years to evaluate 19 insecticides and 12 tank mixtures of different groups of insecticides against the whiteflyBemisia tabaci and its predators and parasitoids under field conditions in cotton. In the first experiment, the whitefly population was lower in treatments with thiacloprid and higher in those with black warrant (a.i. alcohol) and cypermethrin; the number of predators was higher with Agri-50 and spinosad and lowest with cypermethrin, whereas percent parasitism was higher with thiacloprid and lower with methamidophos. In the second experiment, the whitefly population was lower in treatments with buprofezin, pyriproxyfen and diafenthiuron and higher in those with endosulfan, imidacloprid and thiamethoxam; the number of predators was higher with pyriproxyfen and lower with thiamethoxam, whereas percent parasitism was higher with pyriproxyfen and lower with thiamethoxam. In the third experiment, the whitefly population was lower in a treatment mixture with buprofezin + fenpropathrin and higher in that with thiamethoxam + chlorpyrifos; the number of predators was higher with buprofezin + fenpropathrin and lower with deltamethrin + triazophos and deltamethrin + chlorpyrifos, whereas percent parasitism was higher with the mixture of pyriproxyfen + chlorpyrifos and lower in imidacloprid + chlorpyrifos, betacyfluthrin + triazophos, and deltamethrin + triazophos. Effective use of these insecticides to manage whitefly infestations and to save predators and parasitoids is discussed. http:www.phytoparasitica.org posting August 7, 2008.     

6种杀虫剂对旱稻孢囊线虫孵化的影响

为明确水稻常用杀虫剂对旱稻孢囊线虫孵化的影响,在室内条件下测定了毒死蜱、三唑磷、灭线磷、丙溴磷、阿维菌素和杀虫双等6种杀虫剂在不同浓度和时期处理对旱稻孢囊线虫的作用效果。结果表明,6种杀虫剂中丙溴磷、毒死蜱、阿维菌素对旱稻孢囊线虫的孵化具有较高的抑制活性;药剂长期处理对2龄幼虫孵化的抑制效果最好,刚分离的孢囊较预先孵化7d后的孢囊对药剂的敏感性低;三唑磷和灭线磷在较低浓度范围内对孢囊线虫的孵化具有刺激作用。研究结果可为制定旱稻孢囊线虫防治措施提供依据。     

Genetics and mechanism of resistance to deltamethrin in a field population of Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND: Spodoptera litura (F.) causes enormous losses in many economically important crops. The genetics of insecticide resistance has been extensively studied in several insect pests, but there is a lack of information on S. litura. Therefore, the genetics and mechanisms of the resistance of S. litura to deltamethrin were investigated. RESULTS: Bioassays at generation G1 gave resistance ratios of 9, 5, 41, 52 and 49 for deltamethrin, cypermethrin, profenofos, chlorpyrifos and triazofos respectively, when compared with the susceptible Lab-PK strain. Bioassays at G4 with a deltamethrin-selected population (Delta-SEL) showed that selection gave resistance ratios of 63 and 7 for deltamethrin when compared with the Lab-PK and UNSEL strains respectively. Cross-resistance to other insecticides tested was observed in the selected population. A notable feature of the Delta-SEL strain was that resistance to deltamethrin, cypermethrin, profenofos and chlorpyrifos did not decline over the course of five generations. Synergism tests with microsomal oxidase (MO) and esterase-specific inhibitors indicated that the deltamethrin resistance was associated with MO and, possibly, esterase activity. Reciprocal crosses between the Delta-SEL and Lab-PK strains indicated that resistance was autosomal and incompletely dominant. A direct test of monogenic inheritance suggested that resistance to deltamethrin was controlled by more than one locus. CONCLUSION: Stability and dominance of resistance and cross-resistance suggest that insecticides with different modes of action should be recommended to reduce pyrethroid selection pressure.     

Assessment of field evolved resistance to some broad-spectrum insecticides in cotton jassid, <Emphasis Type="Italic">Amrasca devastans</Emphasis> from southern Punjab,Pakistan

Resistance management, targeting insect pests is one of the key components in developing integrated pest management strategies. Arguably, resistance monitoring is a scientific undertaking that can support and inform resistance management tactics and strategies. To monitor the current resistance status in Amrasca devastans against conventional insecticides (deltamethrin, bifenthrin, cypermethrin, chlorpyrifos, profenofos, acephate, and methomyl) which are used by the farming community as the predominant means to control this pest. Field populations of A. devastans were collected from six different districts: Multan, Bahawalpur, Khanewal, Lahore, Dera Ghazi Khan and Muzaffargarh from Punjab in Pakistan. The adult populations tested were 11.10–92.87 times more resistant to deltamethrin, 5.87–14.11 times more to bifenthrin, 3.16–17.5 times more to cypermethrin, 2.65–36.42 times more to chlorpyrifos, 7.28–57.71 times more to profenofos, 1.65–11.13 times more to acephate and 2.55–43.31 times more to methomyl as compared to control (lab population). In our study, no to high levels of resistance were observed against pyrethroids and organophosphates. Development of resistance to these pyrethroids and organophosphates might be due to the injudicious use of these types of insecticides in field crops. This study suggests that use of these insecticides should be minimized to avoid development of resistance in A. devastans. Future studies are also recommended to use new chemistry insecticides with novel modes of action and/or insecticide mixtures that may reduce the reliance of the farming communities on these insecticides.     

氟虫腈等7种杀虫剂对鲫鱼的毒性及安全性试验研究

本文研究了氟虫腈等杀虫剂对鲫鱼的急性毒性作用。室内毒力测定结果表明:溴氰菊酯、高效氯氟氰菊酯对鲫鱼的毒性最高,毒死蜱、三唑磷毒性较高,氟虫腈、阿维菌素较安全,杀虫双对鲫鱼最安全。大田实验结果与室内实验结果基本一致,只是溴氰菊酯在稻田环境下,对鲫鱼的急性毒性大幅度下降。     

溴氰菊酯对马铃薯腐烂茎线虫的毒力及对其运动和摄食的影响

采用药液浸渍法、沙柱法以及与荧光染料Cy3共孵育的方法,以丙溴磷、克百威和阿维菌素为对照药剂,测定了溴氰菊酯对马铃薯腐烂茎线虫Ditylenchus destructor的毒力以及对其运动扩散和摄食的影响。结果表明:溴氰菊酯对马铃薯腐烂茎线虫具有一定的杀灭活性,其LC50值为459.8mg/L,活性低于丙溴磷(159.9mg/L)、克百威(331.9mg/L)和阿维菌素(257.3mg/L);溴氰菊酯对马铃薯腐烂茎线虫运动扩散的抑制作用IC50值为3.1mg/L,其活性低于阿维菌素(0.8mg/L),但高于丙溴磷(8.3mg/L)和克百威(16.1mg/L)。当丙溴磷和克百威质量浓度分别低至0.6和40mg/L时,可刺激90%以上的线虫摄食;当丙溴磷和克百威质量浓度最低分别为360和300mg/L时,可抑制全部线虫的摄食;溴氰菊酯与阿维菌素则对线虫的摄食无刺激作用;用10mg/L的丙溴磷处理线虫2h后再分别用阿维菌素和溴氰菊酯处理,发现阿维菌素和溴氰菊酯质量浓度最低分别为20和200mg/L时可抑制全部马铃薯腐烂茎线虫的摄食。研究表明,溴氰菊酯对马铃薯腐烂茎线虫具有较高的活性,其在线虫防治领域的开发应用潜力较好。     

防治桃小食心虫越冬幼虫的有效药剂及其降解动态

研究树下土表施药防治桃小食心虫越冬幼虫的取代药剂。用毒土法测定了分属4类的13种药剂对桃小食心虫越冬幼虫的触杀毒力,其结果以毒死蜱、三唑磷、高效氯氟氰菊酯、甲基对硫磷和辛硫磷毒力较高,LC_(90)值依次为18．38、22．48、35．95、47．63及49．57 mg·kg~(-1),甲氰菊酯、丙溴磷、阿维菌素、甲胺基阿维菌素、氰戊菊酯、马拉硫磷、丙硫克百威和丁硫克百威LC_(90)值处于77．11～205．86mg·kg~(-1)之间。用高效液相色谱法测定了毒力较高的毒死蜱、三唑磷、高效氯氟氰菊酯以及阿维菌素在土壤中的降解动态,半衰期分别为8．28、11．37、10．17及19．70天。欲达30天的有效控制期,按LC_(90)值计算,这4种药剂在土壤中的初施浓度应分别为226．36、139．90、278．03及346．81mg·kg~(-1)。从药剂毒力、降解速率、相同控制期所需剂量及应用成本综合评价,毒死蜱、三唑磷具有较高的应用价值。     

Resistance of Pakistani field populations of spotted bollworm Earias vittella (Lepidoptera: Noctuidae) to pyrethroid,organophosphorus and new chemical insecticides

BACKGROUND: The spotted bollworm Earias vittella (Fab.) is a serious pest of cotton and okra in Pakistan. Owing to persistent use of insecticides, this pest has developed resistance, especially to pyrethroids. The present studies aimed at determining the extent of resistance to pyrethroid, organophosphorus and new chemical insecticides in Pakistani populations of E. vittella. RESULTS: Field populations of E. vittella were monitored at Multan, Pakistan, from 1999 to 2007 for their resistance against six pyrethroid, four organophosphorus and six new chemical insecticides using a leaf‐dip bioassay. Of the pyrethroids, resistance was generally low to zeta‐cypermethrin and moderate to high or very high to cypermethrin, deltamethrin, esfenvalerate, bifenthrin and lambda‐cyhalothrin. Resistance to organophosphates chlorpyrifos, profenofos, triazophos and phoxim was recorded at very low to low levels. Among new chemicals, E. vittella had no or a very low resistance to spinosad, emamectin benzoate and methoxyfenozide, a very low to low resistance to abamectin, a very low to moderate resistance to indoxacarb and a moderate resistance to chlorfenapyr. CONCLUSION: The results indicate a lack of cross‐resistance between pyrethroid and organophosphorus insecticides in E. vittella. Rotation of insecticides showing no, very low or low resistance, but belonging to different insecticide classes with unrelated modes of action, may prevent or mitigate insecticide resistance in E. vittella. Copyright © 2009 Society of Chemical Industry     

稻田常用农药对四地区二化螟盘绒茧蜂雌成蜂的触杀毒性

为明确稻田常用农药对二化螟幼虫期优势寄生性天敌二化螟盘绒茧蜂Cotesia chilonis(Mat-sumura)的毒性,采用药膜法在室内测定了7种杀虫剂原药以及18种常用农药制剂对扬州、安吉、金华和乐清4个地区二化螟盘绒茧蜂雌成蜂的触杀毒性。结果表明,7种杀虫剂原药中氟虫腈、毒死蜱和三唑磷对该蜂毒性较高,杀虫单、吡虫啉和阿维菌素次之,氯虫苯甲酰胺则最低。12种杀虫剂制剂中20%氯虫苯甲酰胺悬浮剂和3种阿维菌素相关制剂对该蜂毒性相对较低,其余均具高毒性;4种杀菌剂中的异稻.三环唑对该蜂高毒,苯甲.丙环唑次之,井岗.蜡芽菌(井冈霉素)和盐酸吗啉胍.三氮唑核苷则毒性最低;2种除草剂中苄嘧.丙草胺毒性高于苄.二氯。此外,同一种药剂对不同地区雌蜂的毒性也有所不同。     

Triazophos resistance mechanisms in the rice stem borer (Chilo suppressalis Walker)

A field population of the rice stem borer (Chilo suppressalis Walker) with 203.3-fold resistance to triazophos was collected. After 8-generation of continuous selection with triazophos in laboratory, resistance increased to 787.2-fold, and at the same time, the resistance to isocarbophos and methamidophos was also enhanced by 1.9- and 1.4-fold, respectively, implying some cross-resistance between triazophos and these two organophosphate insecticides. Resistance to abamectin was slightly enhanced by triazophos selection, and fipronil and methomyl decreased. Synergism experiments in vivo with TPP, PBO, and DEM were performed to gain a potential indication of roles of detoxicating enzymes in triazophos resistance. The synergism results revealed that TPP (SR, 1.92) and PBO (SR 1.63) had significant synergistic effects on triazophos in resistant rice borers. While DEM (SR 0.83) showed no effects. Assays of enzyme activity in vitro demonstrated that the resistant strain had higher activity of esterase and microsomal O-demethylase than the susceptible strain (1.20- and 1.30-fold, respectively). For glutathione S-transferase activity, no difference was found between the resistant and the susceptible strain when DCNB was used as substrate. However, 1.28-fold higher activity was observed in the resistant strain when CDNB was used. These results showed that esterase and microsomal-O-demethylase play some roles in the resistance. Some iso-enzyme of glutathione S-transferase may involve in the resistance to other insecticides, for this resistant strain was selected from a field population with multiple resistance background. Acetylcholinesterase as the triazophos target was also compared. The results revealed significant differences between the resistant and susceptible strain. The V_max and K_m of the enzyme in resistant strain was only 32 and 65% that in the susceptible strain, respectively. Inhibition tests in vitro showed that I₅₀ of triazophos on AChE of the resistant strain was 2.52-fold higher. Therefore, insensitive AChE may also involved in triazophos resistance mechanism of rice stem borer.     

三唑磷与氟虫腈复配对粘虫的增效机理研究

以粘虫Mythimna separate 4龄幼虫为试虫,从表皮穿透、生物转化、作用靶标3个方面研究了三唑磷·氟虫腈复配剂的增效机理。结果表明,三唑磷与氟虫腈复配后,相互促进了对方对粘虫表皮的穿透作用;三唑磷对酸性磷酸酯酶(ACPase)的竞争性抑制与氟虫腈对ACPase的非竞争性抑制与反竞争性抑制的混合型抑制相结合,使复配剂对ACPase的抑制能力大幅度提高;对谷胱甘肽S-转移酶(GSTs)的联合抑制系数(JIC)达到425.87,表现出显著的增效作用;三唑磷和氟虫腈对乙酰胆碱酯酶(AChE)只有微弱的交互作用。表皮穿透率的提高及其对ACPase和GSTs抑制能力的增强可能是该复配剂对粘虫增效的重要机理。     

新疆棉铃虫自然敏感种群对常用杀虫剂浸叶法的毒力基线

选用阿拉尔棉铃虫自然敏感种群(AL-S),在详细观察2龄中期幼虫的形态、行为特征及比较其生理学特性对药剂敏感性影响的基础上,用生理特性一致的2龄中期幼虫,测定了10种常用杀虫剂浸叶法的毒力基线。结果表明:①2龄中期幼虫的形态和行为特征为头宽≤体宽,体色不透明肉色,体节明显且行动较敏捷。此时2龄幼虫的时龄约为10～22h,体重1.33±0.27mg;②试虫生理特性差异影响对药剂的敏感性。2龄幼虫不同发育历期的敏感性,以前期最敏感,中、后期较接近;雌蛾不同蛾龄的卵发育的2龄幼虫敏感性,以4日龄蛾卵的幼虫敏感性最低,7日龄蛾卵最敏感,5、6日龄蛾的敏感性相近,且介于上述二者之间。故在测定毒力基线时,为保持试虫生理同质性,宜选用5、6日龄雌蛾卵的2龄中期幼虫为佳。③用2龄中期幼虫,获得10种药剂浸叶法的毒力基线,杀虫剂致死中浓度(LC_(50))按以下次序增大:功夫菊酯、溴氰菊酯、氰戊菊酯、硫丹、甲基E605、辛硫磷、毒死蜱、丙溴磷、久效磷、灭多威。     

农药和重金属复合污染物对大型溞的毒性效应

农药和重金属作为水环境中两类常见的污染物,其复合污染已经对水体生态和人类生存环境构成严重威胁。作者研究了3种常用农药（毒死蜱、三唑磷、氟虫腈）及2种常见重金属（铅、镉）对大型溞的急性毒性,同时采用五因素五水平二次通用旋转组合设计方案,研究了复合污染物体系对大型溞的联合毒性效应。结果表明:毒死蜱、三唑磷、氟虫腈、铅离子和镉离子对大型溞的48 h-EC50值分别为6.30、7.27、2.17、454.97和1 175.74 μg/L;5种污染物对大型溞的毒性效应贡献值依次为镉离子 > 三唑磷 > 氟虫腈 > 毒死蜱 > 铅离子;复合污染物对大型溞的毒性呈现出一定的相加效应;当水中毒死蜱质量浓度为0.81 μg/L、三唑磷为17.22 μg/L、氟虫腈为5.65 μg/L、铅离子为83.75 μg/L、镉离子为3 793.15 μg/L时,复合污染物毒性的理论协同效应最大。研究结果可为复合污染物风险评估提供参考。     

Synergism of pyrethroid — organophosphorus insecticide mixtures in insects and their toxicity againstspodoptera littoralis larvae

Synergism of mixtures of pyrethroids with organophosphorus (OP) compounds in insects is reviewed, and the toxicity of such combinations againstSpodoptera littoralis (Boisd.) larvae is reported. Mixtures of one of the pyrethroids cypermethrin, fenvalerate or deltamethrin with one of the OP compounds monocrotophos, profenofos, azinphos-methyl or acephate were assayed at different ratios as 24-h-old dipping residues on alfalfa, which was fed toS. littoralis larvae for 48 h. With most of the binary mixtures containing various OP concentrations in excess of those of the pyrethroids, synergism was demonstrated. In the pairs fenvalerate — azinphos-methyl, deltamethrin — azinphos-methyl and deltamethrin — profenofos, however, no synergism was found. In a detailed investigation with pyrethroid concentrations causing 20% mortality and OP concentrations giving a kill of no higher than ;10%, the above findings on synergism were amply confirmed. A cypermethrinmonocrotophos mixture showed synergism also on cotton leaves sprayed in the field. Synergism could not be demonstrated by topical application of pyrethroid — OP mixtures.     

Molecular analysis of resistance in a deltamethrin-resistant strain of Musca domestica from China

We investigated the molecular basis of resistance in a strain of house fly (BJD) from Beijing, China. This strain showed 567-fold resistance to commonly used deltamethrin. Flies were 64-fold resistant to deltamethrin synergized by piperonyl butoxide (PBO). The 5′-flanking sequence of the cytochrome P450 gene CYP6D1 in BJD strain had a 15-bp insert as in the LPR strain. Two mutations (kdr, super-kdr) in the voltage sensitive sodium channel (VSSC) were also detected in the BJD strain. Our results showed that a combination of resistance alleles for CYP6D1 and VSSC existed in deltamethrin resistant house flies in China.