Toxic effect of deltamethrin on the life table and development of Helicoverpa armigera (Hubner)

Effect of deltamethrin (Decis 2.8% EC) on the fitness of Helicoverpa armigera (Hübner) was determined using demographic studies. Survivorship (I_x) and expectancy (e_x) was high with commencement of age and gradually decreased with progression of age in the exposed and unexposed groups. Highest number of unhatched eggs (~20%) was recorded with LC₅₀ (79.0 mg/L) opposed to 1% in the control. Daily fecundity rate was significantly greater (200 females/day) in the control than 126 in LC₂₀ (5.13 mg/L). Potential fecundity was lowest (179 females/female/generation) with LC₅₀ treatment than 675 in the control. Smallest value of intrinsic rate of increase (r_m) occurred at LC₅₀ (0.0393 females/female/day) while the highest value (0.0539) was at control. Overall larval development was significantly reduced to 18.0 days with LC₅₀ opposed to 24.1 days at control. Pupal period was shortened to 7.6 days with LC₅₀, while it recorded 9.3 days in control.     

Lethal and sublethal effects of thiacloprid on survival,growth and reproduction of Helicoverpa armigera (Lepidoptera: Noctuidae)

The cotton bollworm Helicoverpa armigera (Hübner) is the most destructive pest of cotton, tomato and chickpea in Iran. In this study, the lethal and sublethal effects of thiacloprid were evaluated against cotton bollworm under laboratory condition at 26?±?1?°C, 70?±?5% RH and a photoperiod of 16:8 (L:D). Bioassay experiments were conducted on first larval instars by mixing the insecticide dilutions with artificial diet. The LC₅₀ value of thiacloprid was 329?mg a.i./l. Sublethal effects of LC₃₀ concentration of thiacloprid was studied on biological parameters. In the study of sublethal effects, thiacloprid at LC₃₀ concentration significantly increased larval and pupal developmental times and reduced adults longevity compared with control but showed no significant effects on fecundity of cotton bollworm. Sublethal effects of thiacloprid also significantly reduced pupal weight compared with control. In general, sublethal effects studies showed that thiacloprid had adverse effects on biological parameters of the pest. Thus, our data suggest that thiacloprid had moderate potential against cotton bollworm.     

甲氧虫酰肼对棉铃虫生长发育的亚致死效应研究

以一个对甲氧虫酰肼具有18.5倍抗性的棉铃虫Helicoverpa armigera(Hübner)种群(R)和其同源对照种群(S)为对象,研究了甲氧虫酰肼对棉铃虫生长发育的亚致死效应。结果表明,甲氧虫酰肼亚致死剂量(LC25)处理R和S种群的3龄初幼虫,对S种群幼虫的生长抑制率(37.30%)显著大于R种群(21.20%)。与空白对照处理相比,致死剂量处理R和S种群后,均表现出生长发育延缓,蛹期延长,化蛹率、羽化率、卵孵化率降低,且对S种群的影响更明显。研究结果表明亚致死剂量的甲氧虫酰肼对棉铃虫存在一定的不利影响,但对甲氧虫酰肼具有一定抗性的棉铃虫种群能够减轻这种不利影响。     

Genetics of Indoxacarb resistance in Helicoverpa armigera (Hubner)

The present investigation was done with the aim of studying the genetics of Indoxacarb resistance. Selection of Helicoverpa armigera (Hubner) with Indoxacarb was done for eight generations to develop resistance. Reciprocal crosses between resistant and susceptible populations were made to understand the population genetics of Indoxacarb resistance in H. armigera . Generation-wise selection with Indoxacarb was evaluated for resistance development in H. armigera . The LC₅₀ of Indoxacarb was 2.81 p.p.m. for the first selected generation, and it increased to 272.55 p.p.m. after eight selected generations, which is a 1238.86-fold resistance compared to the susceptible strain. The estimated realized heritability (h²) after eight generations of selection with Indoxacarb was 0.45. The number of generations required for a tenfold increase in LC₅₀ (1/R) was estimated to be 2.59. The response to Indoxacarb selection in H. armigera was 0.39, the estimated selection differential (S) was 0.87, and the phenotypic standard deviation (σp) was 0.03. Reciprocal crosses between Indoxacarb resistant and susceptible strains revealed that the inheritance of Indoxacarb resistance was autosomal: neither maternal effect nor linkage was evident. The values of D_LC (0.10 and 0.09) indicated completely recessive inheritance of Indoxacarb resistance.     

Induction of the mRNA for CYP6B2, a pyrethroid inducible cytochrome p450, in Helicoverpa armigera (Hubner) by dietary monoterpenes

A cDNA clone encoding a cytochrome P450 from H. armigera was used to examine the expression of two homologous cytochrome P450 mRNAs, one of which, CYP6B2, is probably involved in pyrethroid metabolism. The mRNA for CYP6B2 in particular can be induced up to tenfold by peppermint oil and the monoterpene α-pinene as well as to a smaller extent by menthol, butylated hydroxyanisole, and piperonyl butoxide. Both mRNAs are present in the major larval tissues, midgut, fat body, and cuticle, although only the mRNAs in the midgut and fat body are inducible by peppermint oil. The induction is a rapid process occurring within a period of 4 h with a similarly rapid rate of decrease in the absence of the inducing compounds. During normal development both mRNAs are absent from eggs and increase during the larval stage, reaching a maximum during mid fifth instar. Both mRNAs then decrease to undetectable levels during pupation and remain undetectable in the adult stage. © 1997 Wiley-Liss, Inc.     

双酰胺类杀虫剂对棉铃虫和松毛虫赤眼蜂的选择毒力

为了指导棉铃虫防控中化学杀虫剂和天敌昆虫协调使用,本文采用浸叶法和玻管药膜法测定了4种双酰胺类杀虫剂对棉铃虫3龄幼虫和松毛虫赤眼蜂成蜂的毒力.结果表明,供试双酰胺类杀虫剂中氯虫苯甲酰胺、氟苯虫酰胺和氟氰虫酰胺对棉铃虫幼虫表现出了较高的毒力水平(LC50分别为0.2882、0.3894、0.8609 mg/L),稍低于对照药剂甲氨基阿维菌素苯甲酸盐(简称:甲维盐)(LC50为0.06493 mg/L);而溴氰虫酰胺对棉铃虫的毒力(LC50为3.7638 mg/L)明显低于甲维盐.从对天敌昆虫安全性来看,氯虫苯甲酰胺、氟苯虫酰胺和氟氰虫酰胺对松毛虫赤眼蜂的毒性(LC50分别为1.0060、0.9933、1.1541 mg/L)明显低于甲维盐(其LC50为0.1646 mg/L),表现出了较高的安全性;但是,溴氰虫酰胺对松毛虫赤眼蜂毒性较高(LC50为0.4952 mg/L),安全性较差.本研究将为棉铃虫防控中药剂与天敌协调使用提供依据.     

Baseline toxicity of emamectin and spinosad to Helicoverpa armigera (Lepidoptera: Noctuidae) for resistance monitoring

Acute toxicity studies of emamectin and spinosad against Helicoverpa armigera revealed that the pest is highly susceptible to both the insecticides. The median lethal dose (LD₅₀) of emamectin is 3.86 × 10⁻³ µg per larva. The median lethal concentrations (LC₅₀) of emamectin and spinosad were found to be 0.09 and 2.94 ppm, respectively. The discriminating doses were fixed based on the LC₉₅ of the susceptible population of H. armigera as 0.80 ppm for emamectin and 10 ppm for spinosad. Resistance was not observed when the discriminating doses of emamectin and spinosad were applied on field-collected populations of H. armigera from two intensive cotton growing areas, Coimbatore and Madurai, India.     

光学活性拟除虫菊酯对棉铃虫神经细胞钠通道电流的影响

用全细胞膜片钳技术对比分析了alpha体氯氰菊酯与theta体氯氰菊酯对棉铃虫Helicoverpa armigera幼虫离体培养中枢神经细胞Na⁺通道门控过程的影响。结果表明,alpha体氯氰菊酯作用后,神经细胞Na⁺通道电流（I_Na）先增大,同时通道的激活电压向负电位方向移动约10 mV,提示alpha体氯氰菊酯使通道激活电位降低,通道更容易被激活。药剂作用约10 min后,I_Na又迅速降低,表明alpha体氯氰菊酯对开放状态的Na⁺通道有抑制作用。另外,alpha体氯氰菊酯使I_Na到达峰值的时间缩短,但对失活时间无明显影响。Theta体氯氰菊酯也使I_Na激活电位左移,幅值降低,但降低速率较慢。总的结果表明alpha体氯氰菊酯与theta体氯氰菊酯对棉铃虫中枢神经细胞处于关闭和开放状态的钠通道均有作用,且alpha体氯氰菊酯对钠通道电流的抑制作用强于theta体氯氰菊酯。     

Relative contribution of detoxifying enzymes to pyrethroid resistance in a resistant strain of Helicoverpa armigera

Abstract:  The relative contribution of oxidases and esterases to pyrethroid resistance was studied in a YS-FP strain of Helicoverpa armigera from China. The YS-FP strain was derived from a field-collected strain (YS) by 16 generations of selection with a mixture of fenvalerate and phoxim. Compared with the YS strain, the YS-FP strain showed 1850- to >7140-fold resistance to four ester-bonded phenoxybenzyl alcohol pyrethroids (fenvalerate, deltamethrin, cypermethrin and cyhalothrin), >205-fold resistance to a non-ester phenoxybenzyl alcohol pyrethroid (etofenprox) and only 19-fold resistance to an ester-bonded methylated biphenyl alcohol pyrethroid (bifenthrin). The oxidase inhibitor piperonyl butoxide eliminated most the of resistance to fenvalerate, deltamethrin, cypermethrin, cyhalothrin and etofenprox, whereas the esterase inhibitor S,S,S -tributylphosphorothioate had a small synergistic effect for fenvalerate and cyhalothrin only. This suggests that the resistance to these pyrethroids in the YS-FP strain was mainly because of enhanced oxidative detoxification. The monooxygenase activities of the midguts of sixth-instar larvae of the YS-FP strain to substrates p -nitroanisole, ethoxycoumarin and methoxycoumarin were 3.7-, 4.7- and 10-fold, respectively, compared with that of the YS strain. Glutathione S -transferase activity and esterase activity were not significantly altered in the YS-FP strain. This confirms that enhanced oxidative detoxification was a major mechanism contributing to pyrethroid resistance in the YS-FP strain.     

食物对棉铃虫生长发育及繁殖的影响

用棉花、花生、玉米及人工饲料作为食料,模拟幼虫田间取食习性,同时为雌蛾设立补充和无补充营养两个处理,研究了食物对棉铃虫 Helicoverpa armigera (Hübner) 生长发育及繁殖的影响。4种食料组幼虫历期之间有显著差异;雌、雄蛹重花生组显著小于其余三组。雌蛾腹部干重及其脂肪百分含量与雌蛹体重的排列顺序一样,雌蛾腹部干重人工饲料组显著大于棉花组和花生组。雌蛾寿命和繁殖受幼虫食料和成虫食物的双重影响。喂10%蜂蜜时,雌蛾寿命、交配率和产卵量在四个幼虫食料组之间没有显著差异。但喂以清水时,花生组雌蛾均未交配,寿命和产卵量显著小于其余三组。从同种幼虫食料来看,除人工饲料组外,其余3组雌蛾喂清水时的产卵量和寿命均比喂10%蜂蜜溶液时的显著下降。基于这些结果,作者认为棉花、玉米比花生更适合于棉铃虫的生长发育和繁殖。在田间自然栽培状态下,不同食料植物的糖分含量对棉铃虫生长发育和繁殖影响较大,含氮量的变化影响小。     

不同龄期棉铃虫用氰戊菊酯汰选对其抗性发展的影响

利用中抗(15.06倍)品系,室内用氰戊菊酯对棉铃虫Helicoverpa armigera初孵至4龄幼虫分别进行连续汰选,选育9代后,以3龄幼虫汰选的抗性发展最快（31.5倍）, 其次是4龄、2龄幼虫汰选的品系（分别增加25.2倍和14.5倍）,用初孵幼虫汰选的抗性发展最慢（10.2倍）。抗性现实遗传力的测定表明,3龄幼虫汰选的抗性现实遗传力（0.4419）显著大于初孵幼虫的（0.2346）。代谢酶抑制剂的增效实验发现,磷酸三苯酯(TPP)对各品系棉铃虫均无明显增效作用。而增效醚(PBO)对高龄幼虫汰选的品系的增效作用比低龄幼虫汰选的品系增效作用强。测定初孵和3龄幼虫汰选品系试虫的击倒抗性发现,初孵幼虫汰选品系的抗性增加倍数（10.2）与击倒抗性增加的倍数（10.5）相似,而3龄幼虫汰选的抗性增加倍数（31.5）显著高于击倒抗性增加的倍数（19.9）。认为初孵幼虫期多功能氧化酶（MFO）表达不完全,用药主要是筛选击倒抗性,而高龄幼虫期用药则会同时筛选击倒抗性和MFO参与的代谢抗性。因而初孵幼虫期用药抗性发展缓慢。生产上不仅可以提高药剂的防效,同时可以延缓抗性的发展。     

抗胆碱酯酶剂亚致死剂量对棉铃虫毒力的影响及对乙酰胆碱酯酶的诱导作用

辛硫磷、马拉硫磷和灭多威3种抗胆碱酯酶剂亚致死剂量（LD10）预处理棉铃虫Helicoverpa armigera 3龄幼虫24 h后,对辛硫磷、马拉硫磷、灭多威、溴氰菊酯和高效氯氰菊酯5种杀虫药剂的毒力影响有明显差异。酶动力学研究表明：在48 h内,辛硫磷亚致死剂量对棉铃虫乙酰胆碱酯酶比活力有一定的抑制作用,24 h仅为对照组的0.56倍;马拉硫磷、灭多威则可以诱导乙酰胆碱酯酶的比活力增加,诱导最大值时间分别为3 h和12 h。通过对米氏常数（K_m）值分析表明,辛硫磷诱导48 h内对乙酰胆碱酯酶与底物亲和力的影响不大,马拉硫磷、灭多威诱导48 h内乙酰胆碱酯酶对底物亲和力有所下降,其中灭多威诱导组最为明显。3种药剂亚致死剂量处理24 h后,通过蔗糖密度梯度离心表明5%蔗糖梯度层乙酰胆碱酯酶分布百分数明显高于对照组,而20%蔗糖梯度层却明显低于对照组,说明亚致死剂量处理可能引起乙酰胆碱酯酶分子型及不同分子型分布比例的变化。     

棉铃虫幼虫感染棉铃虫微孢子虫后的组织病理变化

1997年田间调查时发现一种寄生于棉铃虫Helicoverpa armigera（Hübner）的微孢子虫Nosema sp.,它对棉铃虫有较强的致病力并可经卵垂直传播。利用透射电镜对棉铃虫幼虫感染该微孢子虫后的组织病理变化进行了初步观察。结果表明：该微孢子虫可侵染棉铃虫的中肠、马氏管、脂肪体、神经等组织;侵染后可导致寄主中肠的微绒毛脱落,线粒体内脊排列方向发生变化,线粒体整体发生变形并最终瓦解;内质网发生断裂;细胞核体积变小并变形,但该微孢子虫并不入侵细胞核;马氏管膨大,边缘向外突出隆起;神经细胞的细胞核变成长条形,细胞界线模糊;在神经细胞内也发现了微孢子虫孢子,证明该微孢子虫也入侵寄主神经细胞。     

Influences of insecticides on toxicity and cuticular penetration of abamectin in Helicoverpa armigera

Synergistic actions for mixtures of abamectin with other insecticides in some insect pests were evaluated, and the possible synergistic mechanism was studied by the comparison in toxicity and cuticular penetration of abamectin between with and without other insecticides or synergists in Helicoverpa armigera larvae. The results of bioassay showed that horticultural mineral oil (HMO), hexaflumuron, chlorpyrifos, and some other insecticides were synergistic to abamectin with 152.0-420.0 of co-toxicity coefficient(CTC) in some agricultural insect pests. In topical application tests, HMO or piperonyl butoxide (PBO) increased the toxicity of abamectin in larvae of H. armigera, but the mortality was not affected by s,s,s-tributylphorotrithioate (DEF) and triphenylphosphate (TPP). The synergistic action of HMO was obviously higher than PBO, and when treated simultaneously with abamectin, HMO gave a more significant synergism than if treated 2 hours ahead. The highest synergistic effect (SE) was found in the mixture of ‘abamectin HMO (1:206)‘. The mortality did not increase or the toxicity drop, when a synergist or HMO was added into the mixture of ‘abamectin HMO‘ or ‘abamectin synergist‘, respectively. Results from the isotope tracing experiments showed that HMO significantly enhanced the penetration of ^3H-abamectin through the cuticle of H.armigera larvae, which resulted in the synergism of the mixture. The cuticular penetration of ^3H-abamectin was not accumulatively affected by chlorpyrifos, nor by hexaflumuron,though there was an inhibition within 30 seconds or 1 hour after treated by these two chemicals respectively. Results suggested that the synergism of abamectin mixed with hexaflumuron or chlorpyrifos might be related to inhibition of metabolic enzymes or target sites in the larvae.     

一种棉铃虫多角体病毒的纯化与鉴定

对一株纯化的棉铃虫多角体病毒进行电镜观察,形态呈不规则型,直径约2 μm,命名为棉铃虫多角体-B(Helicoverpa armigera nucleocapsid nucleopolyhedrovirus-B,HaNPV-B),它对东方粘虫有较好的感染性,与棉铃虫单核型多角体病毒(Helicoverpa armigera single nucleocapsid NPV,HaSNPV)有不同的宿主域.通过半补齐法建立HaNPV-B基因组文库,拼接了一个6 035 bp的核苷酸片段,推测包含6个ORF,其包含基因内容及基因结构与HaSNPV不同,分析表明两者是不同种病毒,这为杆状病毒与宿主的相互作用及共同进化提供了信息.     

Effect of modified meridic diet on the development and growth of tomato fruitworm Helicoverpa armigera (Lepidoptera: Noctuidae)

The efficacy of one new modified and two old meridic diets on Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) for rearing six successive generations was studied. Duration of larval development for insects fed on the modified diet was considerably shortened as most of them went through only five stadia before pupation, while the per cent pupation and per cent eclosion were relatively higher than on other diets. The lowest pupal mortality (6.33 ± 0.13%) was recorded in the F₁ generation reared on the modified diet, whereas the highest pupal mortality (19.49 ± 0.15%) was observed in insects reared on a natural diet in the F₆ generation. Blending of chickpea Cicer arietinum L. and red kidney bean Phaseolus vulgaris L. flours with tomato paste proved highly favorable for adult reproduction. These results suggest that the vitality of the tomato fruitworm did not decline obviously after rearing on a modified diet for several generations.     

An in vitro method for increasing UV-tolerance in a strain of Helicoverpa armigera (Lepidoptera: Noctuidae) nucleopolyhedrovirus

A method for increasing tolerance to ultraviolet (UV) radiation in a strain of nucleopolyhedrovirus of cotton bollworm, Helicoverpa armigera (Hübner) (HearNPV) using a solar simulator is described. The Coimbatore isolate (CBE I) of HearNPV was subjected to a five-step sequence of selection to increase its UV tolerance. Each step consisted of irradiation of wet deposits of the virus to near UV (at energy level of 300W/m²), bioassay against second instar H. armigera larvae and propagation in early fifth instar larvae. Selection steps carried out at 15, 30, 60 and 90 minutes of exposure revealed that the continuous exposure of HearNPV-CBE I at low doses of UV irradiation (270–540 KJ/m²) did not significantly affect the virus activity as measured by its biological activity against second instar larvae. Selection at higher doses (1620 KJ/m²) led to loss of viral activity in the first two exposure cycles; however, there was retention of virulence coupled with increased tolerance to UV doses from third cycle onwards. Further, studies on the persistence of UV tolerant strain of HearNPV-CBE I in comparison with original strain showed that the tolerant strain had more persistence even after 7 days of weathering both under exposed (18% original activity remaining) and shaded (26% original activity remaining) condition on potted cotton plant.