Bioefficacy of Aristolochia tagala Cham. against Spodoptera litura Fab. (Lepidoptera: Noctuidae)

Bioefficacy of leaf and root extracts of Aristolochia tagala Cham. at different concentrations was evaluated at room temperature against Spodoptera litura Fab. Effects on feeding, larvicidal and pupicidal activities and larval–pupal duration were studied. Higher antifeedant activity (56.06%), lethal concentration for feeding inhibition (3.69%), larvicidal (40.66%), pupicidal (28%), total mortality (68.66%) and prolonged larval–pupal duration (12.04–13.08 days) were observed in ethyl acetate leaf extract at 5.0% concentration. Dose dependant effect of test extracts was observed. This plant could be used to isolate active principles and to develop a new botanical formulation in pest management programmes.     

Herbivore-induced resistance in different groundnut germplasm lines to Asian armyworm, Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)

Three groundnut germplasm lines, ICGV86699 (resistant), NCAC 343 (resistant) and TMV 2 (susceptible), were examined for Spodoptera litura (Fab.) resistance. Biochemical parameters such as oxidative enzyme activities, peroxidase (POD) and polyphenol oxidase (PPO), other defensive components such as total phenols, hydrogen peroxide (H₂O₂), malondialdehyde (MDA) and protein contents were evaluated in these germplasm lines after 24, 48, 72 and 96 h following S. litura infestation to characterize the mechanism of resistance. Enzyme activities and total phenols, H₂O₂, MDA and protein contents were increased following infestation; however, significance varied at different time intervals and among germplasm lines depending upon the induced level of resistance. The three germplasm lines differed in resistance mechanisms to S. litura and the resistance may be partly due to higher enzyme activities, and other components studied. Among the three germplasms tested, ICGV86699 showed greater elevation in POD and PPO activities and in phenolic and H₂O₂ contents at different time intervals as compared to NCAC 343 and TMV 2.     

Cross-resistance and genetics of resistance to indoxacarb in Spodoptera litura (Lepidoptera: Noctuidae)

Bioassays (at generation G1) with a newly collected field population of Spodoptera litura (F.) (Lepidoptera: Noctuidae) from Multan, Pakistan, showed resistance ratios of 15, 23, 37, and 16 for indoxacarb, spinosad, abamectin, and emamectin, respectively, compared with a laboratory susceptible population, Lab-PK. At G1, the field population was selected with indoxacarb by using single pair crosses. For Indoxa-SEL, bioassay at G4 found that selection increased resistance ratio to 95 for indoxacarb compared with Lab-PK. Selection with indoxacarb significantly increased resistance to spinosad and emamectin; however, resistance to abamectin was observed to drop. A significant reduction in the resistance to indoxacarb was observed in Indoxa-SEL at G9, indicating unstable resistance to indoxacarb; however, it was stable for fipronil. Synergism tests with microsomal oxidase and esterase-specific inhibitors suggested that the indoxacarb resistance was associated with microsomal oxidase. Reciprocal genetic crosses between Indoxa-SEL and Lab-PK populations indicated that resistance was autosomal and incompletely dominant. Tests of monogenic inheritance suggested that resistance to indoxacarb was controlled by more than one locus.     

Bioefficacy of Ceasalpinea bonduc (L.) Roxb. against Spodoptera litura Fab. (Lepidoptera: Noctuidae)

Bioefficacy of hexane, chloroform and ethyl acetate extracts of the seeds of Ceasalpinea bonduc (L.) Roxb. was studied against third instar larvae of Spodoptera litura at 0.25, 0.5, 1, 2.5 and 5.0% concentrations. Significant antifeedant, larvicidal and pupicidal activities and least LC₅₀ values were observed in chloroform extract. The chloroform extract was subjected to fractionation using silica gel column chromatography. Six fractions were obtained; among these, the third fraction showed high antifeedant, larvicidal and pupicidal activities at 1000 ppm concentration. Abnormalities in adults were also observed. All the activities were concentration dependent. C. bonduc could be useful in integrated pest management programme.     

杀菌剂丙环唑对斜纹夜蛾的毒性

在研究比较了11种农药对斜纹夜蛾Spodoptera litura细胞（简称SL细胞）的毒杀活性基础上,选择毒杀活性最高的杀菌剂丙环唑,对其毒理学机理进行进一步研究。结果表明,丙环唑的细胞毒力最高,在100 μg/mL浓度下处理后48 h,SL细胞的死亡率为98.08％。处理后36 h,丙环唑对SL细胞的LC₅₀值为20.31 μg/mL。丙环唑能明显降低SL细胞的蛋白质含量。以0.5 μg/头的丙环唑注射斜纹夜蛾4龄幼虫,处理后72 h,试虫血淋巴总含量及血细胞数分别下降了26.80％和25.26％;在1.0 μg/头的剂量下,则分别下降了37.67%和36.32%。以0.5 μg/头和1.0 μg/头的丙环唑注射处理后,斜纹夜蛾幼虫体重显著降低。此外,丙环唑能降低斜纹夜蛾幼虫血淋巴含糖量及血淋巴蛋白质含量。在注射处理后96 h和120 h,丙环唑对斜纹夜蛾4龄幼虫的LD₅₀值分别为0.59 μg/头和0.45 μg/头。丙环唑对SL细胞和斜纹夜蛾幼虫均具有较好的毒杀活性,显示出丙环唑类似物控制害虫的可能性。     

Herbivore- and Elicitor- Induced Resistance in Groundnut to Asian armyworm,Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)

Induced defense was studied in three groundnut genotypes ICGV 86699 (resistant), NCAc 343 (resistant) and TMV 2 (susceptible) in response to Spodoptera litura infestation and jasmonic acid (JA) application. The activity of the oxidative enzymes [peroxidase (POD) and polyphenol oxidase (PPO)] and the amounts other host plant defense components [total phenols, hydrogen peroxide (H2O2), malondialdehyde (MDA), and protein content] were recorded at 24, 48, 72 and 96 h in JA pretreated (one day before) plants and infested with S. litura, and JA application and simultaneous infestation with S. litura to understand the defense response of groundnut genotypes against S. litura damage. Data on plant damage, larval survival and larval weights were also recorded. There was a rapid increase in the activities of POD and PPO and in the quantities of total phenols, H2O2, MDA and protein content in the JA pretreated + S. litura infested plants. All the three genotypes showed quick response to JA application and S. litura infestation by increasing the defensive compounds. Among all the genotypes, higher induction was recorded in ICGV 86699 in most of the parameters. Reduced plant damage, low larval survival and larval weights were observed in JA pretreated plants. It suggests that pretreatment with elicitors, such as JA could provide more opportunity for plant defense against herbivores.     

Time-of-day specific changes in pesticide detoxification ability of Spodoptera litura (Lepidoptera: Noctuidae)

Circadian clocks govern daily physiological and molecular rhythms, and putative rhythms in the expression of metabolizing xenobiotics have been described in insects. Such rhythms could have important consequences for outcomes of chemical exposures at different times of the day. The proportion of photophase (light) and scotophase (dark) also influence the enzyme activities. Several studies have been done on the mechanism of insecticide resistance in Spodoptera litura exposed to chemical insecticides. This study is aimed at understanding the circadian variations of cypermethrin detoxification mechanisms in S. litura. The toxicity of insecticide, cypermethrin exposed to three different photoperiods in 3rd instar larvae of S. litura has been investigated. Detoxification enzyme profiles of α- and β-esterases, glutathione S-transferase (GST), and cytochrome P450 (Cyt P450) were assessed. The results showed that larvae were more tolerant to cypermethrin treated larvae at 8 h L: 16 h D photoperiod as compared with two other photoperiods tested. We observed significant increases in α- and β-esterases and cyt P450 activities in 4 and 8 h at different photoperiods. GST activity was significantly changed at different photoperiods at different timings. Activities of specific detoxification enzymes fluctuated during the time, and for specific insecticides, the concentration resulting in 50% mortality varied significantly during the different photoperiods. The time of the day when chemical exposure is imposed should be an important consideration in the experimental design, and use of pesticides.     

氟铃脲对斜纹夜蛾酚氧化酶活性的影响

【目的】探讨氟铃脲对斜纹夜蛾Spodoptera litura酚氧化酶活性的影响.【方法】应用酶动力学法,在确定斜纹夜蛾酚氧化酶最适反应条件基础上,测定氟铃脲与酚氧化酶直接作用及氟铃脲处理幼虫后酚氧化酶的活性.【结果】以邻苯二酚为底物,斜纹夜蛾酚氧化酶的最适pH 6.5,最适温度30℃.氟铃脲没有和酚氧化酶结构中的铜离子结合,而是直接与酶蛋白发生作用.氟铃脲浓度低于1 153 mg/L对离体酚氧化酶有激活作用,在138 mg/L激活作用最大,浓度高于1 153 mg/L则产生抑制作用.用46 mg/L和92 mg/L亚致死剂量氟铃脲连续处理5龄幼虫不同时间后,酚氧化酶活性均显著提高,且高浓度的激活作用大于低浓度的激活作用.进一步测定药剂处理幼虫24,48和72 h的血淋巴、表皮和头部酚氧化酶活性,随着氟铃脲处理时间延长,两个剂量的氟铃脲对血淋巴、表皮及头部酚氧化酶的激活作用逐渐增大,氟铃脲对血淋巴酚氧化酶的激活作用最大,表皮次之,头部最低.氟铃脲处理幼虫后,其预蛹和蛹酚氧化酶的活性也显著提高,表现出一定的后效应.【结论】一定浓度范围内,氟铃脲对斜纹夜蛾酚氧化酶具有激活作用.     

不同温度下斜纹夜蛾的两性生命表

【目的】斜纹夜蛾Spodoptera litura(Fabricius)是一种鳞翅目夜蛾科食叶害虫,在不同的寄主、饲料等条件下表现出不同的生长发育特点。本实验旨在探究温度对斜纹夜蛾生长发育状况和种群参数的影响。【方法】在室内人工气候箱20±1℃,27±1℃和30±1℃(相对湿度和光周期分别为65%±10%和14L∶10D)条件下饲养斜纹夜蛾,观察和组建斜纹夜蛾在3种温度下的年龄-阶段两性生命表。【结果】斜纹夜蛾各个阶段的发育历期随温度升高变短,成虫产卵前期(adult preoviposition period,APOP)和总产卵前期(total preoviposition period,TPOP)同样表现为随温度升高而变短。此外,20±1℃处理的平均产卵量最高(1 810.36粒/雌),27±1℃处理次之(1 623.51粒/雌),30±1℃处理最低(1 084.60粒/雌)。斜纹夜蛾在不同温度条件下内禀增长率(r)、周限增长率(λ)和净增殖率(R0)有显著差异,20±1℃处理的r和λ显著低于27±1℃处理和30±1℃处理;27±1℃处理的R0显著大于20±1℃和30±1℃处理;20±1℃,27±1℃和30±1℃下平均世代周期(T)分别为52.51,30.63和26.87 d,依次减少且相互间差异显著(P0.05)。【结论】斜纹夜蛾在27±1℃和30±1℃温度条件下均表现出很强的增殖能力,该结果可为田间综合防治斜纹夜蛾提供理论依据。     

斜纹夜蛾对氯氟氰菊酯不同抗性水平与解毒代谢酶的关系

为探讨斜纹夜蛾Spodoptera litura (Fabricius)对氯氟氰菊酯抗性水平与解毒代谢酶之间的关系, 以泰安郊区对氯氟氰菊酯抗性为543.7倍的斜纹夜蛾田间种群为材料, 研究了药剂汰选与否的抗性动态及不同抗性水平的解毒代谢酶活性变化。结果表明: 室内继代饲养至第30代, 不接触任何药剂的抗性下降至102.3倍, 用氯氟氰菊酯汰选28代后, 抗性上升到3 049.3倍, 而在药剂汰选至第14代, 抗性已至2 593.8倍时, 停止用氯氟氰菊酯汰选, 到第30代的抗性又降至786.3倍。表明斜纹夜蛾抗氯氟氰菊酯田间种群, 在无药剂选择压力时抗性水平会显著下降, 继续给予药剂汰选会使抗性水平显著上升。检测斜纹夜蛾田间种群5龄幼虫中肠酯酶和谷胱甘肽S-转移酶活性, 发现与敏感种群有显著性差异, 而多功能氧化酶O-脱甲基活性与敏感种群的差异不明显; 给予氯氟氰菊酯药剂汰选, 酯酶、谷胱甘肽S 转移酶和多功能氧化酶O-脱甲基3种酶的活性均呈显著增加趋势; 停止用氯氟氰菊酯汰选后, 3种酶的活性又呈显著下降趋势; 不接触任何药剂, 随着饲养世代数的增加, 其酯酶和谷胱甘肽S-转移酶的活性也呈下降趋势。结果提示斜纹夜蛾幼虫酯酶、谷胱甘肽S-转移酶和多功能氧化酶O-脱甲基活性的提高是斜纹夜蛾对氯氟氰菊酯抗性上升的重要原因。     

Sub-lethal effects of SpltMNPV infection on developmental stages of Spodoptera litura (Lepidoptera: Noctuidae)

Application of different doses of SpltMNPV on final instars of Spodoptera litura showed dose-related mortality. A significant increase in the time for pupation and progeny mortality as well as reduced fecundity was observed in surviving larvae. Impact of sublethal doses on subsequent generation needs attention in designing baculovirus-based pest management.     

Exposure to herbicides reduces larval sensitivity to insecticides in Spodoptera litura (Lepidoptera: Noctuidae)

Herbicides and insecticides are widely used in modern agriculture. It has been reported in various studies that application of insecticides can increase tolerance of herbivorous insects to insecticides. However, limited information exists on susceptibility to insecticides when insects are exposed to herbicides. This study was conducted to investigate the potential impact of the herbicides trifluralin and 2-methyl-4-chlorophenoxyacetic acid sodium salt (MCPA-Na) on the susceptibility of the nocturnal moth Spodoptera litura to the insecticides X-cyhalothrin, phoxim and bifenthrin. We found that larvae exposed to trifluralin or MCPA-Na became significantly less susceptible to both insecticides than nonexposed control larvae. Herbicide-treated larvae did not show altered growth under the used test conditions. However, heads of herbicide-treated larvae showed increased expression of the acetylcholinesterase genes SI Ace I and SI Ace 2. Moreover, the fat body and midgut of herbicide-treated larvae displayed elevated expression of detoxification genes (the carboxylesterase gene SI CarE;the glutathione S-transferase genes SlGSTe2 and SlGSTe3\ the cytochrome P450 monooxygenase genes CYP6B48, CYP9A40 and CYP321B1). The CYP6B48 gene exhibited highest inducibility. In conclusion, the data of this study suggest that exposure of S. litura larvae to herbicides may stimulate detoxification mechanisms that compromise the efficacy of insecticides.     

Effect of plant secondary metabolites on common cutworm,Spodoptera litura (Lepidoptera: Noctuidae)

The effect of various flavonoids, lectins and phenyl β‐_D‐glucoside on larval survival, weights and the activities of digestive (total serine protease and trypsin) and detoxifying (esterase and glutathione‐S‐transferase) enzymes of Spodoptera litura larvae at 7 days after treatment was studied through diet incorporation assay. Flavonoids (rutin, chlorogenic acid, quinic acid, caffeic acid, naringenin, quercitin, kaempferol, myricetin, catechin, and ferulic acid) were incorporated in artificial diet at 100, 500 and 1000 ppm, lectins: groundnut leaf lectin (GLL), concavalin A (ConA) and phenyl β‐_D‐glucoside at 1, 2 and 5 μg/mL. Flavonoids such as rutin, quercitin and kaempferol at 1000 ppm were more toxic to S. litura larvae than quinic acid, caffeic acid, naringenin, myricetin, catechin, and ferulic acid. Larval growth and development were significantly reduced in S. litura larvae fed on a diet with GLL and ConA at 5 μg/mL compared to the larvae fed at 2 and 1 μg/mL concentrations. The larvae fed on flavonoid‐treated diets showed significant reduction in serine protease, trypsin and esterase activities. The flavonoids such as rutin, chlorogenic acid, quinic acid, naringenin, quercitin, kaempferol and myricetin, and lectins, GLL and ConA can be utilized in insect control programs.     

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。     

Efficient incorporation of unsaturated fatty acids into volicitin-related compounds in Spodoptera litura (Lepidoptera: Noctuidae)

We introduced efficient incorporation of unsaturated fatty acids into volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and N-linolenoyl-L-glutamine, insect-derived elicitors of plant volatiles, in the common cutworms Spodoptera litura by the incubation of larval gut tissues with unsaturated (linolenic, linoleic, and oleic acids) or saturated fatty acids (palmitic and stearic acids) sodium salt, and L-[alpha-(15)N]glutamine.     

Ventral exocrine gland of larva of Spodoptera (Prodenia) litura (Fabricius) (Lepidoptera: Noctuidae).

The morphological and histological structure of the ventral exocrine gland of the larva of the tobacco caterpillar, Spodoptera (Prodenia) litura (Fab.) is shown. The proximal region of the gland is capable of protrusion through the prothoracic sternal slit as an elongate organ reaching upto the spinneret. The middle region of the gland shows characteristic giant cells in only one of the walls of the epithelium, while the distal region shows a thin flat epithelium with small round closely situated nuclei resting against the tunica propria. The gland probably secretes a gummy fluid for larval movements rather than a stinking odourous fluid for defense.     

Laboratory evaluation of flight activity of the common cutworm, Spodoptera litura (Lepidoptera: Noctuidae)

Abstract  The flight activity of Spodoptera litura in tethered conditions is evaluated using a computer-mediated flight-mill in the laboratory. The 3–4-day-old moths fly longer and farther than those of other ages. Male and female moths exhibit similar flight activity. Mating status does not influence the flight duration and distance of 2-day-old females. However, these two flight parameters with a 6-day-old mated female is significantly lower than that of unmated ones. The optimum temperature for flight ranged from 16–24°C, whereas the optimum RH ranged from 60%–100%. During 72-h period, the total flight duration and distance of 1-day-old male and female moths were 19.6 h (± 5.8) and 83.3 km (± 28.4), and 24.0 h (± 7.0) and 105.4 km (± 37.4), respectively. These results indicate that S. litura has a great potential to undertake long-distance migratory flights.     

Evaluation of substituted oxime ethers for growth regulatory activity against Spodoptera litura (Lepidoptera: Noctuidae)

Insect growth regulator (IGR) activity of 52 substituted oxime ethers was evaluated against an important polyphagous lepidopteran pest, Spodoptera litura (F.) (Lepidoptera: Noctuidae). Several compounds produced symptoms comparable to exogenously applied juvenile hormone. Maximum ICR activity was exhibited by 4'-(2,6,6-trimethyl-2-cyclohexen-1-yl)-3'-buten-2'(E)-ketoxime-N-O-alkyl ether with an ED50 (morphological) of 40 microg g(-1) body weight, compared with 20 microg g(-1) of juvenile hormone (JH) III. Two more compounds, namely, 4'-(2,6,6-trimethyl-2-cyclohexen-1-yl)-3'-buten-2'(Z)-ketoxime-N-O-methyl propyl ether (ED50 of 192 microg g(-1)) and 4'-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3'-buten-2'(E)-ketoxime-N-O-pentyl ether (ED50 of 380 microg g(-1)) showed considerable IGR activity, whereas 4'-(2,6,6-trimethyl-2-cyclohexen-1-yl)-3'-buten-2'(E)-ketoxime-N-O-pentyl ether was found to be acutely toxic to larvae (ED50 of 268 microg g(-1)). Three compounds used in this study also were synergized by piperonyl butoxide. Synergistic ratios ranged from 1.330 to 4.605. No significant ovicidal activity was obtained.     

Identification and localization of two sensory neuron membrane proteins from Spodoptera litura (Lepidoptera: Noctuidae)

Sensory neuron membrane proteins (SNMPs), which are located on the dendritic membrane of olfactory sensory neurons (OSNs), are proposed to be associated with odor reception in insects. Recent studies have demonstrated that SNMP1 is essential for electrophysiological responses of OSNs to the sex pheromone, cis‐vaccenyl acetate (cVA) in Drosophila melanogaster. To investigate the function of Lepidoptera SNMPs, we cloned two SNMP genes, SlituSNMP1 and SltiuSNMP2, from Spodoptera litura (Lepidoptera: Noctuidae). Sequence alignment and phylogenetic analysis showed that both genes bear the general characteristics of SNMPs, including six conserved cysteine residues and two transmembrane domains. Further expression profile experiments showed that SlituSNMP1 is mainly expressed in the antenna, while SlituSNMP2 is broadly expressed in various tissues. By in situ hybridization experiments, it was found that SlituSNMP1 expressing cells are surrounded by the SlituSNMP2 expressing cells in the pheromone sensitive sensilla, suggesting different functions of the two SNMPs in insect olfaction.