Methyl jasmonate induced responses in four plant species and its effect on Spodoptera litura Fab. performance

Defensive proteins, such as polyphenol oxidase (PPO) and trypsin inhibitor (TI), are induced by herbivore wounding and exogenous methyl jasmonate application in various plant species. This study was conducted to measure induction of PPO and TI in radish, sweet pepper, tomato, and water spinach plants following herbivore wounding (I), methyl jasmonate application (M), and a combination of the two treatments (M + I). The effect of induced responses was also examined against third instar Spodoptera litura Fab. PPO activity was induced in radish by treatment I only; in sweet pepper, by treatments I and M; in tomato, by treatments I, M, and M + I; and in water spinach, by treatments M and M + I. The activity of TI was enhanced 1.2–1.4-fold in radish, sweet pepper, and tomato by M and M + I treatments, whereas in water spinach, it was enhanced 1.2-fold by all 3 treatments. The relative growth rate (RGR) of S. litura was reduced by 53% on radish plants following M treatment only. It was reduced by 37% and 42% on sweet paper plants following M and M + I treatment, respectively. RGR was significantly reduced on test tomato plants following I, M, and M + I treatments. The RGR of S. litura was unaffected on water spinach plants following any treatment. Collectively, the results of this study indicated that induction of plant defensive proteins in response to S. litura feeding or exogenous methyl jasmonate application varied among plant species, which further affected the induced plant resistance to the caterpillars.     

Resistance in hybrid derivatives of Lycopersicon accessions against leaf caterpillar, Spodoptera litura Fab.

Four tomato accessions, namely Ac 238, Roma, Seijima Jeisei and Varushanadu Local selected from preliminary screening of 321 accessions and their hybrid derivatives, namely HY₁F₁ (Varushanadu Local × Ac 238), HY₂F₁ (Varushanadu Local × Roma), HY₃F₁ (Ac 238 × Roma) (first generation), HY₁F₂, HY₂F₂ and HY₃F₂ (second generation) were evaluated for their resistance in comparison with a susceptible check, 1979 against the leaf caterpillar, Spodoptera litura Fab. both under field and laboratory conditions at Annamalainagar, Tamil Nadu, India. In the field evaluation, accession Seijima Jeisei and hybrid HY3F1 recorded the minimum larval population. In glasshouse and laboratory studies, Seijima Jeisei was the least preferred by S. litura for both feeding and oviposition. The hybrid HY₃F₁ exerted pronounced antibiosis effect on S. litura. Among the various biophysical and biochemical bases of resistance, contents of reducing sugar and phenol were found negatively correlated with S. litura larval feeding. Among the hybrids, HY₃F₁ and HY3F2 and the parent Seijima Jeisei recorded higher fruit yield per plant in both seasons. Considerable variation in the resistance traits of the hybrids was observed when compared with the parents.     

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.     

斜纹夜蛾天敌作用的评价

通过组建斜纹夜蛾第４代和第８代自然种群生命表,运用排除作用控制指数分析了生物因子对斜纹夜蛾种群的自然控制作用．结果表明,低龄（１～３龄）幼虫的捕食性天敌是影响斜纹夜蛾种群数量动态的重要因子．对第４代和第８代种群的排除作用控制指数分别为１３．９０４和１２．９４６．如果没有捕食性天敌的作用,下代种群数量将分别增长到当代的１５．１２０６和７４．６７８倍．病原微生物是影响第４代斜纹夜蛾种群数量的另一重要因子,其排除作用控制指数为２．４７２６．     

Rearing and life table of reduviid predator Rhynocoris marginatus Fab. (Het., Reduviidae) on Spodoptera litura Fab. (Lep., Noctuidae) larvae

The tobacco armyworm, Spodoptera litura Fab., a serious pest of many cultivated crops was evaluated as prey for the reduviid predator, Rhynocoris marginatus Fab. The development, sex ratio, fecundity, hatchability and adult longevity of R. marginatus were investigated in the laboratory. Moreover, a life table was constructed for this predator. Observations clearly indicated that total developmental period of this predator was 46.71±1.58 days. In sex ratio, no significant difference was observed between male and female predators. The pre-oviposition period lasted for 18.64±0.76 days and it was 6.31 times shorter than the oviposition period. Female predators lived longer (128.04±8.48 days) than males (82.84±11.09 days). The total number of eggs laid per female predator in its life span was 405.28±22.15 eggs and the incubation period lasted for 6.81±0.10 days. Life-table studies showed that the intrinsic rate of increase was 0.063 female/day. The population multiplied 292.28 times in the cohort generation time of 103.933 days.     

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.     

Biochemical mechanism of chlorantraniliprole resistance in Spodoptera litura (Fab) (Lepidoptera: Noctuidae)

Spodoptera litura, a polyphagus insect pest of economic importance, having the ability to develop resistance to various classes of insecticides was selected for the study. Leaf dip bioassay studies were done after ten generations of selection pressure reported the development of resistance up to 80 folds by S. litura against chlorantraniliprole compared to lab susceptible strain. Bioassay studies conducted using enzyme inhibitors such as triphenyl phosphate (TPP) followed by diethyl-maleate (DEM) and piperonyl butoxide (PBO) showed good amount of synergism with chlorantraniliprole and improved efficacy against resistant strain. Findings of bioassay studies were supported by in-vitro enzyme inhibition assays. Esterase activity in gut homogenate of resistant strain was significantly inhibited by TPP suggesting esterase mediated biochemical resistance development in S. litura against chlorantraniliprole.     

Interaction of Xestia c-nigrum granulovirus with peritrophic matrix and Spodoptera litura nucleopolyhedrovirus in Spodoptera litura

Xestia c-nigrum granulovirus (XcGV) was tested for its ability to increase Spodoptera litura nucleopolyhedrovirus (SINPV) infection in larvae of S. litura (F.). The interaction of XcGV with peritrophic matrix and SINPV in S. litura also was studied to account for the synergism. In dose-response bioassays with a constant XcGV concentration of 5-mg/ ml capsules and SINPV concentration that varied from 10(3) to 10(7) polyhedral inclusion bodies (PIB) per larva, XcGV increased the virulence of SINPV infection in fifth instars of S. litura. The lethal concentration of 50% individuals (LC50) of SINPV combined with XcGV was 3.35 x 10(5)PIB/ml, which was significantly lower than that of SINPV alone (2.17 x 10(6)). Compared with 10(7) PIB/ml SINPV alone, the lethal time of 50% individuals (LT50) of 10(7) PIB/ml SINPV combined with XcGV was not significantly shortened. In addition, no significant improvement in the activity and killing speed of SINPV progeny was noted after propagation with XcGV, indicating that native characters of SINPV associated with viral potency were not altered by XcGV. Investigation via environmental scanning electronic microscopy showed that the peritrophic matrix (PM) of S. litura exposed to XcGV or XcGV enhancin, or the combination treatment, was markedly disrupted. The outer surface of the PM was loose, or ruptured, which potentially facilitated the passage of virions through the PM. Therefore, it is reasonable to conclude that the synergy between XcGV and SINPV was closely associated with the disruption of the PM in S. litura.     

几种虫生真菌对斜纹夜蛾的致病性

用布氏白僵菌、球孢白僵菌、玫烟色拟青霉、绿僵菌和莱氏野村菌5种真菌的固体培养物,对斜纹夜蛾2、3龄幼虫进行了毒力测定.结果表明：布氏白僵菌和莱氏野村菌两种菌株对斜纹夜蛾幼虫有明显的致病效果,对2龄幼虫的致死中时(LT₅₀)分别为2.95 d和4.10 d,累计校正死亡率分别为100%和95.2%;对3龄幼虫的致病力低于2龄,致死中时(LT₅₀)分别为19.67 d和19.63 d,累计校正死亡率分别为56.6%和52.2%.玫烟色拟青霉、球孢白僵菌两菌株也有一定的致病力,对2龄幼虫的致死中时(LT₅₀)分别为4.89 d 和6.34 d,累计校正死亡率分别为85.7%和71.4%.     

Influence of foliar chemical compounds on the development of Spodoptera litura (Fab.) in interspecific derivatives of groundnut

Abstract:  Tobacco armyworm, Spodoptera litura (Fab), a polyphagous insect, is an important pest of groundnut ( Arachis hypogaea L). It is one of the insect pests which had developed resistance to insecticides. Currently there are no cultivars of groundnut which express high level of resistance to S. litura . Wild species of groundnut, which show high levels of resistance, have been identified. Arachis kempff-mercadoi is one such wild species, which is reported to be resistant to S. litura , and indicated that in wild species three flavonoids chlorogenic acid, quercetin and rutin are involved in the components of resistance. In the present study, although these flavonoids had an effect on larval mortality, statistical analysis revealed that quercetin had a major effect due to high correlation of quercetin with chlorogenic acid and rutin. Interspecific derivatives were obtained as a result of crossing cultivated groundnut with A. kempff-mercadoi . In vitro studies showed high percentage of neonate larval mortality when fed on the foliage of interspecific derivatives, majority of interspecific derivatives were detrimental to larval development and had considerable effect on its subsequent progeny. Resistant derivatives were found to have high levels of flavonoids and antibiosis mechanism prevented larval growth. Susceptible derivatives and the female parent, A. hypogaea have low levels of flavonoids.     

Genetics of resistance to Cry1C toxin from Bacillus thuringiensis in Spodoptera litura (Fab.)

The present study was undertaken to determine the genetics of Cry1C resistance in Spodoptera litura. Selection of S. litura (Fab.) with Cry1C was done for eight generations to develop resistance. Reciprocal crosses between resistant and susceptible populations were made to understand the population genetics of Cry1C resistance in S. litura. Generation wise selection with Cry1C was evaluated for resistance development in S. litura. The LC₅₀ of Cry1C was 0.14 µg/cm² for the first selected generation and it increased to 23.98 µg/cm² after eight selected generations, which is a 285.47-fold increase in resistance compared with the susceptible strain. The estimated realized heritability (h²) after eight generations of selection with Cry1C insecticidal protein was 0.44. The number of generations required for the tenfold increase in LC₅₀ (1/R) was estimated to be 3.33. Response to Cry1C selection in S. litura was 0.30, the estimated selection differential was 0.69 and the pheonotypic standard deviation (dP) was 0.24. Reciprocal crosses between Cry1C resistant and susceptible strain of S. litura showed autosomal resistance.     

The Predicted Influence of Climate Change on Lesser Prairie-Chicken Reproductive Parameters

The Southern High Plains is anticipated to experience significant changes in temperature and precipitation due to climate change. These changes may influence the lesser prairie-chicken (Tympanuchus pallidicinctus) in positive or negative ways. We assessed the potential changes in clutch size, incubation start date, and nest survival for lesser prairie-chickens for the years 2050 and 2080 based on modeled predictions of climate change and reproductive data for lesser prairie-chickens from 2001–2011 on the Southern High Plains of Texas and New Mexico. We developed 9 a priori models to assess the relationship between reproductive parameters and biologically relevant weather conditions. We selected weather variable(s) with the most model support and then obtained future predicted values from climatewizard.org. We conducted 1,000 simulations using each reproductive parameter’s linear equation obtained from regression calculations, and the future predicted value for each weather variable to predict future reproductive parameter values for lesser prairie-chickens. There was a high degree of model uncertainty for each reproductive value. Winter temperature had the greatest effect size for all three parameters, suggesting a negative relationship between above-average winter temperature and reproductive output. The above-average winter temperatures are correlated to La Niña events, which negatively affect lesser prairie-chickens through resulting drought conditions. By 2050 and 2080, nest survival was predicted to be below levels considered viable for population persistence; however, our assessment did not consider annual survival of adults, chick survival, or the positive benefit of habitat management and conservation, which may ultimately offset the potentially negative effect of drought on nest survival.     

Enhancing the efficacy and persistency of Spodoptera litura (Fab.) nuclear polyhedrosis virus using UV irradiation protectants

To enhance the field persistency of S. litura nuclear polyhedrosis virus (SLNPV), three chemicals viz. cupric ammonium nitrate, tinopal and cupric sulphate were tried as protectants (0.01 mg/ml) against natural sunlight (UV) irradiation. On exposure for 8 hr and subsequent bioassaying (diet surface treatment), it was found that cupric sulphate protected the polyhedrosis inclusion bodies (PIBs), recording 95.56% mortality which was statistically at par with unexposed PIBs recording 97.78% mortality.     

Influence of post-treatment temperature, solvents and emulsifiers on the toxicity of cypermethrin to larvae of Spodoptera litura (Fab.)

Larvae of the tobacco caterpillar, Spodoptera litura (Fab.) were topically bioassayed with cypermethrin emulsion formulation and proprietary EC in combination with different solvents and emulsifiers for their toxicity at 16 ± 2°C and 27 ± 1°C. Among different solvents, the descending order of efficacy (with relative toxicity in parenthesis) against 9 ± 1 day old larvae of S. litura (Fab.) at 16 ± 2°C than 27 ± 1°C was: xylene (7.41), aromex (5.54), cyclohexane (4.93), C-IX (3.93), benzene (2.40) and toluene (2.26). With emulsifier, the order was: Triton X-100 (7.41), SN₄S (4.60), Teepol (2.90), Tween-80 (1.49), Swascofix DP-50 (1.28), SN₄R (1.10) and S₅₂B (1.07). However, the proprietary cypermethrin EC was 2.31 times more toxic at 16 ± 2°C than at 27 ± 1°C.     

草地贪夜蛾与斜纹夜蛾解毒相关基因的比较分析

草地贪夜蛾Spodoptera frugiperda近期在中国为害猖獗,由于繁殖速度快,迁飞能力强,在本土呈现爆发趋势,严重为害了我国农作物。与本地近缘物种斜纹夜蛾Spodoptera litura相比,草地贪夜蛾更偏好玉米、水稻、小麦等禾本科农作物,且对多种化学杀虫剂及转基因Bt玉米产生抗性。寄主适应性以及杀虫剂抗性与解毒代谢相关蛋白密切相关。因此,本研究对这两种夜蛾科害虫的解毒代谢相关蛋白——细胞色素P450、谷胱甘肽转移酶(GST)及ABC转运蛋白进行了全基因组水平系统的搜集和数目比较,构建系统发育树并对P450和GST部分基因扩张分支进行氨基酸差异位点分析。结果显示,在草地贪夜蛾中共鉴定出213个P450基因、58个GST基因、102个ABC基因,其中P450基因与GST基因数目远远多于斜纹夜蛾(116,37),而ABC基因数目与斜纹夜蛾(99)接近。系统发育树分析表明,草地贪夜蛾P450在CYP6、CYP9以及CYP4功能簇,GST在部分进化分支上都发生了显著基因扩张,发生显著扩张的基因中有数个氨基酸突变,其中一些突变被预测可能影响蛋白质功能。但出乎意料的是,ABC亚家族B和E在斜纹夜蛾聚集成簇并发生了显著的基因扩张现象。以上结果暗示入侵种草地贪夜蛾和本地近缘物种斜纹夜蛾在抗性方面可能发展出各自独特的应对机制。本研究为解析草地贪夜蛾解毒抗性特征机制提供基因数据,为草地贪夜蛾的生物防治及抗性研究提供参考依据。     

温度和食料对斜纹夜蛾种群的影响

用正弦模型Ｖ（Ｔ）＝Ａ＋Ｂｓｉｎ（Ｃ０＋Ｃ１ｅ＾Ｃ３Ｔ＋Ｃ２ｅ＾－Ｃ３Ｔ）拟合了斜纹夜蛾（Ｓｐｏｄｏｐｔｅｒａ ｌｉｔｕｒａ）发育与温度的关系,并用直接最优法估算了斜纹夜蛾不同发育阶段的温度阈值和所需热量。根据不同温度下的实验种群生命表资料,拟合了斜纹夜蛾不同发育阶段的存活率与温度关系的模型,卵、低龄幼虫、高龄幼虫、蛹的理论最适温度分别为２６．７、２４．７、２４．９、２５．８℃。本文研究了甘蓝、     

In-vitro assessment of food consumption,utilization indices and losses promises of leafworm,Spodoptera litura (Fab.), on okra crop

The lepidopteran insect pests have significant importance in vegetable production. The present study was performed to investigate the baseline studies about the assessment of feeding and consumption potential, utilization indices and losses promises of leafworm, Spodoptera litura (Fab.) on Okra. The data regarding feeding potential, food utilization and consumption indices as well as losses of different larval instars were recorded and subjected to appropriate statistical analysis. The results showed that, in the beginning, the approximate digestibility of various instars was increase, e.g. third instar (51.36%–64.03%), fourth instar (63.42%–69.45%) and fifth instar (70.25%–76.10%). However, after a certain period, the digestibility was decreased and efficiency to convert the ingested food into biomass varied significantly. The consumption index values increased with an increase in time but the consumption and growth rate was declined of fourth instar larvae. The ingestion and digestion increased of third (10.01–13.06, 8.32–11.91 mg), fourth (11.27–17.28, 10.96–14.03 mg) and fifth (12.60–19.40, 11.93–15.28 mg) larval instars. The corrected weight of consumed leaves increased with a gain in body weight. However, in the third instar, a decline was observed on the last day of feeding. Maximum leaf area was consumed by fifth instar larvae (44.66 cm²) followed by fourth (35.41 cm²) and third (27.98 cm²) instars. In conclusion, all the dependent parameters, including food utilization potential, consumption indices and losses were higher for fifth instar larvae than others. These results emphasized the re-establishment of fundamental (economic threshold level: ETL, economic injury level: EIL) integrated pest management concepts.     

斜纹夜蛾羧酸酯酶基因的克隆、序列分析及表达水平

为了明确斜纹夜蛾Spodoptera litura对溴氰菊酯产生抗性的分子机理, 本研究利用RT-PCR技术和RACE方法获得了1个斜纹夜蛾羧酸酯酶基因的全长cDNA序列, 命名为Slest2。序列分析表明, 该cDNA全长1 796 bp（GenBank 登录号: DQ445461）, 5′和3′UTR区分别长63和119 bp,开放阅读框编码一个由537个氨基酸残基组成的羧酸酯酶蛋白。通过对氨基酸同源性分析表明, 该羧酸酯酶与其他物种的酯酶均具有很高的氨基酸相似性,并具有多个在不同酯酶蛋白家族中均保守的区域。采用实时定量PCR技术比较了Slest2在斜纹夜蛾抗、感品系中的表达水平。当以cDNA为模板检测mRNA转录水平时发现, Slest2在抗性品系中的转录水平是敏感品系的46.85倍; 以基因组DNA为模板检测Slest2基因的拷贝数时发现, Slest2在抗、感性品系中的拷贝数无显著差异（前者为后者的1.16倍）。这些结果表明, 抗性与敏感品系具有相似的Slest2基因拷贝数, 但它们在抗性品系中的转录水平显著升高。由此推测Slest2基因的转录水平升高与斜纹夜蛾对溴氰菊酯的抗药性密切相关。     

Pest scenario of Spodoptera litura (Fab.) on groundnut under representative concentration pathways (RCPs) based climate change scenarios

Multi-model ensemble of Maximum (Tmax) and Minimum (Tmin) temperature data of four Representative Concentration Pathways viz., RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 of Coupled Model Intercomparison Project 5 (CMIP5) models were generated for ten major groundnut growing locations of the India to predict the number of generations of Spodoptera litura (Fab.) using Growing Degree Days approach during three future climate viz., Near (NF), Distant (DF) and Very Distant (VDF) periods and were compared over 1976–2005 baseline period (BL). Projections indicate significant increase in Tmax (0.7–4.7 °C) and Tmin (0.7–5.1 °C) in NF, DF and VDF periods under the four RCP scenarios at the ten groundnut growing locations. Higher percent increase of the number of generations of S. litura was predicted to occur in VDF (6–38%) over baseline, followed by DF (5–22%) and NF (4–9%) periods with reduction of generation time (5–26%) across the four RCP scenarios. Reduction of crop duration was higher (12–22 days) in long duration groundnut than in medium and short duration groundnut. Decrease in crop duration was higher in VDF (12.1–20.8 days) than DF (8.26–13.15 days) and NF (4.46–6.15 days) climate change periods under RCP 8.5 scenario. Increase in number of generations of S. litura was predicted even with altered crop duration of groundnut. Among locations, more number of generations of S. litura with reduced generation time are likely at Vridhachalam and Tirupathi locations. Geographical location (74–77%) and climate period (15–19%), together explained over 90 percent of the total variation in the number of generations and generation time of S. litura. These findings suggest that the incidence of S. litura on groundnut could be higher in future.     

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.