Litura Larvae Research Articles

WITHDRAWN: Effect of photoperiod on larval development of Spodoptera litura maintained on diet supplemented with melatonin and luzindole treatments

Abstract Long term exposure of synthetic chemicals has raised insect resistance in the field and increased alarm in finding alternative tools to control this pest. More importantly, Spodoptera litura Fab. feeds more than 120 host species and is one of the most damaging agricultural pest mostly in Southeast Asian countries. Photoperiod is an important environmental factor which affects the larval development and reproduction. Thus the present study emphasis the developmental and reproductive effects of different photoperiod developing individuals in a cohort with response to melatonin and luzindole treatment against S. litura. The total developmental duration reveals that 0: 24 melatonin treatment showed longest duration as compared with control and luzindole treatments. Correspondingly, The highest body mass development at 0 L:24D photoperiod as compared with other photoperiod and treatments. The reproductive assays revealed that adults were shows in highest ratio in 8:16 photoperiod in adult Longevity fecundity and egg hatchability in melatonin treatment as compared with control. Similarly, histology of treated S. litura larvae in 12L: 12D photoperiod showed significant morphological and cellular damage of the epithelial columnar cells and lumen cells as compared with control. Thus as an endnote the present investigation reveals that melatonin induces significant alterations in developmental and reproductive rate of tobacco cutworm.

The Synergy Effect of Azadirachtin and Minor Components of Neem Seed Oil on Antifeedant Activity of Spodoptera litura

Azadirachtin in neem oil ( Azadirachta indica A.Juss ) might have potential synergism effect with a minor compound in the neem oil as an antifeedant. This study aimed to determine the content of minor components that have the most significant contribution to the effect of synergy with the main component (azadirachtin) in antifeedant activity against Spodoptera litura . Neem oil was fractionated with n-hexane, ethyl acetate, and water. The antifeedant activity of three neem oil fractions was evaluated using the 4 th instar of S. litura larvae. The bioassay was conducted using the choice leaf disc test with 2.5; 5; 10; and 20 % (v/v) concentrations of each fraction. The concentration of the fractions showed equal azadirachtin content, hence the antifeedant activity represented the effect of the minor component in the fraction. The best activity was shown by water fraction (84-100 %). Probit analysis of the antifeedant activity of all fractions showed that water fraction has the best effective inhibitory (EI 50 ) at 1.0 %. The minor component in the water fraction was dominated by phenol compounds (48.5 %) which were suspected to synergize with the main component (azadirachtin) in increasing the antifeedant activity on S. litura . These results indicated the phenol compound in this fraction has the role in increasing azadirachtin antifeedant activity against S. litura .

Efficacy of Entomopathogenic Nematodes Against the Tobacco Cutworm, Spodoptera litura (Lepidoptera: Noctuidae).

Spodoptera litura (F.) is an obnoxious cosmopolitan pest that causes serious damage to different economic crops. Entomopathogenic nematodes (EPN) have the potential to control the S. litura larvae. Fifteen EPN isolates were screened, and Steinernema sp. 64-2, four isolates of S. carpocapsae (Weiser), S. longicaudum (Shen & Wang) X-7, and two isolates of H. indica (Poinar, Karunaka & David) were found to cause higher mortality of the second, third, and fourth instars of S. litura than the other tested isolates, with larval mortality rates > 90% after 48 h of exposure. An exposure rate of 12.5 infective juveniles per larva was enough for S. carpocapsae A24, All, and G-R3a-2 and S. longicaudum X-7 to cause 100% mortality of the second instar, and for S. longicaudum X-7 and H. indica 212-2 to cause 100% mortality of the third instar. Five EPN isolates were tested on their virulence at different temperatures and found that all the five EPN isolates performed well against the S. litura larvae at 25 and 30°C, but were not active at 10 and 15°C. Two S. carpocapsae isolates (All and Mex) were virulent against the S. litura larvae at lower temperatures. The five tested EPN isolates were also found to have the ability to infect and kill the pupae of S. litura in the laboratory. The present study further proves that EPN are effective at controlling S. litura, which may partially substitute the use of chemical insecticides, thus reduce the overuse of chemical insecticides.

An easy, inexpensive, and sensitive method for the quantification of chitin in insect peritrophic membrane by image processing.

Chitin, poly (β-(1→4)-N-acetyl-d-glucosamine), is an important biopolymer for insects that is utilized as a major component of peritrophic membrane. The chitin content in peritrophic membrane is of expedient interest from a pest control perspective, although it is hard to quantify chitin. In this study, we establish a facile method for the quantification of chitin in peritrophic membrane by image processing. In this method, chitin was indirectly quantified using chitosan-I3- complex, which exhibited a specific red-purple color. A calibration curve using a chitosan solution showed good linearity in a concentration range of 0.05-0.5μg/μL. We quantified the amount of chitin in peritrophic membrane of Spodoptera litura (Lepidoptera: Noctuidae) larvae using this method. Throughout the study, only common inexpensive regents and easily attainable apparatuses were employed. This method can be easily applied to the sensitive quantification of the amounts of chitin and chitosan in materials by wide range of researchers. Abbreviations: LOD: limit of detection; LOQ: limit of quantification; ROI: region of interest; RSD: relative standard deviation.

Improved insect resistance against Spodoptera litura in transgenic sweetpotato by overexpressing Cry1Aa toxin.

Overexpressing the Cry1Aa gene in sweetpotato significantly reduced pest damage through disrupting the integrity of the midgut of Spodoptera litura larvae for resistance against target Lepidoptera insect pests in sweetpotato. Sweetpotato is susceptible to insect pests and diseases leading to yield losses during pest outbreaks. Lepidoptera insects such as S litura are especially important pests of sweetpotato. The effect of Cry1Aa gene on S. litura was investigated by overexpressing Cry1Aa gene in sweetpotato to relieve symptoms due to pest damage. When transgenic leaves were fed to the larvae of S. litura, the growth of the larvae was reduced, the larval quality decreased, and mortality was increased compared with the larvae that fed on wild-type leaves. Further anatomical analysis revealed that the columnar cells of the midgut epithelium of the BT group were significantly damaged, loosened, or disordered. Furthermore, the integrity of the midgut was destroyed. In addition, when potted seedlings of the wild-type and BT sweetpotato were inoculated with the same number of S. litura larvae, wild-type plants died on the eighth day after infestation, while BT transgenic lines still grew normally. This study showed that transgenic sweetpotato overexpressing Cry1Aa can prevent S. liturainfestation, and thus increase the yield of sweetpotato.

Purification and characterization of protease inhibitors from rice bean (Vigna umbellata) and their efficacy against Spodoptera litura (Fabricius) gut proteinases

A protease inhibitor from rice bean was isolated and purified to assess its potential against gut proteases of Spodoptera litura, a devastating pest of several economically important crops globally. The purified inhibitor showed a single band protein on SDS-PAGE corresponding to molecular weight of 24.0 kDa. The inhibitor was purified to near homogeneity with 181.55 fold purification and final yield of 29.18 per cent. The inhibitory potential of purified rice bean trypsin protease inhibitor on larvae of Spodoptera gut proteases was studied which showed maximum azocaseinolytic (1.93U), trypsin (0.66U) and chymotrypsin activity (0.37 U) in second larval instar which gradually decreased upto late fifth larval instar stage. Inhibitory assay revealed that rice bean trypsin inhibitors were strong inhibitor of Spodoptera litura and inhibited more than 80 per cent for trypsin and around 69 per cent for chymotrypsin activity. To further determine the efficacy of rice bean protease inhibitors, feeding assays were conducted by adding rice bean flour in larval artificial diet. High mortality rate was observed in Spodoptera litura larvae after 72 hrs when rice bean was given as sole diet (100% rice bean composition). The results obtained from present study provide important clues in designing strategies for sustainable use of rice bean protease inhibitors in developing insect-tolerant transgenic plants.

Matrine Enhances the Pathogenicity of Beauveria brongniartii Against Spodoptera litura (Lepidoptera: Noctuidae).

The repetitive application of pesticides at high doses against Spodoptera litura Fabricius has resulted in development of pesticide resistance and harmful effects to the natural environmental. Hence, finding alternate pest control strategies, such as entomopathogenic fungi or their application in combination with other natural chemicals, is of great importance to solve the abovementioned problems. This study presents the toxic effects of Beauveria brongniartii and matrine (individual or in combination with each other) against tobacco cutworm (S. litura). Different matrine treatments caused a dose dependent increase in S. litura mortality at different time intervals. The biological parameters of B. brongniartii (germination rate and average daily mycelia growth) were not inhibited by different matrine treatments. Different conidial concentrations of B. brongniartii caused significantly different mortalities of 2nd instar S. litura larvae at different time intervals. Different combined treatments of B. brongniartii and matrine showed a significant synergistic effect against S. litura under laboratory and semi-field conditions. The current findings showed a strong synergistic action for combined application of B. brongniartii and matrine against S. litura. Our results will provide baseline information on combined application of entomopathogenic fungi and natural chemicals in integrated pest management programs against S. litura.

Biological Activity of Ethanolic Leaves Extract Lantana camara Against Cabbage Catterpillars for Environmentally Biopesticides

Chemical insecticides that have been relied upon to control cabbage catterpillars have become the main cause of pest resistance, high residues in crop products and decreased biodiversity of natural enemies in the environment. Active ingredients of plants plays an important role in providing opportunities for the development of a plant extracts, particularly applied for agriculture using the organic extract as bioinsecticide. This paper reports the ethanolic leaves extraction of L. camara against the C. pavonana and S. litura larvae which are the main pest on cabbage plants in Indonesia. The objective of this research is to evaluate the antifidan performance of ethanolic leaves extract to C. pavonana and S. litura larvae. The extract was prepared by maceration and evaporation and followed by antifeedant bioassay test. The antifeedant test was used leaf disc deep method with choice and no choice test to find out the effective minimum concentration on feeding detterent activity. The mean leaf area consumed were analyzed by using non parametric statistics of Mann-Whitney U. The results showed that the antifeedant minimum effective concentration of ethanolic leaves extract L. camara to C. pavonana larvae at 2000 ppm (choice test) and 1000 ppm (no choice test) in consider as medium antifeedant categori, to S. litura larvae at 500 ppm (choice test) and performance antifeedant in consider as medium antifeedant categori.

Tobacco Cutworm (Spodoptera Litura) Larvae Silenced in the NADPH-Cytochrome P450 Reductase Gene Show Increased Susceptibility to Phoxim.

Nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome P450 reductases (CPRs) function as redox partners of cytochrome P450 monooxygenases (P450s). CPRs and P450s in insects have been found to participate in insecticide resistance. However, the CPR of the moth Spodoptera litura has not been well characterized yet. Based on previously obtained transcriptome information, a full-length CPR cDNA of S. litura (SlCPR) was PCR-cloned. The deduced amino acid sequence contains domains and residues predicted to be essential for CPR function. Phylogenetic analysis with insect CPR amino acid sequences showed that SlCPR is closely related to CPRs of Lepidoptera. Quantitative reverse transcriptase PCR (RT-qPCR) was used to determine expression levels of SlCPR in different developmental stages and tissues of S. litura. SlCPR expression was strongest at the sixth-instar larvae stage and fifth-instar larvae showed highest expression in the midgut. Expression of SlCPR in the midgut and fat body was strongly upregulated when fifth-instar larvae were exposed to phoxim at LC15 (4 μg/mL) and LC50 (20 μg/mL) doses. RNA interference (RNAi) mediated silencing of SlCPR increased larval mortality by 34.6% (LC15 dose) and 53.5% (LC50 dose). Our results provide key information on the SlCPR gene and indicate that SlCPR expression levels in S. litura larvae influence their susceptibility to phoxim and possibly other insecticides.

Bio-Insecticidal Potential of Nucleopolyhedrovirus and Granulovirus Mixtures to Control the Fall Armyworm Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae).

The ability of the isolate VG008 of S. frugiperda granulovirus (SpfrGV) to enhance the infectivity of the isolate SfCOL of S. frugiperda multiple nucleopolyhedrovirus (SpfrMNPV) was evaluated on S. frugiperda larvae. Bioassays were performed with mixtures by using different proportions 90%:10% (M1), 95%:5% (M2) and 97.5%:2.5% (M3) of SfCOL:VG008, respectively. All mixtures showed higher insecticidal activity that SfCOL. The mixture M3 showed the highest enhancement of SfCOL reducing 11.40 times the Mean Lethal Concentration and 96 h in the Mean Time to Death. The enhancer activity of proteins derived from VG008 (GVPs) were also evaluated in mixture with SfCOL. The GVPs increased 27% larval mortality caused by SfCOL and damaged the peritrophic membrane of S. litura larvae, suggesting that the key point in this enhancing activity is the initial step of the larva colonization, the midgut infection. M3 was formulated and evaluated under greenhouse conditions in maize plants using different doses. The highest efficacy was obtained with the highest dose of M3 (8 × 1011 OBs/ha), which was similar to that found when formulated SfCOL was applied using an approximately twofold higher dose. The viral mixture M3 was selected as the active ingredient for developing a new biopesticide for a more efficient management of the pest in the field.

Copper exposure enhances Spodoptera litura larval tolerance to β-cypermethrin

Environmental xenobiotics can influence the tolerance of insects to chemical insecticides. Heavy metals are widespread distributed, can be easily bio-accumulated in plants and subsequently within phytophagous insects via the food chains. However, less attention has been paid to the effect of heavy metal exposure on their insecticide tolerance. In this study, pre-exposure of copper (Cu, 25–100 mg kg−1) significantly enhanced the subsequent tolerance of Spodoptera litura to β-cypermethrin, a widely used pyrethroid insecticide in crop field. Cytochrome P450 monooxygenases (CYPs) activities were cross-induced in larvae exposed to Cu and β-cypermethrin, while the activities of glutathione S-transferase (GST) and carboxylesterase (CarE) were not affected. Application of piperonyl butoxide (PBO), a P450 synergist, effectively impaired the tolerance to β-cypermethrin in Cu-exposed S. litura larvae with a synergistic ratio of 1.72, indicating that P450s contribute to larval tolerance to β-cypermethrin induced by Cu exposure. Among the four CYP6AB family genes examined, only larval midgut-specific CYP6AB12 was found to be cross-induced by Cu and β-cypermethrin. RNA interference (RNAi)-mediated silencing of CYP6AB12 effectively decreased the mRNA levels of the target gene, and significantly reduced the larval tolerance to β-cypermethrin following exposure to Cu. These results showed that pre-exposure of heavy metal Cu enhanced larval tolerance to β-cypermethrin in S. litura, possibly through the cross-induction of P450s. Our findings provide new insights on the relationship between heavy metals and chemical insecticides that may benefit both the risk evaluation of heavy metal contamination and development of pest management strategies.

Insecticidal activity of culture filtrates from liquid medium of Beauveria bassiana isolates from South Sumatra (Indonesia) wetland soil against larvae of Spodoptera litura

Abstract. Ayudya DR, Herlinda S, Suwandi S. 2019. Insecticidal activity of culture filtrates from liquid medium of Beauveria bassiana isolates from South Sumatra (Indonesia) wetland soil against larvae of Spodoptera litura. Biodiversitas 20: 2101-2109. The obstacle in utilizing entomopathogenic fungi to control pest insects in wetlands is the inability of their isolates to survive during the saprophytic phase due to the soil being very acidic. Therefore, the exploration of fungi being able to survive in the acidic soil was utilized in the acidic ecosystem. This study aimed to test the toxic activity of Beauveria bassiana culture filtrates from liquid medium at pH 2.5 and 6 against Spodoptera litura larvae. Total of ten isolates collected from South Sumatra, Indonesia was grown in liquid media at pH of 2.5 and 6 for six weeks. The result showed that the culture filtrate from liquid medium at pH 6 was more toxic against the larvae than that at pH 2.5. The mortality of the larvae at pH 6 reached 92%, while that at pH 2.5 it reached 13.33% only. The findings of present study revealed that the culture filtrate isolates of BPdR, BJgTs, BSwTd2, BSwTd3, BSwTd4, BKKPp2 from pH 2.5 media still caused high larvae mortality (6.67-13.33%). These seven isolates are superior due to their toxic nature at pH 2.5. Consequently, present study has increased the chances of success in utilizing these isolates for biological control in acidic ecosystems, such as peatlands, tidal lowlands, and freshwater swamps.

Enhancement of Jasmonate-Mediated Antiherbivore Defense Responses in Tomato by Acetic Acid, a Potent Inducer for Plant Protection.

Acetic acid (AA) has been proved as a chemical that could prime the jasmonic acid (JA) signaling pathway for plant drought tolerance. In this study, the capability of AA for priming of tomato defense against a chewing caterpillar Spodoptera litura and its underlying molecular mechanism were evaluated. AA pretreatment significantly increased tomato resistance against S. litura larvae. Upon larval attack, tomato plants pretreated with AA exhibited increased transcript levels of defense-related genes and elevated activities of polyphenol oxidase (PPO) and peroxidase (POD), and accumulation of protease inhibitor. Moreover, AA pretreatment resulted in upregulated transcription of JA biosynthesis genes and elevated JA accumulation in tomato seedlings upon insect attack. Furthermore, an apparent loss of AA-induced resistance was observed in a JA pathway-impaired mutant suppressor of prosystemin-mediated responses8 (spr8). These results indicate that AA enhances jasmonate-mediated antiherbivore defense responses in tomato. This raises the possibility of use of AA, a basic and simple biochemical compound, as a promising inducer for management of agricultural pests.

Field evaluation of synthetic and neem-derived alternative insecticides in developing action thresholds against cauliflower pests

Synthetic chemical pesticides can enhance crop yields but also have undesired effects. Alternative ‘botanical insecticides’ may also have non-target effects on pollinators and biocontrol services. Employing action thresholds (ATs) can reduce pesticide (whether synthetic or botanical) use compared to fixed-interval applications. Here the azadirachtin-based botanical formulation NeemAzal and a neem seed extract (NSE) were evaluated in field spraying trials alongside commonly-used synthetics (Voliam Flexi [chlorentraniliprole plus thiamethoxam] and imidacloprid) in developing ATs for the regular and cosmopolitan cauliflower pests Brevicoryne brassicae, Plutella xylostella and Spodoptera litura. We considered the size of the S. litura larvae infesting the crop in order to derive ATs. ATs per plant were higher for NeemAzal (0.55 larvae for P. xylostella and 3 larvae for large-sized S. litura) than for Voliam Flexi (0.30 larvae for P. xylostella and 0.80 larvae for S. litura) but were similar for B. brassicae (50 individuals). Higher ATs when using azadirachtin were associated with the diverse modes of action of botanicals, for instance NeemAzal and NSE deterred oviposition of S. litura. Although the exact values of ATs are likely to have regional limits, our approach can be applied for determining ATs against common lepidopteran and aphid pests in many other vegetable crop agro-ecosystems.

Bioefficacy of Hexane Extract of Inula racemosa (Asteraceae) Against Spodoptera litura (Lepidoptera: Noctuidae)

Phytoinsecticides are considered as an effective and environment friendly alternative to synthetic chemicals for integrated pest management. Asteraceae, the largest plant family is well known for its enormously diverse characteristic content of sesquiterpene lactones. In this study the biological activity of hexane extract of Inula racemosa (Hook) was evaluated against Spodoptera litura (Fabricius). The extract exhibited larvicidal and growth inhibitory activities. A moderate antifeedant effect was recorded with maximum feeding deterrence of 24.85% at 1500 ppm of the extract. Diet supplemented with 1500–2000 ppm of the extract induced significantly higher mortality in S. litura larvae compared to control. All concentrations showed a very strong growth inhibitory effect in a dose dependent manner. The highest concentration (2500 ppm) extended the development of S. litura by 21.06 days relative to control. Due to toxic effects of I. racemosa, the adult emergence decreased significantly at concentrations ranging between 1500–2500 ppm. Sublethal effects of the extract were also manifested as morphological deformities in larvae and pupae of S. litura. Nutritional assay studies indicated reduction in growth and consumption rate as well as utilization of ingested and digested food when plant extract was fed to larvae, suggesting both antifeedant and toxic activities. The hexane extract of I. racemosa has significant influence on relative metabolic rate, causing higher metabolic cost to S. litura.

Sodium chloride primes JA-independent defense against Spodoptera litura (Fabricius) larvae in Arabidopsis thaliana

ABSTRACTPriming for better defense performance is an important strategy in acclimation to the ever-changing environment. In the present study, defense priming induced by sodium chloride at the seedling stage significantly increased the expression of defense gene VSP2, the content of total glucosinolates and the level of the reactive oxygen species in mature Arabidopsis thaliana plants after transferred into the stress-free environment. The previously primed plants could effectively resist the feeding of Spodoptera litura (Fabricius) larvae. Salt-priming enhanced defense of Arabidopsis plants in the absence of either MYC2 or AOS, which encodes a critical transcription factor in JA-signaling and an important enzyme in JA biosynthesis, respectively. Our results supported the JA-independent defense primed by sodium chloride, as well as the elevated ROS and glucosinolate level in primed plants. In addition, the feasibility of using mild salt-priming to improve crop performance in field was proposed.

SpCYS, a cystatin gene from wild potato (Solanum pinnatisectum), is involved in the resistance against Spodoptera litura

Cysteine proteinase inhibitor (cystatin) genes belong to one family of proteinase inhibitors and play an important role in the resistance to insect pests. Cystatin (CYS) genes have been studied in different plant–insect interactions, but there are few reports about the importance of potato cystatin genes. In this study, a cystatin gene named SpCYS was characterized from the wild diploid potato Solanum pinnatisectum Dun, which exhibits high resistance to insect pests. We also investigated the impact of SpCYS in the development of Spodoptera litura when feed from leaves of genetically modified potato. Bioinformatic analysis revealed that SpCYS encoded protein possessed conserved domains of the cystatin family. The SpCYS expression was observed in leaves, stems, roots and tubers with the expression level being almost the same in roots, stems and leaves but greater in tubers. After mechanical damage, SpCYS expression in leaves was induced reaching its peak at 9 h and then decreased to normal levels. Further, we constructed transgenic lines of cultivated potato (cultivar Desiree) expressing SpCYS and performed insect bioassays and feeding preference experiments. Both tests showed that the over-expression of SpCYS lowered the weight increase rate of both Spodoptera litura larvae and pupa. S. litura larvae preferred to feed on the leaves of non-transformed controls rather than the transgenic lines. Taken together, our data suggest that SpCYS is a significant asset for the defense mechanism of potato against S. litura.

Mass production of the entomopathogenic nematode, Steinernema carpocapsae on Tenebrio molitor and Spodoptera litura

Abstract. Authors. 2019. Mass production of the entomopathogenic nematode, Steinernema carpocapsae on Tenebrio Molitor and Spodoptera litura. Biodiversitas 20: 1344-1349. Steinernema carpocapsae is the most developed biological agents to control pests nowadays, to support this nematode as a biological agent mass production technique is required. S. carpocapsae can be produced via in vivo methods. In vivo production has some advantages, such as cheap, easy, and sustainable to be developed in small farm agriculture. The purpose of this research was to evaluate the mass production of S. carpocapsae using Tenebrio molitor and Spodoptera litura larvae as hosts. Twenty-five last instar larvae were inoculated with different concentrations of infective juvenile (IJ) (e.g., 100, 200, 300 and 400 IJ/larvae) of S. carpocapsae Asembagus. The production of S. carpocapsae with concentrations of 100, 200, 300 and 400 IJ/larvae on T. molitor and S. litura showed 3.62x103; 6.29x103; 1.13x104; 1.52x104; 1.13x104; 1.46x104; 1.54x104; and 1.94x104 IJ/larvae, respectively. The IJ harvest from T. molitor and S. litura shows the longest body length for IJ at a concentration of 400 IJ/larva of 437.48µm and 591.42µm, respectively. This study indicates that T. molitor and S. litura can be used to produce S. carpocapsae. The production of S. carpocapsae with a concentration of 400 IJ / larvae on T. molitor and S. litura showed the highest total yield and body length of IJ.

A plant-based extract mixture for controlling Spodoptera litura (Lepidoptera: Noctuidae)

BackgroundSpodoptera litura larvae are polyphagous insects that have become a significant pest in recent years. The spread of this pest has led to the continuous usage of insecticides on crops. Some plant extracts have been used as a mixture to control insect pests and improve productivity.MethodsA plant-based mixture was mixed at a ratio of 1:1 v/v to demonstrate the effect on contact toxicity, feeding (no-choice test), and enzyme activities on S. litura. The active compounds of P. retrofractum and A. calamus were isolated by preparative thin-layer chromatography (PTLC).ResultsOur results showed that binary mixtures from P. retrofractum and A. calamus exhibit the highest contact toxicity and antifeedant activity at a 1:1 ratio of LD30:LD10 dose (3.213 µg/larva P. retrofractum + 3.294 µg/larva A. calamus). The main active ingredient from each crude extract was (2E,4E,14Z)-N-isobutylicosa-2,4,14-trienamide from P. retrofractum, and beta-asarone and alpha-asarone from A. calamus. Additionally, A. calamus seems to be the synergistic compound. Some compound mixtures increased the glutathione-S-transferase activities in vivo; whereas, almost no significant differences in esterase activities were noted.ConclusionThe results indicated that the ethanolic crude extracts of P. retrofractum and A. calamus mixtures could be used as the pesticidal compound and to develop a binary mixture formulation for controlling lepidopteran pests. However, the toxicity of this mixture to mammals needed to be explored before commercial development.

Heavy metal exposure through artificial diet reduces growth and survival of Spodoptera litura (Lepidoptera: Noctuidae).

Insect physiology is affected by the presence of toxins in the surrounding environment of insects as well as their food sources. The objective of this study was to determine the effect of heavy metal exposure to two low concentrations (50μg/g and 150μg/g) of lead (Pb) and zinc (Zn) through artificial diet to the larvae on biological parameters of Asian armyworm (Spodoptera litura Fabricius) (Lepidoptera: Noctuidae). Both Pb and Zn, even at low concentrations, had relatively high toxic effects on S. litura larvae (P < 0.01). S. litura larval weight and length suffered the maximum reduction when the larvae were fed on diet mixed with the high Pb concentration (150μg/g) tested compared to the other treatments. At the same Pb concentration (150μg/g), values of larva growth index, pupa growth index, immature growth index, standardized growth index, and fitness index were 4.66, 7.33, 7.82, 5.35, and 10.00 times lower, respectively, than those of control. At the same Zn concentration (150μg/g), values of larval growth index, pupal growth index, immature growth index, standardized growth index, and fitness index were 5.61, 3.00, 3.04, 3.23, and 9.24 times lower, respectively, than those of control. The survival rate of S. litura larvae was also lower (12.5%) when the larvae were fed on diet mixed with Pb at 150μg/g after 10days of observation. Overall, the presence of those heavy metals in the environment, even at low concentrations, would exert an adverse impact on larvae development of this insect. From this point of view, findings could provide a basis for long-term evaluation of heavy metal risk and its impact on populations of important agricultural pests.