Spodoptera Litura Larvae Research Articles

Effect of gallic acid on the larvae of Spodoptera litura and its parasitoid Bracon hebetor

The antibiosis effect of gallic acid on Spodoptera litura F. (Lepidoptera: Noctuidae) and its parasitoid evaluated by feeding six days old larvae on artificial diet incorporated with different concentrations (5 ppm, 25 ppm, 125 ppm, 625 ppm, 3125 ppm) of the phenolic compound revealed higher concentration (LC50) of gallic acid had a negative impact on the survival and physiology of S. litura and its parasitoid Bracon hebetor (Say) (Hymenoptera:Braconidae). The mortality of S. litura larvae was increased whereas adult emergence declined with increasing concentration of gallic acid. The developmental period was delayed significantly and all the nutritional indices were reduced significantly with increase in concentration. Higher concentration (LC50) of gallic acid adversely affected egg hatching, larval mortality, adult emergence and total development period of B. hebetor. At lower concentration (LC30) the effect on B. hebetor adults and larvae was non-significant with respect to control. Gene expression for the enzymes viz., Superoxide dismutase, Glutathione peroxidase, Peroxidase, Esterases and Glutathione S transferases increased while the total hemocyte count of S. litura larvae decreased with treatment. Our findings suggest that gallic acid even at lower concentration (LC30) can impair the growth of S. litura larvae without causing any significant harm to its parasitoid B. hebetor and has immense potential to be used as biopesticides.

Azadirachtin downregulates the expression of the CREB gene and protein in the brain and directly or indirectly affects the cognitive behavior of the Spodoptera litura fourth-instar larvae.

Azadirachtin has the potential to be used for pest control. Nevertheless, few studies have investigated the effects of azadirachtin on the cognitive behavior of pests. In this study, expression of the cAMP response element-binding protein (CREB) and its gene were studied via a series of experiments in Spodoptera litura larvae treated with azadirachtin. RNA-Seq analysis of S. litura larvae treated with azadirachtin was undertaken. According to Kyoto Encyclopedia of Genes and Genomes analysis, the top 20 enriched pathways included neuroactive ligand-receptor interaction pathways, with seven significantly differentially expressed genes including CREB. Quantitative real time polymerase chain reaction (qRT-PCR) results indicated that the CREB gene was expressed during all developmental stages of S. litura, but relative expression of the CREB gene was significantly downregulated after treatment with azadirachtin. Grayscale statistical analysis also showed that expression levels of protein kinase A (PKA), extracellular signal-regulated kinase (ERK) and CREB proteins were significantly downregulated after treatment with azadirachtin. Moreover, RNA interference results showed that the effect of azadirachtin on the cognitive behavior of S. litura was consistent with that seen after interfering with CREB. In addition, larval selectivity to addictive odor sources was reduced, and the initial reaction time was increased. This study clarified that azadirachtin can affect the cognitive behavior of S. litura and treatment with azadirachtin resulted in a downregulation of gene and protein expression of CREB and its pathway proteins. © 2020 Society of Chemical Industry.

Feeding Inhibition by Chitosan on Larvae of Spodoptera litura (Lepidoptera: Noctuidae)

The high usage of synthetic insecticides for controlling Spodoptera litura could be detrimental to the environment, especially on non-target organisms. Therefore, more environmentally friendly pest management techniques should be used, for example, using a natural product such as chitosan. The objective of this study was to understand the effect of feeding inhibition by chitosan on the feeding activity of the third instar larvae of S. litura. The feeding inhibition test was carried out using the choice methods in a factorial completely randomized design (CRD) with seven treatments: i.e. chitosan 5×103, 15×103, 25×103, 35×103, 45×103 ppm and profenofos 0.18×103, 0.34×103 ppm, and one control treatment. The test of the choice methods was carried out by three larval laying positions: (1) between the control and treatment feeds (Position A), (2) above the treated feed (Position B), and (3) above the control feed (Position C), and were replicated three times. The non-choice test was done in a completely randomized design (CRD) with seven treatments plus control and were replicated four times. The results showed that the chitosan in the concentration range of 5×103‒45×103 ppm reduced feeding by S. litura larvae by 2.587 to 34.974% in the choice method, and 11.610 to 50,712% in the non-choice method. This feeding inhibition increased significantly with the increment of chitosan concentration. However, the inhibition effects by chitosan was weaker than the inhibition by profenofos LC50 in both tests at a concentration of 0.34×103 ppm: 44.331% and 62.491% respectively. In conclusion, chitosan with a concentration of 45×103 ppm at all larval laying positions showed the highest value of feeding inhibition activity on the third instar larvae of S. litura compared to other chitosan concentrations in both methods.

Larvicidal toxicity of various insecticides against Tobacco caterpillar, Spodoptera litura, Fabricius (Lepidoptera: Noctuidae)

The present study was envisaged to check the toxic effect of certain insecticides (chlorpyriphos, spinosad, novaluron, acetamiprid and thyme oil) on third instar larvae of Spodoptera litura by using three different bioassays i.e. topical treatment, leaf dip and artificial diet method at different concentrations viz., 5, 25,125 and 625 ppm. Observations on larval mortality were recorded from each treatment at 24, 48 and 72 hours intervals. Spinosad was found to be most toxic on the basis of larval mortality followed by chlorpyriphos, novaluron, thyme oil and acetamiprid in topical bioassay. But in leaf dip bioassay, thyme oil at 5 ppm caused 100 percent larval mortality. Acetamiprid proved as poor insecticide against this pest causing 26.66, 16.66 and 10 percent mortality after 72 hours of treatment in topical, leaf dip, and artificial diet bioassay at highest concentration, respectively. In artificial diet method, highest mortality percent was recorded in chlorpyriphos and spinosad i.e. 86.66 percent after 48 and 72 hours of treatment, respectively.

Toxicity of Bacillus thuringiensis against second instar larvae of Spodoptera litura on different host plants

Spodoptera litura is serious pest of many horticultural and agricultural crops. S. litura can cause severe economic loss of crops like cotton, cabbage and okra. Different methods are adopted to control this notorious insect pest throughout the globe but biological control is one of them that proved best against it. In 2019, current study was conducted to check the toxicity of Bacillus thuringiensis on 2nd larval instars under laboratory conditions by using different hosts. Mortality data was recorded at 24, 48 and 72 hours of post treatment. The results showed that maximum mortality was recorded on okra (41.46%) followed by cotton (34.67%) and cabbage (23.87%) after 24 hours. After 72 hours of post treatment, maximum mortality of larvae was observed on Bt treated leaves of cabbage than okra. The results indicated that 100% mortality was recorded on cabbage after 72 hours of treatment. Bt treated cabbage leaves were found most effective with 11.21% mortality while cotton gave least effective results with 9.99%. The current study concluded that microbial control is best approach to control insect pest under laboratory as well as field conditions.

Effect of Aspergillus flavus on lipid peroxidation and activity of antioxidant enzymes in midgut tissue of Spodoptera litura larvae

In the present study, effect of Aspergillus flavus was analysed on lipid peroxidation and activities of antioxidant enzymes in midgut of Spodoptera litura. Fungus was administered to the larvae of S. litura using artificial diet method having 1.34 mg/mL (LC50) concentration. The fungus toxicity was observed after 24, 48, 72 and 96 h post treatment in the midgut tissue of insect larvae by examining lipid peroxidation (MDA content) and activities of antioxidant enzymes viz superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APOX) and glutathione-S-transferase (GST) as oxidative stress markers. Additionally, repair of the damage caused due to fungal treatment was also assessed to decipher the longevity of effect by giving control diet to the exposed larvae for two days after particular time exposure using same parameters. In particular, significant (p ≤ 0.05) increased level of lipid peroxidation and antioxidant enzymes activities was observed in all exposure time groups with respect to control which showed that midgut of exposed larvae has oxidative predominance. Repair studies demonstrated the negligible repair in insect larvae. In conclusion, A. flavus contributed to strong oxidative stress and toxicity in S. litura larvae.

Biphasic Dose-Response of Components From Coptis chinensis on Feeding and Detoxification Enzymes of Spodoptera litura Larvae.

Due to long-term coevolution, secondary metabolites present in plants apparently function as chemical defense against insect feeding, while various detoxification enzymes in insects are adaptively induced as a prosurvival mechanism. Coptis chinensis, a medicinal plant used in traditional Chinese medicine for a thousand years, was found to be less prey to insects in our earlier field observations. Herein, 4 crude extracts obtained from sequential partition of aqueous extract of Rhizoma coptidis with petroleum ether, ethyl acetate, and n-butanol exhibited antifeedant activity against Spodoptera litura (Fabricius) larvae at high doses and inducing activity at low doses. Furthermore, a similar biphasic dose–response of the antifeedant activity against S litura larvae was also observed for jateorhizine, palmatine, and obakunone in Coptis chinensis. Notably, the enzyme activities of glutathione-S-transferase and carboxyl esterase in S litura larvae affected by the different components (jateorhizine, palmatine, obakunone, berberine, and coptisine) of C chinensis also showed a biphasic dose–response with an increasing trend at low doses and a decreasing trend at high doses. Together, our study suggests that the components of C chinensis may play a chemical defensive role against S litura larvae in a hormetic manner.

Insecticidal effects of phenolic compounds on the development of polyphagous Spodoptera litura larvae

Insecticidal effects of phenolic compounds on the development of polyphagous Spodoptera litura larvae

Antagonistic Effect of Truncated Fragments of Bacillus thuringiensis Vip3Aa on the Larvicidal Activity of its Full-length Protein.

Vip3Aa is a vegetative insecticidal protein produced by Bacillus thuringiensis. The protein is produced as an 88-kDa protoxin that could be processed by insect gut proteases into a 22-kDa N-terminal and a 66-kDa C-terminal fragments. The C-terminal part could bind to a specific receptor while the N-terminal part is required for toxicity and structural stability. To demonstrate the antagonistic effect of truncated fragments on the insecticidal activity of the full-length Vip3Aa. The full-length protein (Vip3Aa), a 66-kDa C-terminal fragment (Vip3Aa-D199) and a predicted carbohydrate binding module (CBM) were produced in Escherichia coli. Purified proteins were mixed at different ratios and fed to Spodoptera litura and Spodoptera exigua larvae. Mortality was recorded and compared between larvae fed with individual toxin and mixtures of the full-length and truncated toxins. Production level of the Vip3Aa-D199 was significantly decreased comparing to that of the full-length protein. Vip3Aa-D199 and CBM fragment were not toxic to insect larvae whereas Vip3Aa showed high toxicity with LC50 about 200 ng/cm2. Feeding the larvae with mixtures of the Vip3Aa and Vip3Aa-D199 at different ratios revealed antagonistic effect of the Vip3Aa-D199 on the toxicity of Vip3Aa. Results showed that the lethal time (LT 50 and LT 95) of larvae fed the mixture toxins was longer than those fed the Vip3Aa alone. In addition, a CBM fragment could inhibit toxicity of the full-length Vip3Aa. Our results demonstrated that the Vip3Aa-D199 and a CBM fragment could complete for the membrane binding thus rendering activity of the full-length Vip3Aa.

Accumulation and excretion of zinc and their effects on growth and food utilization of Spodoptera litura (Lepidoptera: Noctuidae)

By exposing larvae of the holometabolous insect Spodoptera litura to the artificial diets supplemented with a range of Zinc (Zn) contents, we investigated Zn ingestion, excretion and accumulation in the insect throughout its life cycle. The effects of Zn stress on the survival, growth and food utilization of S. litura were also determined. Zn concentrations in the body (larvae, pupae, and adults), faeces, exuviates, puparium, eggs increased with the increasing Zn concentrations in the diets, while Zn excretion and accumulation by S. litura in 750 mg/kg Zn treatments was lower than the 600 mg/kg Zn treatment. In the 450 mg/kg Zn treatment, the Zn accumulation in S. litura at different developmental stages differed as follows: larvae > pupa > adult. S. litura ingested Zn via feeding and could excrete most of the Zn via faeces (compared with Zn excretion via exuviates) to reduce its internal Zn accumulation (compared with Zn ingestion). Survival and weight were significantly inhibited, and the prolonged period of development (larvae, pupae) and shortened longevity of adults were found in S. litura exposed to Zn stress greater than 450 mg Zn/kg. In the 150–450 mg/kg Zn treatments, the 6th instar larvae increased their relative consumption rate (RCR) and approximate digestibility (AD) (namely, food eaten) to gain weight, which resulted in greater Zn accumulation in the body. Therefore, below the threshold level (being close to 450 mg/kg Zn), S. litura seemed to have a strong homeostatic adjustment ability (increase the amount of food eaten, thereby increasing AD, RCR and Zn excretion via faeces and exuviates) to sustain their weight, and Zn was beneficial and harmless. Although larvae treated with 750 mg/kg Zn had a similar RCR and AD as the control, a reduced weight gain and prolonged larval period resulted in significantly lower relative growth rate (RGR), which indicated surviving insects may allocate more energy from foods for detoxification than for growth.

Entomopathogenecity of nematode Panagrolaimus spp. (Rhabditida: Panagrolaimidae) against lepidopteran pest Spodoptera litura

Agricultural pests cause huge loss to agricultural production. Their control using biopesticides is gaining importance. Entomopathogenic nematodes (EPNs) are most promising biopesticides in agriculture. EPN like other biopesticides has a very specific action on one species or related species as against chemical insecticides. In addition, the median lethal time for EPNs is also lower. Hence there is a need for novel virulent EPN which is effective against wide range of insects and has a low median lethal dose. In this study, we isolated different strains of EPN using modified insect bait method from 10 different soil samples. Six nematode strains were isolated and tested for pathogenicity against Spodoptera litura egg, larvae, and pupae. Agricultural corn field (AC) strain showed very high virulence against other strains. AC strain 18S rDNA sequencing was done and phylogenetic tree constructed to evaluate its relatedness to other species. The AC strains were identified as Panagrolaimus spp. and the sequence was submitted to Genbank. This species was found to be very effective against all the developmental stages of S. litura

Inhibition of the glutathione biosynthetic pathway increases phytochemical toxicity to Spodoptera litura and Nilaparvata lugens

Phytochemicals are toxic to insects, but their insecticidal efficiencies are usually low compared to synthetic insecticides. Understanding the mechanism of insect adaptation to phytochemicals will provide guidance for increasing their efficacy. Reduced glutathione (GSH) is a scavenger of reactive oxygen species (ROS) induced by phytochemicals. However, in insects, the pathway of GSH biosynthesis in response to phytochemicals is unclear. We found that exposure to 0.5% indole-3-methanol (I3C), xanthotoxin, and rotenone (ROT) significantly retarded the growth of Spodoptera litura larvae. The oxidative stress in S. litura larvae exposed to phytochemicals was increased. The up-regulation of glutamate cysteine ligase but not glutathione reductase revealed that the de novo synthesis pathway is responsible for GSH synthesis in phytochemical-treated larvae. Treatment with the inhibitor (BSO) of γ-glutamylcysteine synthetase (gclc), a subunit of glutamate cysteine ligase, resulted in decreases of GSH levels and GST activities, increases of ROS levels in I3C-treated larvae, which finally caused midgut necrosis and larval death. Treatment with BSO or I3C alone did not cause larval death. The addition of GSH could partly reduce the influence of I3C and BSO on S. litura growth. Nilaparvata lugens gclc RNAi confirmed the result of BSO treatment in S. litura. N. lugens gclc RNAi significantly increased the mortality of ROT-sprayed N. lugens, in which ROS levels were significantly increased. All data indicate that gclc is involved in insect response to phytochemical treatment. Treatment with dsgclc will increase the insecticidal efficacy of plant-derived compounds.

Induction of 2-cyanoethyl-isoxazolin-5-one as an antifeedant against the tobacco cutworm (Spodoptera litura) by jasmonic acid in sweet pea leaf.

Although sweet pea (Lathyrus odoratus) beans contain toxic β-aminopropionitrile, the plant itself is readily attacked by insects and is, therefore, protected through the use of pesticides. Consequently, the induction of L. odoratus resistance to insect attack via exogenous treatment is promising for pest control development. Screening of inducible elicitor effects showed that treatment of sweet pea foliage with jasmonic acid (JA) can induce antifeeding-based resistance to tobacco cutworm (Spodoptera litura) larvae. Spectroscopic analysis identified 2-cyanoethyl-isoxazolin-5-one (2-CEIX) as the antifeedant with a half-maximal effective concentration of 33.6µmol/g fr. wt., i.e., exogenous JA treatment induced antifeeding activity due to the accumulation of 2-CEIX. Moreover, 2-CEIX-induced mortality of S. litura larvae was evaluated by a dipping test and the half-maximal lethal dose was determined to be 5.9 mg/mL. Therefore, 2-CEIX was concluded to be a suitable induced resistance target for elicitors or a lead compound for insecticide development.

The diversity of entomopathogenic fungi collected from leaves and rhizospheres of rice implementing integrated pest management

Abstract. Afandhi A, Pertiwi EP, Purba DP, Widjayanti T, Leksono AS. 2020. The diversity of entomopathogenic fungi collected from leaves and rhizospheres of rice implementing integrated pest management. Biodiversitas 21: 2690-2695. Rice is an important food source for most of the world’s population. However, its production often faces pest and disease problems. This study aimed to determine the diversity of entomopathogenic fungi from the leaves and rhizospheres of rice plants, implementing applied integrated pest management (IPM), and to test the pathogenicity of insect fungi species against Spodoptera litura and Tenebrio molitor larvae collection. Entomopathogenic fungi were collected from the leaves and rhizospheres of two rice fields: a field in which IPM is implemented and a conventional field. A total of 24 species were collected from the leaves and rhizospheres in three locations. Pathogenicity test against S. litura larvae was conducted using the Beauveria sp. isolate, whereas pathogenicity test against T. molitor was conducted using the other isolates. Paddy fields in which IPM has been implemented have higher diversity and species richness compared with a conventional field. Location 1 (3 years of IPM implementation) has the highest diversity (2.04 of leaf collection and 1.65 of rhizosphere collection), location 2 has the lowest fungi diversity collected from rhizosphere, whereas location 3 (conventional implementation) has the lowest diversity of leaf collection (1.68). Laboratory testing of Beauveria spp. against S. litura revealed that all species were effective for pest control. Entomopathogenic fungi collected from leaves (Paecilomyces sp.) increased T. molitor mortality by 60%, whereas those isolated from rhizospheres had no effective control of the pest.

Effects of temperature on the development and fecundity of Microplitis similis (Hymenoptera: Braconidae), a parasitoid of Spodoptera litura (Lepidoptera: Noctuidae)

AbstractMicroplitis similis (Hymenoptera: Braconidae) is a solitary endoparasitoid of Spodoptera litura larvae (Lepidoptera: Noctuidae). Here, the effects of constant temperature (18, 21, 24, 27, 30, 33 and 36 °C) on the development and fecundity of M. similis developing in S. litura were studied in the laboratory to clarify the range of its potential distribution and better understand its potential as a biological control agent. The developmental duration of M. similis varied from 10.6 (33 °C) to 27.9 days (18 °C). The developmental threshold temperature and effective accumulative temperature of M. similis were 9.96 °C and 231.14 Degree‐days, respectively. The average adult longevity of M. similis ranged from 5.1 (33 °C) to 26.8 days (18 °C). The maximum fecundity of the parasitoid was observed at 27 and 30 °C, which were 43.07 and 39.73 eggs, respectively. The minimum fecundity of the parasitoid was observed at 18 °C, which was 8.27 eggs. The intrinsic rate of increase (rm) and finite rate of increase (λ) of M. similis were the highest at 30 °C. The net reproduction rate (R0) was the highest at 27 °C and 30 °C, which were 44.34 and 40.39, respectively. We concluded that temperatures in the range 27–30 °C are the most suitable for development and reproduction of M. similis. Our study provides detailed basic information for development and reproduction of M. similis under different temperature conditions.

Novel formulations of Bacillus thuringiensis var. kurstaki: an eco-friendly approach for management of lepidopteran pests.

Bacillus thuringiensis (Bt) and entomopathogenic fungi (EPF) are in use for management of insect pests. Continuous use of Bt can lead to problem of resistance development in insect pests. Hence use of combination formulations (CF) of microbials with diverse modes of action has been attempted to slow down the process of resistance development. Suspension concentrate (SC) formulations of a local strain of Bt var. kurstaki DOR Bt-127 were developed singly and in combination with conidia of the EPF Nomuraea rileyi (Nr) and Beauveria bassiana (Bb). Electron microscopy of Bt + Bb CF treated larvae of Helicoverpa armigera revealed simultaneous infection by both microbials indicating their compatibility. Endotoxin contents in Bt-SC, Bt + Bb and Bt + Nr CFs were 5.0, 4.7 and 4.7%, respectively. These formulations were effective against larvae of Spodoptera litura, H. armigera and Achaea janata coupled with a lowering of the effective requirement of Bt and EPF. In multi-location field trials, Bt-SC and Bt + Nr CF were highly effective against S. litura and A. janata on castor as well as H. armigera and Thysanoplusia orichalcea on sunflower. However, Bt + Bb CF was highly effective only on sunflower against H. armigera and T. orichalcea. All formulations had 24months shelf-life at room temperature. DOR Bt-127 based SC formulations developed singly and in combination with Nr and Bb were effective against major lepidopteran pests of castor and sunflower and did not lose viability under storage at room temperature. The CFs of Bt with EPF could prove promising for mitigating resistance development to Bt.

Toxicity of entomopathogenic fungal culture filtrate of lowland and highland soil of South Sumatra (Indonesia) against Spodoptera litura larvae

Abstract. Gustianingtyas M, Herlinda S, Suwandi, Suparman, Hamidson H, Hasbi, Setiawan A, Verawaty M, Elfita, Arsi. 2020. Toxicity of entomopathogenic fungal culture filtrate of lowland and highland soil of South Sumatra against Spodoptera litura larvae. Biodiversitas 21: 1839-1849. The use of secondary fungal metabolites for the active ingredient of mycoinsecticide is more effective and more easily integrated with other pest control techniques. This study aimed to measure the toxicity of the culture filtrate of entomopathogenic fungi originating from South Sumatra against the Spodoptera litura larvae. Beauveria bassiana (25 isolates) and Metarhizium anisopliae (20 isolates) of South Sumatra were cultured in liquid media and filtered to produce culture filtrate. The larvae which were sick due to the filtrate showed the symptoms of decreased appetite and were not actively moving, while the dead larvae were characterized by being wrinkled, dry, black integument, and odorless. Mortality caused by B. bassiana filtrate was the highest 98% (BJgTs isolate) and not significantly different from the BSwTd2 isolate (94.67%). Yet, the LT50 BSwTd2 isolate was shorter (5.92 days) compared to the LT50 BJgTs isolate (6.35 days). The most toxic M. anisopliae filtrate produced the mortality of 96% (MKbTp2 isolate) and 85.33% (MPdB isolate) each of which had LT50 of 7.36 days and 8.09 days, respectively. So, the most toxic culture filtrate was BSwTd2 isolate of B. bassiana and MKbTp2 isolate of M. anisopliae. The entomopathogenic fungi producing filtrate which are toxic have the potential to be active ingredients of mycoinsecticides.

Histological changes in the midgut of Spodoptera litura larvae exposured by the extract of Mirabilis jalapa leaves

Mirabilis jalapa in Indonesia is better known as Bunga Pukul Empat (the four o‘clock flower) which has the potential a natural insecticide to overcome pests in agricultural crops, such as Spodoptera litura insects. If S. litura larva is infected by toxic compounds, it will cause larval mortality which can be observed in the midgut (middle intestine). This research used a Completely Randomized Design of 4 treatments with 1 control and 4 times of iteration in each treatment using 0% (control), 0.2%, 0.4%, 0.8% and 1.6% (b/v) of M. jalapa leave extract concentration. The observation result of S. litura midgut histological structure showed that the higher concentration of M. jalapa leaf extract, the more damage occurred in its midgut tissue. Microphotography at a concentration of 0.2%; 0.4%; and 0.8% showed that some cells have undergone swelling, disintegration, and lysis. The worst damage was found at the concentration of 1.6%, in which the basal of epithelial cells undergone a wide range of disintegration, peritrophic membrane disappeared, all epithelial cell lysis, muscular layer became thin, the structure of basement membrane was indistinct, the form of goblet cells became irregular, and the longitudinal muscle disappeared. Based on the results, extract of M. jalapa has potential as a botanical biopesticide.

Field evaluation of Bt 127 SC formulation against Spodoptera litura (F.) in soybean

Bt 127 SC formulation was field tested against Spodoptera litura larvae infesting soybean at Dharwad. Amongthe biopesticides, Bt 127 SC formulation @ 3 ml/l of water has proved to be significantly superior over commercial Bt formulation Delfin and untreated control and recorded lowest S. litura after both the sprays. There was a higher reduction in larval population on the seventh day after treatment both in Bt 127 SC formulation (0.54 l/mrl) and Bt commercial Delfin (0.75 l/mrl) treated plots as bacterial infection starts to manifest leading to high mortality of larva within 3-5 days after treatment. Soybean seed yield due to treatment by Bt 127 SC formulation (1733 kg/ha) and Bt commercial Delfin (1694 kg/ha) were on par but lower in comparison to the broad spectrum chemical insecticides that are effective against different orders of insects. There was negligible population of natural enemies in the plots before and after the treatments.

Efek subletal campuran ekstrak daun srikaya (Annona squamosa L.) dan rimpang kunyit (Curcuma domestica Val.) terhadap larva Spodoptera litura F.

Spodoptera litura (Lepidoptera: Noctuidae) larvae are polyphagous insects whose populations cause damage to various types of plantations, horticulture, and food so that control efforts need to be done. One way to control the environment of environmentally friendly S. litura larvae is to use a plant-based insecticide, a mixture of A. squamosa leaf extract and C. domestica rhizome (test extract appendix). The purpose of this study was to determine the subletal effect of the test extract mixture on S. litura larvae, namely the duration of larvae and pupae stage, pupae weight, morphology and imago viability, and the ability of female imago to lay eggs to produce offspring. The test was carried out by the method of feed dip into the test extract mixture. Data on pupae weight were analyzed with ANOVA, followed by Duncan's further test with a 5% confidence level using SPSS 21 program. The results showed that the test extract mixture extended the stages of larvae and pupae, reduced pupa weight, imago wings did not develop fully, reduced imago size, and did not imago able to produce eggs. The results of this study could then be further tested on a greenhouse scale and photochemical analysis of a test extract mixture to determine bioactive compounds that act as plant-based insecticides.