Agrotis Ipsilon Larvae Research Articles

Assessing the efficacy of un and gamma-irradiated entomopathogenic nematode, Steinernema carpocapsae as an eco-friendly approach to control Agrotis ipsilon larvae

The black cutworm, Agrotis ipsilon (Hufnagel) is one of the most devastating agricultural pests that attack different crops worldwide. Entomopathogenic nematodes (EPNs) have been utilized in classical, conservation, and augmentative biological control programs. Consequently, this study was designed to estimate the efficacy of an unirradiated and gamma-irradiated entomopathogenic nematode, Steinernema carpocapsae (all), against A. ipsilon larvae as a safe control tool to reduce chemical environmental hazards. The virulence of different concentrations (10, 20, 30 and 40 IJs/ml) of unirradiated and gamma-irradiated (with 2 Gy) of S. carpocapsae was evaluated. Changes in peroxidase (Px) and polyphenyl oxidase (PPO) zymographic patterns were also investigated after larvae were treated with LC50 values for S. carpocapsae. The results revealed that larval mortality increased with increasing S. carpocapsae concentration and time after treatment. The 2 Gy gamma-irradiated S. carocapsae caused a greater pathogenic effect than the unirradiated S. carocapsae, where the LC50 values of 2 Gy gamma-irradiated S. carocapsae were 31.19 and 17.78 IJs/ml after 1 and 2 days, respectively, compared to 113.23 and 65.83 IJs/ml for unirradiated S. carocapsae. For the toxicity index, gamma irradiation at a dose of 2 Gy was selected and given an arbitrary 100 units and considered a standard treatment. Analysis of gel electrophoresis revealed 3 bands of Px and PPO in control larvae; treatment with unirradiated and irradiated S. carpocapsae caused the disappearance of the first band of both enzymes and lowered the intensity of the other 2 bands. The laboratory studies revealed that 2 Gy gamma-irradiated S. carpocapsae could be used as an eco-safe management tool against A. ipsilon larvae under field conditions.

Identification and evaluation of isolated entomopathogenic fungus from Egyptian soil against the black cutworm larvae of Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

BackgroundThe black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is considered as one of the most destructive pests of many field crops in Egypt. Entomopathogenic fungi (EPF) have long been accepted as relatively safe alternatives to chemical insecticides. In the past decades, many researchers have compared the effective local isolates of EPF to the formulated product of the same fungus and reported that local isolates were more efficient than formulations when used against target insects.ResultsThe present study discussed the pathogenic activity of local isolate after scientific characterization. Two insect species [Galleria mellonella L. and Agrotis ipsilon (Hufn.)] were used in this evaluation. The fungus was isolated from soil samples by trapping method, and fourth-instar larvae of Galleria were used to evaluate the pathogenicity of the isolate. The isolate was identified as Beauveria bassiana. Different levels of the fungus development depending on the test temperatures (20, 25, 30, 35 and 40 °C) were tested. Optimal growth of the isolate fungus was recorded at 25 °C. The corrected mortality rate for fourth-instar larvae of G. mellonella treated with the isolate spores at 6.4 × 105 spores/ml was (96%) after 10 days, while the mortality of last instar larvae of A. ipsilon was (48 and 100%) at the concentrations of 9.2 × 104 and 2.9 × 106 spores/ml, respectively, after 14 days compared to (24%) in the control. Both pupation and the sex ratio in adults were affected at different levels according to the concentration. The effect was also very clear in the increased rates of malformation in adults.ConclusionThe EPF, B. bassiana, isolated from the soil, was highly effective against G. mellonella larvae in storage and A. ipsilon larvae in soil; therefore, it could be recommended as an alternative control agent for chemical pesticides.

Insect growth regulators and chinaberry (Melia azedarach) fruit acetone extract disrupt intermediary metabolism and alter immunocyte profile in Agrotis ipsilon larvae

Insect growth regulators and chinaberry (Melia azedarach) fruit acetone extract disrupt intermediary metabolism and alter immunocyte profile in Agrotis ipsilon larvae

Effect of physic nut oil against potato cutworm, Agrotis ipsilon

Field and laboratory evaluation of Jatropha curcas oil on Agrotis ipsilon larvae was carried out in the Soil Arthropod Pests Laboratory as well as on farmer’s field. Experimental findings showed that all the four different concentrations (2.5, 5, 10 & 20%) of J. curcas oil were effective and registered 100 per cent mortality of the larvae after 72 hours of application under laboratory conditions. In case of field study, the lowest tuber infestation of potato (9.88 and 11.06 per cent of based on both number and weight basis respectively) and the highest yield (117.38 q/ha) were recorded in 10 per cent concentration of formulated J. curcas oil treated plots.

The Potency of Fungal-Fabricated Selenium Nanoparticles to Improve the Growth Performance of Helianthus annuus L. and Control of Cutworm Agrotis ipsilon

The application of green nanotechnology in agriculture has been receiving substantial attention, especially in the development of new nano-fertilizers and nano-insecticides. Herein, the metabolites secreted by the fungal strain Penicillium chrysogenum are used as a reducing agent for selenium ions to form selenium nanoparticles (Se-NPs). The synthesized Se-NPs were characterized using color change, UV-Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), and dynamic light scattering (DLS). The biomass filtrate of the fungal strain changed from colorless to a ruby red color after mixing with sodium selenite with a maximum surface plasmon resonance at 262 nm. Data exhibits the successful formation of spherical, amorphous Se-NPs with sizes ranging between 3–15 nm and a weight percentage of 38.52%. The efficacy of Se-NPs on the growth performance of sunflower (Helianthus annuus L.) and inhibition of cutworm Agrotis ipsilon was investigated. The field experiment revealed the potentiality of Se-NPs to enhance the growth parameters and carotenoid content in sunflower, especially at 20 ppm. The chlorophylls, carbohydrates, proteins, phenolic compounds, and free proline contents were markedly promoted in response to Se-NPs concentrations. The antioxidant enzymes (peroxidase, catalase, superoxide dismutase, and polyphenol oxidase) were significantly decreased compared with the control. Data analysis showed that the highest mortality for the 1st, 2nd, 3rd, 4th, and 5th instar larvae of Agrotis ipsilon was achieved at 25 ppm with percentages of 89.7 ± 0.3, 78.3 ± 0.3, 72.3 ± 0.6, 63.7 ± 0.3, and 68.7 ± 0.3 respectively after 72 h.

Cross‐habituation to deterrents correlates with desensitisation of the corresponding deterrent neuron in the larva of the black cutworm, Agrotis ipsilon

AbstractHabituation (accepting food sources previously rejected) and cross‐habituation (accepting food sources containing deterrents after exposure to unrelated deterrents) induced by dietary experience are observed in lepidopteran larvae, but the physiological mechanisms underlying these phenomena are poorly understood. In this study, behavioural and electrophysiological responsiveness to three unrelated deterrents were investigated in larvae of Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae). Caterpillars were fed with one of four diets: ‘normal’ artificial diet or diet with low amounts of the alkaloid strychnine, the phenolic chlorogenic acid (CA), or the diterpene fumaropimaric acid (FA). These three chemicals are structurally different and are all deterrent to A. ipsilon caterpillars. In behavioural, dual‐choice assays with chemical‐treated leaf discs, caterpillars reared on normal diet fed less on treated discs, i.e., were highly deterred by the three chemicals. However, caterpillars fed on chemical‐infused diets did not distinguish between treated and non‐treated discs, i.e., they showed behavioural habituation. In triple‐choice leaf disc assays, larvae fed with CA were deterred by both CA and FA and vice versa, i.e., larvae fed diet with CA or FA showed cross‐habituation. There was no cross‐habituation between strychnine and CA/FA. Electrophysiological recordings revealed that the same deterrent neuron in the lateral sensilla styloconica responds to CA and FA. Desensitisation of this neuron, through exposure to CA or FA in diet, was correlated with the observed cross‐habituation. A different deterrent neuron, in the medial sensilla styloconica, responded to strychnine. Thus, no generalisation of either habituation or desensitisation occurred to deterrents that elicited responses from different deterrent neurons in the lateral and the medial sensilla styloconica. Cross‐habituation to deterrents correlated with desensitisation of the corresponding deterrent neuron.

Biochemical Studies in Larvae of Agrotis ipsilon (Hüfnagel) Affected by Recent Insecticides

As field populations of black cutworms grow more resistant to conventional insecticides, the need for new and effective chemical means to control this insect is more important than ever. In this study, we examined the biochemical mechanisms underlying the toxicity of the sublethal effect of the new insecticides (emamectin benzoate, indoxicarb, chloranitraniliprole, and pyridalyl) against two strains of Agrotis ipsilon comprising the laboratory-susceptible (L-S) and the field-resistant (BK-R). Activity measurements of the main detoxification enzymes showed that new insecticides inhibited the activities of both glutamic oxaloacetic transaminase (GOT) and glutamine pyruvic transaminase (GPT), whereas the significant activity of glutathione S-transferase (GST) was observed, suggesting that the inhibition of detoxification contributes to the enhancement toxicity against A. ipsilon larvae. A significant decrease in the effect of sublethal dose was also observed between the control larvae in the content of protein, lipid, and glycogen, and treated larvae in two strains. According to these results, the treated larvae were negatively affected in both two tested strains compared with untreated larvae in control.

Field Application and Biochemical Studies of Certain Selected Photosensitizer Against Black Cutworm, Agrotis ipsilon

Agrotis ipsilon larvae known as black cutworm is one of the most destructive and serious underground insect pests. Which attacks various field crops and causes great damage especially it prefers attacking the young plant in the growing stages. The extensive used of insecticides to control it to protect the yield from reduction led to build-up resistance to these insecticides. So, field experiments were approved to evaluate the effectiveness of certain photosensitizer compounds methylene blue, safranin, bromophenol blue belonging to various chemical groups against Agrotis ipsilon larvae in potato crop in El- Giza Governorate in Egypt for the duration of two successive seasons, February 2020 and 2021 under field conditions using double values of LC50 and LC90 of these compounds. A highly significant decrease in the population of A. ipsilon post 3 days of treatment with all tested photosensitize using poisonous baits and a significant difference between the two seasons. On the light of the median and quarter lethal effects of the three tested photosensitizer compounds, methylene blue, bromophenol blue and safranin on the total proteins, total lipids, cholinesterase, acid and alkaline phosphatase in the 4th larval instars of the black cutworm, A. ipsilon the results proved that all tested compounds caused decreased in these biochemical contents except bromophenol blue treatment slightly increase in acid phosphatase at LC25 and methylene blue increased in total lipids content at both LC25 and LC50 relative to control.

Nutritional Responses of the Black Cutworm, Agrotis ipsilon (Hufn.), Larvae under Toxicity Effects of Five Wild Botanical Extracts from Sinai, Egypt

Aims: To identify the chemical components of five wild Botanical oils (BOs) and their larvicidal influences on the anti-nutritional indices of the 4th instar larvae of Agrotis ipsilon.
 Study Design: A comparative study with the randomized design, using five plant Extracts replicated five times.
 Place and Duration of Study: Mentha longifolia, Artemisia judaica, Majorana hortensis, Origanum syriacum, and Achillea santolina were collected from the Sinai desert, Egypt. Study procedures were done at the Laboratory of Botany and Zoology, Faculty of Science, Zagazig University, Egypt, between December 2018 and June 2020.
 Methodology: An analysis of the tested BOs components was done using a Shimadzu GC-9A gas chromatograph. Five sub-lethal concentrations of each plant were prepared (5 replicate/treatment) to evaluate medium lethality against A. ipsilon larvae (20 larvae/replicate). Untreated larvae were used distilled water only as a control. Ten larvae of each treatment were treated with only one LC50 to estimate the effect of different tested BOs on anti-nutritional Activities.
 Results: The main component of the M. longifolia and A. judaica oil was Piperitone at 39.79 and 37.55%, respectively; whereas the M. hortensis, O. syriacum, and A. santolina oil was Terpinen-4-ol, Thymol, and Fragranyl acetate at 29.82, 31.21, and 25.67%, respectively. According to LC50 of the tested BOs, the toxicity of A. judaica, M. longifolia, O. syriacum, respectively, were the most effective oils, while M. hortensis and A. santolina oils were the least susceptibilities. The more toxic oils reduced food consumption, causing a significant decrease in relative consumption rate (RCR), growth rate (RGR), and efficiency of conversion of ingested food (ECI)/digested (ECD). The previous oils also showed a significant increase in metabolic cost (MC) and anti-feeding activities against A. ipsilon larvae compared to M. hortensis and A. santolina.
 Conclusion: It is suggested that A. judaica and M. longifolia extracts contain high Piperitone content and could be accepted as toxicants to control A. ipsilon.

The Toxicity Effect of Certain Photosensitizing Compounds on Some Biological Aspects of Field Strain of Agrotis ipsilon (Hufnagel) Larvae

The black cutworm, Agrotis ipsilon larvae is the most serious pest around the world; it attacked the plant in the growing stage of many crops such as cotton, potato, corn, and tomato causing great damage for them and others which led to reduce the yield. So many chemical insecticides are used for controlling this pest which may buildup resistance to these pesticides Therefore, it is needed to evaluate some chemical compounds that belonged to different categories such as safranin, methylene blue and bromophenol blue against the 4th larval instars of A. ipsilon using poison baits. The results clearly demonstrated that the tested compounds had, a stomach and contact toxicity through the larval feeding on treated baits also, all these toxicants exhibited antifeedant and starvation effects in addition resulting larval paralysis post-feeding. Results on the basis the medium lethal concentrations LC50 of the tested compounds varied on the larval stage, the promising treatment among the investigated compounds were safranin that showed the lowest LC50, which was more toxic as stomach poison followed by methylene blue and the lowest effect was noticed in case of bromophenol blue treatment. The effect of both LC50 and LC25values of these compounds showed a remarkable significant increase in both larval and pupal durations with retardation in their development as well as an increase in the mortality percentage and the malformation for both the resulting pupae and adults. Also, the toxicants affected the fertility of adults. Therefore, these photosensitizers, compounds can be used for controlling the black cutworm on their hosts as toxic baits’ alternatives to traditional chemical pesticides, for increasing their toxicity and decreasing insect-resistant build up as a method implementing the integrated pest control program.

Silica Nano Particles Bait Against the Black Cutworm, Agrotis ipsilon (Hufn.)

The present study was conducted to determine the effect of baits containing nano particles of silica against the fourth instar larvae of Agrotis ipsilon (Hufn.) along sequential daily intervals post treatment under laboratory conditions. The determined percentages of larval mortality due to the admixed baits with SiNPs increased up to 100% after 15 days of application. The admixing of nanoparticles of silica in the bait during the sensitive period of larval development caused morphological abnormalities that are generally irreversible and often lead to death, beside certain biochemical changes of some inorganic elements in the haemolymph of the treated insects. It could be concluded that the tested nanoparticles of silica were most effective and indicated the highest concentration reductions of inorganic constituents in larval haemolymph, especially calcium, sodium and potassium. Therefore, more attention must be directed towards the inorganic constituents in the larval haemolymph as biomarkers for SiNPs efficacy.

Toxicity of some insecticides against Agrotis spp. infesting cabbage

Toxicity of seven insecticides viz., bifenthrin, chlorantraniliprole, cypermethrin, emamectin benzoate, flubendiamide, novaluron and spinosad was evaluated through leaf dip and topical methods of bioassay against third instar larvae of Agrotis ipsilon (Hufnagel) and A. segetum (Denis and Schiffermuller). Based on LC50 values, chlorantraniliprole was found the most effective against third instar larvae of A. ipsilon (0.0298 ppm) as well as A. segetum (0.0321 ppm) while cypermethrin was the least effective, with LC50 values of 31.0706 and 33.4636 ppm, respectively. On the basis of LD50, chlorantraniliprole was observed to be the most effective against third instar larvae of A. ipsilon (0.00086 μg a.i./larva) as well as A. segetum (0.00085 μg a.i./larva) while novaluron being the least effective with LD50 values 0.8382 and 0.7441 μg a.i./larva, respectively.

Transcriptome profiling analysis of the intoxication response in midgut tissue of Agrotis ipsilon larvae to Bacillus thuringiensis Vip3Aa protoxin

Vip insecticidal proteins are produced by Bacillus thuringiensis (Bt) during its vegetative growth phase. In the present study, Vip3Aa11 and Vip3Aa39 proteins were investigated. These two proteins present 39 amino acid differential sites and they shared 95.06% amino acid sequence similarity. They are effective against some Lepidoptera insect larvae. In a previous study, using artificial diet bioassays, we estimated the LC50 of Vip3Aa11 and Vip3Aa39 strains against Agrotis ipsilon larvae were 73.41 μg/mL (with 95% confidence interval of 2.34–11.19) and 5.43 μg/mL (with 95% confidence interval of 43.20–115.03), respectively. To investigate the response of Agrotis ipsilon transcriptome in defending against Vip3Aa11 and Vip3Aa39 toxins, we performed high-throughput RNA-sequencing on cDNA generated from the midguts of Agrotis ipsilon larvae that consumed a control diet (CK-M-A), Vip3Aa11 (Vip3Aa11-M-A) and Vip3Aa39 (Vip3Aa39-M-A) proteins. We generated about 98.87 Gb bases in total on BGISEQ-500 sequencing platform. After assembling all samples together and filtering the abundance, we got 51,887 unigenes, the total length, average length, N50 and GC content of unigenes are 64,523,651 bp, 1243 bp, 2330 bp and 41.81% respectively. We revealed 558 midgut genes differential expressed in Vip3Aa11-M-A and 65 midgut genes differentially expressed in Vip3Aa39-M-A. The differentially expressed genes were enriched for serine proteases and potential Bt Vip toxin midgut receptor genes. Eleven serine proteases related genes and 13 Bt toxin potential receptor genes with differential expression were found. Based on transcriptome profiling, we focused on validation the sensitivity of these two Vip3Aa proteins to trypsin and their binding properties to Agrotis ipsilon midgut BBMV (Brush Border Membrane Vesicles). The results show that the sensitivity of the two proteins to trypsin is similar. Binding experiments revealed that both proteins can bind to Agrotis ipsilon midgut BBMV, and there is a competitive binding between them. This transcriptome dataset provided a comprehensive sequence resource of Agrotis ipsilon and provides a foundation for comparative studies with other species of insects.

Comparative Toxicity of Neem and Peppermint Oils Nano Formulations against Agrotis ipsilon (Hufn.) Larvae (Lepidoptera: Noctuidae)

Applications of nanotechnology in agriculture will result in the development of efficient and potential approaches towards the management of insect pests. The toxicity effects of four essential oils peppermint, thyme, camphor and sage oils were tested against the fourth instar larvae of Agrotis ipsilon to select the most effective essential oil to be converted to the nano form. According to the results obtained, peppermint oil was the most toxic compound, which has been used in the present investigation compared with neem oil. The toxicity of bulk and nano- formulations of neem and pepper mint oils were tested against 2nd and 4th instar larvae of A. ipsilon under laboratory conditions of 25±2 °C& 65 -70 % R.H.relative humidity The results show that the LC50 value (the concentration used which kill 50% of the tested individuals)of loaded neem or pepper mint were lower (0.62 and 36.47 ppm) compared with neem or pepper mint oil nano-emulsion and bulk neem for the second larval instar. The different formulations of neem are more potent than in case of peppermint oil, as LC50 and LC90 values were significantly lower.The same trend was found concerning the 4th larval instar. Age of treated larvae had a detrimental effect on the response to the compounds tested. It was noticed that the younger larvae were much more sensitive to the prepared compounds compared to the older ones. The least LC50 value for loaded neem nano-emulsion was 6.68 ppm compared with the highest value for bulk neem oil (16.68 ppm ). Also, LC90 values followed the same trend as in case ofLC50. Again, the toxicity of loaded peppermint oil had the most insecticidal activity as expressed by the lowest LC50 value (51.9 ppm) with more insecticidal effect than the bulk(125.43 ppm) or nano-emulsion (85.43 ppm). The present results indicated that these novel systems could be used in integrated pest management program for A. ipsilon control.

Insight into the Mode of Action of Celangulin V on the Transmembrane Potential of Midgut Cells in Lepidopteran Larvae.

Celangulin V (CV) is the main insecticidal constituent of Celastrus angulatus. The V-ATPase H subunit of the midgut cells of lepidopteran larvae is the putative target protein of CV. Here, we compared the effects of CV on the midgut membrane potentials of Mythimna separata and Agrotis ipsilon larvae with those of the Cry1Ab toxin from Bacillus thuringiensis and with those of inactive CV-MIA, a synthetic derivative of CV. We investigated the changes in the apical membrane potentials (Vam) and basolateral membrane potentials (Vbm) of the midguts of sixth-instar larvae force-fed with the test toxins. We also measured the Vam and Vbm of larval midguts that were directly incubated with the test toxins. Similar to the effect of Cry1Ab, the Vam of CV-treated midguts rapidly decayed over time in a dose-dependent manner. By contrast, CV-MIA did not influence Vam. Meanwhile, the Vam of A. ipsilon larval midguts directly incubated with CV decayed less than that of M. separata larval midguts, whereas that of larvae force-fed with CV did not significantly change. Similar to Cry1Ab, CV did not affect the Vbm of isolated midguts. CV significantly inhibited V-ATPase activity in a dose-dependent manner. Therefore, CV initially inhibits V-ATPase in the apical membrane and affects intracellular pH, homeostasis, and nutrient transport mechanisms in lepidopteran midgut cells.

Designing of a Recombinant Agip Bacmid Construct with Infectious Properties Against Black Cutworm Agrotis ipsilon Larvae.

In this study, Agrotis ipsilon nucleopolyhedrovirus bacmid has been constructed as an infectious bacmid in an attempt to allow genome recombination and generation of virus mutants. Since the FseI, a unique restriction site, is located in a viral coding region (ORF_119), PCR was performed to partially amplify the ORF_119 fragment containing the FseI site to facilitate the bacmid construction in a proper way without interrupting the ORF expression. Construction with repeated fragments at the end of the cloned viral was carried out in an attempt to facilitate circulation during infection in insect cells. The amplified gp_119 fragment was cloned into the BAC_Bsu361 plasmid derived from the AcMNPV Bac-to-Bac® system. Recombinant plasmid was used to subclone the Agrotis ipsilon nucleopolyhedrovirus (AgipNPV)-linearized genome using the FseI unique site. The Agip bacmid DNA extracted from Escherichia coli was used to transfect A. ipsilon third instar larvae by injection into the hemolymph. The produced occlusion bodies were purified from infected larvae and used to feed healthy larvae for amplifying the virus, and infectivity was recorded. Using bacmid technology will facilitate manipulation of the AgipNPV genome and help in determining the genetic factors involved in virus virulence and biology.

Different Effects of Bacillus thuringiensis Toxin Cry1Ab on Midgut Cell Transmembrane Potential of Mythimna separata and Agrotis ipsilon Larvae.

Bacillus thuringiensis (Bt) Cry toxins from the Cry1A family demonstrate significantly different toxicities against members of the family Noctuidae for unknown reasons. In this study, membrane potential was measured and analyzed in freshly isolated midgut samples from Mythimna separata and Agrotis ipsilon larvae under oral administration and in vitro incubation with Bt toxin Cry1Ab to elucidate the mechanism of action for further control of these pests. Bioassay results showed that the larvae of M. separata achieved a LD50 of 258.84 ng/larva at 24 h after ingestion; M. separata larvae were at least eightfold more sensitive than A. ipsilon larvae to Cry1Ab. Force-feeding showed that the observed midgut apical-membrane potential (Vam) of M. separata larvae was significantly depolarized from −82.9 ± 6.6 mV to −19.9 ± 7.2 mV at 8 h after ingestion of 1 μg activated Cry1Ab, whereas no obvious changes were detected in A. ipsilon larvae with dosage of 5 μg Cry1Ab. The activated Cry1Ab caused a distinct concentration-dependent depolarization of the apical membrane; Vam was reduced by 50% after 14.7 ± 0.2, 9.8 ± 0.4, and 7.6 ± 0.6 min of treatment with 1, 5, and 10 μg/mL Cry1Ab, respectively. Cry1Ab showed a minimal effect on A. ipsilon larvae even at 20 μg/mL, and Vam decreased by 26.3% ± 2.3% after 15 min. The concentrations of Cry1Ab displayed no significant effect on the basolateral side of the epithelium. The Vam of A. ipsilon (−33.19 ± 6.29 mV, n = 51) was only half that of M. separata (−80.94 ± 6.95 mV, n = 75). The different degrees of sensitivity to Cry1Ab were speculatively associated with various habits, as well as the diverse physiological or biochemical characteristics of the midgut cell membranes.

Virulence and Pathogenicity of Recombinant Nucleopolyhedroviruses Expressing a Scorpion Toxin and an Insect Enzyme onAgrotis ipsilon(Lepidoptera: Noctuidae) Larvae

Bioassay experiments for investigating the potential of recombinant nucleopolyhedroviruses expressing a scorpion toxin (AaIT), and a juvenile hormone esterase from Manduca sexta (Linnaeus) (AcMsJHE) in killing first instar larvae of Agrotis ipsilon (Hufnagel) were tested in comparison with the wild type virus (AcMNPV). Protein expression and viral replication in insect were determined using SDS-PAGE and agarose gel electrophoresis. Results of lethal concentrations indicate that AaIT was the most efficient virus compared with AcMsJHE or AcMNPV. Median lethal concentration of AaIT was 4.0 × 105 PIBs/ml compared with 7.0 × 105 and 7.6 × 105 PIBs/ml for AcMsJHE and AcMNPV, respectively. AaIT killed the treated first instar larvae of A. ipsilon markedly faster than AcMsJHE or AcMNPV, and significantly affected third instar larval weight after 96 hours post-infection (h.p.i.), which the LT50s of AaIT were 94 and 89 h.p.i. when 1 × 106 and 1 × 108 PIBs/ml were used, respectively. SDS-PAGE for protein separation ...

Pathogencity induced by the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae in Agrotis ipsilon (Hufn.)

Scanning electron microscopy (SEM) allowed observing Beauveria bassiana and Metarhizium anisopliae adhesion and penetration structure on Agrotis ipsilon larvae. SEM of A. ipsilon larvae treated with the Lc50 of the fungus, B. bassiana revealed adhesion and penetration structures in the infected larvae. Growth of the fungus on the infected larvae and signs of hyphal penetration of insect cuticle as well as proliferation of the cuticle were also appearing. On the other hand, the fungus, M. anisopliae as declared by SEM showed a dense network together and cause the green spores on the insect cuticle. Also, SEM allowed observing the spores and hyphae of the fungus in the body cavity of infected larvae. Scanning electron microscopy is allowed tool to observe the mode of action of entomopathogenic fungi and to observe how they are able to colonize and infect the host.

Comparative study on the Efficacy of Agrotis segetum Granulosis virus (AgseGVEG) against Agrotis ipsilon under semi-field conditions

The present work was carried out to evaluate the efficacy of Agrotis segetum granulosis virus (AgseGVEG) against Agrotis ipsilon larvae in semi-field experiments using spray and wheat bran bait method. A Fluorescent brightener (Tinopal UNPA-GX) was added for enhancement of Agrotis segetum granulosis virus (AgseGVEG). Results showed that, addition of F. brightener 1% to AgseGVEG suspension using surface contamination technique of semi synthetic diet increased the susceptibility of 3rd and 4th instars of A. ipsilon larvae; the LC50 was 2.08×108 OB / ml and 6.10×108 OB/ml, respectively. The LT50 values of AgseGVEG (9.07×1010 OB/ml) +F. brightener 1% was7.67 and 7.85 days for 3rd and 4th instars. In addition, semi-field conditions, F. brightener 1% as sun screen enhanced AgseGVEG persistence on Cotton foliage after spray, the calculated lethal inactivation median time for 50 % reduction in virulence (lethal median inactivation time, LIT50) for 2nd instar larvae was0.97 or 2.27 days for virus alone-treatment and AgseGV+ F. brightener additive, respectively. The calculated potency value for F. brightener was 2.335 Fold. Mixture of AgseGVEG+ F. brightener 1% in bran bait formulation increased mortality% of A. ipsilon in two concentrations of AgseGVEG (9.07×109 and 9.07×108 OB/ ml) + F. brightener 1% and decreased the number of cut cotton plants infested with 3rd instar larvae of A. ipsilon compared to untreated control. The damage reduction to Cotton seedlings with A. ipsilon, was 83.33% and 70% for 3rd and 4th instars larvae, respectively, in the AgseGVEG (9.07×109 OB/ml) + F. brightener 1% compared to control. In conclusion in both spray and bran tested treatments larvae infected with AgseGVEG+ F. brightener 1% died more rapidly than those infected with AgseGVEG alone ; indicating that AgseGVEG appears to have better potential as a control agent for A. ipsilon by adding enhancement additive.