Isolation and identification of microbiota from Egyptian common insect pests invading economically important crops

Insects bodies contain multiple distinctive microbial colonies which play key role in the metabolism, development and health of an insect. In the current study bacterial and fungal microbiota were isolated from larval feces and adult wings of two major insect pests in Egypt, the Cotton leaf worm Spodoptera littoralis and the black cutworm Agrotis ipsilon. Isolated pathogens were identified and characterized according to the scientific described methods in such cases. Two different genera of bacteria (Bacillus & Serratia) were isolated from larval feces of both insects while isolated fungus were Paecilomyces variotii and Absidia corymbifera from the feces of A. ipsilon larvae, while Rhozopus stolonifer and Penicillium chrysogenum were isolated from adults wings of the same insect. The fungus Aspergillus flavus, Aspergillus niger and Mucor circinilloides were isolated from feces of S. littoralis larvae. Numerous species of bacteria and fungi had been documented as a bio-agent against many insect pests, and most of them exhibited disruption in life-cycle of different species of Lepidopterous pests. The obtained data sheds light on microbial colonies associated with two major insect pests, however further studies are required to involve the isolated microbiota in the biological control programs of insect pests.

The Novel Agrotis ipsilon Nora Virus Confers Deleterious Effects to the Fitness of Spodoptera frugiperda (Lepidoptera: Noctuidae)

In the present study, we identified a novel, positive-sense single-stranded RNA virus in the Chinese black cutworm, Agrotis ipsilon. It has a genome length of 11,312 nucleotides, excluding the poly(A) tails, and contains five open reading frames. The ORF2 encodes the conserved domains of RNA helicase and RNA-dependent RNA polymerase, while ORF4 and 5 encode three viral proteins. Herein, the A. ipsilon virus was clustered with a Helicoverpa armigera Nora virus and was thus provisionally named “Agrotis ipsilon Nora virus” (AINV). AINV was successfully transmitted into a novel host, Spodoptera frugiperda, through injection, causing a stable infection. This found the possibility of horizontal AINV transmission among moths belonging to the same taxonomic family. Nonetheless, AINV infection was deleterious to S. frugiperda and mainly mediated by antiviral and amino acid metabolism-related pathways. Furthermore, the infection significantly increased the S. frugiperda larval period but significantly reduced its moth eclosion rate. It suggests that AINV is probably to be a parasitic virus of S. frugiperda.

Correction: Moustafa et al. Insecticidal Activity of Lemongrass Essential Oil as an Eco-Friendly Agent against the Black Cutworm Agrotis ipsilon (Lepidoptera: Noctuidae). Insects 2021, 12, 737

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Insecticidal Activity of Lemongrass Essential Oil as an Eco-Friendly Agent against the Black Cutworm Agrotis ipsilon (Lepidoptera: Noctuidae)

Background: The destructive insect pest Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) is a polyphagous species targeting many economically important plants. The extensive and arbitrary use of insecticides has resulted in the build-up of insecticide resistance and pesticide residues accumulating in food. Therefore, it is becoming evident that alternative pest management tools are needed to reduce risks to humans, the environment, and non-target organisms, and at the same time, they should be used in field application at the lowest cost. Methods: In view of this objective, the present study demonstrates the toxicity of lemongrass (Cymbopogon citratus (DC.) Stapf) essential oil (EO), against the black cutworm A. ipsilon under controlled laboratory conditions in terms of measuring the activity of peroxidase and detoxification enzymes. The chemical components of the EO were analyzed using GC–MS. Results: The results show that after 96 h post treatment, the LC15 and LC50 values were 427.67 and 2623.06 mg/L, respectively, of C. citratus EO on second-instar larvae of A. ipsilon. A slight significance in elongation of the larval duration with LC15 and LC50 value was found with control. By GC–MS analysis, the main compounds identified in the EO were α-citral and β-citral with percentages of 35.91%, and 35%, respectively. The oxidative stress indicates a significant increase in CAT and lipid peroxidase enzyme activity after 96 h post treatment at the LC15 and LC50. Conversely, the detoxification enzyme activity shows an inhibition of CarE and GST enzymes of larvae exposed to LC15 and LC50 values in response to C. citratus EO. Conclusions: The present data show that lemongrass EO has insecticidal activity against the black cutworm, A. ipsilon.

Nano-Insecticides Against the Black Cutworm Agrotis ipsilon (Lepidoptera: Noctuidae): Toxicity, Development, Enzyme activity, and DNA Mutagenicity

High-frequency doses of chemical pesticides cause environmental pollution with high pesticide residues. In addition, increasing insecticide resistance in many insect pests requires novel pest control methods. Nanotechnology could be a promising field of modern agriculture, and is receiving considerable attention in the development of novel nano-agrochemicals, such as nanoinsectticides and nanofertilizers. This study assessed the effects of the lethal and sublethal concentrations of chlorantraniliprole, thiocyclam, and their nano-forms on the development, reproductive activity, oxidative stress enzyme activity, and DNA changes at the molecular level of the polyphagous species of black cutworm Agrotis ipsilon. The results revealed that A. ipsilon larvae were more susceptible to the nano-formsthan the regular forms of both nano chlorine and sulfur within the chlorantraniliprole and thiocyclam insecticides, respectively, with higher toxicities than the regular forms (ca. 3.86, and ca.2.06-fold, respectively). Significant differences in biological parameters, including developmental time and reproductive activity (fecundity and hatchability percent) were also observed. Correspondingly, increases in oxidative stress enzyme activities were observed, as were mutagenic effects on the genomic DNA of A. ipsilon after application of the LC50 of the nano-forms of both insecticides compared to the control. The positive results obtained here have led us to apply these nano-forms indifferent insect models in additional studies.

An insight into black cutworm (Agrotis ipsilon): A glimpse on globally important crop pest

Many agricultural pests create problems for farmers leading to production loss. Since agriculture plays an important role in the economy of a nation, controlling and management of such pests is of great importance. Cutworms are notorious agricultural pests infesting a wide variety of crops leading to production loss. Cutworms are distributed worldwide and many species of cutworms have also been reported feeding on all kinds of crops. Agrotis ipsilon is one of the most common cutworm species prevailing in different continents. Understanding the biology and management of these pests will be of great use for farmers. In this article, brief information on cutworms; specifically A. ipsilon species is highlighted. A brief description of host, migration, control and management of A. ipsilon are also highlighted.

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.