The cotton leafworm, Spodoptera littoralis (Boisd.), is an insect that causes serious damages to more than 112 plant species belonging to 44 different families. Botanical extracts of Ipomoea carnea were very efficient against fourth instar larvae of Spodoptera littoralis. Based on LC50 and LC90 values, Ipomoea carnea acetone extracts were recorded 24.622 and 164.947 ppm, respectively. While hexane extracts were 232.677 and 15,377.590 ppm, respectively. Also, the treatment of fourth instar larva of S. littoralis with chlorpyrifos insecticide caused 9.497 and 91.126 ppm, respectively. The chemical constituents of acetone extract of I. carnea by using GC–MS analysis resulted in the most active compounds that were palmatic (iso propyl-hexadecanoate), silane, [[(3.alpha.,5.alpha.,20R)-pregnane-3,20-diyl]bis(oxy)] bis (trimethyl-(cas)5. and pederone that recorded (44.025%, 11.455% and 9.325%, respectively). Ipomoea carnea extracts were produced with different deformation abnormalities of all S. littoralis stages.Keywords: Schistocerca gregaria, Ipomoea carnea, botanical extracts, bioassay.

Insecticide resistance in agricultural pests has prompted the need to discover novel compounds with new modes of action. We investigated the potency of secondary metabolites from seventy endophytic actinobacteria against laboratory and field strains of Spodoptera littoralis (fourth instar), comparable to the bioinsecticide spinetoram (Radiant SC 12%). Endophytes from Artemisia herba-alba and A. judaica were highly effective. Chemical profiling of the most potent metabolite of the strain Streptomyces sp. ES2 was investigated using LC-QTOF-MS-MS technique, and the activity was validated through molecular docking studies. Metabolic extracts from actinobacteria belonging to Streptomyces, Nocardioides, and Pseudonocardia showed immediate and latent death to the Spodoptera littoralis fourth instar larvae. The metabolite from strain ES2 has shown the most promising and significant histopathological and inhibitory effects on the fourth instar larvae. ES2 metabolite caused lesions in the body wall cuticle, indicating a different mode of action than that of Radiant. Chemical profiling of ES2 showed the presence of cyromazine (molt inhibitor), 4-nitrophenol, and diazinon as key constituents. In conclusion, these findings suggest that secondary metabolites from endophytic actinobacteria inhabiting wild medicinal plants can be a sustainable source for promising natural biocontrol agents. This is the first illustration of the insecticidal activity of Artemisia spp. microbiome, and natural cyromazine synthesis by actinobacteria.

The journal of Toxicology and pest control is one of the series issued twice by the Egyptian Academic Journal of Biological Sciences, and is devoted to publication of original papers related to the interaction between insects and their environment. The goal of the journal is to advance the scientific understanding of mechanisms of toxicity. Emphasis will be placed on toxic effects observed at relevant exposures, which have direct impact on safety evaluation and risk assessment. The journal therefore welcomes papers on biology ranging from molecular and cell biology, biochemistry and physiology to ecology and environment, also systematics, microbiology, toxicology, hydrobiology, radiobiology and biotechnology. www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.

Insecticide resistance in agricultural pests has prompted the need to discover novel compounds with new modes of action. We investigated the potency of secondary metabolites from seventy endophytic actinobacteria against laboratory and field strains of Spodoptera littoralis (4th instar), comparable to spinetoram (Radiant® 12% SC). Endophytes from Artemisia herba-alba (syn. Seriphidium herba-alba) and Artemisia judaica were highly effective. Chemical profiling of the most potent metabolite was investigated using LC-QTOF-MS-MS technique, and the activity was validated through molecular docking studies. Metabolic extracts from seven actinobacteria (belonging to Streptomyces, Nocardioides, Kitasatospora and Pseudonocardia) have shown lethality to the 4th instar larvae. The metabolite ES2, from Kitasatospora sp., caused significant histopathological and inhibitory effects on 4th instar larvae. Additionally, ES2 caused lesions in the body wall cuticle, indicating a different mode of action than that of spinetoram. Chemical profiling of ES2 have shown presence of cyromazine (molt inhibitor), 4-nitrophenol and diazinon as key constituents. In conclusion, these findings suggest that, secondary metabolites from endophytic actinobacteria inhabiting wild medicinal plants are sustainable source for promising natural biocontrol agents. This is the first illustration of insecticidal activity of the Artemisia spp. microbiome, and the first report on a natural cyromazine synthesized by actinobacteria.