Eco-friendly secondary metabolites from Conyza dioscoridis against Spodoptera littoralis

Abstract

2 ry metabolites of bioactive chloroform/ methanol extract of Conyza dioscoridis using chromatographic techniques and spectroscopic analysis led to identify five major compounds; β-amyrin-3-acetate, β-lupeol-3-acetate, β-amyrenone, dotriacontane and 5,4ʹ-dihydroxy-6,7-dimethoxyflavone. The percentage of cumulative mortalities during pupal and adult stages reached to 76.6% and 83.3%, respectively after feeding 4 th larval instar of Spodoptera littoralis on C. dioscoridis crude extract with insecticidal activity in a dose-dependent manner. Whereas, β-amyrenone, lupeol acetate and 5,4ʹ-dihydroxy-6,7dimethoxyflavone suppressed 50, 60 and 73.3% of 4 th instar larvae of S. littoralis at concentration 0.3, 0.5 and 0.5%, respectively. Also, the extract showed marked decreasing in acetyl cholinesterase activity, total lipids and protein contents. The GC/MS analysis of volatile oil of C. dioscoridis aerial part led to identify 63 sensory metabolites that represent 93.68% of total volatile constituents. The oil was characterized by a high percentage of oxygenated sesquiterpenes (36.00%) and sesquiterpene hydrocarbons (21.09%), in addition phenylated and aliphatic hydrocarbons (15.43% and 14.58%, respectively). C. dioscoridis exhibited acute toxicity on both sexes, reduced adult longevity, oviposition deterrents and reduced fertility on S. littoralis. So, it used as new natural target insecticidal agent for S. littoralis, biodegradable alternatives to chemical insecticides and can used as a natural tool in pest management program.

Disturbance of the Acetylcholinesterase Activity in Haemolymph and Fat Bodies of The Desert Locust, Schistocerca gregaria (Orthoptera: Acrididae) by Margosan-O® (0.3% Azadirachtin)

“…Among five tested plants against M. domestica, treatment of 2 nd instar larvae with a 25% concentration of Penganum harmala led to a reduction in the AchE activity (Zahoor et al, 2020). After treatment of the 4 th larval instar of S. littoralis with chloroform/methanol extract of Conyza dioscoridis aerial parts, the acetylcholinesterase activity was remarkably reduced in the larval body homogenate (Matloub et al, 2021). Results of the present study were in agreement with those reported results since the treatment of the newly moulted penultimate instar nymphs of S. gregaria with margosan-O ® resulted in a considerable inhibition of AchE activity in fat bodies of only the late-aged nymphs.…”

Secondary plant metabolites as promising pesticides for increasing crop yields

“…In cases with the use of higher concentrations of extracts (2, 4), a slight increase in vivacity was recorded (ATEN 1.0 -1.25%) or a serious decrease (AANN 1.0 -8.25%). In variants (1,3,5), where green grass was treated in solutions of agents with a lower concentration, an increase in the yield of caterpillars (revitalization) was observed by 4.50-8.75 absolute percent. In terms of production of egg, this is a fairly high percentage, indicating a significant increase in the quality of egg.…”

“…Such studies [3,4] describe the growth-regulating activity of a number of isoprenoids related to sesquiterpenoids with different types of carbon skeleton. The research results showed that the sesquiterpenoids α -santonine (1), zerumbone (2) and C16-guayanolide (3) (Figure 1), isolated from plants, increase the yield of rice after one-day soaking of seeds in their solutions at a dilution of 1: 10,000 compared to the control by 14.17% (α-santonine, zerumbone) and 7.5% (C16-guayanolide).…”

“…Currently, the class of terpenoids, including sesquiterpene lactones, are attracting the attention of a wide range of researchers, not only by interesting chemical and structural features, but mainly by a wide spectrum of biological action. Sesquiterpene lactones, being a large group of secondary metabolites, are widespread in plants, and at present, the structure of more than 4000 of their representatives with acyclic, mono-, di-and tricyclic carbon skeletons has been isolated and established [3][4][5].…”

Biological and Histological Effects of Certain Insecticides on Spodoptera littoralis (Bosid)

“…As one of the most important global economic problems, the protection of crops from pests is urgently needed. Many different countries search for natural alternatives to chemical dangerous pesticides using safe compound with minimal costs and ecological side effects (Matloub et al 2021). This insect is attacking more than 112 host plants mainly on vegetable, field, ornamental crops and many other economic plants.…”