Efficacy of Acacia nilotica, Eucalyptus camaldulensis, and Salix safsafs on the mortality and development of two vector-borne mosquito species, Culex pipiens and Aedes aegypti, in the laboratory and field

Chemical composition and bio-efficacy of agro-waste plant extracts and their potential as bioinsecticides against Culex pipiens mosquitoes

Mosquitoes are considered one of the most lethal creatures on the planet and are responsible for millions of fatalities annually through the transmission of several diseases to humans. Green trash is commonly employed in agricultural fertilizer manufacturing and microbial bioprocesses for energy production. However, there is limited information available on the conversion of green waste into biocides. This study investigates the viability of utilizing green waste as a new biopesticide against Culex pipiens mosquito larvae. The current study found that plant extracts from Punica granatum (98.4 % mortality), Citrus sinensis (92 % mortality), Brassica oleracea (88 % mortality), Oryza sativa (81.6 % mortality), and Colocasia esculenta (53.6 % mortality) were very good at killing Cx. pipiens larvae 24 h post-treatment. The LC50 values were 314.43, 370.72, 465.59, 666.67, and 1798.03 ppm for P. granatum, C. sinensis, B. oleracea, O. sativa, and C. esculenta, respectively. All plant extracts, particularly P. granatum extract (14.93 and 41.87 U/g), showed a significant reduction in acid and alkaline phosphate activity. Additionally, pomegranate extract showed a significant decrease (90 %) in field larval density, with a stability of up to five days post-treatment. GC-MS results showed more chemical classes, such as terpenes, esters, fatty acids, alkanes, and phenolic compounds. HPLC analysis revealed that the analyzed extracts had a high concentration of phenolic and flavonoid components. Moreover, there are many variations among these plants in the amount of each compound. The docking interaction showed a simulation of the atomic-level interaction between a protein and a small molecule through the binding site of target proteins, explaining the most critical elements influencing the enzyme's activity or inhibitions. The study's findings showed that the various phytochemicals found in agro-waste plants had high larvicidal activity and provide a safe and efficient substitute to conventional pesticides for pest management, as well as a potential future in biotechnology.

Synthesis of eco-friendly lipid-magnetite nanocomposite encapsulated Poinciana extract as promising insecticide against Culex pipiens

Mosquito-borne diseases represent a growing health challenge over time. Nanostructured lipid carriers (NLCs) are the second generation of solid lipid nanoparticles (SLNs), and they continue to attract significant interest as potential diagnostic and therapeutic tools in disease inhibition and insect control. Activated ingredients presented in the Poinciana leaves were extracted and GC-MS data indicated an increased abundance of terpenes, flavonoids, and phenolic substances. Poinciana extract was encapsulated to the vicinity of nanostructure lipid carrier, Po-NLC, and surface modified with magnetic nanoparticles, Po-NLC-MNPs. The synthesized nanoparticles depicted average particle size of 73.2 and 75.55 nm while zeta potential of (- 29.4) and (‒ 4.44 mV) for Po-NLC and Po-NLC-MNPs, respectively. Transmission electron microscope and morphology determination showed regular, irregular spherical and oval shapes with diverse single particle size. X-rays diffraction pattern of the freely synthesized MNPs was compared to the decorated NLC and the results manifested that the NLC was successfully decorated with MNPs. The larvicidal activity of plant extract, Poinciana extract (Po), and their nanoparticle conjugates against 3rd instar larvae of Culex pipiens was evaluated at 50, 100, 200, 500, 1000, and 1500 ppm concentrations. Both high and low concentrations of Po-NLC-MNPs, indicated potential larval mortality than plant extracts (Po extract) itself. The mortality rate reached 100% for 3rd instar larvae. Based on their relative toxicity, (Po-NLC-MNPs) was the best at killing larvae, followed by Po-NLC. The synthesized nps were checked for their cytotoxic effect against wi38 cell line. The in-vitro cytotoxicity results indicated that there was no significant cytotoxicity and the nanocomposite barely caused weak changes in the tested cells. The synthesized nanoparticles have potential to create a new generation of eco-friendly, effective alternatives for controlling mosquito-borne diseases.

Differentiation of Vespa velutina nigrithorax Colonies Using Volatile Organic Compound Profiles of Hornets and Nests

Vespa velutina (Lepeletier, 1836) (Hymenoptera: Vespidae) is a eusocial insect that lives in colonies of hundreds to thousands of individuals, which are divided into castes according to their task: queens, workers, and males. The proper functioning of the colony requires communication between the individuals that make up the colony. Chemical signals (pheromones) are the most common means of communication used by these insects to alarm and differentiate between individuals belonging or not to the colony. In this work, profiles of volatile organic compounds were obtained from the hornets and the external cover of four secondary nests located in the Basque Country. The obtained profiles were treated using chemometric tools. The grouping of hornets and nests according to the different colonies and geographical location was observed. In total, 37 compounds were found in common in hornets and nests. Most of them have been reported in the literature as belonging to different insects and plant species. This would corroborate the transfer of chemical compounds between the nest and the hornets' nest and vice versa. This information could be applied to the development of more efficient control methods for this invasive species, such as attractive traps or baits containing the relevant compounds.

Biological effects of Bougainvillea glabra, Delonix regia, Lantana camara, and Platycladus orientalis extracts and their possible metabolomics therapeutics against the West Nile virus vector, Culex pipiens (Diptera: Culicidae)

Plants are a treasure trove of biological materials containing a wide range of potential phytochemicals that are target-specific, rapidly biodegradable, and environmentally friendly, with multiple medicinal effects. Unfortunately, the development of resistance to synthetic pesticides and antibiotics led to the discovery of new antibiotics, antioxidants, and biopesticides. This has also led to the creation of new medications that work very well. The current study aimed to prove that ornamental plants contain specialized active substances that are used in several biological processes. Mosquitoes, one of the deadliest animals on the planet, cause millions of fatalities each year by transmitting several human illnesses. Phytochemicals are possible biological agents for controlling pests that are harmful. The potential of leaf extracts of Bougainvillea glabra, Delonix regia, Lantana camara, and Platycladus orientalis against Culex pipiens and microbial agents was evaluated. Acetone extracts had more toxic effects against Cx. pipiens larvae (99.0-100 %, 72 h post-treatment), and the LC50 values were 142.8, 189.5, 95.4, and 71.1 ppm for B. glabra, D. regia, L. camara, and P. orientalis, respectively. Plant extracts tested in this study showed high insecticidal, antimicrobial, and antioxidant potential. GC-MS and HPLC analyses showed a higher number of terpenes, flavonoids, and phenolic compounds. The ADME analysis of element, caryophyllene oxide, caryophyllene, and copaene showed that they were similar to drugs and that they were better absorbed by the body and able to pass through the blood-brain barrier. Our results confirm the ability of ornamental plants to have promising larvicidal and antimicrobial activity and biotechnology.

Larvicidal activity of Acacia nilotica extracts against Culex pipiens and their suggested mode of action by molecular simulation docking

Mosquitoes are one of the deadliest and most hazardous animals on Earth, where they transmit several diseases that kill millions of people annually. There is an ongoing search almost everywhere in the world for more effective and contemporary ways to control mosquitoes other than pesticides. Phytochemicals are affordable, biodegradable biological agents that specialize in eliminating pests that represent a risk to public health. The effectiveness of Acacia nilotica methanol and aqueous leaf extracts against 4th instar larvae was evaluated. The results revealed that the methanol extract of A. nilotica had a noticeable influence on the mortality rate of mosquito larvae, especially at high concentrations. Not only did the mortality rate rise significantly, but the hatching of the mosquito eggs was potentially suppressed.Terpenes, fatty acids, esters, glycosides, pyrrolidine alkane, piperazine, and phenols were the most prevalent components in the methanol extract, while the aqueous extract of A. nilotica exclusively showed the presence of fatty acids. The insecticidal susceptibility tests of both aqueous and alcoholic extract of A. nilotica confirmed that the Acacia plant could serves as a secure and efficient substitute for chemical pesticides because of its promising effect on killing larvae and egg hatching delaying addition to their safety as one of the natural pesticides. Molecular docking study was performed using one of the crucial and life-controlling protein targets, fatty acid binding protein (FABP) and the most active ingredients as testing ligands to describe their binding ability. Most of the structurally related compounds to the co-crystallized ligand, OLA, like hexadecanoic acid furnished high binding affinity to the target protein with very strong and stable intermolecular hydrogen bonding and this is quite similar to OLA itself. Some other structural non-related compounds revealed extraordinarily strong binding abilities like Methoxy phenyl piperazine. Most of the binding reactivities of the majortested structures are due to high structure similarity between the positive control, OLA, and tested compounds. Such structure similarity reinforced with the binding abilities of some detected compounds in the A. nilotica extract could present a reasonable interpretation for its insecticidal activity via deactivating the FABP protein. The FABP4 enzyme inhibition activity was assessed for of both methanolic and aqueous of acacia plant extract and the inhibition results of methanol extract depicted noticeable potency if compared to orlistat, with half-maximal inhibitory concentration (IC50) of 0.681, and 0.535 µg/ml, respectively.

The Chemical Ecology of Plant Natural Products

Plants are excellent chemists with an impressive capability of biosynthesizing a large variety of natural products (also known as secondary or specialized metabolites) to resist various biotic and abiotic stresses. In this chapter, 989 plant natural products and their ecological functions in plant-herbivore, plant-microorganism, and plant-plant interactions are reviewed. These compounds include terpenoids, phenols, alkaloids, and other structural types. Terpenoids usually provide direct or indirect defense functions for plants, while phenolic compounds play important roles in regulating the interactions between plants and other organisms. Alkaloids are frequently toxic to herbivores and microorganisms, and can therefore also provide defense functions. The information presented should provide the basis for in-depth research of these plant natural products and their natural functions, and also for their further development and utilization.