Insecticidal activity and phytochemical analysis of Pyrus communis L. extracts against malarial vector, Anopheles pharoensis Theobald, 1901 (Diptera: Culicidae)

We aimed at investigating the insecticidal activity of Pyrus communis L. against the malarial vector, Anopheles pharoensis Theobald, 1901 and its phytochemical constituents. Leaves were collected and the crude extracts were prepared using hexane (PCH) and methanol (PCM). Tested PCH and PCM possess larvicidal activity against A. pharoensis with LC50 and LC90 values of 179.9, 41.2 and 314.1, 68.9 ppm, respectively. A significant reduction in the number of eggs laid by females A. pharoensis that developed from larvae treated with PCH and PCM was noticed. Also, PCH treatment showed highest repellent activity compared with PCM. GC/MS analysis of the PCH revealed the presence of 55 identified compounds subdivided into 2 major classes viz. phenyl alkanes (38.65 %) and oxygenated sesquiterpenoids (36.41 %). LC/MS of PCM had led to the identification of 37 compounds, mainly flavonoids, chalcones, phenolic acids and tannins. The results demonstrate the insecticidal potential of leaves methanol and hexane extracts from P. communis as green insecticidal agents for the control of malarial vector, A. pharoensis.

An Eco-Friendly Approach to the Control of Pathogenic Microbes and Anopheles stephensi Malarial Vector Using Magnesium Oxide Nanoparticles (Mg-NPs) Fabricated by Penicillium chrysogenum

The discovery of eco-friendly, rapid, and cost-effective compounds to control diseases caused by microbes and insects are the main challenges. Herein, the magnesium oxide nanoparticles (MgO-NPs) are successfully fabricated by harnessing the metabolites secreted by Penicillium chrysogenum. The fabricated MgO-NPs were characterized using UV-Vis, XRD, TEM, DLS, EDX, FT-IR, and XPS analyses. Data showed the successful formation of crystallographic, spherical, well-dispersed MgO-NPs with sizes of 7–40 nm at a maximum wavelength of 250 nm. The EDX analysis confirms the presence of Mg and O ions as the main components with weight percentages of 13.62% and 7.76%, respectively. The activity of MgO-NPs as an antimicrobial agent was investigated against pathogens Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans, and exhibited zone of inhibitions of 12.0 ± 0.0, 12.7 ± 0.9, 23.3 ± 0.8, 17.7 ± 1.6, and 14.7 ± 0.6 mm respectively, at 200 µg mL−1. The activity is decreased by decreasing the MgO-NPs concentration. The biogenic MgO-NPs exhibit high efficacy against different larvae instar and pupa of Anopheles stephensi, with LC50 values of 12.5–15.5 ppm for I–IV larvae instar and 16.5 ppm for the pupa. Additionally, 5 mg/cm2 of MgO-NPs showed the highest protection percentages against adults of Anopheles stephensi, with values of 100% for 150 min and 67.6% ± 1.4% for 210 min.

First report on the presence of natural Wolbachia population from major malarial vector mosquitoes Anopheles culicifacies s.l., and Anopheles stephensi from Tamil Nadu, India

Wolbachia is an alpha-proteobacteria present in several arthropods. The present study focussed on the identification of Wolbachia in wild malarial vector mosquitoes. This was achieved by molecular identification of Wolbachia from collected mosquitoes. A total of four hundred and eight seven mosquito samples were collected. Morphometric and molecular analysis revealed that they belong to Anopheles culicifacies s.l., (48.25%) and Anopheles stephensi (51.75%). The presence of Wolbachia was identified using 16S rRNA, wsp and FtsZ genes, where nested PCR of 16S rRNA alone was successful and then sequenced. Only seven mosquitoes (1.4%) were positive for Wolbachia. In silico and restriction digestion of 16S rRNA gene product using RsaI enzyme showed that the identified Wolbachia belongs to supergroup B. The prevalence rate of natural Wolbachia was lesser in native malarial vector An. culicifacies s.l. and An. stephensi was about 1.7% and 1.2%, respectively. This is the first report on the presence of Wolbachia in Anopheles culicifacies s.l. and Anopheles stephensi.