Mosquitoes are the potential vectors of several viral diseases such as filariasis, malaria, dengue, yellow fever, Zika fever and encephalitis in humans as well as other species. Dengue, the most common mosquito-borne disease in humans caused by the dengue virus is transmitted by the vector Ae. aegypti. Fever, chills, nausea and neurological disorders are the frequent symptoms of Zika and dengue. Thanks to various anthropogenic activities such as deforestation, industrialized farming and poor drainage facilities there has been a significant rise in mosquitoes and vector-borne diseases. Control measures such as the destruction of mosquito breeding places, a reduction in global warming, as well as the use of natural and chemical repellents, mainly DEET, picaridin, temephos and IR-3535 have proven to be effective in many instances. Although potent, these chemicals cause swelling, rashes, and eye irritation in adults and children, and are also toxic to the skin and nervous system. Due to their shorter protection period and harmful nature towards non-target organisms, the use of chemical repellents is greatly reduced, and more research and development is taking place in the field of plant-derived repellents, which are found to be selective, biodegradable and harmless to non-target species. Many tribal and rural communities across the world have been using plant-based extracts since ancient times for various traditional and medical purposes, and to ward off mosquitoes and various other insects. In this regard, new species of plants are being identified through ethnobotanical surveys and tested for their repellency against Ae. aegypti. This review aims to provide insight into many such plant extracts, essential oils and their metabolites, which have been tested for their mosquitocidal activity against different life cycle forms of Ae. Aegypti, as well as for their efficacy in controlling mosquitoes.

The active and inexpensive catalyst cupric oxide (CuO) loaded foliar fertilizer of graphitic carbon nitride (g-C₃N₄) is investigated for biological applications due to its low cost and easy synthesis. The synthesized CuO NPs, bulk g-C₃N₄, exfoliated g-C₃N₄, and different weight percentages of 30 wt%, 40 wt%, 50 wt%, 60 wt%, and 70 wt% CuO-loaded g-C₃N₄ are characterized using different analytical techniques, including powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and ultraviolet-visible spectroscopy. The nanocomposite of CuO NPs loaded g-C₃N₄ exhibits antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The 20 μg/mL of 70 wt% CuO/g-C₃N₄ nanocomposite showed an efficiency of 98% for Gram-positive bacteria, 80% for E. Coli, and 85% for P. aeruginosa. In the same way, since the 70 wt% CuO/g-C₃N₄ nanocomposite showed the best results for antibacterial activity, the same compound was evaluated for anti-fungal activity. For this purpose, the fungi Fusarium oxysporum and Trichoderma viride were used. The anti-fungal activity experiments were not conducted in the presence of sunlight, and no appreciable fungal inhibition was observed. As per the literature, the presence of the catalyst g-C₃N₄, without an external light source, reduces the fungal inhibition performance. Hence, in the future, some modifications in the experimental conditions should be considered to improve the anti-fungal activity.

A marine-derived red alga, along with their active constituents, were actively screened for their biocontrol potential against major insect pests. The current study explored the larvicidal activity of crude methanolic extracts of the red alga Halymenia dilatata (Mx-Hd) against Aedes aegypti (Linn.), and their enzyme inhibition, repellent activity, and non-target toxicity was screened against non-target species. The toxicity of Mx-Hd to exposed larvae was dose-dependent, and it was significant at the maximum concentration of 100 ppm (parts per million) across the second, third, and fourth instars of Ae. aegypti. The LC₅₀ and LC₉₀ Mx-Hd concentrations for second-instar larvae were 37 and 93 ppm, respectively. Moreover, the level of major detoxifying enzymes was altered in response to the Mx-Hd treatment. The repellent activity of Mx-Hd showed maximum repellent protection at 100 ppm dosage for up to 210 min. The toxicity against non-target species showed that Mx-Hd was safe or less toxic at the prominent dosage (1000 ppm). The photomicrography results provided a prominent damage rate in fourth-instar midgut cells and tissues treated with Mx-Hd. Overall, the present study delivered an insect toxicological screening study of bioactive red alga extracts against a dengue mosquito vector, as well as a baseline for better commercialization of bioactive insecticides. Also, the bioeconomy of algal-based pesticides in managing mosquito larvae presents an exciting avenue for sustainable and eco-friendly pest control.

Green synthesis of silver nanoparticles (AgNPs) has gained greater interest among chemists and researchers in this current scenario. The present research investigates the larvicidal and anti-proliferation activity of AgNPs derived from Knoxia sumatrensis aqueous leaf extract (K. sumatrensis-ALE) as a potential capping and reducing candidate. The synthesized AgNPs were characterized through-UV-spectra absorption peak at 425 nm. The XRD and FT-IR studied displayed the crystalline nature and presence of functional groups in prepared samples. FE-SEM showed the hexagonal shape of NPs with the size of 7.73 to 32.84 nm. The synthesized AgNPs displayed superior antioxidant and anti-proliferative activity (IC₅₀ 53.29 µg/mL) of breast cancer cell line (MCF-7). Additionally, larvicidal activity against mosquito vector Culex quinquefasciatus larvae delivered (LC₅₀-0.40, mg/L, and LC₉₀-15.83) significant mortality rate post treatment with synthesized AgNPs. Overall, the present research illustrates that the synthesized AgNPs have high biological potential and present a perfect contender in the pharmacological and mosquitocidal arena.