Mosquitoes play a crucial role as primary vectors for the transmission of diseases such as malaria, dengue, and yellow fever. Currently, the prevalence of filariasis and other related conditions is recognized as one of the most critical global health challenges (Hafeez et al., 2011). The World Health Organization (WHO) recently reported a staggering 1.64 million cases of dengue worldwide, with a fatality rate surpassing that of malaria cases (WHO, 2022). Furthermore, the extensive use of synthetic insecticides, as well as organochlorine and phosphorous compounds, is leading to environmental issues, including direct health risks to humans (Bernardes et al., 2015). In tropical countries, particularly in urban areas, dengue fever is predominantly caused by the flavivirus and is transmitted by Aedes aegypti mosquitoes (Pinheiro and Corber, 1997). Of the approximately 500 anopheline species identified worldwide, over 50 are capable of transmitting malaria through the bite of infected female mosquitoes (Schlagenhauf-Lawlor, 2008). Anopheles mosquitoes can also transmit Wuchereria bancrofti, the parasite responsible for lymphatic filariasis, as well as Plasmodium falciparum sporozoites (Rozendaal, 1997). The most perilous malarial parasite, Plasmodium falciparum, forms a symbiotic relationship with Anopheles stephensi, one of its principal natural mosquito hosts, which facilitates its transmission through the contagious bites of Anopheles mosquitoes (Shaw et al., 2022). Culex mosquitoes, on the other hand, are responsible for transmitting a wide range of viruses and are associated with the spread of various diseases, including filariasis and avian malaria (Aly et al., 2023). Globally, approximately 550 species of Culex mosquitoes have been documented thus far (Vinogradova, 2000). The most commonly encountered species within the Culex genus, C. quinquefasciatus, transmits bancroftian filariasis and is typically found near contaminated water sources, often associated with organic waste. In contrast, Culex tritaeniorhynchus, responsible for transmitting Japanese encephalitis in Asia, prefers clean water and is commonly found in ditches or rice fields (Diagana et al., 2007). The mosquito species Culex quinquefasciatus thrives in heavily contaminated sewers, congregates in small areas near human dwellings, and readily feeds on mammals, particularly humans. Furthermore, some experts have attributed its widespread distribution and abundance worldwide to its ability to exploit various modes of human transportation (Barr, 1957). To combat the increasing number of insect vectors, carbamates, pyrethrins, and pyrethroids have traditionally been employed. Additionally, it has been discovered that the malarial parasite is independently developing artemisinin resistance and spreading locally in Africa (Balikagala et al., 2021). Consequently, alternative prevention methods are imperative in the modern era, necessitating the development of environmentally safe, biodegradable, and cost-effective insecticides through indigenous approaches. These methods should be legally sound, scientifically valid, and technologically advanced, offering more robust defenses against vectors. In comparison to terrestrial plants, seaweeds contain essential biologically active compounds. The numerous seaweeds found in coastal habitats are considered an excellent source of biologically active substances, including secondary metabolites, polysaccharides, minerals, vitamins, amino acids, and fatty acids (Perumal et al., 2022). Previous research has shown that metabolites from phaeophycean algae (brown seaweed) are highly effective antibiotics against tumors, bacteria, and larvae (Kordjazi et al., 2019). In this context, natural polymers are typically preferred due to their lower toxicity to target species and their innate biodegradability.

Human societies across the globe have been engaged in relentless efforts to combat vectors and other harmful insect species. Numerous studies have shown that phytochemicals derived from plants can serve as larvicides, inhibit insect growth, and possess other repellent properties (Murugan et al., 2007). Marine halophytes, such as seaweeds, mangroves, and seagrasses, constitute a specialized group of plants adapted to extreme saline conditions. The secondary metabolites found in seaweeds exhibit a wide range of bioactivities, including effects on the human nervous system and larvicidal and nematicidal properties in lower animals (Bazes et al., 2009). Some earlier research has demonstrated that extracts from Sophora alopecuroides result in high larval mortality (86.66%) in third instar Aedes albopictus larvae (Shoukat et al., 2020). Similarly, essential oil extracted from the Seriphidium brevifolium plant displayed potent larvicidal activity against Aedes albopictus, with an LC50 value of 49.46 μg/mL (Rizvi et al., 2020). Previous reports have indicated that primary and secondary metabolites found in seaweeds possess diverse and unique biological properties (Akay et al., 2011). Most brown seaweeds, in particular, exhibit favorable antimicrobial, larvicidal, pupicidal, and pharmacological properties (Eom et al., 2012; Choi et al., 2014; Dhanasundaram et al., 2022). The focus of the current investigation is to assess the larvicidal activity of solvent extracts from common seaweeds against mosquito vectors, namely Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi.