Malaria is a vector-borne disease, which is transmitted by female arthropod (mosquito) belonging to the Anopheles genus12. The disease is prevalent in Africa, with documented information in literature indicating, the Anopheles gambiae species as the predominant transmitter3. It is documented in literature that mosquitoes transmit more diseases, compared to other arthropods 4. Statistical data in literature showed that there are over 40 genera of mosquitoes distributed into over 3,000 species, out of which only about 30 - 40 species transmit malaria in nature 25.

Several metabolites have been identified from various plants, including over 10,000 alkaloids and 25,000 terpenes derivatives 6. Notwithstanding, the therapeutic efficacies in these applied metabolites varies upon some compounding parameters; including, seasonal influence, location, age, individual susceptibility and environmental stresses on the plant 7, or the applied part of the plant such as root, stem, fruits, leaves, and seeds 8, as well as the applied solvent medium used for the plant extraction 9.

The efficacy of C. alata have been documented in literature for the treatment of constipation, stomach pain, and ringworm 10. Microdesmispuberula was known for the treatment of gonorrhoea and erectile dysfunction 11. The antibacterial properties of Spilanthesfilicaulisleaf decoction have also been reported 12.

The application of synthetic therapy like drug administration can only abate morbidity burden and reinfection frequency 13, while pesticides poses potential ecotixicity 9. Due to the prevalence of malaria and search for eco-friendly control measures, multifaceted strategies have become necessary, including researches and application of plant-derived methods 2. Therefore, the investigation on the larvicidal potential of Cassia alata have become necessary.

The mortality rates of all methanolic leaf extracts of the plants (C. alata, M. puberula and S. filicaulis), assayed against the larvae is presented in Table 1. Results showed that the positive control had total mortality at concentration below 10.00 ppm, while the negative control demonstrated no mortalities against the vectors (Table 1). For the Cassia alata bioassay results showed that mortality rate increased significantly with higher concentration (p<0.05). However, mortality rates ranging from 46.66 – 100.00%, with the minimal and total minimal mortality rates at concentrations 10 and 60 ppm respectively (Table 1).

The no adverse effect level was observed at concentration of 0 ppm. Furthermore, based on dose-response curve the Cassia alata bioassay had biolarvicidal activity with LC₅₀ value of 13.72 ppm (Figure 1). The result for the methanolic-leaf-extract bioassay of M. puberula showed that mortality rate significantly ranged from 30.00 – 100.00% as presented in Table 1. The minimal mortality rate was observed at concentration of 10 ppm, while the total minimal mortality rate was observed at concentration of 70 ppm Table 1. Meanwhile no adverse effect level was at concentration of 0 ppm Table 1. Based on the dose-response the activity of methanolic leaf extract of M. puberula was demonstrated with LC₅₀ value of 21.24 ppm (Figure 1). Results of the S. filicaulis methanolic-leaf-extract showed that mortality rates ranged from 16.66 – 100.00% (p<0.05). The minimal and total minimal concentration were 10 and 80 ppm respectively Table 1, with LC₅₀ value of 28.86 ppm (Figure 1).

Results of this study is comparable to a recent study for the larvicidal methanolic leaf (32.13 – 100.00%) and Hexane flower of S. alata (21.94 – 100.00%) of Senna alata (16). The comparative larvicidal efficacies of the leaves, bark, stem and root of Jatropha curcas(Euphorbiaceae) against 3^rd and 4^th instar larvae Anopheles gambiae was reported by Ohimain et al., 9. Results of their studies demonstrated activities with LC₁₀₀ and LC₅₀ values for crude extract of the bark (437.5 and 87.5 ppm), methanolic-extract of the root (312.5 and 62.5 ppm), methanolic-extracts of the stem (237.5 and 47.5 ppm), leaves (75 and 15 ppm), and the bark (30 and 6 ppm), which was the most active.

The larvicidal activities of solvent-extracts of Hyptissuavolens and Ocimun sanctum were investigated against mosquito larva by Ohimain et al., 17. Results showed that the methanolic-extract of H. suaveolensinduced was the most active with LC₅₀ values of 73.25 ppm, followed by the chloroform and hexane extracts that demonstrated activities with LC₅₀ values of 76.25 and 97.25 ppm respectively. Comparatively, the O. sanctum bioassay demonstrated activities LC₅₀ values of 125.00 for methanolic-extract, 150.00 for chloroform-extract and 194.08 ppm for hexane-extract.

Several authors have reported phytochemicals in C. alata, M. puberula, and S. filicaulis that supported their antimicrobial activities 1819. Phytochemical like alkaloid, flavonoid, saponin, tannin and phenol were predominantly found in the leaves of C. alata20. Several author have confirmed the phytochemistry of M. puberula, this include phytochemicals like; alkaloid, flavonoid, saponin and steroids 20. The activities of S. filicaulis have been ascribed to predominant phytochemicals such as athraquinones, alkaloid, flavonoid, tannin and phenol 151920.

This study investigated the biolarvicidal potential of the methanolic extracts of C. alata, M. puberula¸ and S. filicaulis. Intrestingly, all extracts of the plant showed larvicidal activities with the C. alata extract exhibiting higher mortality, followed by S. filicaulis and M. puberula. Solvent methanolic-extracts of these plants, are hereby recommended for the formulation of biolarvicide for the control of malaria.