Abstract:
Background and Purpose: Plants contain complex bioactive compounds with insecticide
properties. The present study was designed to characterize and determine the larvicidal potency
of crude methanol and hexane extracts of Urtica massaica against laboratory-cultured Anopheles
gambiae larvae.
Materials and Methods: This research was a laboratory-based experiment. Bioactive compounds
were extracted using methanol and hexane, while larvae for bioassay were laboratory stock. The
effectiveness of the extracts was evaluated using the World Health Organisation (WHO) >80%
mortality threshold and methods, respectively. The extract dose was taken as the independent
variable, while observed mortalities were the dependent variable. Dimethyl sulfoxide and distilled
water were used as negative controls. Descriptive statistics and one-way analysis of variance were
performed for statistical justifications of bioactive quantities and insecticidal properties of the
extracts. Significant level was set at P<0.05.
Results: Five groups of chemical compounds were extracted: Phenolic > amino acids and nitrogen
derivatives>steroids and terpenoids > flavonoids, nitrogen derivatives, and others. Nineteen
compounds were from roots, 17 from leaves, and 12 from stems. β-Sitosterol, 3,4-diferuloylquinic,
and catechin were more while benzoic acid, L-leucine, N-(m-anisoyl)-, methyl ester, and myricetin
were the least abundant in leaves, stem, and roots, respectively. Extracts from the stem killed
more than 80% of exposed larvae for doses of 10 mL/100 cm3 (e/w) than those of the other parts
(root and leaves). The observed mortalities, however, were not significantly different (P>0.05),
irrespective of the dose or control used.
