Comparison of the effects of extracts from three Vitex plant species on Anopheles gambiae s.s. (Diptera: Culicidae) larvae

Abstract

Acetone and methanol extracts of different parts of three Vitex species (leaves and stem bark of Vitex trifolia, leaves, stem bark and root bark of Vitex schiliebenii and stem and root bark of Vitex payos) were evaluated for their potential to control Anopheles gambiae Giles s.s. larvae (Diptera: Culicidae). The extracts gave different levels and rate of mortality of the larvae. Some (methanol extract of V. trifolia leaves, acetone extracts of stem bark and leaves of V. schiliebenii, acetone extract of root bark of V. payos) caused 100% mortality at 100 ppm in 72 h, with those of V. schiliebenii and V. payos showing faster rate of mortality (LT₅₀=8 h) than that of V. trifolia (LT₅₀=14 h). At lower doses of these extracts (≤50 ppm), most of the larvae failed to transform to normal pupae but gave larval-pupal intermediates between 4 and 14 days of exposure. Some pupated normally but the adults that emerged appeared to be weak and died within 48 h. Extracts of the stem bark of V. payos showed interesting effects on the larvae. Initially, the larvae were relatively hyperactive compared to those in control treatments. Later, the ones that did not transform to larval-pupal intermediates became stretched and inactive and died and floated in clusters on the surface. These observations suggest some interesting growth-disrupting constituents in the plants, with possible application in the practical control of mosquito larvae in aquatic ecosystems.

Methanolic extract of Agerantum conyzoides exhibited toxicity and growth disruption activities against Anopheles gambiae sensu stricto and Anopheles arabiensis larvae

“…Studies carried out by Nyamoita et al, [41], Nathan et al, [45] and Nathan et al, [46] reported that in addition to their lethality, the secondary metabolites of the botanicals used resulted in protracted larval phase, disrupted growth and malformation of the exoskeleton. Although there was no elongation of gut as observed in [29] and [47], incomplete melanization process was observed in larvae and some pupae examined under light microscopy (Fig.…”

“…The bioassays were conducted in accordance with the World Health Organization guidelines for testing larvicides [40] and adopted by Nyamoita et al, [41]. Crude methanolic extract (250 mg, 125 mg, 50 mg and 25 mg) was separately dissolved in 1 ml of analytical grade ethanol (Fisher Scientific, Loughborough, UK) and diluted with 499 ml of distilled water to make a 500 ml stock solution.…”

Growth-disrupting Murraya koenigii leaf extracts on Anopheles gambiae larvae and identification of associated candidate bioactive constituents

“…The morphogenetic larvae-pupae developmental effects and decreased survival may be due to dysregulation of juvenile hormone in the mosquito by the M. koenigii phytochemicals, as evidenced by documented impact of phytochemicals in An. gambiae (Lee et al, 2015;Nyamoita et al, 2013) and other insects (Tusun et al, 2017), and/or midgut damage as observed in Culex quinquefasciatus larvae exposed to Garlic Vine extracts (Granados-Echegoyen et al, 2014;Procópio et al, 2015).…”

“…Extracts from Vitex trifolia have been shown to disrupt An. gambiae larval growth (Nyamoita et al, 2013) and those from Turraea abyssinica are both larvicidal and adulticidal to An. gambiae (Owino et al, 2014).…”

A comprehensive review of ethnomedicinal approaches, phytochemical analysis, and pharmacological potential of Vitex trifolia L.

“…Additionally, a comparative in vivo study on the effects of extracts from three Vitex species on A. gambiae s.s. larvae at concentrations ≤ 50 ppm and 24 h time interval, found significant potency in the methanol extract of V. trifolia leaves, acetone extracts of V. schiliebenii stem bark and leaves, and acetone extract of V. payos (Lour.) Notably, V. schiliebenii and V. payos extracts demonstrated a faster mortality rate in A. gambiae s.s. larvae compared to V. trifolia , indicating their potential as effective agents for controlling A. gambiae s.s. larvae, and their promise for further investigation in mosquito control programs to combat malaria transmission ( Nyamoita et al, 2013 ).…”