Rotenoid content and in vitro acaricidal activity of Tephrosia vogelii leaf extract on the tick Rhipicephalus appendiculatus

Abstract

This study aimed to determine the rotenoid content of leaf extracts of the white (TVW) and purple (TVP) varieties of Tephrosia vogelii, both collected in North-Kivu Province, Democratic Republic of Congo and to evaluate their in vitro acaricidal efficacy on the tick Rhipicephalus appendiculatus. The high performance liquid chromatography analysis of rotenoid compounds from those extracts revealed that the contents of rotenone and deguelin were respectively higher in the leaves of TVW (0.044% and 1.13%) than in TVP (0.014% and 0.66%). Batches of 20 live adult ticks were immersed for 15 min in six different doses of each plant extract (0.625; 1.25; 2.5; 5; 10 and 20mg/mL of distilled water) and in the solution of Milbitraz(®) (12.5%m/v emulsifiable concentrate of amitraz) as a positive control. Additionally 9.5% ethanol and distilled water control groups were included. Tick mortalities were recorded every 24h for 5 days. The results indicated that there was no significant difference (P>0.05) between the acaricidal effect of Milbitraz(®) and the plant material used at a dose of at least 2.5 or 5mg/mL for TVW and TVP respectively. However, the dose response relationship determined at the fifth day after treatment showed a similar acaricidal effect for the two plant varieties with similar lethal dose 50 (LD(50)) of 0.83 and 0.81 mg/mL for TVW and TVP respectively. It is concluded that T. vogelii leaves may be used for the control of R. appendiculatus in areas where synthetic acaricides are either not available or affordable. However, T. vogelii extract should be sprayed in order to limit the potential risks of ecotoxicity linked to rotenoid compounds.

Phytochemical Analysis of Tephrosia vogelii across East Africa Reveals Three Chemotypes that Influence Its Use as a Pesticidal Plant

“…Our results indicate that T. vogelii is most widely used for pest control among other uses as shown in the survey results. Farmers' responses in this study, align with reports about the use of T. vogelii in controlling pests in vegetables and in stored products [15] and ectoparasite control in domestic animals [12,24,27]. The wider use of T. vogelii for small-scale farmers could be associated with previous projects that promoted integrated pest management using T. vogelii and research on soil improvement [28,29].…”

“…f. (Leguminosae) is a plant species reported to be used widely for its medicinal, insecticidal, and soil enrichment potential in tropical Africa [1][2][3][4][5][6]. Specifically, research on T. vogelii reported medicinal properties such as anti-cancer activity [7][8][9] and efficacy as an ectoparasite treatment for domestic animals including poultry [10][11][12][13][14]. A number of studies have sought to validate the reported use of T. vogelii as a botanical insecticide under laboratory and field conditions and have reported its effectiveness for crop protection and reduced impacts on beneficial ecosystem services [15][16][17].…”

In vitro acaricidal activity of Bobgunnia madagascariensis Desv. against Amblyomma variegatum (Fabricius) (Acari: Ixodidae)

“…The presence of rotenoids, deguelin, rotenone, sarcolobine, tephrosin and α-toxicarol, in the leaves of T. vogelii, has been reported to be responsible for its pest control efficacy . Kalume et al (2012) reported that the rotenoid content of T. vogelii leaves was associated with its acaricidal activity against the cattle tick Rhipicephalus appendiculatus. Therefore, these compounds were mostly likely responsible for the observed acaricidal activity of T. vogelii leaf extracts.…”

The Potential of Using Indigenous Pesticidal Plants for Insect Pest Control to Small Scale Farmers in Africa

“…This is practiced in remote areas of Africa, commonly regarded as illegal fishing [61]. It is reported that leaves of T. vogelii contain high amounts of rotenone and deguelin [62] responsible for the toxicity to fish. Tephrosia vogelii has however a great potential in agriculture in the control of insect pests and in soil enrichment through nitrogen fixation [59].…”