Toxicity of ethanolic extracts from Lippia origanoides and Gliricidia sepium to Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae)

ABSTRACT

Botanical compounds with insecticidal and acaricidal activities have been used in pest management with different levels of success. Toxicity of ethanolic extracts obtained from wild oregano (Lippia origanoides) and gliricidia (Gliricidia sepium) to Tetranychus cinnabarinus (Boisduval) were evaluated. Mite population was collected from black bean plants growing in Urachiche Municipality, Yaracuy State, Venezuela. Ethanolic extracts of wild oregano and gliricidia leaves were evaluated at different concentrations (5, 10, 15, and 20 percent) using the leaf disk immersion technique. The presence of alkaloids, flavonoids, phenols and tannins, essential oils and saponins was verified in the plant material used in our study. Tetranychus cinnabarinus oviposition decreased at a rate of 43.7 percent or 57 percent when 5 percent oregano or gliricidia extracts were used, respectively. Also, 10 percent oregano or gliricidia extracts caused 42.2 percent or 72.5 percent of mortality to T. cinnabarinus, respectively. Ethanolic extracts showed acaricidal effects on T. cinnabarinus, as evidenced by maximum mortality (96.6 percent and 100 percent caused by wild oregano and gliricidia, respectively) when used at a concentration of 20 percent. Our results showed that gliricidia and wild oregano are promising for the management of T. cinnabarinus, although their field efficacy remains to be evaluated.