Essential oils as environmentally friendly insecticides for controlling cotton mealybug, Phenacoccus solenopsis (Tinsley) (Hemiptera: Pseudococcidae)

Abstract

Eight plant essential oils were extracted and tested for their efficiency as natural insecticides against the cotton mealybug, P. solenopsis (Tinsley). In-vitro bioassay, the contact toxicity of the tested oils to adult females and 2nd instar nymphs was determined. Also, repellence activity of the tested oils were tested. The most effective oil against adult female’s after 72 hrs of application was L. nobilis followed by Apium graveolens, M. longifolia, C. articulates, M. sativa, A. graveolens, O. vulgar, then F. vulgar. The 2nd instar nymphs showed more susceptibility for all tested essential. Regarding repellency, M. longifolia showed the highest repellency effect but unfortunately with high degradation rate. The most repellent essential oils with satisfactory stability were L. nobilis, F. vulgar and C. articulates. Also, the efficacy of the tested oils were tested against P. solenopsis in open field conditions. The most efficient oil at 72hrs after treatment was L. nobilis which showed great reduction percentage (89.3%) followed by Apium graveolens (88.6%), M. longifolia (88.6%), C. articulates (87.8%), M. sativa (87.7%), A. graveolens (86.9%), O. vulgar (85.9%) and F. vulgar (85.2%), respectively.