plant extracts contain many active compounds, which are tremendously fruitful for plant defence against several insect pests. the prime objectives of the present study were to calculate the extraction yield and to evaluate the leaf extracts of Citrullus colocynthis (L.), Cannabis indica (L.) and Artemisia argyi (L.) against Brevicoryne brassicae and to conduct biochemical analysis by gas chromatography-mass spectrometry (Gc-MS). the results suggested that when using ethanol, C. colocynthis produced a high dry yield (12.45%), followed by that of C. indica and A. argyi, which were 12.37% and 10.95%, respectively. The toxicity results showed that A. argyi was toxic to B. brassicae with an Lc 50 of 3.91 mg mL −1 , followed by the toxicity of C. colocynthis and C. indica, exhibiting Lc 50 values of 6.26 and 10.04 mg mL −1 , respectively, which were obtained via a residual assay; with a contact assay, the Lc 50 values of C. colocynthis, C. indica and A. argyi were 0.22 mg mL −1 , 1.96 and 2.87 mg mL −1 , respectively. the interaction of plant extracts, concentration and time revealed that the maximum mortality based on a concentration of 20 mg L −1 was 55.50%, the time-based mortality was 55% at 72 h of exposure, and the treatment-based mortality was 44.13% for A. argyi via the residual assay. on the other hand, the maximum concentration-based mortality was 74.44% at 20 mg mL −1 , the time-based mortality was 66.38% after 72 h of exposure, and 57.30% treatment-based mortality was afforded by A. argyi via the contact assay. the biochemical analysis presented ten constituents in both the A. argyi and C. colocynthis extracts and twenty in that of C. indica, corresponding to 99.80%, 99.99% and 97% of the total extracts, respectively. Moreover, the detected caryophylleneonides (sesquiterpenes), α-bisabolol and dronabinol (Δ 9-tHc) from C. indica and erucylamide and octasiloxane hexamethyl from C. colocynthis exhibited insecticidal properties, which might be responsible for aphid mortality. However, A. argyi was evaluated for the first time against B. brassicae. It was concluded that all the plant extracts possessed significant insecticidal properties and could be introduced as botanical insecticides after field evaluations. The cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae), is a serious pest native to Europe but now found globally 1,2 , and it causes significant losses to economically important crops, including broccoli, oilseed rape, brussels sprouts, cauliflower, black and white mustard, toria, Chinese cabbage, kale, and other field crops 1. It also causes yellowing, stunting, and plant wilting and acts as a vector of several viral diseases in crucifers, including cauliflower mosaic virus and turnip mosaic virus 3,4. In the case of severe infestation, plants become covered with aphids, resulting in leaf surfaces roofed with black mould due to honey secretion, which can ultimately cause
