Insecticidal potential of medicinal plants found in Central Amazon region against cabbage aphid Brevicoryne brassicae (L.) (Hemiptera: Aphididae).
The present work aimed to evaluate the insecticidal potential of five plant native or widely cultivated species of Central Amazon, Brazil - Crescentia cujete L., Himatanthus articulatus (Vahl) Woodson, Syzygium malaccense (L.) Merr. & L.M. Perry, Schnella sp. and Protium sp. - against cabbage aphid [Brevicoryne brassicae (L.)]. The extracts were used at a concentration of 10% and the botanical insecticide based on azadirachtin (Azamax®) was used as control. For insecticide evaluation, discs of kale leaves with 3.5 cm diameter were individualized in Petri dishes (6 cm ø) and infested with 10 nymphs of B. brassicae (up to 48 h old). 1.0 mL of each treatment was sprayed over the discs and after 24 h the mortality was evaluated. For repellence test, discs of kale leaves (3.5 cm ø) were divided into 2 parts: 1.0 mL of each treatment was sprayed over a half of the disc, in the same concentrations used for insecticide activity. One hour later, 5 adults of B. brassicae were transferred to the center of the leaf disc and after 24 h the number of adults over the treated and non treatd area of the kale disc was measured. The results were submitted to normality test and analysis of variance (ANOVA). The direct and residual contact of the extracts of C. cujete, H. articulatus and Schnella sp. caused a mortality of nimphs between 97.6 and 100%. These results were more expressive than S. malaccense (54.6%) and Azamax® (35.1%). None repellent action caused by the extracts over B. brassicae was detected.