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Exploiting the Insecticidal Potential of the Invasive Siam Weed, Chromolaena odorata L. (Asteraceae) in the Management of the Major Pests of Cabbage and their Natural Enemies in Southern Ghana

Ezena GN, Akotsen-Mensah C and Fening KO

Cabbage is an important leafy vegetable widely cultivated and consumed in Ghana. It offers a good source of vitamins and minerals to the human body. Despite its importance cabbage production is constrained by insect pests attack. Chemical control has being the main strategy, but without much success, thus the need for alternative options for pest management. Field experiments were conducted in the major and minor rainy seasons of 2014 to evaluate the insecticidal potential of Siam weed, ChromolaenaodorataL. at three concentrations (10, 20 and 30 g/L w/v) in the management of the key pests of cabbage and its effect on their natural enemies. Neem seed extract (50 g/L) and Lambda cyhalothrin (Sunhalothrin® 2.5 ml/L) were used as reference insecticides with tap water as a control. The key pests recorded during the major season were the cabbage aphid, Brevicorynebrassicae, and cabbage webworm, Hellulaundalis, whiles Diamondback moths (DBM), Plutellaxylostellaand B. brassicaewere recorded in the minor season. Generally, the three concentrations of C. odoratawere efficacious in controlling aphids and DBM than the tap water and conventional insecticide, Sunhalothrin® in both the minor and major seasons. However, the 10 and 20 g/L C. odoratarecorded the highest buildup of natural enemy populations and also had higher yield as compared to 30 g/L C. odorata, Sunhalothrin®, and tap water. The cabbage plots sprayed with neem obtained the highest yield