Field and laboratory evaluations of different botanical insecticides for the control of Dactylopius opuntiae (Cockerell) on cactus pear in Morocco

Abstract

The prickly-pear cactus Opuntia ficus-indica L. is grown throughout Morocco and has an important economic role as a source of food, animal feed and income for rural populations. However, currently this crop is suffering from attack by the wild cochineal Dactylopius opuntiae, which has caused huge production losses. This study was conducted to evaluate the effectiveness of five botanical extracts and a detergent for the control of nymphs and adult females of D. opuntiae in laboratory bioassays and field conditions. Under laboratory conditions, the detergent black soap at 60 g/l caused 100% mortality of D. opuntiae adult females and nymphs, 48 h after treatment. Capsicum annuum fruit extract at 10% gave 100% mortality of nymphs at 96 h after application and 56% mortality of adult females at 192 h after treatment. Under field conditions, black soap at 60 g/l applied in combination with C. annuum at 200 g/l caused the highest mortality on adult females (87.31%) at 168 h after application, and 84.9% on nymphs at 72 h after treatment. The black soap at 60 g/l had the greatest impact on mortality of D. opuntiae nymphs and adult females when applied at low to medium levels of D. opuntiae infestation. The double application of black soap at 60 g/l over a 3-day spray interval significantly increased the mortality of adult females up to 82.5% at 3 days after the second application. These findings showed that the use of the biodegradable products, black soap at 60 g/l in double application or in combination with C. annuum extract at 200 g/l, could be incorporated in the management package for the control of D. opuntiae as a safe alternative to chemical insecticides.