Dactylopius opuntiae (Cockerell, 1929) (Hemiptera: Dactylopiidae) of cactus pear in Morocco: contact and fumigant insecticidal activities of four essential oils and hydrosols and their chemical composition

Morocco's prickly pear has high economic value. However, it is infested by the prickly pear cochineal (Dactylopius opuntiae (Cockerell, 1929) (Hemiptera: Dactylopiidae)), causing massive losses; almost 60% were infected and destroyed chemical pesticides are used to control this pest; however, they have negative consequences like resistance, and present long-term risks to the environment as well as humans. Thus, the present work aims to study the insecticidal effect of bioactive natural extracts. Essential oils and hydrosols of oregano (Origanum vulgare L.), thyme (Thymus vulgaris L.), pennyroyal (Mentha pulegium L.), and peppermint (Mentha piperita L.) were tested. Two concentrations were used for essential oils (1.5% and 3%) and hydrosols (100% and 75%) with contact and fumigant applications. The mortality rate was determined after 24 h of treatment. The highest mortality (99.44%) was recorded using contact application at 3% of O.vulgare E.O. Also, its hydrosol has important insecticidal activity reaching 80% of the mortality rate. The chemical composition of essential oils using gas chromatography coupled with mass spectrometry (GC/MS) was studied. The main bioactive compounds were carvacrol and m-cymene for O. vulgare and T. vulgaris EOs, pulegone and l-menthone for M. pulegium EO, linalool and linalyl acetate for M. piperita EO. Data obtained relieved the importance of these plants as sources of natural bioactive compounds against D. opuntiae.