Assessment of mineral oils, black soap, and essential oils for controlling Dactylopius opuntiae (Cockerell. 1929) (Hemiptera: Dactylopiidae)

The cactus pear is extensively cultivated in Morocco, but its evolution as a high-value crop has been disrupted since the introduction of Datylopius opuntiae , in 2014. The objective of this study was to test, in laboratory, greenhouse, and field, the efficacy of mineral oils, black soap, and essential oils from three plants: Origanum vulgare , Artemisia herba-alba , and Brassica alba against this insect, and to evaluate their phytotoxic effects on one-year-old cladodes in the field. The treatments in the laboratory were applied using a completely randomized design with four repetitions on 10 first-instar larvae and 10 adult females. In the greenhouse and in the field, these treatments were applied to cladodes infested by D. opuntiae , distributed according to a completely randomized design and a randomized complete block design with four repetitions, respectively. The phytotoxicity test was conducted using a randomized complete block design with five repetitions. The results showed significant efficacy of the five tested products. In the laboratory, the essential oil of O. vulgare and black soap emerged as the most effective treatments, achieving a maximum mortality rate of 100% against adult females 96 h after application. The same level of mortality was observed in nymphs at 24 h and 48 h after treatment by O. vulgare essential oil and black soap, respectively. This efficacy was confirmed in greenhouse with percentages of 100% (144 h after treatment) and 99.44 ± 0.95% (168 h after treatment) respectively, for black soap and O. vulgare essential oil. In the field, the essential oils of O. vulgare and A. herba-alba showed the highest efficacy with a mortality rate of 100%, 48 h after treatment. The evaluation of phytotoxicity in the field showed a significant phytotoxic effect of O. vulgare essential oil applied at a 5% dose. The other treatments did not show any significant phytotoxic effect on one-year-old cladodes.