Garlic and peppermint as biopesticides for citrus pest control.

Drawbacks associated with conventional pesticides have caused a view change and a search for an alternative but sustainable way of managing agricultural pests. Owing to their numerous roles in plant relationship with its environment, essential oils (EOs) are being investigated as an alternative to synthetic pesticides. This work studied garlic (Allium sativum L.) and Peppermint (Mentha piperita) essential oils for their insecticidal efficacy on Delottococcus aberiae (De Lotto), an invasive mealybug in the Spanish citriculture and the green citrus aphid Aphis spiraecola (Patch) at 0.05 and 0.1% concentration. Similarly, the side-effects of both EOs on two key natural enemies of citrus mealybugs, the predator Cryptolaemus montrouzieri and the parasitoid Anagyrus vladimiri, as well as on the predatory mite Neoseiulus californicus, were evaluated. Garlic EO caused more mortality than peppermint EO at 0.1% in every life stage of Delottococcus aberiae under laboratory condition but not on Aphis spiraecola under greenhouse experiment. Also, both EOs caused no significant residual effect on the natural enemies even at the highest concentration tested in this experiment. Finally, the ability of the EOs, especially Peppermint, to trigger plant defences was demonstrated. This work opens the door for further research on using EOs as an alternative but sustainable agricultural pest management strategy. Investigation into possible combinations of essential oils to manage these pests will present more insight into preventing the development of resistance.