Management of the diamondback moth via citrus oil

Abstract

Plutella xylostella is an important pest of brassica crops throughout the world and causes harm to family farming in the city of Bezerros in the state of Pernambuco, Brazil. The annual cost of controlling this pest surpasses 14 million dollars in northeastern Brazil. The main form of controlling this pest in these agricultural niches is the use of synthetic insecticides, such as deltamethrin, which has led to the emergence of resistant P. xylostella populations. The aim of the present study was to determine the chemical composition of essential oils from Citrus aurantium, C. limon and C. aurantiifolia and evaluate the insecticidal activity of these essential oils and selected constituents (α-terpinene, myrcene, α-pinene, ρ-cymene, β-pinene, limonene and terpinen-4-ol) on different stages of development of two populations of P. xylostella – one susceptible and one resistant to deltamethrin. A further aim was to determine the phytotoxic effects these essential oils and selected constituents on the host plant. Among the oils and chemical constituents tested, the oil from C. limon and terpinen-4-ol were the most promising and had the same level of toxicity to the populations of P. xylostella investigated. Compared to the positive controls (deltamethrin and azadirachtin), these products were more toxic and exhibited greater antifeedant action for the resistant population. Moreover, none of the oils exhibited phytotoxicity to the host plant. In conclusion, essential oils from the species of Citrus investigated and selected constituents act on different stages of development of P. xylostella (larvae and eggs) with different modes of action (larvicidal, ovicidal and antifeedant).