Comparing Terpenes from Plant Essential Oils as Pesticides for the Poultry Red Mite (Dermanyssus gallinae)

Resistance to conventional synthetic pesticides has been widely reported in ticks, parasitic mites and other pests of veterinary and medical significance. New and novel approaches to manage these pests are therefore needed to ensure efficient control programmes that can be implemented now and in the future. Recent research in this area has focused on the pesticidal potential of plant essential oils. These products are attractive as pesticide candidates on the grounds of low mammalian toxicity, short environmental persistence and complex chemistries (limiting the development of pest resistance against them). Although issues may exist concerning reliability in efficacy of essential oils, these may be overcome by identifying and developing bioactive oil components for use in pest management. In the current work, three such components (terpenes) found in essential oils (eugenol, geraniol and citral) were tested against the poultry red mite Dermanyssus gallinae. All provided 100\% mortality in toxicity tests when undiluted. Even at 1\% of this dose, eugenol was 20\% effective against experimental pest populations, although the remaining terpenes were largely ineffective at this concentration.