Abstract
Due to the advantages of multiple modes of insecticidal action and negligible persistence in the environment, plant essential oils (EOs) have great potential for the control of stored grain pests. However, they are seldom used in pest control practice in terms of issues such as low penetrability and easy sorption by commodities. In order to improve the application efficacy of EOs in stored gain pest control, this study evaluated fumigation toxicity of Mentha canadensis EO alone and in combination with nitrogen-based controlled atmospheres (CAs) against major stored grain pests. The EO extracted from the aerial part of Mentha canadensis was mainly composed of (+)-pulegone (56.1 %), nonanal (27.8 %), D-germacrene (5.1 %), D-limonene (3.8 %), and (E)-phytol (2.6 %). Mentha canadensis EO showed high fumigation toxicity against adults of Rhyzopertha dominica, Sitophilus zeamais, Cryptolestes ferrugineus, and Liposcelis entomophila while exhibited low fumigation toxicity against adult Tribolium castaneum. When M. canadensis EO was combined with 98 % or 100 % N2, they showed significant synergistic toxicity against adults of R. dominica, S. zeamais, C. ferrugineus, and L. entomophila. Joint action between M. canadensis EO and high N2 was dependent on the composition of exposure atmosphere and insect species. The synergistic action of M. canadensis EO combined with 100 % N2 was higher than that of the combination of M. canadensis EO and 98 % N2, and adult R. dominica was more sensitive to their synergistic action than adults of other three insect species. Mentha canadensis EO showed high fumigation toxicity against most stored grain pests and exhibited significant synergistic toxicity when employed in combination with high N2. The synergistic action of M. canadensis EO on nitrogen-based CAs will help solving issues of difficulty in maintaining high N2 due to inferior airtightness of storages.
•Mentha canadensis essential oil shows high fumigation toxicity against some stored grain pests.•Joint action of plant oils and high N2 depends on both the N2 concentration and the target pest.•Mentha canadensis essential oil combined with high N2 exerts synergistic fumigant toxicity.•Combinations of plant oils and high N2 have potential in stored grain pest management.
