Preliminary Assessment of Repellency and Toxicity of Essential Oils against <i>Sitophilus zeamais</i> Motschulsky (Coleoptera: Curculionidae) on Stored Organic Corn Grains

Sawo Eesiah; Jianmei Yu; Beatrice Dingha; Barbara Amoah; Nona Mikiashvili

doi:10.3390/foods11182907

Foods (Sep 2022)

Preliminary Assessment of Repellency and Toxicity of Essential Oils against <i>Sitophilus zeamais</i> Motschulsky (Coleoptera: Curculionidae) on Stored Organic Corn Grains

Sawo Eesiah,
Jianmei Yu,
Beatrice Dingha,
Barbara Amoah,
Nona Mikiashvili

Affiliations

Sawo Eesiah: Food and Nutritional Sciences Program, Department of Family and Consumer Sciences, North Carolina A&T State University, 1601 East Market Street, Greensboro, NC 27411, USA
Jianmei Yu: Food and Nutritional Sciences Program, Department of Family and Consumer Sciences, North Carolina A&T State University, 1601 East Market Street, Greensboro, NC 27411, USA
Beatrice Dingha: Department of Natural Resources and Environmental Design, North Carolina A&T State University, 1601 East Market Street, Greensboro, NC 27411, USA
Barbara Amoah: Department of Natural Resources and Environmental Design, North Carolina A&T State University, 1601 East Market Street, Greensboro, NC 27411, USA
Nona Mikiashvili: Food and Nutritional Sciences Program, Department of Family and Consumer Sciences, North Carolina A&T State University, 1601 East Market Street, Greensboro, NC 27411, USA

DOI: https://doi.org/10.3390/foods11182907
Journal volume & issue: Vol. 11, no. 18
p. 2907

Abstract

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Insect infestation of cereal grains during post-harvest storage not only causes significant grain loss, but also reduces grain quality and makes grains more susceptible to mold infection. Synthetic pesticides are banned from being used in organic grain storage setting due to their high toxicity. The main insect damaging stored corn grains is maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). The purpose of this study was to evaluate insect repellency and insecticidal potentials of some generally recognized as safe (GRAS) essential oils (EOs) (including cinnamon, clove, thyme, oregano, and orange terpene oils) at concentrations of 1–20% against the maize weevil using an olfactometer and a simulated fumigation method, respectively. The olfactory tests show that cinnamon oil had the highest repellency (90%) to the weevils among the EOs tested. The insecticidal activity study indicates that maize weevil mortality increased with EO concentration and storage time with cinnamon, clove, and thyme oils being more effective. No weevil death was observed at 1% EOs; weevil mortality was 3.3–36% at 5%, which varied with the type of EO and storage time. At 10% or higher concentrations, all tested EO showed comparable or higher insecticidal activity than pirimiphos methyl-positive control at its recommended concentration (5 mg/kg corn). No significant increase in weevil mortality was observed with further increase in EO concentration, with exceptions of oregano oil and thyme oil. The highest weevil mortality levels were observed at week 7 for 15% cinnamon oil (100%) and eugenol (100%), followed by 20% thyme oil (93%). The study indicates that some EOs have great potential to serve as synthetic insecticide alternatives to protect organic corn grains from maize weevil damage during storage. This is important to food security, safety and environmental health.

Published in Foods

ISSN: 2304-8158 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Chemical technology
Website: http://www.mdpi.com/journal/foods

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