Determining the Toxicity of Thyme Essential Oils against Sitophilus granarius L. and Sitophilus oryzae L. (Coleoptera: Curculionidae) Adults

Abstract

The present study aimed to determine the effects of three different doses of three thyme essential oils on Sitophilus oryzae (L.) and Sitophilus granarius (L.) (Coleoptera: Curculionidae). The present study was conducted under controlled laboratory conditions (25°C temperature and 65% relative humidity) in 2020. Various thyme varieties (Origanum majorona (L.), Origanum saccatum P.H. Davis, Thymbra spicata var spicata L. ( Lamiaceae)), cultivated in Diyarbakır province ecological conditions were employed in the study. After the 4th day of the experiment, the highest mortality rates (100%) were observed with the highest doses of T. spicata var spicata and O. majarona on S. granarius adults, while the mortality rate was 73.75% with O. saccatum. The LC90 values for T. spicata var. spicata, O. majarona, and O. saccatum were 0.9, 0.1, and 1.3 µl/ml respectively. After the 4th day, 100% S. oryzae adult mortality was observed with higher doses of O. majarona (0.5%; 1% v/v), while 1% (v/v) T. spicata var spicata dose led to a 72.50%, and 1% (v/v) O. saccatum oil dose led to 46.25% mortality.

Keywords

• grain pest
• essential oils
• thyme oil
• s. granarius
• s. oryzae