Influence of winter savory (Satureja montana) aqueous extract on mortality of lesser grain borer (Rhyzopertha dominica)

Abstract

Losses of grain quality and quantity as a result of insect activity during storage impose the need for proper pest control. One of the major pests of stored wheat is the lesser grain borer (LGB), Rhyzopertha dominica. This pest is usually controlled with insecticides. However, there is recently a growing interest in the use of plant-based products in pest management. Plants are a rich source of active compounds and for centuries have been used for the control of harmful insects. This study was carried out in order to evaluate the effects of Satureja montana aqueous extract on LGB adults in contact and contact-digestive tests. The mortality of LGB adults during contact exposure to S. montana extract was low, regardless of the concentration (16.7-33.3% after 24 h and 30.0-33.3% after 48 h). After 24 h of contact-digestive exposure, the highest mortality was caused by 2% S. montana extract (23.3%), while after 48 h the level of mortality increased in all treatments with S. montana extract (0.5, 1, and 2%) and was 28.4, 28.4, and 41.7%, respectively. After 72 h of contact-digestive exposure, it ranged from 57.5 to 63.5%, while in the control it remained the same (2.7%). After 7 days of such exposure, it was 91.6-98.4%, depending on the concentration. Based on the obtained results, we conclude that S. montana aqueous extract caused mortality of LGB adults, the level of this mortality depending on concentration of the applied extract and duration of the experiment