Acute and persistence effects of oil of Hippophae rhamnoides and Calendula officinalis on Sitophilus granarius (Coleoptera: Curculionidae) in stored maize

Herbal oil vapours from Hippophae rhamnoides L. (Elaeagnaceae), and Calendula officinalis L. (Asteraceae) were tested for their toxicity against the adults of Sitophilus granarius L.. According to our hypothesis the mentioned oils can become potential bioagents against stored product pests. The results revealed that both studied essential oils exerted strongly toxic effect on S. granarius, but C. officinalis triggered higher mortality. The efficacy (94.62±2.63%) was reached after a 48-h exposure to H. rhamnoides oil at 2 ml kg –1 while the application of 2 ml kg –1 of C. officinalis oil for 24 h produced 98.94±1.00% mortality rate. Insect mortality was hyperbolically-featured, and increased with the duration of the exposure to the examined oils. Mortality was 100% at 5 ml kg –1 of H. rhamnoides after 24-h duration of its application, while with C. officinalis the same value could be reached after a 12-h exposure to the oil. The progeny pronouncedly recovered from the treatment of both essential oils applied.