Acute toxicity and sublethal effects of extracted essential oils of Piper nigrum and Artemisia khorassanica on Trogoderma granarium (Col.: Dermestidae)

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is a serious pest of cereal grains such as wheat. In the present research, the lethal and sublethal effects of essential oils (EOs) from Piper nigrum L. and Artemisia khorassanica Podl. were determined against 1st instar larvae of T. granarium. To study the sublethal effects, 1st instar larvae were exposed to the LC30 of each EO, and the life table parameters of the surviving insects were assessed. Artemisia khorassanica (LC50: 39.88 μl/liter air) had higher fumigant toxicity for T. granarium when compared to P. nigrum (LC50: 71.46 μl/liter air). Furthermore, the insecticidal effects of A. khorassanica (LT50: 13.51 h) were faster than P. nigrum (LT50: 15.75 h). Significant differences in the larval and pupal durations were observed in the EO treatments when compared to the control. In addition, the exposure to sublethal concentration of the EOs tested significantly reduced immature survival rate, adult longevity and fecundity. The net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (λ) was significantly affected by EOs tested being lowest in the insects exposed to A. khorassanica. According to our findings, both EOs tested, especially A. khorassanica, are useful for the effective control of T. granarium in warehouses.