Fumigant toxicity of essential oil from Vitex pseudo-negundo against Tribolium castaneum (Herbst) and Sitophilus oryzae (L.)

The objective of the current study was to determine the chemical constituents and fumigant toxicity of an essential oil that was isolated via hydrodistillation from dry leaves of Vitex pseudo-negundo (Hausskn.) Hand.-Mzz. The chemical composition of the essential oil was assessed via GC and GC-MS. 1, 8-Cineol (18.23%), α-Pinene (16.20%) and Sabinene (5.67%) were determined to be the major constituents of the oil. The fumigant toxicity of the essential oil was tested against 1–7 day-old adults of Tribolium castaneum (Herbst) and Sitophilus oryzae (L.) at 27 ± 1 °C and 60 ± 5% r.h. in darkness. The mortality of adults was tested at different concentrations ranging from 37.0 to 925.9 μL/L air and different exposure times (1–30 h). The results demonstrated that the mortality increased with increases in concentration and exposure time. At concentrations higher than 185.2 μL/L air, the mortality was recorded at more than 50% after 10 h, and reached 100% after 12–16 h. Data probit analysis demonstrated that S. oryzae (LC50 = 31.96 μL/L air) was more susceptible than T. castaneum (LC50 =  47.27 μL/L air). These results showed that the essential oil from V. pseudo-negundo could be applicable to the management of populations of stored-product insects.