Bioactivity of Pistacia atlantica desf. Subsp. Kurdica (Zohary) Rech. F. and Pistacia khinjuk stocks essential oils against Callosobruchus maculatus (F, 1775) (Coloeptera: Bruchidae) under laboratory conditions

One of the major storage insect pests of cowpea and many other grains is Callosobruchus maculatus (F.) (Col.: Bruchidae). The use of plant materials rather than conventional pesticides to control these pests is a promising alternative to neurotoxic insecticides. In this study, for the first time, the fumigant, contact toxicity and repellent activity of Pistacia atlantica Desf. Subsp. kurdica (Zohary) Rech. f. (gum, fruit and leaves) and Pistacia khinjuk Stocks (fruit and leaf) essential oils were tested against adults of C. maculatus. The essential oil from P. khinjuk fruit showed a stronger fumigant activity against C. maculatus after 24 h exposure (LC50 = 22 μl/l air) compared to the leaves (LC50 = 29 μl/l air). As for P. atlantica subsp. kurdica, the essential oil from the gum showed the highest activity at 24 h (LC50 = 7.0 μl/l air) compared to the fruit (LC50 = 18 μl/l air) and leaves (LC50 = 24 μl/l air). In contact toxicity bioassays, the P. khinjuk fruit and leaf oils caused significant mortality to C. maculatus adults upon contact for 24 h (LC50 = 0.12 μl/cm2 and LC50 = 0.14 μl/cm2, respectively), while the P. atlantica subsp. kurdica gum was the most toxic at 24 h (LC50 = 0.07 μl/cm2) compared to the fruit oil (LC50 = 0.11 μl/cm2) and leaf oil (LC50 = 0.08 μl/cm2). At the highest concentration of 0.0234 μl/cm3, the respective repellency percentages for P. atlantica subsp. kurdica gum, leaves and fruit oils at 24 h were 82%, 77% and 70%. For P. khinjuk, the respective repellency percentages for the leaf and fruit oils at 24 h were 76% and 67% at the highest concentration (0.0234 μl/cm3). These results indicate strong fumigant and contact toxicity, and repellent activity for all the tested essential oils against C. maculatus. Hence, the data can be exploited further to develop a management strategy against C. maculatus.