Insecticidal Efficacy of Satureja hortensis L. and Satureja khuzistanica Jamzad Essential Oils Against Callosobruchus maculatus (F.)

The cowpea weevil, Callosobruchus maculatus (F.), stands out as one of the most destructive field-to-storage pests of leguminous crops. This study investigates the potential of essential oils derived from two Satureja species, Satureja hortensis L. and Satureja khuzistanica Jamzad, for managing C. maculatus. Bioassay results revealed that both S. hortensis (72 h LC50 = 0.20 µL/g) and S. khuzistanica (72 h LC50 = 0.19 µL/g) essential oils exhibited significant toxicity against C. maculatus adults. The essential oils extended development time, reduced adult longevity, and decreased fecundity of the pest. Key population parameters, including intrinsic growth rate (r) and net reproductive rate (R0), were significantly lowered, particularly by S. hortensis essential oil. Age-specific survival (lx) and fecundity (mx) rates were also declined in treated groups, with delayed reproductive peaks compared to controls. Chemical analyses of S. hortensis and S. khuzistanica essential oils indicated that carvacrol (30.9% and 62.9%, respectively), γ-terpinene (25.5% and 4.3%), p-cymene (9.7% and 7.9%), and thymol (3.7% and 9.3%) were the major components. Hierarchical cluster analysis (HCA) was carried out to compare and contrast the compositions with previous works. The results demonstrated that S. hortensis and S. khuzistanica essential oils, given their lethal and sublethal effects against C. maculatus, can be introduced as natural alternatives to hazardous chemical insecticides, highlighting the need for further research in this field.