Toxicity and enzyme inhibition activities of the essential oil and dominant constituents derived from Artemisia absinthium L. against adult Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

Abstract

The extensive use of synthetic chemical pesticides has led to negative effects on the environment and human health. Therefore, scientists are in search of natural products, especially those from plant sources, which are less hazardous, eco-friendly, and effective alternatives to the conventional pesticides. Essential oils are potential alternatives to the synthetic chemical pesticides. However, the toxicity of Artemisia absinthium against Asian citrus psyllid Diaphorina citri has not been documented. Therefore, here we focused on the A. absinthium essential oil (ABEO) extracted from the population grown under the climatic conditions of Pakistan’s high plateaus, as a natural pesticide for the control of the citrus psyllid. The results indicated that the oil caused significant acute mortalities in both topical and residual contact applications, with 50% lethal dose (LD50) and 50% lethal concentration (LC50) values of 5.2 μg/insect and 24.4 mg/mL. Among the constituents tested only carvacrol, (−)-α-bisabolol and chamazulene were toxic, with LD50 values of 6.9, 8.2, and 10.3 μg/insect via topical application and LC50 values of 28.5, 33.5, and 39.4 mg/mL via residual contact exposure. Several combinations of dominant constituents were both additive and synergistic when applied topically, especially carvacrol + (−)-α-bisabolol + chamazulene (1:1:1) displayed synergistic effect, with a poison ratio of 1.39. Furthermore, the essential oil and carvacrol inhibit acetylcholinesterase activity in citrus psyllid. It has been concluded that the essential oil and some of the compounds from A. absinthium might be developed as eco-friendly approaches for the control of citrus psyllid.