Insecticidal Effect of the Fruit Extract Bitter Melon (Citrullus colocynthis) on Locust Chrotogonus trachypterus (Orth: Pyrgomorphidae)

摘要

Chrotogonus trachypterus Blanchard is an active grasshopper on farms in Sistan and Baluchestan province, Iran, in high populations and is one of the most important pests of vegetables, alfalfa, early growth stages of Gramineae and many crops. Chemical pesticides have harmful effects on the environment and human health; therefore, the use of natural insecticides derived from plants play significant role in pest management because of lower costs, lack of environmental pollution and protection of human health. In this study, lethal effect of Citrullus colocynthis fruit extract was evaluated on the Ch. trachypterus grasshopper under controlled laboratory conditions (at a temperature of 24±2°C, relative humidity of 75 ±5%, and photoperiod of 16: 8) in a completely randomized design with three replications. The plant was collected from its natural habitat around the city of Iranshahr, Iran, and then dried in the shade. The extraction was performed using methanol. The results obtained from experiments showed significant increase in mortality of tested insects after 24 hours with increasing concentrations of plant extracts. The effect of this extract with concentrations of 10. 20, 25, 35 and 40 milligrams per milliliter were tested on adult Ch. trachypterus grasshoppers. The highest mortality rale (87.50%) was found at a concentration of 40 milligrams per milliliter and the lowest mortality rate (23.33%) was observed at concentrations of 10 milligrams per milliliter. The mortality rate elevated with increasing concentration in all treatments. The LC 50 value lor C. colocynthis plant on adult grasshopper was calculated 18.58 milligrams per milliliter.