Efficacy of Oleic Acid and Linoleic Acid Vapors on the Stable Phases of Trogoderma granarium (Coleoptera: Dermestidae)

Abstract

The current study is conducted with the aim of evaluating two fatty acids effectiveness and efficiency of steaming, Oleic acid and Linoleic acid, as a natural and safe alternative to chemical pesticides in controlling the hairy grain beetle Trogoderma granarium Evert fixed phases (eggs, pupae). This laboratory study included the use of four concentrations (50, 100, 200, and 150) ppm, with exposure periods that varied according to the insect role. They were (24, 16, 8) hours in the first and (36, 24, 12) hours per/2nd. The results demonstrated the treatment of insect eggs with oleic and linoleic acid vapors presenting the hatching inhibition highest rates, reaching 72.22 and 76.66% at a concentration (200 ppm) and an exposure period (24 hours), with a superior effect of linoleic acid vapor in causing inhibition rates at all concentrations and exposure used periods. The reason for the inhibition in both may be attributed to the ability of the vapor of the two acids to penetrate the egg wall and affect its protoplasm, thus thwarting the growth and development of the embryo. Also, pupae treatment with the vapor of the two acids giving the killing highest rates, reaching75.55 and 71.10, respectively, at a concentration (200 ppm) and an exposure period of (36 hours), with superiority to the effect of oleic acid vapor in killing rates at all concentrations besides using exposure periods. The cause of killing in both vapors may be ascribed to their harmful effects on the respiratory and nervous systems of the pupae, causing them to suffocate and paralyze. As for the results of the statistical analysis, they indicate the significance of each of the effects of concentrations and periods of exposure and the overlap between them to the two acids at both phases.