Modes of entry of petroleum distilled

STADLER T Y BUTELER M

Rosario

Jornada; 94ª Reunión Nacional de Física; 2009

Asociación Física Argentina

Petroleum oils are some of the oldest and safest pesticides   in use. In spite of the numerous improvements achieved   in oil technology, the mode of entry and the insecticide action   mechanism of these products have been the subject of   considerable debate and conjecture over many years. The   literature reviewed suggests that insecticide oils can penetrate   the insect body through the integument as well as   through the tracheal system. Suffocation by spiracle blockage   was held as the most accepted theory on its mode   of action. However, an in depth analysis of the interaction   between oils and insects body surface from a physical perspective   suggests that suffocation occurs only when insects   are over-sprayed or dipped in oil. Based on this analysis, it   is more likely that when petroleum oils contact the insect   surface, capillary forces and complex physical interactions   take place in the cuticular layer, which lead to differences in   the melting point and permeability of cuticle waxes. This in   turn, alters the waterproofing properties of the cuticle and   also leads to penetration of spray oils that can be carried   to different lipophilic tissues. The changes in the cuticle   caused by oils, which range from changes in melting point   of the cuticular wax layer up to cuticle dewaxing, strongly   suggest cuticular penetration as the foremost mode of entry   of insecticide oils.