RESPONSE OF SARCOPTES-SCABIEI VAR CANIS (ACARI, SARCOPTIDAE) TO LIPIDS OF MAMMALIAN SKIN

Bioassays were conducted to determine if Sarcoptes scabiei (L.) were a ttracted to lipid compounds that occur in or on the epidermis of human or other mammalian skin. Seventeen lipid compounds attracted S. scabi ei including odd and even carbon chain lengths and saturated and unsat urated fatty acids, fatty acid methyl esters, a steroid, a steroid pre cursor, and a triglyceride. The attractive saturated fatty acids were pentanoic (5:0), hexanoic (6:0), octanoic (8:0), lauric (12:0), pentad ecanoic (15:0), and stearic (18:0) acids. The unsaturated fatty acids oleic (18:1 Delta(9)), linoleic (18:2 Delta(9, 12)), and arachidonic ( 20:4 Delta(5, 8, 11, 14)) acids also attracted scabies mites. No conce ntration of sebacic (10:0), myristic (14:0), palmitic (16:0), or arach idic (20:0) acids attracted any life stage of S. scabiei. Five fatty a cid methyl esters attracted at least one life stage of mites. Choleste rol and squalene, its transient precursor, were both attractive as was the triglyceride, tripalmitin. The molar concentration of lipids that elicited the greatest response by a particular life stage varied betw een compounds (ranging from 1 to 0.0001 M). Some lipids were attractiv e at several concentrations, whereas for others a response was elicite d by only one concentration. A comparison of different life stages sho wed that adults, especially females, were attracted more than immature s to most of the compounds. The data show that lipids that occur in th e epidermis of human or other mammalian skin attract scabies mites. Th erefore, host skin lipids may contribute to host specificity, attract mites to specific anatomical areas of the body, or play key roles in o ther host-parasite relationships.