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Research Project: MOLECULAR BIOLOGY AND PHYSIOLOGY OF BITING FLIES AFFECTING LIVESTOCK

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Title: Polar cuticular lipids differ in male and female sandflies (Phlebotomus papatasi)

Author
item Renthal, Robert - University Of Texas At San Antonio
item Li, Andrew
item Gao, Xiaoli - University Of Texas Health Science Center
item Perez De Leon, Adalberto - Beto

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2014
Publication Date: 11/1/2014
Publication URL: http://handle.nal.usda.gov/10113/62313
Citation: Renthal, R., Li, A.Y., Gao, X., Perez De Leon, A.A. 2014. Polar cuticular lipids differ in male and female sandflies (Phlebotomus papatasi). Comparative Biochemistry and Physiology. 51(6):1237-1241.

Interpretive Summary: Leishmaniases are diseases caused by single-cell parasites species in the genus Leishmania that are transmitted to humans by the bites of infected female phlebotomine sand flies and thus serve as disease vectors. The most common form of leishmaniasis affects the skin and it is called cutaneous leishmaniasis, which affects over one million people around the world and causes as many as 30,000 deaths each year. Sand flies and the infectious disease agents they carry are also a significant hindrance to U.S. military operations throughout the Middle East and much of the tropical and subtropical areas of the world. The sand fly Phlebotomus papatasi is an important blood feeder and the main vector of Leishmania major, which causes zoonotic cutaneous leishmaniasis in parts of the Afro-Eurasian region. Cutaneous leishmaniasis caused by L. major is termed zoonotic because the parasite is transmitted by P. papatasi from animals to humans. Insect-killing products, or insecticides, have been used to control this disease vector, but satisfactory efficacy was not achieved in many cases due to insecticide resistance and unfavorable environmental factors. Novel sand fly control technologies are needed to protect people and U.S. military personnel. Experiments reported here identified a variety of compounds with a separation of electric charge that tend to be not soluble in water, or polar lipids, which are present in the outer skeleton of unfed and blood-fed females, and males of sand flies. A highly sensitive system for chemical analysis was used to determine the mass of the molecules comprising the samples tested. The content of some polar lipids was significantly elevated in females after the blood meal, and it is hypothesized that they could function as short-range pheromones in courtship behavior. This hypothesis will be tested in behavioral experiments. If such polar lipids work as sex pheromones, they could be used in a toxin-baited sand fly trap to monitor and control the vector of zoonotic cutaneous leishmaniasis in the Afro-Eurasian region.

Technical Abstract: The sand fly Phlebotomus papatasi is an important blood feeder and the main vector of Leishmania major, which causes zoonotic cutaneous leishmaniasis in parts of the Afro-Eurasian region. Polar cuticular lipids in P. papatasi were analyzed by high resolution mass spectrometry. Blood-fed females, non-blood-fed females, and males were analyzed separately and compared. The major polar cuticular lipids were found to be long-chain diols and fatty acids. Relatively high levels of diacylglycerols were found in blood-fed females and males. A wide variety of lipids were found at low levels, including esters, sterols, monoacylglycerols, and hydroxyl fatty acids. Blood-fed females had several lyso lipids and N-acyl amino acids that were not found on unfed females or males. These substances may be surfactants used in blood-feeding. Four substances were identified on males at two-fold higher levels than on females: tetradienoic acid, methoxyhexadecasphinganine, butyl octadecanoate, and DG (14:1/12:0/0:0). As these could be short-range pheromones involved in courtship, they will be further analyzed in behavioral bioassays. If such polar lipids work as sex pheromones, they could be used in a toxin-baited sand fly trap to monitor and control the vector of zoonotic cutaneous leishmaniasis in the Afro-Eurasian region.