The establishment of a behavioral bioassay to study Lutzomyia verrucarum male sex pheromones using Lutzomyia longipalpis as a model species.

摘要

Each year, up to 1.6 million people contract leishmaniasis from the bite of a phlebotomine sand fly infected with the Leishmania (Kinetoplastida: Trypanosomatidae) pathogen. Therefore, the control of sand flies has been the topic of intense research for many years. Traditional control methods, such as pesticides, have not provided solace when applied singly. However, the discovery of biological compounds used by sand flies as a means of chemical communication has been applied and combined with multiple other control techniques in an integrated pest management (IPM) scheme. This study focused on the development an effective bioassay method for use in the characterization of the Lutzomyia verrucarum sensu stricto (ss) male sex pheromone. Lutzomyia verrucarum ss vectors both Leishmania peruviana, the causative agent of Andean cutaneous leishmaniasis and Bartonella baciliformis, the etiological agent of bartonellosis or Carrion's disease. As little is known about compounds that mediate intraspecific communication (pheromones) in Lu. verrucarum ss, this study represented an important first step towards the final goal of developing an IPM strategy for Lu. verrucarum ss. As Lu. verrucarum ss is only accessible in Peru, the closely related Lu. longipalpis was used in this study. This study sought to (1) develop an operative bioassay and (2) determine the biological qualities that define optimum sand fly responders in the chosen bioassay. Linear three-chamber and cage olfactometers were tested for their effectiveness as a bioassay system, and vertical and horizontal trap orientation was also evaluated for the ability to attract and capture sand flies. As the male produced sex pheromone of Lu. longipalpis is known to attract unmated conspecific females, extracts of Lu. longipalpis males were used to gauge the responsiveness of females. Bioassays tested the effect of female response to conspecific male extracts, and categories of tested females varied in hours of male exposure (HME) (e.g., ≤ 8 HME, ≤ 24 HME, and ≤ 48 HME) as well as being blood fed or not. Additionally, the timing of male maturity was also determined. Results indicated that cage olfactometers more accurately gauged the natural behaviors of Lu. longipalpis females than did linear olfactometers. Horizontal and vertical traps performed equally well, and blood fed females with ≤ 24 HME were found to be the most responsive to male Lu. longipalpis extracts. Also, all Lu. longipalpis males matured by 20 hours under laboratory conditions, and maturity was found to occur in as few as 4 hours. These results not only contribute to our understanding of Lu. longipalpis, but have also identified responsive targets and defined appropriate methodologies for use with Lu. verrucarum ss.