Avaliação repelente de Icaridina aplicado em tecido de algodão sobre Lutzomyia longipalpis (Lutz & Neiva, 1912)

Abstract

Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) is the main insect vector of the protozoan Leishmania infantum (ROSS, 1903), the etiological agent of Visceral Leishmaniasis (LV) or Calazar in Brazil. For vector control, the use of insecticidal chemical compounds is highlighted, however, the use of this strategy has been causing resistance in populations of L. longipalpis, considerably increasing the cases of VL in recent years in Brazil. Approaches using repellent materials are considered new alternative to prevent the bite of this insect. Icaridine is one of the approved compounds for the production of insect repellent products in Brazil and other countries since 2009. Therefore, the aim of this study was to evaluate the repellent action of different concentrations (5%, 10%, 25% e 50%) of Icaridine emulsion applied on cotton fabric on adults of L longipalpis. For this, the experiment had the participation of 8 volunteers (4 men and 4 women), and the use of 15 females and 15 males of L. longipalpis evaluated according to the method “Arm in cage”. The different concentrations of Icaridine were elaborated by dilution in 98% alcohol in the Textile Engineering Laboratory of UFRN. The evaluations in each volunteer included the absence of Icaridine (control group) and presence in different concentrations, which occurred within 144 hours and test after washing the cotton fabric with Icaridine that donned the forearm of the volunteers. The results observed in this study reveal that the average landings decreased significantly when the trials involved the Icaridine. It was possible to observe a significant difference (p <0.05) in the average of landings in analyzes from the sex of the volunteer at concentrations of 5% (men = 13.29; women = 8.63) and 10% (men = 8, 72; women = 4.53) with a decrease in this difference at the highest concentrations (25% and 50%). The total protection time (TPT) in the highest concentrations, 25 and 50%, the medians of TPT were higher compared to the lowest concentrations, with 120 and 144 hours, respectively. The average total of landings in the seven repetitions, including the post-wash test, differed significantly (p<0.05) from the control test and Icaridine concentrations, where the average control landing was 52.74 and in different concentrations was 10,03; 6.62; 1.02; 0.27 for 5, 10, 25 and 50%, respectively. Repetition Rate (%R) of 100% was observed for all concentrations within the first 1 hour of testing. Posteriorly, this repellency rate was maintained only at 25 and 50% concentrations until 72 and 96 hours after impregnation, respectively. The% R above 95% in the daily tests and after washing the impregnated tissue, served to mark a Minimum Effective Concentration (MEC), where it was observed that 25% of Icaridine maintained %R> 95% providing protection from 98.18%. With this study, it was possible to define that different concentrations of Icaridine were efficient as repellent, varying in relation to TPT and % R. The concentration of 25% was the EMF, presenting better efficiency in the tests presenting relevant results for L. longipalpis repellency, which may become an efficient strategy for the control of bites of this insect vector.