REPELLENT EVALUATION OF ICARIDINE APPLIED ON COTTON FABRIC ON Lutzomyia longipalpis (LUTZ & NEIVA, 1912)
Neglected Diseases. Phlebotomines. Behavior. Visceral leishmaniasis.
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 4 volunteers (two men and two women), and the use of 15
females and 15 males of L. longipalpis evaluated according to the method “Arm in
cage”. The evaluations in each volunteer included the absence of Icaridine (control
group) and presence in different concentrations, which occurred within 168 hours
after application of the compound in the cotton fabric that donned the forearm of the
volunteers. The different concentrations of Icaridine were elaborated by dilution in
98% alcohol in the Textile Engineering Laboratory of UFRN. 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 in the
average of the landings in the concentrations of 5% (men = 20.63; women = 6.19)
and 10% (men = 22.75; women = 4.75) of Icaridine. The Total Protection Time (TPT)
of each concentration applied to the tissue varied in each volunteer. The
concentration of 5% of Icaridine obtained efficiency time range ranging from one to
24 hours. The 10% concentration obtained a 48-hour protection standard in three
volunteers (min: 1h, max: 48h). At 25% concentration TPT was different in all
volunteers (min.: 48h, max .: 144h), and 50% of the Icaridine emulsion had a
minimum TPT of 96 hours and a maximum protection of 168h. The total average
landings at 168 hours of testing differed significantly (p <0.05) from the control test
and concentrations of 5, 10 and 25%, where the average landing for the control was
55.78 and at different concentrations. was 10.66; 8.41; 1.38; 0.13 to 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 48 and 96 hours after impregnation, respectively.
The %R above 90% (ED90) in 168 hours served to mark a Minimum Effective
Concentration (MEC), where it was observed that 25% Icaridine maintained % R>
90% during 168 hours (97.52 %). 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.