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. 2017 May 18:5:e3292.
doi: 10.7717/peerj.3292. eCollection 2017.

Toxicity, repellency and flushing out in Triatoma infestans (Hemiptera: Reduviidae) exposed to the repellents DEET and IR3535

Mercedes M N Reynoso  1 , Emilia A Seccacini  1 , Javier A Calcagno  2 , Eduardo N Zerba  1   3 , Raúl A Alzogaray  1   3
Affiliations

Toxicity, repellency and flushing out in Triatoma infestans (Hemiptera: Reduviidae) exposed to the repellents DEET and IR3535

Mercedes M N Reynoso et al. PeerJ. .

Abstract

DEET and IR3535 are insect repellents present worldwide in commercial products; their efficacy has been mainly evaluated in mosquitoes. This study compares the toxicological effects and the behavioral responses induced by both repellents on the blood-sucking bug Triatoma infestans Klug (Hemiptera: Reduviidae), one of the main vectors of Chagas disease. When applied topically, the Median Lethal Dose (72 h) for DEET was 220.8 µg/insect. Using IR3535, topical application of 500 µg/insect killed no nymphs. The minimum concentration that produced repellency was the same for both compounds: 1,15 µg/cm2. The effect of a mixture DEET:IR3535 1:1 was similar to that of their pure components. Flushing out was assessed in a chamber with a shelter containing groups of ten nymphs. The repellents were aerosolized on the shelter and the number of insects leaving it was recorded for 60 min. During that time, 0.006 g/m3 of the positive control tetramethrin flushed out 76.7% of the nymphs, while 1.76 g/m3 of DEET or IR3535 flushed out 30 and 0%, respectively. The concentrations required for both compounds to produce toxicity or flushing out are too high to have any practical applications. However, they showed a promising repellency. Additional research should be done to evaluate their possible use for personal protection against T. infestans bites.

Keywords: Blood-sucking bugs; Diethyltoluamide; Ethyl 3-[acetyl(butyl)amino]propanoate; Locomotor activity.

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Conflict of interest statement

The authors declare there are no competing interests.

Figures

Figure 1
Figure 1. Glass chamber used for flushing out bioassays.
1, Exhaust fan (it is used to exhaust the contaminated air out of the glass chamber after each assay); 2, hole sealed with a rubber stopper; 3, front panel; 4, black cardboard triangular hollow prism (insects refuge); 5, two cold light tubes.
Figure 2
Figure 2. Repellency of pure and mixed DEET and IR3535 in fifth instar nymphs of Triatoma infestans.
Distribution Coefficient = (AT − At)∕AT, where AT is the total area occupied by the nymph on the arena, and At is the area occupied by the nymph on the treated zone throughout the experiment.
Figure 3
Figure 3. Flushing out in fifth instar nymphs of Triatoma infestans exposed to aerosolized DEET.
In the legend, values in brackets are expressed in units of g/m3. Different letters indicate significant differences (P < 0.05) (IR3535 produced 0% of flushing out in all replicates, so it was not included in the ANOVA). All replicates of IR3535 produced 0% of flushing out.
See this image and copyright information in PMC

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