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

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.

Novel repellents for the blood-sucking insects Rhodnius prolixus and Triatoma infestans, vectors of Chagas disease

“…Efficiency at low doses is one of the key characteristics that is required for a good, new repellent [25]. The need to employ high concentrations of DEET to achieve repellency has limited its application in disrupting triatomine-human contacts, as several studies have already shown [15,[27][28][29][30]. Although its use is deemed safe, DEET has some disadvantages: it needs to be constantly reapplied; it has a short range of action due to its low volatility and can melt plastics and vinyl [4,25].…”

“…Studies with R. prolixus and T. infestans have revealed that whether the host is present or not, only high doses (i.e. > 90%) have a repellent effect, making DEET rather impractical for reducing human-triatomine contacts [15,[27][28][29][30]. In addition to these and other related findings in triatomines (i.e.…”

Actividad Repelente De Los Aceites Esenciales Amomyrtus Meli, Peumus Boldus Y Senecio Nutans, en Triatoma Infestans (Hemiptera Reduviidae)

“…En este estudio se utilizó un control positivo, DEET, que es un repelente sintético universal utilizado en varios productos comerciales con un efecto informado sobre T. infestans (Reynoso, et al 2017). Según nuestros resultados, el AE de las plantas estudiadas puede lograr efectos repelentes similares al de la DEET.…”