How long is long enough? Decreasing effects in Aedes aegypti larval mortality by plant extracts over time

Gilberto Dinis Cozzer,Junir Antônio Lutinski,Daniel Albeny Simões,Maria Assunta Busato,Walter Antônio Roman,Renan De Souza Rezende

doi:10.5327/z21769478806

Abstract

Aedes aegypti has overcome all kinds of mosquito control attempts over the last century. Strategies for population control resorts to the use of synthetic insecticides, which can lead to problems like human intoxication and environmental contamination. The effects of Bacillus thuringiensis var. israelensis (Bti), Ilex paraguariensis (yerba mate), and Ilex theezans (caúna herb) extracts against A. aegypti larvae were evaluated. The bioassays were conducted under controlled laboratory conditions of temperature (27 ± 3°C) and photoperiod (12 h). Hydroalcoholic extract of the leaves of I. theezans displayed better residual effect compared to the aqueous extract of I. paraguariensis fruits. The strongest residual effect of I. theezans was probably due to the presence of certain chemicals in its leaves, such as coumarins, hemolytic saponins, and cyanogenic glucosides, which were absent in I. paraguariensis. The results herein contributed to the prospection of natural insecticides and opened the possibility for subsequent studies on the use of plant extracts in field situations in a short-time scale.

Highlights

Over the last century, the mosquito Aedes aegypti (Linnaeus, 1762) has overcome all mosquito control attempts
Larval mortality was significantly different between treatments (I. paraguariensis and I. theezans), weeks (1 to 8), and interaction factors for both GLMs models
The highest larval mortality was found in the Bacillus thuringiensis var. israelensis (Bti) treatment, followed by I. theezans, I. paraguariensis, and positive control (Table 1; Figure 1A)

Summary

Introduction

The mosquito Aedes aegypti (Linnaeus, 1762) has overcome all mosquito control attempts. A. aegypti females are well known by their capacity of naturally and/or under laboratory conditions replicate and transmit over 100 kinds of viruses (Weaver and Reisen, 2010). The viruses of Dengue, Chikungunya, Zika, and, most recently, the Mayaro (Weaver and Reisen, 2010) virus can be listed in Brazil, which represent a real threat to public health (Lopes et al, 2014). Its medical importance requires the population control of this species to reduce virus transmission and, its epidemic status. The most effective disease prevention method still focus on targeting the mosquito population by eliminating mosquito breeding places (Brasil, 2002)

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