Abstract
ABSTRACT: Bacillus thuringiensis subsp. israelensis has been used to control the Aedes aegypti (Diptera: Culicidae) mosquito larvae, the vector of virus diseases such as dengue, Chikungunya and Zika fever, which have become a major public health problem in Brazil and other tropical countries since the climate favors the proliferation and development of the transmitting vector. Because B. thuringiensis has shown potential for controlling insects of the Diptera order, this work aimed at testing the Bacillus thuringiensis subsp. thuringiensis strain T01-328 and its proteins Cry2Aa and Cry2Ab for control A. aegypti and at comparing the results to the B. thuringiensis subsp. israelensis specific dipteran strain. To this end, bioassays using spore-crystal of both strains, and Cry2Aa and Cry2Ab proteins from the heterologous expression in Escherichia coli, were performed against A. aegypti larvae. The results showed that the B. thuringiensis thuringiensis T01-328 has insecticidal activity against the larvae, but it is less toxic than B. thuringiensis subsp. israelensis. Cry2Aa and Cry2Ab proteins expressed heterologously were effective for controlling A. aegypti larvae. Therefore, the results indicate that the Cry2Aa and Cry2Ab proteins of the B. thuringiensis thuringiensis T01-328 can be used as an alternative to assist in the control of A. aegypti.
Highlights
Dengue is one of the major public health problems in tropical countries, and its incidence has increased dramatically around the world in recent decades
Bioassays with the spore/crystal mixture were performed to evaluate the insecticidal activity of B. thuringiensis thuringiensis strain T01-328 against A. aegypti larvae (Table 1)
The LC50 9.1 x 108 spore-crystal/mL obtained in the trials confirmed larva susceptibility to B. thuringiensis thuringiensis
Summary
Dengue is one of the major public health problems in tropical countries, and its incidence has increased dramatically around the world in recent decades. During the 2017 Epidemiological Week, 251,711 probable cases of dengue were registered in the country according to the Health Department (BRASIL, 2018), the actual numbers of dengue cases are underestimated and in many cases incorrectly classified. In 2014 and 2015, health officials identified cases of Chikungunya and Zika fevers in Brazil, both caused by viruses that are carried and transmitted by Aedes aegypti mosquitoes (BRASIL, 2014). Zika fever, caused by the Zika virus (ZIKV), can be transmitted via mosquito bite, as well as sexually from human to human and vertically, from mother to fetus (D’ORTENZIO et al, 2016; MANSUY et al, 2016). Maternal transmission to the fetus presents a serious risk of causing fetal congenital anomalies (SCHULER-FACCINI et al, 2016)
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