Evaluation of the Persistence of Three Larvicides Used To Control Aedes aegypti In Arapiraca, Northeastern Brazil

Abstract

The chemical control of the mosquito Aedes aegypti is a great challenge worldwide, since several populations of this species are already resistant to traditional insecticides, such as temephos. In Brazil, alternative larvicides, such as Bacillus thuringiensis israelensis ( Bti) and pyriproxyfen, have been used more recently. In this study we evaluated the persistence of pyriproxyfen (Sumilarv 0.5%G), 2 commercial formulations of Bti (Vectobac WDG and Vectobac G), and temephos (Fersol 1G) under field and simulated field conditions with treatments exposed to sun and shadow. In the field tests, the 2 formulations of Bti presented less persistence in the 8th wk of evaluation (46% and 37% positivity) compared with temephos (3.6% and 6.8% positivity) and Sumilarv (6.6% and 3.8% positivity) in containers exposed to the sun and shadow, respectively. In the simulated field trial, temephos and the 2 formulations of Bti presented high persistence (100% mortality at 8th wk) when applied in the water box and in deposits placed in the shade. In containers exposed to the sun, the persistence of these products was lower (>80% mortality by temephos after 4 wk, Bti formulations for 3 wk, and Sumilarv for 6 wk). Based on these data, however, Sumilarv presented better performance in the containers exposed to the sun than the 2 formulations of Bti (Vectobac G and Vectobac WDG), which were affected by the sun.

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“…The microorganism Bacillus thuringiensis subsp. israelensis (Bti) is increasingly used worldwide for mosquito control and is promising as an alternative and safe larvicide (WHO, 2009;Aksoy et al, 2015;Pruszynski et al, 2017;Amorim et al, 2019). It is a facultative anaerobic, gram-positive bacterium that forms characteristic protein inclusions adjacent to the endospore.…”

“…Therefore, in this study, this mosquito was selected to test for the effectiveness of the developed Bti. In addition, there have been a variety of reports in which Bti was used against Aedes aegypti, the major vector of dengue fever (Amorim, 2019;Ritchie, 2010), while quite a few studies have tested the use of Bti against C. quinquefasciatus. The control effectiveness of Bti is typically defined as ITU/mg of product (Rishikesk and Qulennec, 1983).…”

Efficacy Bacillus thuringiensis var. israelensis serotype H-14 (Bti H-14) for control Aedes spp. density in Denpasar, Bali

“…Bacillus thuringiensis has been used in several countries such as Brazil, Malaysia, Cambodia, and Singapore. [14][15][16][17] Bali is a tourism area with a high level of mobility and is endemic to dengue, so an environmentally friendly vector control effort is needed. This study aims to determine the effectiveness of the bioinsecticide Bacillus thuringiensis var.…”