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Plants battle the mosquito

Sisal leaves (left) and sucupira seeds display properties that kill Aedes aegypti larvae

Saulo G. Coelho/EMBRAPA Sisal leaves (left) and sucupira seeds display properties that kill Aedes aegypti larvaeSaulo G. Coelho/EMBRAPA

Oil extracted from the fruit and seeds of the white sucupira, a tree of the Brazilian Cerrado savannah, and juice from the leaves of the sisal plant, originally from Mexico and now grown in Brazil for its fiber, display properties that can completely eliminate the larvae of Aedes aegypti, the mosquito that transmits dengue, Zika, and chikungunya, according to two teams of Brazilian researchers. At federal universities in the states of Amapá (Unifap), Goiás (UFGO), and Rio de Janeiro (UFF), researchers used oil from the Pterodon emarginatus Vogel sucupira to develop a nanoemulsion that acts as a larvicide when diluted in water. Funded by the National Council for Scientific and Technological Development (CNPq) and the Amapá Research Foundation (FAPEAP), the study was published in the journal PLOS One on January 7, 2016. No solvents are used in making the oil-based product developed by the scientists and it is not toxic to either the environment or humans. The same holds true for the larvicide developed from the leaves of the sisal plant (Agave sisalana) by researchers from the Federal University of Paraíba (UFPB) and the Brazilian Agricultural Research Corporation, Cotton Division, in Campina Grande, Paraíba. According to the researchers, the juice attacks the larva’s intestine, completely doing away with the insect. The researchers performed the same tests on other stages of the insect’s life, such as egg, pupa, and adult, but the product had no impact. The explanation is that after the larvae eat the solution, they most likely die because they cannot digest the product. The larvicide will have to be marketed in the form of a powder that can be diluted in water since the fresh juice degrades quickly. The research was conducted in partnership with the Bahia Association of Plant Fiber Industries and the Food and Agriculture Organization of the United Nations (FAO).