CENA/USPFlies produced in the São Francisco Valley: technological solutionCENA/USP
One of the main pests in the orchards, the Mediterranean fruit fly (Ceratitis capitata), which causes losses in the order of US$ 120 million to Brazilian fruit growers, is being combated with sterile males produced at a biofactory installed in Juazeiro, in the backlands of Bahia. The place chosen to house Moscamed Brasil, the official name of the enterprise, is to be found in the center of the largest tropical fruit producing and exporting region of the country, in the São Francisco Valley. The losses are caused by the females of the flies, which deposit their eggs inside the fruit. The larvae develop and feed themselves on the pulp, making it unviable to trade them. To combat them, the sterile males created in the laboratory are let loose in the plantations to mate with the wild females. The biological control of the fly population occurs because these females, when mating with the sterile males, do not leave descendents. They only mate with one or a few males during their reproductive cycle.
The production of the flies in the laboratory starts with a lineage of genetically modified females in which the female population of these insects has a gene deactivated, the one that is responsible for the synthesis of a protein for resistance to the heat. The eggs from this lineage are thermally treated with water heated to a temperature of 34ºC for 12 hours. The embryos of the females do not resist the heat treatment and die, while the males are left over. “In the breeding process, we are only interested in the males, which are important for transferring the unviable spermatozoids”, says Moscamed’s director-president, a retired professor from the Genetics Department of the Biosciences Institute of the University of São Paulo (USP).
The males survive and are irradiated with a cobalt source to make them sterile. The irradiation, initially done at the Agriculture Nuclear Energy Center (CENA) of the University of São Paulo, in Piracicaba, is currently carried out at the Federal University of Pernambuco. A short time from now it will begin to be done at Moscamed, which will receive equipment donated by the International Atomic Energy Agency, an organization of the United Nations.
Insects in the plane
The release of the sterile males is done by model aircraft monitored by remote control, developed by pupils of the Federal University of the São Francisco Valley. Each plane has a 3-meter wingspan and manages to carry 1.5 million flies. The insects can also be released manually, but this is a lengthier and more expensive process. Before release, a monitoring of the wild flies is done. Based on the quantity monitored, a larger or smaller number of sterile males is released. “We have a system of traps for males and females that makes possible a more precise calculation of the number to be released in an area”, Malavasi says.
To be sure that the sterile males really fulfill their role in the semi-arid area, a validation study was made in two very different regions: in Livramento, in Chapada Diamantina, in Bahia, and in anther area inside the São Francisco Valley. “This study was necessary because we work with temperatures from 35 to 40 degrees every day”, the researcher explains. In other places where sterile insects are released, like California, in the United States, and the south of Argentina, the temperatures are far milder.
Moscamed is the first factory of its kind in Brazil. It began to operate last March, and it currently produces about 5 million sterile insects a week, a figure that should reach 120 million by the end of the year. The largest factory in the world belongs to the United States Department of Agriculture and is installed in Guatemala, in Central America. There, about 2.3 billion insects a week are produced. Such a gigantic production has a raison d’être: the Mediterranean fruit fly is responsible for losses in the order of US$ 2 billion in the whole world. In Brazil, this pest prevented farmers from accessing competitive markets, like the United States, Japan and some countries of Europe. “At USP, we developed several processes that made it possible to open up the export market like mangoes, papayas and melons”, Malavasi says. But they are processes that make production expensive, because they involve post-harvest treatments applied directly onto the product, without causing consumers any problem, but altering the final quality of the fruit.
When he retired, the professor was invited to implant the biofactory, which received contributions of R$ 12 million from the Ministries of Agriculture, Science and Technology, and National Integration, besides a donation of the plot of land of 60 thousand meters and 5 thousand meters of constructed area, worth R$ 7 million, by the Government of the State of Bahia. As Moscamed is a social organization linked to the Ministry of Agriculture, it can sell products and services and have a profit, but it has to reinvest everything it earns in the business itself. “After selling the sterile fly to the governments of Bahia, Pernambuco and Ceará, we are now in negotiation with Morocco, for us to be able to make a profit and to decrease the cost for the Brazilian producer”, says Malavasi. For the Brazilian fruit grower, the releasing of sterile insects works out at around US$ 180 a million. When sold abroad, the insects cost US$ 230 a million.
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