A Brazilian native wasp can parasite two fruit fly species. The Doryctobracon areolatus wasp reached 40% of pest parasitism. The wasp places its eggs within the larva of the fly, which will become food for the wasp larva when it hatches. The practice is promising for integrated pest management. Because it is clean, the practice does not breach restrictions from European countries that that have banned importing fruits treated with chemicals. An innovative technology uses native parasitoids to control fruit flies (A.fraterculus and C. capitata). Researchers from Embrapa Temperate Agriculture's Entomology Lab in Pelotas, RS, used the Doryctobracon areolatuswasp, which parasited up to 40% of the fly larvae, considered one of the major problems of fruit farming in the world. The scientists inform that the results are promising and indicate potential to be used in orchards as a biological control technique in the scope of an Integrated Pest Management (IPM) strategy. The parasitoid could be recommended for both organic cultivation and conventional orchards. Since it is a strategy that does not use chemicals, the wasp's action complies with the recent normative instruction from the Brazilian Ministry of Agriculture (no.19 of Aug 7, 2019) that regulates procedures so that Brazilian fruits can receive international certification for products of plant origin. “Several countries of the European Union impose restrictions to the use of chemical defensives in fruit crops, thus, in order to export to such markets, Brazil has to replace pesticide applications with clean pest control alternatives”, clarifies the entomologist Dori Edson Nava, a researcher at Embrapa.. What is biological control? It is the regulation of the number of plants and animals by natural enemies, which are known as biotic mortality agents. Such natural enemies include predators, parasitoids and microorganisms. It is a rational control method that adheres to the principles of sustainability and that aims to use natural enemies that cause little impact on the environment and on human health in comparison with the use of chemical products. Learn more about the subject on Embrapa's theme page. How does it work? In practice, the use of this parasitoid involves wasp production stages in laboratory, followed by their release in orchards under fruit fly attack. After the release, the female parasitoids locate the pest larvae inside the fruits to perform the oviposition (lay new eggs into the larvae). From the egg laid by the parasitoid another larva will eclode and feed from the host's entrails, until it turns into a pupa within the fruit fly's puparium. The wasps emerge after a few days, thus preventing the perpetuation of the fruit fly. The research Initially, the scientists collected basic information on the pest's biology and ecology and about the Doryctobracon areolatus parasitoid in particular. The second stage sought to establish a breeding technique both for the host (the fruit fly) and the parasitoid. “The idea is to improve breeding techniques to be cheaper and less labour intensive. Labour represents about 50% of the production cost”, Nava observes. The techniques were developed and are already available for farmers. They also studied stages related to insecticide selectivity to the parasitoid, search behavior and parasitism, among others. All these stages are important to assess the possible use of the wasp in biological control programs. “What we seek is to answer the question: what is the parasitism (control) rate in field conditions? Is its use viable? ”, Nava inquires. The scientist stresses that biological control is not the only option against fruit flies. It should be used jointly with other control methods within the Integrated Pest Management (IPM) philosophy. Learn more about the work with parasitoids - Terra Sul show Alternative fruit fly control Moreover, the availability of biological control agents is timely, as most fruit trees do not have a set of recommended phytosanitary products. In the study, the initial results indicate parasitism rates that vary from 6.2% to 40%. Such figures depend on the time of wasp release, pest infestation levels, fruit fly species, and other factors. There will be further stages of assessments and studies that are scheduled for the upcoming years. The research team does not have an estimate for production costs with the use of parasitoids yet. Nava reveals that the initial cost tends to be higher and then it will reduce in the course of time as technology iss popularized and used on a bigger scale. “There is a perception among farmers and the general community that the use of biological control reduces production costs. In the truth, the cost of control depends on market. The bigger the market, the lower the cost”, assesses Nava. Alternative controls - Terra Sul show The future of the study The scientist informs that there are other stages to go through to establish parameters for the parasitoid release (time, quantity, frequency, etc). The biological control technology is developed in partnership with a local company, Partamon. The idea is that it trades the technology in the future. Besides Partamon, the parasitoid Doryctobracon areolatus (on the right) could be produced in biofactories, such as Moscasul, which is being set up in Vacaria, Rio Grande do Sul, and which will use the Sterile Insect Technique and parasitoids for the biological control of fruit flies. “Besides generating the technology, there is a need to advance in fruit fly management programs and to involve not only fruit farmers, but also private and public institutions”, the researcher adds. This occurs due the need to perform a more geographically comprehensive control for the fruit fly group, since local control only solves the problem momentarily. The difficulties of chemical control Nowadays, for fruit flies, Brazil has registered and permitted chemical products only for citrus, apple and peach orchards. For most crops there are few or no registered chemical pesticides. “Most fruit trees do not have more products registered for fruit fly control. Moreover, the ones that are available, especially from the organophosphorus group, have already been banned by the European Union countries”, informs the Embrapa researcher. According to him, a good portion of the countries already uses biological control as a pest control strategy. He underscores the performance of Mexico, Israel and Chile, as references in the biological control of fruit flies, which enables them to export fruit to several world consumer markets. The damage caused by the fly Orchards with fruit fly infestation are not apt for exports and the losses also cause financial losses in the Brazilian domestic market. Nava explains that the fruit fly larvae destroy the fruit pulp to feed themselves. "When the females lay eggs, they introduce the ovipositor, causing an injury [an opening], which facilitates the entrance of rot-causing fungi. Moreover, the damages cause early ripening and subsequent fruit fall”, Nava details. Biological cycle of fruit flies in peach tree Studies indicate that out of the annual 14.7 billion dollars of economic losses in agriculture caused by insects, 1.6 billion is associated with fruit production. According to the assessments carried out by MAPA, in 2015, for Brazil, considering losses in production, trade and control costs, fruit flies alone cause an annual loss of 180 million Brazilian Reals. What are fruit flies? Fruit flies belong to the Tephritidae family. Several species have been describes, but only a few cause economic losses. These include the South American fruit fly Anastrepha fraterculus and the Mediterranean fly Ceratitis capitata. Researcher explains the difference between the fruit fly species Nava says that the South American fruit fly is a species of neotropical origin, which occurs from the South of the United States to Argentina. In Brazil, this species is found in all the regions of the country, and attacks both cultivated and native fruit trees of over 90 host species from 20 botanical families. In the states of Rio Grande do Sul and Santa Catarina, it is the predominant species”, the researcher states. Fructification of the main hosts of Anastrepha fraterculus in the temperate regions Meanwhile the Mediterranean fly is an exotic species that was introduced in Brazil around the 1900s which has global economic relevance, as it is distributed in tropical and subtropical areas. It is also present in every state of the country, with a higher concentration in the border with Uruguay and Argentina. “Research has estimated that, for instance, if C.capitata halves Brazilian citrus production, the economic losses can amount to 242 million dollars”, Nava stresses. Controlling the fly One of the ways to control the pest is through the use of phytosanitary products in selective application, as toxic bait or cover application. After the restrictions to the use of phytosanitary products due to the market ban of insecticides from the organophosphorus group, the sector has been seeking other alternatives. One of them is the establishment of program Fruit Fly Control Warning System. in Southern Brazil. It covers a large area involving regions to the South of Rio Grande do Sul and part of the fruit producing region in Serra Gaúcha where peach trees are cultivated. Started about a decade ago, the project has contributed to farmers' defining the correct moment to apply insecticides, to improving the production system and obtaining a higher-quality and cleaner product. All such activities have provided significant advances in fruit fly management and fit in the current concept of pest management in large areas, which face pests that have high mobility. Brazil is world's third largest fruit exporter Brazil is the third largest fruit producer in the world after China and India, with a planted area of 2.3 million hectares and about 44 million tons production per harvest. In 2018, the country produced 124,300 tons of fresh and processed fruit to be sent to several countries. Out of the total fruit production, only 2.5% is destined to exports, according to the Brazilian Association of Exporting Fruits Growers (Abrafrutas). Experts believe that there is potential to increase the exported volume, but the country needds to tackle the challenge of controlling pests by reducing or eliminating the use of agrochemicals, one of the main factors that hinder an increment in international sales. Fruit farming in Brazil is diversified, as it is part of the economy and local social development in all of its regions. And there are fruit flies in every producing region. Translation: Mariana Medeiros