By Alexandre Diniz, José Roberto Postali Parra, and Aloisio Coelho Jr.
Some biological control programs involve large-scale rearing of millions insect predators that are released near agricultural crops. In Brazil, researchers have implemented of a number of successful biological control programs.
Brazil is the world’s largest producer of sugarcane, which has one of the oldest biological control programs. The crop’s most important pest is the sugarcane borer (Diatraea saccharalis), which is controlled by the release of the larval parasitoid Cotesia flavipes. Another natural enemy used for this pest is the egg parasitoid Trichogramma galloi. This program started in the 1970s, and today C. flavipes are released in an area that is larger than 30,000 square kilometers, while T. galloi are released in another 5,000 square kilometers — a combined area that is larger than Belgium.
The use of Trichogramma parasitoids has been growing in the country. During the 2013-14 growing season, a species called Trichogramma pretiosum was used in about 250,000 hectares of soybean to control the cotton bollworm (Helicoverpa armigera) and the soybean looper (Chrysodeixis includens), and even more are used for other crops, such as cotton, corn, beans, and fruit.
In addition to the caterpillars, soybeans are attacked by stink bugs. In the 1990s a biological control program used the egg parasitoid Trissolcus basalis against the stink bugs and proved to be very effective, especially in organic and micro-catchment basins areas. However, the program was discontinued because it is difficult to produce stink bug hosts of T. basalis on which to rear the parasitoids. In 2013 a freeze-dried diet was developed to rear the stink bugs, which create a new reason to restart this program, especially considering the area occupied by soybean in Brazil, which is 31.57 million hectares.
Another example involves biological control of the citrus leafminer (Phyllocnistis citrella) with the imported parasitoid Ageniaspis citricola, which dramatically reduced leafminer populations and the occurrence of citrus canker. This projected was developed in 1998 by universities and by private and public research organizations, and it gave excellent results in several states in Brazil.
Tamarixia radiata is another parasitoid that has been used to control the Asian citrus psyllid (Diaphorina citri), which transmits citrus greening disease (HLB) and is considered to be the major citrus pest in the country at this time. After 10 years of basic and applied research, the parasitoid began to be reared on a large scale, and today there are six bio-factories that produce the parasitoid for release in infested areas. T. radiata has reduced Asian citrus psyllid populations by as much as 70 percent in areas where it was released, and this natural enemy has been integrated with other control methods (chemical and cultural).
Brazil also has release programs involving predatory mites in the genera Neoseiulus and Phytoseiulus on more than 15,000 hectares. These mites are used in smaller crops such as strawberries and flowers, although their effectiveness is not yet known because there is not enough data yet.
These results are the product of a large number of biological control working groups from universities and research centers around the country. The work of these organizations has resulted in the publication of a series of books and articles on the subject, allowing the adoption of this type of management by growers who have never used it before. In addition, over the last 10 years a number of companies have emerged that specialize in the production of natural enemies, which has made Brazilian agriculture more sustainable.
Alexandre Diniz is an entomology professor at Sorocaba University. José Roberto Postali Parra is a professor at the University of Sao Paulo. Aloisio Coelho Jr. is a postdoctoral fellow at the the University of São Paulo and is a consultant in the private sector.