Biological pest control is the topic of lecture

Researcher Roberto Teixeira Alves, from Embrapa Cerrados (DF), presented on May 17th, during AgroBrasília 2018, the lecture “Biological Control of Pests”. The presentation was attended by technicians, producers, researchers and students in the Brasília auditorium of the Ivaldo Cenci Technological Park, where the fair was held from May 15th to 19th. The lecture was promoted by Embrapa and the Brazilian Federation of Direct Planting and Irrigation.

Alves began the lecture by explaining the reason for the emergence of insect pests. In pristine native vegetation environments, insect populations are in balance. But when deforestation and another species of plant are grown in these areas, natural barriers are eliminated, increasing the food supply for those insects that prefer the new plant species. As a result, the population of one or more insects increases, causing economic losses – these will be insect pests.

The Brazilian agricultural landscape, with large areas of crops of different crops and their different cycles, serves as food for insect pests, which will have more time to multiply. As the researcher pointed out, the problem is aggravated by the inadequate use of pesticides, characterized by the non-use of Integrated Pest Management (IPM); the timing of insecticide application; inadequate dosages of insecticides, “cocktails”, non-selective insecticides for natural enemies and the use of the same chemical groups and mode of action, factors that lead to the induction of resistance in insect pests to products.

The researcher cited and exemplified the various methods of pest control, such as legislative, mechanical, cultural, physical, resistant plants, behavioral, chemical and biological control. “There is no plant immune to everything nor one method better than the other. The right thing to do is to raise awareness about carrying out MIP, and to do this you need to know how to use each type of control individually”, explained Alves.

Just like a house, the MIP is made up of bases and pillars. The bases are the taxonomy, biology and ecology of insect pests; constant and efficient monitoring of the pest in all crops in the system to make decisions on the control to be adopted; the level of control, which precedes the level of damage; and the conditions of the agroecosystem. The pillars are the available control methods – cultural, biological, behavioral, genetic, varietal and chemical. “MIP aims to eliminate or minimize the use of chemical products. If you can minimize it, you will spend less money,” said Alves.

The researcher pointed out several reasons why biological control, one of the pillars of IPM, is not used on a large scale in different countries, mainly the lack of knowledge about the practices. “The farmer has to familiarize himself with biological control, the products and how to apply them, starting in small areas. Not just the farm owner, but all the employees need to, little by little, be convinced and believe in him,” he said.

Alves conceptualized biological control as a method of controlling pests using natural enemies, which are organisms that keep the population levels of these pests in balance. Biological control represents only 2% of the national agricultural pesticides market, which generates US$9 billion annually. 

He explained that biological control is carried out by species of predators, parasites/parasitoids and pathogens, citing examples of these species. Predatory species such as the ladybug and Cycloneda sanguinea feed on the insect pest, and are not specific. Parasites and parasitoids such as Trichogramma spp. and Trissolcus basalis are more specific and, normally, require a host to complete the development cycle, which can kill it, in the case of parasitoids. 

Pathogens are microorganisms that cause diseases in insects. They can be facultative (they develop in the host or in an artificial culture medium), such as the fungus Metarhizium anisopliae and the bacteria Bacillus thuringiensis, or obligatory, such as Baculovirus anticarsia, which only develop in the insect.

The researcher pointed out the three types of biological control. Natural biological control is carried out by the population of natural enemies that occur naturally in the environment – ​​Embrapa developed the “Guia InNat” smartphone application to help identify natural enemies of agricultural pests. Classic biological control, little used in Brazil, consists of the import and colonization of parasitoids or predators to control exotic or native pests.

Applied biological control, the most common of the three, deals with the release of pathogens, parasitoids or predators produced in the laboratory with the aim of quickly reducing the pest population to the equilibrium level. It can be done with drone sprayers and the infection route for fungi is normally via the integument, and for bacteria and viruses it is via the oral route.

Alves explained the mode of action of products based on fungi, bacteria and entomopathogenic viruses, parasitoid insects and nematodes, citing examples such as M. anisopliae, a fungus used to control the sugar cane leafhopper; B. thuringiensis, bacteria used to control caterpillars and black mosquitoes; B. anticarsia, virus for soybean caterpillar control; Cotesia flavipes, an insect parasitoid of the sugarcane borer, and Trichogramma spp., an insect parasitoid of lepidopteran eggs; and Steinernema puertoricence, a nematode for controlling Sphenophorus levis and Migdolus fryanus in sugarcane. The researcher showed the lists of products that are registered with the Ministry of Agriculture, Livestock and Supply.

The use of mycoinsecticides in biological pest control in Brazil covers an area equivalent to 2 million hectares annually, an area that is expected to double in the next three years. Alves highlighted the work in which he evaluated different formulations of a mycoinsecticide with the fungus M. anisopliae to control the sugar cane leafhopper. The fungus is also used in mycoinsecticides to control grasshoppers of the genera Deois, Notozulia and Mahanarva. 

The researcher cited other species of fungi that control insect pests, such as Metarhizium acridium for locust control; Nomuraea rileyi, which controls the soybean caterpillar (Anticarsia gemmatalis); Sporothrix insectorum for control of the rubber lace bug (Leptopharsa heveae); Beauveria bassiana, used to control banana moth (Cosmopolites sordidus); and Trichoderma spp., used to control fungi that cause diseases in the soil.

The application of mycoinsecticides can be carried out overland, using manual or motorized knapsack sprayers, a tractor equipped with an atomizer or a spray bar; or by air, with an airplane or helicopter equipped with a spray bar (water-based formulation) or an airplane equipped with a “Swathmaster” solids applicator (granulated formulation). According to the researcher's studies, the ideal condition for the mycoinsecticide to be effective is for the application to guarantee the deposition of 20 to 30 drops/cm² on the target.

Alves criticized the homemade production of biodefensive products, pointing out the risks for crops and people. He cited an Embrapa study that he identified, on farms that produce their own biodefensive products to reduce costs, fecal coliforms and the bacteria Enterococcus gallinarum and E. casseliflavus, which can cause endocarditis in animals. “It is necessary to have asepsis, sterilization to produce without contamination. What’s cheap is expensive,” he said.

The researcher ended the talk by commenting that each participant must collaborate in the dissemination of technical information about biological control so that the appropriate use of the method is increased, which will avoid chemical residues in food, contamination of natural resources and poisoning of rural workers.