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Caroline Dias de Souza e Carlos Frederico Wilcken

Coordinator of the Cooperative Program on Forest Protection at IPEF and Professor of Forest Entomology at FCA/UNESP-Botucatu


Integrated management of forest pests

Eucalyptus cultivation is seriously threatened by several pests capable of reducing productivity. The growth in the extension of plantations over the years is one of the factors for the increase in the number of pest occurrences. According to the annual report of the Brazilian Tree Industry, the total area of trees planted in Brazil, in 2021, was 9.93 million hectares, with a growth of 1.9% compared to 2020. upward trend in the occurrence of pests.

According to data from the annual survey of forest pests, from the Cooperative Program on Forest Protection, from the Institute of Forestry Research and Studies, in 2021, we had 46% of the surveyed areas attacked by insect pests (excluding leaf-cutting ants), an increase of 16% compared to 2020 (30%).

The increase in areas affected by pests has also generated an increase in the registration and use of chemical and biological insecticides in forest plantations. In this scenario, the companies' intensive adherence to forest certification processes gains prominence, encouraging the implementation of more sustainable methods in the management of pests in forest plantations in Brazil.

The Integrated Management of Forest Pests, characterized not only by the use of different control methods, but also by economic, social and environmental sustainability, is widely adopted by forest companies that have a forest certification seal, mainly those with international recognition.

The concept of Integrated Pest Management emerged in the 1970s, after the emergence of problems such as resistance of pests to insecticides, biological imbalance with the reduction of populations of natural enemies, in addition to problems of environmental contamination generated by the excessive use of chemicals in the pest, disease and weed control. Still, with the emergence of Integrated Pest Management , biological control also reappeared, but with new approaches, through conservation and multiplication of natural enemies, introduction of beneficial agents and use of entomopathogens in pest control.

Integrated pest management can be defined as a decision system for the use of isolated or associated control methods, employed in a management strategy based on cost-benefit, considering sustainability. Integrated Pest Management consists of diagnosis or assessment, decision-making and selection of control methods, with planning being an extremely important tool in all these components.

In the diagnosis process, pest populations, their natural enemies, and the factors that influence their occurrence are identified and monitored. In decision making, we choose to control or not. The decision is based on sampling plans and decision-making indices. For this, it is necessary to determine the population level that causes economic damage, and it is also necessary to evaluate the parasitism or predation and the population growth trend of the insect based on the history of the area. Finally, the choice of control method, with emphasis on less impacting methods, such as biological control or plant resistance. When the use of chemicals is necessary, the choice is oriented towards insecticides that are more selective and specific to the target pests and, currently, less toxic to pollinators.

In forestry plantations, the use of Integrated Pest Management has been increasing , despite the difficulty in determining the level of economic damage. The establishment of a wide monitoring network, with the use of appropriate techniques and technological evolution, has been helping in this matter. The main examples of Integrated Pest Management in eucalyptus in the country are for defoliating caterpillars, leaf-cutting ants and nursery pests.

Defoliator caterpillars were the highlight in 2021, with reported occurrence in more than 850,000 hectares, according to data from the Cooperative Program on Forest Protection, from the Institute of Forestry Research and Studies. For defoliating caterpillars, the monitoring system is often based on the joint use of different techniques, such as determining the intensity of defoliation, counting the number of caterpillars per leaf, evaluating excrements and installing light traps. The management of this group of pests is carried out with the integration of several methods, such as plant resistance to insects, chemical control and biological control with parasitoids, predators and entomopathogens.

In the Pinus culture, as examples of Integrated Pest Management, we can mention the management of species of the giant Pinus aphid, Cinara species, and the wood wasp, Sirex noctilio. The wood wasp is the best example of Integrated Pest Management in Pinus, considering the research carried out by Embrapa Florestas, with the determination of damage and losses caused by the pest, development of the sampling and monitoring method, with trap trees and remote sensing air, and choice of control method, mainly biological, using the parasitic nematode Deladenus siricidicola and parasitoids such as Ibalia leucospoies and Megarhyssa nortoni, as well as silvicultural methods, such as thinning to reduce stress on trees.

Classical biological control is also one of the main management strategies for exotic eucalyptus pests. We can mention the importation of the parasitoid of the shell psyllid Psyllaephagus bliteus from Mexico, in 2005, from the root-wasp parasitoid Selitrichodes neseri from South Africa in 2015 and the parasitic tan bug Cleruchoides noackae from Australia in 2012.

The management of these pests also involves the use of other biological control agents, insecticides and resistant genetic material. For the tan bug, the parasitoid Cleruchoides noackae was released in several states, such as Minas Gerais, São Paulo, Espírito Santo, Rio Grande do Sul, Paraná, Mato Grosso do Sul, Bahia and Maranhão, with an evident reduction in infestations and damage in the years following its release. Currently, Cleruchoides noackae can be found present in practically all populations of Thaumastocoris peregrinus in Brazil.

Another important case was the management of the eucalyptus weevil Gonipterus platensis, in Espírito Santo. This pest arrived in Espírito Santo in 2004 and caused extensive defoliation, reaching approximately 70,000 hectares between 2004 and 2005. The company developed a monitoring method, considering visual assessments and sampling of branches.

The search for the egg parasitoid Anaphes was carried out nitens in eucalyptus forests in Rio Grande do Sul, brought to the Universidade Estadual Paulista in Botucatu to start laboratory breeding, and the parasitoids were sent to a mass breeding laboratory, at the time of Aracruz Florestal, for later release in the field . Until the parasitoid production increased, the pest was fought with applications of the biological insecticide based on the fungus Beauveria bassiana. In early 2006, the pest was already under control, and it remains so until today.

The use of integrated techniques for managing pests in forest crops is already a reality, despite all the difficulties, as these are planted forests. With the adoption of Integrated Pest Management, we noticed not only the reduction of damage to plantations, with a consequent decrease in productivity losses, but also the more rational use of chemical insecticides, contributing to the sustainability of the forestry sector. However, there are still many opportunities for improvement and development of new technologies, such as the use of drones to monitor and control pests and the adoption of biotechnological tools, such as the use of genetically modified plants.