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Leonardo Rodrigues Barbosa

Researcher at Embrapa Florestas


Tan bug: current situation and management options

The introduction of exotic pests in eucalyptus plantations in Brazil is historic and they have increased with the globalization of trade relations and the increasing traffic of people and goods. Among the main species established in the country is the eucalyptus tan bug, Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), which has caused direct losses for eucalyptus cultivation.

Since its introduction in Brazil, in 2008, population outbreaks of this pest began, causing productivity losses, increased expenses with pest control and impacting existing pest management programs, in addition to increasing the risk of forest fires, due to the drying and subsequent fall of the leaves of the trees.

The tan bug is a sucking insect that lives in groups, with nymphs and adults occurring preferentially on the abaxial part of the oldest leaves of the plant. As symptoms of its attack, we observe, in the field, leaves with a silvery appearance that later evolves to a tan appearance, leading to partial or total defoliation of the tree, with losses in the productivity of the eucalyptus wood of up to 20%, in high populations of this plague.

The adult insect and the nymphs have a light brown color and a flattened body, they have the habit of walking a lot on the leaves and the trunk and are generally easy to see, with the size of the adult varying from 2 to 4 millimeters. Each generation of life of this insect lasts an average of 50 days. Bedbug attacks are more frequent in plantations between one and five years old, mainly associated with the driest months of the year.

The overlap of generations is checked throughout the year, and a large amount of nymphs and adults can occur on eucalyptus leaves. A peculiar characteristic of this bug is the rapid movement of nymphs and adults through the leaves, when disturbed. Since 2009, the Cooperative Program on Forestry Protection, of the Forest Research and Studies Institute, has applied a questionnaire to forest companies and producers to estimate the area attacked by pests in eucalyptus plantations. Bed bug population outbreaks have fluctuated over the years, and the most intense attacks were recorded in 2012.

In that year, the presence of the pest was recorded in approximately 21% of the surveyed planting area, which is equivalent to 245,000 hectares attacked. Between 2020 and 2021, infestations reached more than 200,000 hectares, for a total surveyed area of 3.5 million hectares. Therefore, this pest still requires management actions to minimize its impact.

In order to contain its advance in Brazil, the Cooperative Program on Forest Protection, of the Institute of Forestry Research and Studies, created, in 2008, a cooperative project with the participation of Embrapa Florestas, Embrapa Meio Ambiente, Universidade Federal de Viçosa and Universidade Paulista State in Botucatu.

This group established a management and biological control program for the tan bug, which, among other actions, introduced from Australia, in 2012, the egg parasitoid Cleruchoides noackae. The articulation between regulatory bodies and pesticide companies and the conduction of research for the adoption of chemical control of the bedbug were another important contribution of this project to the management of the pest.

Management tactics available for the bed bug include chemical control to contain population outbreaks and biological control with Cleruchoides noackae, for times when the population density of the pest is not very high. The basis for adopting these tactics is monitoring. To detect the pest, yellow adhesive cards, 12.5 centimeters long and 10 centimeters wide, are used, attached to tree trunks at 1.8 meters in height. The sampling intensity is one card for every 500 or 1,000 hectares of eucalyptus, depending on the history of the area and the ease of operation of each company.

These cards are exchanged and evaluated every 30 days to count the number of individuals of this pest. The intensity of the attack must be evaluated in loco, cutting two branches (plants up to two years old) or a tree (plants over two years old) every five to 10 hectares, sampling 10 leaves from the middle third of the tree to count nymphs, adults and postures of the tan bug. The good establishment of Cleruchoides noackae in several regions of Brazil, over the last ten years, with parasitism rates close to 60%, demonstrates the value of this parasitoid for the biological control of this pest.

In parallel with the development of the biological control program, options for its chemical and microbial management were studied and encouraged, which culminated in the registration, as of 2012, of different molecules and products for pest control. Currently, there are 4 products registered with the Ministry of Agriculture, Livestock and Supply for control, involving molecules from the pyrethroid and neonicotinoid chemical groups.

The ability to produce Cleruchoides noackae in large quantities and with quality, in laboratory creation, was decisive for the success of the bedbug biological control program in Brazil. The strategies developed in the country were replicated in several other countries where bedbugs are a problem. In addition, Brazil contributed to neighboring countries, sending the parasitoid to Uruguay, which, in turn, sent it to Argentina, thus ensuring the expansion of biological control of this pest in the Southern Cone.

Another important contribution was the studies on the adaptation of Cleruchoides noackae to the climatic conditions of the North and Northeast of Brazil (MATOPIBA). In the last year, its establishment in Maranhão was confirmed, and studies to evaluate its efficiency are being conducted. We are currently working on strategies that can optimize the production of Cleruchoides noackae in the laboratory and expand the biological control approach for the management of the tan bug. All the knowledge and techniques developed will be transferred to the forestry companies.