First record of thrips, a soybean pest, identified in Acre

Thrips are among the insects that have gained importance in Brazilian soybean crops in recent decades. Small and often difficult to see with the naked eye, these insects can cause significant damage to plants, reducing crop development and, in some cases, transmitting viruses of agricultural importance.

The dissertation entitled “Prospecting for pests and natural enemies in soybean cultivation and adjacent forest remnant,” corresponding to a study carried out by Embrapa Acre and the postgraduate student from the Federal University of Acre, Maria Érica Costa de Lima, recorded, for the first time, the occurrence of the species Caliothrips phaseoli, popularly known as “soybean thrips” or “bean thrips,” associated with soybean cultivation in the state of Acre. The record was made in an agricultural area of ​​Rio Branco, during the 2024/2025 growing season, in a field adjacent to an Amazonian forest remnant.

The discovery expands knowledge about the distribution of this species in Brazil and reinforces the need for phytosanitary monitoring in areas recently incorporated into soybean production in Western Amazonia. Thrips belong to the order Thysanoptera and include species with different feeding habits. Some live associated with fungi and decomposing organic matter, while others are phytophagous, feeding directly on plant tissues.

In agriculture, certain species stand out for their potential to cause economic damage. In soybean crops, thrips scrape the surface of the leaves and suck the cell contents, causing silvery spots, necrosis, and a reduction in the plant's photosynthetic area.

In cases of high infestation levels, the damage can be significant. Although they are very small insects, thrips can cause significant damage to soybean crops. Studies conducted in South America have shown that severe infestations of soybean thrips (Caliothrips phaseoli) can reduce plant photosynthesis and cause productivity losses of up to 17%, depending on the intensity of the infestation and growing conditions.

Although this species has been recorded in soybeans for the first time in Acre, it had already been reported in other producing regions of Brazil, especially in the South, Southeast, and Midwest regions, as well as the states of Maranhão, Tocantins, Piauí, and Bahia.

The species is considered polyphagous, meaning it is capable of developing on different host plants. Besides soybeans, it had already been found on forage peanuts, mint, and sunflowers in Acre, as well as on other cultivated species belonging to various botanical families in Brazil. Its identification in soybean fields demonstrates the species' adaptation to the new agricultural landscape of the state.

In addition to the direct damage caused by feeding, some thrips species are even more important because they act as vectors of plant viruses. Among these species, Frankliniella schultzei stands out, frequently associated with soybean crops in other regions of Brazil and known for transmitting orthotospoviruses, such as Groundnut Ringspot Virus (GRSV). These viruses can cause foliar symptoms, reduced growth, and productivity losses. Although this species was not detected in the survey conducted in Acre, it is important to emphasize that continuous monitoring is fundamental, especially given the expansion of soybean cultivation in the Amazon region. In recent years, soybeans have taken on an increasingly important role in Acre's agriculture, becoming one of the state's main agricultural export products.

With the expansion of soybean cultivation, the need for studies on insect pests, natural enemies, and potential vectors of plant diseases present in the region also increases. The first record of Caliothrips phaseoli in soybeans in Acre represents an important step in this process and contributes to expanding knowledge about insects associated with the crop in the Brazilian Amazon.

*Per Rodrigo Souza Santos, biologist, PhD in Agronomy (Agricultural Entomology) and researcher at Embrapa Acre