Soybeans are one of Brazil's main commodities, and their growth in recent decades has placed them among the most important crops in the national agribusiness (COLUSSI, 2016). Currently, they occupy a prominent role in Brazilian agribusiness, and to achieve high productivity, initial pest monitoring is crucial for crop success.
In this initial period, soil moisture conditions, the presence of crop residues, and high temperatures create a favorable environment for the occurrence of various mites, caterpillars, and soil insects, which can compromise the condition of the plants.
The lesser cornstalk borer (Elasmopalpus lignosellus) has a life cycle of 25 to 40 days, attacking mainly during the V1 and V2 phenological stages, where they penetrate the base of the stem and settle by sucking the sap (FUNDAÇÃO MT, 2021). Its attack can be confused with failures in vigor and germination, for this reason a field analysis of the caterpillar population in the area is fundamental.
Management is preventive, with:
• crop rotation,
• early desiccation,
• seed treatment (ST).
Whiteflies cause the most damage during the nymph stage, when the insect feeds on the phloem on the underside of leaves, reducing photosynthesis and promoting the development of sooty mold. The biological cycle is rapid at high temperatures, which allows for multiple generations throughout the growing season (Lourenção & Nagata, 2020).
According to the Embrapa Soja booklet (2023), an infestation can lead to losses of up to 50% in final productivity, requiring close attention at the beginning of the crop cycle.
Its control through IPM includes the elimination of hosts and seed treatment with registered insecticides, such as abamectin or molecules from the diamide group.
The Diabrotica speciosa beetle can cause damage from the larval stage to the adult stage, has a life cycle of 24 to 40 days, and is susceptible to climate changes that can alter its cycle. According to Gomez (2021), the larvae are white with a black head, and during this stage they can feed on germinating seeds, roots, and rhizobia nodules (reducing nitrogen fixation), negatively impacting crop yield.
They feed on leaves and shoots, making small holes in the leaves, which can cause significant defoliation. This compromises the plant's photosynthetic area, leading to a significant reduction in the production of photoassimilates, affecting leaf growth and development, which ultimately leads to a loss of productivity.
Control of Diabrotica larvae should be done preventively with seed treatment. For the control of adults, the use of organophosphate, carbamate, and neonicotinoid insecticides provides effective control (MARTINI, 2021).
The brown stink bug (Scaptocoris castanea), both adults and nymphs, attack soybean roots, sucking their sap, from the seedling stage to harvest, resulting in reduced water and nutrient absorption. In relation to unattacked plants, they show reduced growth and chlorosis in the leaves. If the attack occurs in the early stages of the crop, the plants may die, resulting in a decrease in the plant stand of the field (Oliveira, 2021).
Chemical control of Scaptocoris castanea is not efficient due to its subterranean habit. Biological control, however, is efficient.
The cutworm (Agrotis ipsilon) lays its eggs on leaves and stems near the ground. After hatching, the larvae take shelter in the soil during the day and feed at night, cutting the seedlings just above the collar. The caterpillars also curl up into a "C" shape when touched, which facilitates their identification. The attack reduces the stand and compromises the initial establishment of the crop.
For the control of the cutworm, integrated management is recommended, emphasizing good soil preparation and the elimination of host plants. The intensity of the attack is linked to the history of the area and the preceding crop. The most prominent control is the early management of cover and host plants (MICHEREFF, 2022). When high populations occur in soybeans, insecticides can be applied in the late afternoon or at night (Embrapa, 2021).
The two-spotted spider mite (Tetranychus urticae) generally occurs in dry years, forming webs. They have a sucking feeding habit, piercing the surface cells, thus reducing the photosynthetic rate. The attacked plant shows chlorosis with small yellow spots, causing defoliation and even plant death (Gomez, 2021).
In situations of associated water stress, the attack can lead to premature leaf drop and compromise plant development.
Control can be carried out with registered acaricides, such as abamectin-based products. Applications of pyrethroid-based insecticides associated with high temperatures and low air humidity can cause a rapid population increase.
Given this, monitoring pests at the beginning of the soybean cycle is a crucial step for the success of the entire crop, since early pests can compromise the stand and significantly reduce yield potential. In this context, attention to the first phenological stages (V0 to V3) and decision-making based on field data are indispensable tools.
By integrating Integrated Pest Management (IPM) with seed treatment practices and the correct choice of cultivars, the producer ensures uniform plant development and reduces costs with future applications, replacing corrective actions with preventive strategies.
Access the 3tentos portal and learn about the solutions in integrated management, seed treatment, and pest monitoring that strengthen the potential of your crop from sowing, ensuring a safe and productive start to the season.
Text written by Vitor Hugo Zanatta de Cristo and Vitor Riva Tallamini, members of AGR Jr. Consultoria Agronômica, Junior Enterprise of the Agronomy Course at UFSM Campus Frederico Westphalen, under the guidance of Professor Gizelli Moiano de Paula.
REFERENCES
Night attack of cutworms. Cultivar Hortaliças e Frutas Magazine, ed. 77, Feb. 14, 2018.
COLUSSI, Joana et al. The soybean agribusiness: An analysis of the profitability of soybean cultivation in Brazil. ESPACIOS Magazine, v. 37, 2016.
EMBRAPA SOJA. Manual for Identification of Soybean Crop Pests. Londrina: Embrapa Soja, 2022.
EMBRAPA SOJA. Monitoring and Integrated Management of Whitefly in Soybean Crops. Londrina: Embrapa Soja, 2023.
FUNDAÇÃO MT. Early soybean pests: diagnosis and prevention. Technical Bulletin, 2021.
GALLI, J. A.; HOFFMANN-CAMPO, C. B. Insect pests and integrated pest management (IPM) in soybean cultivation. Londrina: Embrapa Soja, 2019.
GOMEZ, Daniel Ricardo Sosa. Leaf beetles. In: EMBRAPA TECHNOLOGICAL INFORMATION AGENCY (Ageitec). Soybean: integrated pest management. Londrina: Embrapa Soja, 2021.
CUTWORM. In: EMBRAPA TECHNOLOGICAL INFORMATION AGENCY (Ageitec). Soybean: integrated pest management. Embrapa, 2021.
LOURENÇÃO, A. L.; NAGATA, T. Whitefly in soybean and bean: biology, damage and control. Londrina: Embrapa Soja, Technical Circular 138, 2020.
MARTINI, Sandro. Control of Diabrotica speciosa in soybean (Glycine max) crops. Undergraduate Thesis (Agronomy) – University of Cuiabá, Sorriso, 2021.
MICHEREFF FILHO, Miguel; GUIMARÃES, Jorge Anderson; MOURA, Alexandre Pinho de. Cutworms. In: EMBRAPA TECHNOLOGICAL INFORMATION AGENCY (Ageitec). Onion: pests. Embrapa, 2022.
OLIVEIRA, Lenita Jacobs. Root bug complex. In: EMBRAPA TECHNOLOGICAL INFORMATION AGENCY (Ageitec). Soybean: integrated pest management. Embrapa, 2021.
PICANÇO, M. C. Agricultural Entomology: pests and their management. Viçosa: UFV, 2020.
RODRIGUES, Karen Helena de Andrade. Control of Diabrotica speciosa. Cultivar Grandes Culturas Magazine, ed. 292, Aug. 23, 2024.
UFV – Federal University of Viçosa. Department of Entomology. Soybean Pests: Biology and Integrated Control. Viçosa: UFV, 2020.
Cover image: Embrapa Soja.
