2023-09-27 18:28:11
By Geraldo Gouveia, researcher and technical field specialist in Agronomy at the Agrogalaxy Technological Center (CTA)
The corn leafhopper, also known as Dalbulus maidis, is a pest very familiar to rural producers of this crop in Brazil. However, a new threat has been identified: the African leafhopper, Leptodelphax maculigera.
Originally found in Africa, the African leafhopper has been documented in several countries on the continent, such as the Mascarene Islands, Ivory Coast, Madagascar, Kenya and Cameroon. Until recently, this species had not been identified in the Americas and was not classified as a quarantine pest by the Brazilian Ministry of Agriculture, Livestock and Supply (MAPA) (KOJI et al., 2012; FERREIRA et al., 2023).
The African leafhopper is an oligophagous species, that is, it feeds on several plants from the grass family and its first record in the Americas took place in Brazil, more specifically in the state of Goiás, when between July and November 2022, samples of L. maculigera, including young and adult forms, were collected and studied by the Federal University of Goiás. At the time, the African leafhopper was associated with important agricultural crops, such as corn, Brachiaria, elephant grass, BRS Capiaçu grass varieties and beans, with species identification was validated through morphological analyzes of the male genital parts of the insect (FERREIRA et al., 2023).
The second report of the presence of the African leafhopper in Brazil was reported in Rio Grande do Sul, on monitoring devices from the Cooperative Technical Network (RTC) at the CCGL experimental station, in Cruz Alta. According to Glauber Renato Stürmer, an entomology specialist at CCGL, these individuals, similar to the well-known corn planthopper (Dalbulus maidis), were attracted and captured by a colorful sticky trap.
The state of Paraná was the third to report the presence of the African leafhopper in Brazil. At the time, the pest was found in crops in the municipality of Londrina (PR), in the north of the state, where technicians from the Institute of Rural Development of Paraná (IDR-Paraná) sent samples to the Applied Entomology Laboratory at the State University of Ponta Grossa (UEPG).
Due to the similarity between the two species, it is easy to miscategorize them as “corn leafhoppers” during field inspections, mainly because the presence of L. maculigera was previously unknown in Brazil, however, recommended management strategies for D. maidis should also be adopted for L. maculigera.
Management Strategies
Effective management of these pests requires integrated approaches that combine several strategies, including:
Crop rotation: agricultural practice that consists of alternating different types of crops in the same area over time. This technique helps break the life cycle of leafhoppers and other pests, reducing their population over time. Additionally, it improves soil health and reduces the need for chemicals.
Choosing tolerant hybrids: Selecting corn hybrids that are leafhopper tolerant is another valuable strategy. These hybrids are developed to better resist the pest, reducing the need for chemical interventions and increasing crop productivity.
Reduction of the sowing window (crop overlap): Reducing the seeding window through overlapping the crop can limit the period in which leafhoppers can infest the field. This can be done by planting the corn at different stages, so that the leafhoppers do not have an extended period to feed and reproduce.
Elimination of voluntary corn: is one that grows without being planted intentionally, usually from grains that fell to the ground in previous harvests. These plants can serve as hosts for leafhoppers, so their elimination is crucial for effective management.
Seed treatment: Treating seeds with insecticides before planting is another form of control. This protects young plants during the early stages of growth when they are most vulnerable to infestation.
Foliar application of chemicals associated with biologicals from V2 onwards: From the V2 stage of corn onwards, the foliar application of chemical products in combination with biological agents can be an effective strategy for leafhopper control. Chemicals work quickly to kill the pest, while biological agents offer longer-lasting control, reducing the number of subsequent applications.
Tolerance Inductor: The use of tolerance inducers in corn plants plays a significant role in the integrated management of leafhoppers and associated diseases. Plants stressed by conditions such as drought and nutritional deficiencies tend to be more vulnerable to pests and diseases. With the application of inducers, the plant’s tolerance to abiotic stresses is potentially improved, helping the plant maintain its health and vigor, making it less attractive or susceptible to leafhoppers and the pathogens they transmit. Additionally, many of these inducers can reinforce plant cell walls or induce the production of compounds that make the plant less palatable to pests, resulting in reduced leafhopper feeding and reproduction. Like resistance inducers, tolerance inducers can also amplify plants’ defensive responses, allowing them to respond more quickly and effectively when attacked or infected. In this context, the AgroGalaxy Technological Center has been achieving excellent results with the use of tolerance inducers in corn crops to help control leafhoppers.
Nutritional balance between macro and micronutrients: Balanced nutrition is essential for plant health and vigor, especially in corn, which faces threats such as leafhoppers. Properly nourished plants are more vigorous and healthy, having efficient defensive systems that make them less susceptible to pests. Specific nutrients, such as calcium and silicon, strengthen cell walls, making them less accessible to leafhoppers. Furthermore, balanced nutrition enhances the production of defensive secondary metabolites and allows for a more agile response to threats. A well-nourished plant recovers more quickly, minimizing losses. This nutritional balance also enables the plant to face abiotic stresses, such as drought or salinity, and provides greater resilience to various challenges, including climate change and other pests.
In summary, effective management of the corn leafhopper, through an integrated approach of different strategies, not only results in more efficient control of this specific pest, but also extends to the efficient control of the emerging African leafhopper. The implementation of these combined tactics contributes to more sustainable and effective agriculture in combating both pests.
Sources researched:
Ferreira, K. R.; Bartlett, C. R.; Asche, M.; Silva, L. R. S.; Magalhães, V. S.; Gondinho, K. C. A. (2023). First record of the african species leptodelphax maculigera (stål, 1859) (hemiptera: delphacidae) in brazil.
KOJI, S.; FUJINUMA, S.; MIDEGA, CAO; MOHAMED, HM; ISHIKAWA, T.; WILSON, MR; ASCHE , M. ; DEGELO, S.; ADATI, T.; PICKETT, JA; KHAN, ZR Seasonal abundance of Maiestas banda (Hemiptera: Cicadellidae) associated with Napier grass (Pennisetum purpureum) in Kenya. J Pest Sci 85, 37–46.
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