Wind direction could bring locust clouds to Brazil

The cloud of locusts moving through Argentina arrived today in the region of the Province of Corrientes, on the border with Rio Grande do Sul. Depending on the direction of the wind and environmental conditions, the plague could soon enter Brazilian territory, through the state of Rio Grande do Sul .

Schistocerca cancellata or South American grasshopper, as it is popularly known, has great dispersion capacity. “The term is used to refer to some species of acrids capable of forming 'swarms' or 'clouds' under certain climatic and food conditions and that move across large areas, as is currently occurring in Argentina”, details the Institute researcher National Agricultural Technology (Inta), Daniela Vitti Scarel . 

On June 17, the locust cloud entered the territory of the province of Santa Fé, in Argentina, after having been reported days earlier in the provinces of Chaco and Formosa, in Paraguay. The insect's distribution area includes Paraguay, Bolivia and Brazil, in addition to Argentina (in the center and northwest) in provinces such as Córdoba, Santiago del Estero, Catamarca and La Rioja. “Thus, it is expected that displacements will occur in these regions, in addition to being able to move to other territories accompanied by environmental conditions, such as the strong winds from the north that made them move, reaching the city of Lanteri, province of Santa Fe, Argentina” , reports.

It is not the first time that the South American grasshopper has had outbreaks in the region. In 2015 there were reports of locust clouds and damage to crops in the country, in the provinces of Santiago del Estero and Tucumán. In 2017 there was also a locust outbreak (at the end of June) concentrated in the area of ​​three provinces of Argentina (Santa Fé, Chaco and Santiago del Estero).

Researchers have not identified, to date, any differences between the current outbreak and those that occurred previously, but one of the hypotheses is that the reproduction of the plague was favored and the consequent increase in the population. “We did not notice differences between the different records at different times. What possibly changes are the environmental conditions that direct the cloud to one territory or another. Probably, in recent years, environmental conditions have allowed greater reproduction and, therefore, the population has increased year by year, although we are not yet studying it”, he estimates.

At the moment, the north of Santa Fe, Argentina, is still under assessment for damage caused by the insect. “The South American grasshopper is a polyphagous species, which can feed on a wide variety of plant species, including natural vegetation and agricultural crops”, he warns. The damage, according to the researcher, can be of considerable magnitude, but varies according to the stage of the pest in its biological cycle, depending on the time the insect remains in the crop or batch and the state of the pest.

Warmer winter is an ally of locusts. “Winters with temperatures above historical averages or with high temperatures are a condition for grasshopper populations to be more active and mobile, increasing their number of generations per year and, therefore, their population density.”

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Early identification of outbreaks and pest control will contribute to the effectiveness of pest management. “The opportune time to control this pest is in the nymph stage (juvenile, as it has not yet developed its wings). In this stadium it remains at ground level and moves in jumps, without moving in large areas. Chemical control, at this stage, would make it possible to reduce the population density of individuals, which can later fly in the form of clouds, avoiding damage to natural vegetation and agricultural crops. Products to control this species must be registered and authorized by the competent authority”, warns the researcher.

In Argentina, the South American locust is characterized as a national pest and is under official monitoring and surveillance. “There is a national program that defines strategies and guidelines for its management, which corresponds to the Argentine National Agro-Food Health and Quality Service (Senasa), called the National Acrididae Program. The obligation to report and carry out control tasks by producers, owners and tenants of agricultural establishments is established. Inta monitors the program’s actions and collaborates with the work in the territory”, he reports. 

The arrival of the outbreak in Brazil may be a matter of time. “It all depends on environmental conditions, specifically the direction of the winds. Currently, the locust cloud is in the province of Corrientes, which borders this region of Brazil. Likewise, it must be taken into account that Rio Grande do Sul is in the area of ​​possible displacement of this pest”, recalls the researcher. 

Learn more at: Cloud of locusts heading to Brazil