The Present State of the Locust and Grasshopper Problem in Brazil
L. L. BARRIENTOS1
1The author has traveled extensively as FAO (UN) locust consultant in Central America and Brazil (1989-1993).
Puerto de Bagdad No. 256 Fracc. Industrial, Cd. Victoria, Tam., MEXICO 87 010
ABSTRACT. For the past 10-15 years Brazil has undergone wide-ranging outbreaks of locusts and grasshoppers. Rhammatocerus schistocercoides (in the State of Mato Grosso/western central region, 1984-88/1991-92), Schistocerca pallens and Stiphra robusta (in Pernambuco, Paraíba, Piaui and Rio Grande do Norte/northeastern region, 1984-86/ 1991-92) ; Rhammatocerus conspersus, R. pictus and Staurorhectus longicornis (in Rio Grande do Sul/southern region, 1989-1992) are some of the species that have become major pests.
At present there are locust / grasshopper outbreaks in at least five Brazilian States, including Mato Grosso, Paraiba, Rio Grande do Norte and Pernambuco. Although climatic conditions play an important role in locust outbreaks, the major factors that have originated this problem in Brazil are related to changes in land management, deforestation, introduction of new crops and to some extent the lack of monitoring and vigilance once the outbreaks are suppressed.
As a result of the implementation of locust /grasshopper control campaigns in Mato Grosso (1984-1988) and Rio Grande do Sul (1991-92), it has become evident that the locust /grasshopper problem in Brazil needs a different approach.
To deal properly with the situation the Government needs to establish an integrated locust /grasshopper control program but little is known about alternative control methods and in some cases even the ecology of the species is poorly understood. Preliminary studies on biological control and ecology of several species involved are being carried out at present in Brazil in order to undertake a long term project to establish an integrated locust / grasshopper control program.
This paper outlines the present situation of the locust and grasshopper problem in Brazil. It provides up-to-date information on the most recent outbreaks and analyses those factors that may have caused an increase in locust / grasshopper populations in several states. The limitations and implications of current control campaigns are discussed and the need to establish an integrated control program is stressed.
[KEY WORDS : locust /grasshopper problem, Brazil, alternative control methods]
INTRODUCTION
Compared to other world regions, e.g., Africa and Central America, where locust have caused damage to agriculture since ancient times (Duranton et al, 1987, Barrientos et al. 1992), the locust / grasshopper problem in Brazil is relatively recent : In recorded history locust problems in Brazil were first reported from 1938 to 1946, when swarms of Schistocerca cancellata (Serville, 1838) migrated from Argentina and Paraguay, invading the states of Rio Grande do Sul, Santa Catarina and Parana (Duranton et al. 1987, Cosenza 1987). Subsequently, in 1969 severe infestations of Rhammatocerus pictus (Bruner, 1900) occurred in the State of Sao Paulo. From 1971 to 1974 Dichroplus bergii (Stål, 1878) and Staurorhectus longicornis Giglio-Tos, 1897 caused severe damage to agriculture in the state of Minas Gerais. More recently (1984-1988), serious outbreaks of Rhammatocerus schistocercoides (Rehn, 1906) and Schistocerca pallens (Thunberg, 1815) occurred in the states of Mato Grosso and Pernambuco, respectively (Cosenza 1987, Cosenza et al. 1990).
At present there are locust / grasshopper outbreaks in at least five states of the country, including Rio Grande do Sul, Mato Grosso, Paraíba, Rio Grande do Norte and Pernambuco (Fig. 1).
Although climatic conditions are known to play an important role in locust outbreaks, the main factors that have originated this problem in Brazil are related to changes in land management, deforestation, introduction of new crops and to some extent the lack of monitoring and vigilance once the outbreaks are suppressed. As a result of the implementation of the locust / grasshopper chemical control campaigns in Mato Grosso (1984-1988) and Rio Grande do Sul (1991-92), it has become evident that the locust / grasshopper problem in Brazil needs a different approach.
To deal properly with the situation, the Government needs to establish an integrated locust / grasshopper control program but little is known about alternative control methods and in some cases even the ecology of the species is poorly understood. Preliminary studies on biological control and ecology of several species involved are being carried out at present in Brazil. The aim is to undertake a long term project to establish an integrated locust / grasshopper control program.
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Fig. 1. Map of Brazil showing the states with locust / grasshopper problems and the species problem in each state. |
