The Present State of the Locust and Grasshopper Problem in Brazil

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, Paraiba, 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 [