Influence oí the climatic factors on the development and establishment of the locust Rhammatocerus schístocercoídes (Orthoptera:Acrididae) in the Colombian orinoquia

Abstract

During the first term of 1994 the Colombian Orinoquia suffered an unexpected locust invasion which devouring a lot of natural grasses and some crops from a large area of the region. The origin of this insect expansion was attributed to several causes like the Brazilian origin where the plague has been reported before. The International Institute of Biological Control of England identified the insect in 1995 as Rhammatocerus schisto­cercoides (Rehn 1906) (Acrididae: Gompho­cerinae). Comparing climatological conditions of two representative locations in Colombia and Brazil, and evaluating the wind in the inferior trophosfera to a 500 Mb level it was determined that the insect did not care from  Brazil to Colombia. Also, it was determined that the specie is milive (ruin Colombian Orinoquia. and migrated from the northeast to the case plains, with (he prevailing winds which has an average wind velocity oí' 3 m/s_ Each development stage of the insect was climatologically characterized for the climatic conditions oí the Colombino east plains, in were The, locust have one generation per yen. The study indicated that the Colombian east plates show good conditions for the locust copulation and laying eggs. However, it does not have the best climatic conditions for the establishment of locust R. schistocercoides in the region, due to the rain season effects over the first three nymph periods of the insect limiting its normal development. At the end of 1996, the population of the pest was very low, because of the high precipitation rained during the first nymphal stage in April. It is possible to postulate that the future populations of insects will be seriously diminished in the eastern plains, especially near to the mountains where climatic conditions are adverse to the pest cine to the precipitation are higher than 4000 mm per year.