The evolution of the populations dynamics of cereals sunn pests, during autumn, at the wintering places (forests), in Brăila county, during 2007, 2008 and 2009

Abstract

One of the most dangerous pests for wheat crop, in our country, is cereals sunn pest - Eurygaster sp. Eurygaster genus comprises many species (Filipescu C et col., 1993). For our country, the following species present economic importance: E. integriceps, E. maura and E. austriaca (Tâlmaciu M. 2005). The species mentioned present many similarities in what concerns the anatomy, being quite difficult to differentiate them from aspectual point of view. Their biology and ecology is very similar. All these three mentioned species of Eurygaster migrate into forests, from the areas that had been cultivated with wheat, during August (Perju T., 1995). Here they spend their hibernating rest after which, during spring, they migrate again into the straw cereals crops, especially into wheat crops. After migration and after a period of feeding, the copulation takes place and then eggs spawn (Boguleanu Gh. et col. 1980). The incubation lasts between 7 – 14 days, and then the larvae appear. The larva state lasts for approximately one month, after which the new adults appear. After a period of feeding with wheat beans, they start migrating to the forests, during August (Manolache C., Boguleanu Gh., 1967). After 15th of September, entire population of sunn pests retires into the forests for wintering until the spring of the next year. Due to the fact that the damages produced by this pest can significantly affect the production and quality of the wheat, cereals’ sunn pest is considered a pest of highly importance for agriculture. To this extent, surveys are performed in each forest from the county, during autumn (15th of September – 15th of October) and spring (15th of March – 5th of April), in order to determine the reserve of hibernating adults. In Brăila County, these surveys are performed in 11 forests that sum up an area of 3633 ha. They are situated on different types of soil and they have a different floristic composition. Following to the surveys performed, there had been found significant differences in what concerns the number of hibernating adults. The surveys’ results present special importance for the farmers that cultivate straw cereals. The surveys that had been performed for several years had shown that the cereals sunn pest population had suffered high numerical fluctuations.