Résumé
The early detection of the arrival of pests on a crop is a decision tool for the spraying of pesticides. Observation of pest dynanics and especially adult Lepidoptera is becoming essential with the use of direct sowing systems using plant cover crops and the development of crops sown out of season ('safrinha'). At Fazenda Motrão, the use of sexual pheromones of different Lepidoptera species such as the member of the Gelechiidae family Pectinophora gossypiella (distributors: Biocontrole and Isca Tecnologias) and the noctuids Spodoptera fiugipeda and other species of the genus (S. exigua, S. latifascia, S. albula (= sunia), from Biocontrole) was started in the 2003/2004 cropping season. S. fiugrperda, S. eridania and S. coanioides were found in the traps. The average number of adults of the first, dominant, species varied from 0 to 25 per trap per week, with the highest value recorded at the beginning of July. Three other species of the same genus, S. descoinsí, S. ddíchos and S. albula, were detected for the fist time and identified by study of their genitalia. Annual curves of the population dynamics of adult P. gossypiella tapped m 2004 did not reveal any differences between the two pheromone sources. Two population peaks were recorded in mid-July and the end of August 2004, with 124.8 and 133.5 adults per trap per week respectively. (Résumé d'auteur)