Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in cotton: vertical distribution of egg masses, effects of adult density and plant age on oviposition behavior Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) em algodoeiro: distribuição vertical de posturas, efeitos da densidade de adultos e da idade das plantas sobre o comportamento de oviposição

The objective of this work was to determine the most suitable density of adults per plant, ideal plant age, and vertical distribution of eggs in different parts of the plant in a greenhouse investigation for future resistance studies and improvement of S. frugiperda management practices in cotton. The experiments of Spodotera frugiperda oviposition in relation to adult density, relationship between cotton plant age and Spodoptera frugiperda oviposition, Spodoptera frugiperda non-preference for oviposition on cotton varieties were conducted with plants of cotton variety BRS Ita 90. The experiments were conducted with plants of cotton variety BRS Ita 90. Non-preference (antixenosis) for oviposition was studied in FiberMax 966, FiberMax 977, DeltaOpal, DeltaPenta, Acala 90, Coodetec 408, Coodetec 409, Coodetec 410, BRS Cedro, BRS Ipe, BRS Aroeira, IPR 96, IPR 20, BRS Araca, IAC 24, and BRS Ita 90 varieties. We concluded that the fall armyworm S. frugiperda prefers to oviposit on plants with approximately 60 days of age, on the lower surface of leaves located in the upper third of the plant tests under greenhouse conditions. A density of at least three pairs of S. frugiperda adults per plant was sufficient to conduct non-preference-for-oviposition tests under greenhouse conditions. Coodetec 408, BRS Aroeira, BRS Araca, BRS Ita 90 and DeltaPenta varieties showed non-preference-for-oviposition resistance to S. frugiperda. In regions with high infestations of S. frugiperda, it would be prudent for the cultivation the use of BRS Ita 90 cotton variety.