Reproductive isolation mechanisms between members of the Spodoptera latifascia - S-cosmioides - S-descoinsi (Lepidoptera : Noctuidae) neotropical species complex.

Spodoptera latifascia Walker, S. cosmioides Walker and S. descoinsi Lalanne -Cassou & Silvain are members of a neotropical species complex. S. latifasc ia is found in Central America, Southern USA and West Indies, S. cosmioides in tropical South America and S. descoinsi in the Amazon basin where it is parapatric with S. cosmioides. In addition to differences in the habitus a nd some genitalic traits, the three species show a temporal shift in their female sexual activity. They also differ by the ratio of two main compounds in their pheromone glands. Under laboratory conditions, hybrids can be obt ained but the mating rates depend on the crosses. We discuss here the role of the female calling periods and pheromone differences as factors of repro ductive isolation among the species.