Butler followed Clay's Ark with the critically acclaimed short story "Bloodchild" (1984). Set on an alien planet, it depicts the complex relationship between human refugees and the insect-like aliens who keep them in a preserve to protect them, but also to use them as hosts for breeding their young. Sometimes called Butler's "pregnant man story," "Bloodchild" won the Nebula, Hugo, and Locus Awards, and the Science Fiction Chronicle Reader Award.  Three years later, Butler published Dawn, the first installment of what would become known as the Xenogenesis trilogy. The series examines the theme of alienation by creating situations in which humans are forced to coexist with other species to survive and extends Butler's recurring exploration of genetically-altered, hybrid individuals and communities. In Dawn, protagonist Lilith Iyapo finds herself in a spaceship after surviving a nuclear apocalypse that destroys Earth. Saved by the Oankali aliens, the human survivors must combine their DNA with an ooloi, the Oankali's third sex, in order to create a new race that eliminates a self-destructive flaw in humans--their aggressive hierarchical tendencies. Butler followed Dawn with "The Evening and the Morning and the Night" (1987), a story about how certain female sufferers of "Duryea-Gode Disease," a genetic disorder which causes dissociative states, obsessive self-mutilation, and violent psychosis, are able to control others afflicted with the disease.  Adulthood Rites (1988) and Imago (1989) the second and the third books in the Xenogenesis trilogy, focus on the predatory and prideful tendencies that affect human evolution, as humans now revolt against Lilith's Oankali-engineered progeny. Set thirty years after humanity's return to Earth, Adulthood Rites centers on the kidnapping of Lilith's part-human, part alien child, Akin, by a human-only group who are against the Oankali. Akin learns about both aspects of his identity through his life with the humans as well as the Akjai. The Oankali-only group becomes their mediator, and ultimately creates a human-only colony in Mars. In Imago, the Oankali create a third species more powerful than themselves: the shape-shifting healer Jodahs, a human-Oankali ooloi who must find suitable human male and female mates to survive its metamorphosis and finds them in the most unexpected of places, in a village of renegade humans.

Answer this question "When was the trilogy published?" by extracting the answer from the text above.
1989