Late third stage (7-day-old) larvae and 1-day-old pupae of Anastrepha suspensa Loew (Diptera: Tephritidae) were dipped for 5 min in suspensions of 25% WP Dimilin® (diflubenzuron) at six dosages ranging from 0.003–0.1% a.i. Diflubenzuron caused significant (P < 0.05) mortality during the pupal stages of both groups treated. Consequently, the resulting adult populations were drastically reduced. The incidence of crumpled wings, deformed abdomens and ovipositors in these adults was 2–7 times and 4–9 times higher than the respective controls of treated larvae and pupae. The morphological abnormalities altered mating competitiveness of males and successful copulation and oviposition by females. Fecundity of females was reduced and diflubenzuron effects persisted into the first generation and caused decreased egg viability.

Adults fed a 0.1% a.i. diflubenzuron-treated diet for 27 days had no significant mortality, but had decreased fecundity. However, their pattern of oviposition did not differ from the control. Fecundity levels similar to the control's were achieved 6 days after the treated diet was replaced by normal diet. Diflubenzuron treatment of adults also drastically decreased the survivorship of first-generation individuals between egg-hatch and pupation. However, almost all individuals that pupated emerged as adults. No abnormalities were observed in first-generation adults or in the survivorship of their offspring.