Anastrepha suspensa (Loew) is an economically important pest, restricted to the Greater Antilles and southern Florida. It infests a wide variety of hosts and is of quarantine importance in citrus, a multi-million dollar industry in Florida. The observed recent increase in citrus infested with A. suspensa in Florida has raised questions regarding host-specificity of certain populations and genetic diversity of the pest throughout its geographical distribution. Cytochrome oxidase I (COI) DNA sequence data was used to characterize the genetic diversity of A. suspensa from Florida and Caribbean populations reared from different host plants. Maximum likelihood and Bayesian phylogenetic methods were used to analyse COI data. Sequence variation among mitochondrial COI genes from 107 A. suspensa samples collected throughout Florida and the Caribbean ranged between 0 and 10% and placed all A. suspensa as a monophyletic group that united all A. suspensa in a clade sister to a Central American group of the A. fraterculus paraphyletic species complex. The most likely tree of the COI locus indicated that COI sequence variation was too low to provide resolution at the subspecies level, therefore monophyletic groups based on host-plant use, geography (Florida, Jamaica, Cayman Islands, Puerto Rico or Dominican Republic) or population sampled are not supported. This result indicates that either no population segregation has occurred based on these biological or geographical distinctions and that this is a generalist, polyphagous invasive genotype. Alternatively, if populations are distinct, the segregation event was more recent than can be distinguished based on COI sequence variation.

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.