Chromosomes, Reproductive Biology, and Developmental Stages of Aponomma varanensis (Acari: Ixodidae)

The tick Aponomma varanensis attached to a king cobra (Ophiophagus hannah) was accidentally imported into the United States and was discovered at the Bronx Zoo. Two generations of tick progeny were reared and investigated under laboratory conditions. A. varanensis males possess 21 chromosomes (20 autosomes and 1 sex chromosome). The processes of spermatogenesis and spermiogenesis are similar to those found in other ticks. However, the males are unusual in that timing of meiosis and spermatid production are not as synchronized among individuals as in other metastriate ticks, and they produce elongated spermatids without having a blood meal. Although elongated spermatids were present in unfed males, they were not transferred to females off the host under our experimental conditions. All stages of A. varanensis fed successfully on rat snakes (Elaphe obsoleta). Larvae also fed on eastern box turtles (Terrapene Carolina), but not southern toads (Bufo terrestris), five-lined skinks (Eumeces fasciatus), or laboratory mice (Mus musculus). Most of the A. varanensis behaved similarly to a typical three-host tick and dropped from the host after each feeding, but approximately 3% of fed larvae remained attached and ecdysed on the host, and the resulting nymphs immediately began feeding. Unfed larvae were exceptionally long-lived (more than 22 mo).