Seasonality and Distribution of Immature Amblyomma maculatum(Acari: Ixodidae) in Mississippi: A Review and New Records

The Gulf Coast tick (Amblyomma maculatum Koch), a known vector of medical and veterinary concern, is well established in Mississippi.  Although seasonality and distribution patterns of this species of adults have been documented, those of immatures (larvae and nymphs) have not.  In this study, a review of literature was combined with new and unpublished data to identify trends in immature A. maculatum activity.  Compiled data from dates ranging from 1920-2014, consisted of 2,368 total specimens of A. maculatum collected in Mississippi.  Of those, 2,295 (96.92%) were adults: only 27 (1.14%) were nymphs and 46 (1.94%) were larvae.  Only 4 larval collections were recorded (one each in June and November and two in October).  Seventeen nymphal collections were recorded with peaks in March and August, roughly corresponding to bi-modal distribution observed in larval records.  Bi-modal distribution suggests the possibility that there may be two batches of A. maculatum per year, or that immatures go through a stage of inactivity during periods of both winter and summer months.  As expected, nymphs were collected in southern portions of Mississippi earliest, but unexpectedly, adults were collected earlier further north.  Surprisingly, it was noted that larvae were collected progressively later in the year further south.