Dissection and Internal Anatomy of the Giant Tropical Bont Tick Amblyomma Variegatum

Abstract

Ticks are parasites arthropods that feed on the blood of animals and humans, serving as vectors responsible for numerous diseases worldwide. The tropical bont tick, Amblyomma variegatum, is a primary vector of Ehrlichia ruminantium, the causative agent of heartwater disease, endemic in sub-Saharan Africa and several Caribbean islands. Due to their economic and public health impacts, A. variegatum and heartwater have been classified  as high-consequence foreign animal diseases and pests by the United States Department of Agriculture’s Animal and Plant Health Inspection Service. Understanding the ecology and biology of A. variegatum is thus crucial to developing effective control methods to limit its geographic spread.  A key initial step in this endeavor involves the precise isolation and detailed functional characterization of tick organs to better understand vector competence. However, complete anatomical descriptions of internal structures within the Amblyomma genus remain scarce. In this study, we present a thorough characterization of the internal anatomy of unfed nymphs, partially engorged males, and unfed and partially engorged females of the tick species A. variegatum. By accurately identifying and mapping organs of interest, we highlight notable morphological differences from other tick species.This foundational work not only enhances our understanding of A. variegatum anatomy but also serves as a crucial resource for investigating tick-borne disease transmission. Ultimately, these findings support the development of targeted vector control strategies, applicable to both endemic and non-endemic regions.

Keywords: Amblyomma variegatum, heartwater, dissection, tick organs, anatomy, hard-bodied ticks