Insights into abdominal structures atozoal ultrastructure of coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae)

Abstract

Importance of the work: The coffee berry borer, Hypothenemus hampei is an insect pest
of coffee worldwide; however, its abdominal ultrastructure remains undescribed, despite
its importance for informing targeted strategies to reduce its population and economic impact.
Objectives: To describe, using light and transmission electron microscopy (TEM), the
structure of the abdominal region of H. hampei with a focus on the ultrastructure of the
spermatozoa.
Materials and Methods: A sample of 20 mature male H. hampei, each with a total length
of 0.5–1.2 mm, was collected and processed using TEM.
Results: The epithelial ultrastructure of the midgut comprised enterocytes and
regenerative cells. Numerous mitochondria and lysosomes were observed together with
well-developed rough endoplasmic reticulum in the enterocytes. Abundant lipid droplets
and glycogen molecules were scattered in the cytoplasm of lipid cells, which were mostly
found close to the integument. Testicular maturation was associated with the appearance
of spermatids and spermatozoa. The elongated spermatozoon was composed of a head
that had two main layers (an acrosomal layer and a central nucleus), a midpiece of
elongated and twisted mitochondria and a tail with a typical 9 + 9 + 2 flagellar axoneme.
Main finding: The presence of uniflagellate and biflagellate forms not only sheds light on
insect evolution and phylogeny but also raises questions about their functional role in the
reproductive success of H. hampei.