Ultrastructural observation of the ovipositor and its sensilla of Tirathaba rufivena Walker

Tirathaba rufivena Walker is an important pest of palm plants, such as coconut, areca palm, and oil palm. The ovipositor and its sensilla in female adults may play crucial roles in locating suitable oviposition sites.

In this study, we used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to observe and analyze the morphological structure of the ovipositor and the sensilla on it.

The ovipositor of T. rufivena was found to be a telescopic tubular structure formed by the specialization of the 8^th to 10^th abdominal segments. Four types of sensilla chaetica on the ovipositor were identified. Sensilla chaetica I and II were long, slender, hair-like structures that were straight and sturdy, located on the anal papillae and the 8^th abdominal segment, respectively, and were relatively long. Sensilla chaetica III was shorter than I and II, but its length varies significantly, with visible dendritic structures inside. Sensilla chaetica IV was sturdy with blunt, porous tips, mainly distributed on the outer edge of the anal papillae's dorsal surface. Additionally, numerous microtrichia were widely distributed on the ovipositor.

This study contributes to the further understanding of the oviposition behavior mechanism of T. rufivena and provides a scientific basis for developing green control methods such as plant-derived attractants and oviposition deterrents.