General morphology and ultrastructure of the female reproductive apparatus of Trichomalopsis shirakii crawford (Hymenoptera, Pteromalidae)

Abstract

The morphology and ultrastructure of the female reproductive system were examined for a larval-pupal parasitoid Trichomalopsis shirakii Crawford of Oulema oryzae Kuwayama using light and electron microscopes. The reproductive system includes two ovaries, two pairs of accessory glands, an unbranched venom gland, a large venom reservoir and a Dufour gland. Each ovariole contains follicles and oocytes at different stages of maturation. A fibrous layer covers the surface of mature egg. The accessory glands are made up of a layer of secretory cells surrounded by muscle fibers. In these secretory cells, numerous mitochondria, electron-dense secretory granules and vesicles filled with dense granular particles are present. These granular particles appear as virus-like particles (VLPs). The venom gland consists of a single layer of secretory cells which are organelle rich with abundant rough endoplasmic reticulum, mitochondria and vesicular organelles, a layer of duct cells and an inner intima. The reservoir consists of a muscular sheath, epidermal cells with few organelles and an intima layer. The Dufour gland has a relatively large lumen surrounded by a single layer of columnar epithelial cells which are characterized by clusters of smooth endoplasmic reticulum and lipid droplets. Aside from the venom, the fibrous layer coating the egg and the granular particles which may be VLPs have been discovered in our study. They may serve as one of the parasitoid-associated factors in their host-parasitoid relationship and play a role in host immune suppression. Microsc. Res. Tech. 79:625-636, 2016. © 2016 Wiley Periodicals, Inc.

Ontogenetic morphological changes of the venom apparatus in 4 eupelmid egg parasitoids

“…Their structure is similar to those of 2 species of Pteromalidae, the larval–pupal parasitoid Trichomalopsis shirakii and the pupal parasitoid Pteromalus puparum , with all having unbranched venom glands. In addition, all lack primary, secondary and tertiary venom ducts and the venom glands connect directly to the venom reservoir, which in turn connects directly to the ovipositor (Zhu et al ., 2008; Mao et al ., 2016). However, the venom reservoir of the eupelmid species does not have a distinct constriction at its centre (Fig.…”

“…However, there is variation in the configuration of the ducts connecting to the reservoir and the relative positioning vs the venom gland. In certain species, such as the 4 studied herein and in T. shirakii and A. difficilis , the venom gland attaches directly to the reservoir (Quicke et al ., 1997; Mao et al ., 2016), whereas, in some taxa both the venom reservoir and the gland converge via respective ducts, ultimately joining a primary duct linked to the ovipositor (Quicke et al ., 1997). There are also visible differences in the morphology of the venom reservoir among various parasitoid wasps.…”

“…Venom systems are commonly found throughout Hymenoptera, and their general structure has been thoroughly investigated in various ichneumonid and braconid wasps (Edson and Vinson, 1979; Edson et al ., 1982; Quicke et al ., 1992, 1997; Zaldivar-Riverón et al ., 2004). The structural characteristics of the venom apparatus have also been extensively investigated across other Hymenopteran families, including social bees (Bridges and Owen, 1984; Roat et al ., 2006), wasps (Schoeters and Billen, 1995 a ; Gnatzy and Volknandt, 2000), ants (Billen, 1990; Schoeters and Billen, 1995 b ; Billen and Al-Khalifa, 2018) and parasitic wasps (Edson et al ., 1982; Blass and Ruthmann, 1989; Wan et al ., 2006; Mao et al ., 2016) (Table 1).…”

“…This process frequently provides vital ecosystem services by regulating host populations and contributing to the preservation of ecological equilibrium (Bragança et al ., 1998). Research has been conducted on the venom apparatus of both larval and larval–pupal parasitoids (Zhu et al ., 2008; Mao et al ., 2016). However, there are limited studies on the composition of venom in egg parasitoids, and no other factors associated with these egg parasitoids have been identified (Zhao et al ., 2023).…”

Morphology of the Ovary and Spermatheca of the Leafcutter Ant Acromyrmex rugosus Queens (Hymenoptera: Formicidae)

“…In ants, the ovaries are classified as meroistic polytrophic in which the nurse cells accompany the oocytes, forming the ovarian follicles. These follicles consist of an oocytic chamber and a nurse chamber, surrounded by a layer of follicular cells (Antunes et al 2002;Cruz-Landim 2009;Mao et al 2016).…”