Mating Stimulates the Immune Response and Sperm Storage-Related Genes Expression in Spermathecae of Bumblebee (Bombus terrestris) Queen

Bumblebee queens have remarkable spermathecae that store sperm for year-round reproduction. The spermathecal gland is regarded as a secretory organ that could benefit sperm storage. Queen mating provokes substantial physiological, behavioral, and gene expression changes. Here, the transcriptomes of spermathecae were compared between virgins and mated queens of the bumblebee, Bombus terrestris L., at 24 h post mating. Differentially expressed genes were further validated by real time quantitative PCR and immunofluorescence assay. In total, the expression of 11, 069 and 10, 862 genes were identified in virgins and mated queens, respectively. We identified that 176 differentially expressed genes between virgin and mated queen spermathecae: 110 (62.5%) genes were upregulated, and 66 (37.5%) genes were downregulated in mated queens. Most of the differentially expressed genes validated by RT-qPCR were concentrated on immune response [i.e., leucine-rich repeat-containing protein 70 (35.8-fold), phenoloxidase 2 (41.9-fold), and defensin (4.9-fold)] and sperm storage [i.e., chymotrypsin inhibitor (6.2-fold), trehalose transporter Tret1 (1.7-, 1.9-, 2.4-, and 2.4-fold), and heterogeneous nuclear ribonucleoprotein A3 (1.2-, and 2.6-fold)] functions in the spermathecae of mated queens. Procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) was hypothesized to promote the mating behavior according to RT-qPCR and immunofluorescence assay. The expression levels of most upregulated immune genes were decreased significantly at 3 days post mating. In conclusion, the external sperm transfer into spermathecae led to the significantly upregulated immune response genes in bumblebees. These gene expression differences in queen spermathecae contribute to understanding the bumblebee post mating regulatory network.

Destination of apyrene sperm following migration from the bursa copulatrix in the monandrous swallowtail butterfly Byasa alcinous

Most male lepidopterans produce fertile eupyrene sperm and non-fertile apyrene sperm, both of which are transferred to the female in a spermatophore during mating. Apyrene sperm outnumbers eupyrene sperm and both sperm types migrate from the bursa copulatrix to the spermatheca after mating. While eupyrene sperm are maintained in the spermatheca until oviposition, the number of apyrene sperm decreases with time. It is unclear whether apyrene sperm disappear from all sperm storage organs in females because both sperm types are often observed in the spermathecal gland. To investigate this, the numbers of both sperm types were estimated in the spermatheca and spermathecal gland of female Byasa alcinous (a monandrous butterfly) 6, 12, 48, 96, and 192 h after mating terminated. Apyrene sperm arrived in the spermatheca earlier than eupyrene sperm; however, some eupyrene and apyrene sperm migrated to the spermathecal gland from the spermatheca at almost the same time. The number of apyrene sperm reached a peak 12 h after the termination of mating and then decreased with time in both the spermatheca and spermathecal gland. Our results suggest that the role of apyrene sperm might be completed early after arriving in the spermatheca of B. alcinous.

Testing the diagnostic value of the dorsal sac and other structures of the roof of the female genital chamber within the plant bugs genus Psallus Fieber (Hemiptera, Heteroptera, Miridae, Phylinae)

The roof (dorsal wall) of the female genital chamber (bursa copulatrix) was compared in 31 species representing six subgenera of the taxonomically difficult genus Psallus Fieber, 1858. This investigation tested the potential value of different elements of the dorsal wall (dorsal sac, sclerotized rings, spermathecal gland, lateral oviducts, and infolding of the lateral margins), anticipating diagnostic characters and phylogenetic information for a genus in need of revision. The dorsal sac, a very variable membranous pouch differentiated from the vaginal wall, appears highly informative in providing reliable diagnostic characters at species level; to some extent it may also reveal related species. At subgenus or genus level, the dorsal sac must be examined with other equally informative structures of the roof. In some cases, strong evidence is provided by these structures aiding the recognition of related and unrelated species. The subgenus Pityopsallus Wagner forms a homogenous species-group which does not seems closely related to Psallus s.l. and should be raised to generic status as already proposed by several authors. The subgenus Hylopsallus Wagner appears to gather several species united by at least one synapomorphy after removing unrelated species such as P. (Hylopsallus) callunae Reuter. Also, it is clear that Psallus pardalis Seidenstücker and Psallus jungaricus Vinokurov & Luo should be excluded from Psallus. One or several characters in the roof of some phyline species (Atractotomus Fieber, Campylomma Reuter, Europiella Reuter, Phoenicocoris Reuter, Plagiognathus Fieber, Phylus Hahn, Sthenarus Fieber) appear to be distinct from those of Psallus species.

Comparative morphology of spermathecae in solitary and primitively eusocial bees (Hymenoptera; Apoidea)

Spermathecae of solitary and primitively eusocial bees from five major families were compared according to their chamber size, epithelial cell height (wall thickness), number and shape of glands, number of sperm pumps, and diameter of the duct, using whole mounts and serial sections. A thick spermathecal wall with a small chamber in our exemplar colletid, megachilid, and andrenid bees, a large chamber with a thick wall in social Apidae, and a thin wall with a large chamber in social halictids indicate that a big chamber may be associated with increased colony size. A thin epithelium in the receptacle of halictid bees suggests relegation of spermathecal secretion to the spermathecal gland. A relatively thick spermathecal wall in the Apinae indicates the potential importance of both the epithelial cell layer of the receptacle and the enlarged spermathecal gland in maintaining large numbers of stored sperm. There was one sperm pump in all taxa surveyed except the representative Halictidae, in which this structure was paired. Elongated spermathecal glands may typify the spermathecae of eusocial bees.