Injection of seminal fluid into the hemocoel of honey bee queens (Apis mellifera) can stimulate post-mating changes

Abstract

Honey bee queens undergo dramatic behavioral (e.g., reduced sexual receptivity), physiological (e.g., ovary activation, ovulation, and modulation of pheromone production) and transcriptional changes after they complete mating. To elucidate how queen post-mating changes are influenced by seminal fluid, the non-spermatozoa-containing component of semen, we injected queens with semen or seminal fluid alone. We assessed queen sexual receptivity (as measured by likelihood to take mating flights), ovary activation, worker retinue response (which is influenced by queen pheromone production), and transcriptional changes in queen abdominal fat body and brain tissues. Injection with either seminal fluid or semen resulted in decreased sexual receptivity, increased attractiveness of queens to workers, and altered expression of several genes that are also regulated by natural mating in queens. The post-mating and transcriptional changes of queens receiving seminal fluid were not significantly different from queens injected with semen, suggesting that components in seminal fluid, such as seminal fluid proteins, are largely responsible for stimulating post-mating changes in queens. Managed honey bee (Apis mellifera) colonies provide an estimated $175 billion in pollination services for a large variety of crops worldwide with an estimated $14.6 billion value in the United States alone 1-3. While the number of honey bee colonies has increased between 1961 and 2007 4 , the U.S. and some regions of Europe have exhibited high annual colony losses, with the U.S. experiencing an average annual loss of 33% recorded since 2006 5-13. Premature queen loss is one of the top causes of colony loss reported by beekeepers both in the U.S. and in Europe 6,7,13. Therefore, improving colony health and survivorship in large part will depend on understanding factors affecting queen health and productivity as well as investigating the role of drones (haploid male bees) on queen health. A honey bee colony consists of a single egg-laying queen, hundreds to thousands of seasonal drones, and tens of thousands of sterile female workers 14. Approximately 1 week after emergence as an adult, the queen will take one or more mating flights to large congregations of males called drone congregation areas (DCAs) 14,15. Honey bee queens are polyandrous, which means they mate with multiple drones; queens have recently been reported to mate as many as 34-77 drones 16. During copulation, drone semen is transferred to the queen's oviduct where only 3-5% of each drone's spermatozoa are stored in a specialized organ called the spermatheca 14,15,17,18. The process of mating initiates dramatic behavioral, physiological, and molecular changes in queens 19-24. Behaviorally, mated queens become sexually unreceptive, as evidenced by the cessation of mating flights and their reduced attraction to light 14,25. The ovaries of newly-mated queens begin activating and their ovarioles thicken and start to produce eggs, upon which the queens initiate egg-laying and continue to do so...

Seminal fluid proteins induce transcriptome changes in the Aedes aegypti female lower reproductive tract

“…LRTs from MAG extract-injected and mated females had lower transcript levels of AAEL008342, which encodes a monocarboxylate transporter. Monocarboxylate transporters were also down-regulated in female honeybees injected with seminal fluid when compared to buffer-injected [ 105 ]. Down-regulation of oxidoreductase (AAEL09685) and up-regulation of AAEL012382, which contains a predicted C-terminal nucleosidase domain, and of AAEL014719, an inosine-uridine preferring nucleoside hydrolase, were also detected.…”

Nutrient Utilization during Male Maturation and Protein Digestion in the Oriental Hornet

“…Of all the processes occurring during male maturation, the development of the reproductive system undoubtedly has the greatest impact on male reproductive success; it generally includes the production of seminal fluids and mucus matter by the seminal vesicles and accessory glands and the migration of spermatozoa from the testes to the seminal vesicles [ 45 , 46 , 47 ]. The seminal fluids contain proteins, sugars, and phospholipids, and the accessory secretions are composed of cyclic peptides and fatty acids that create a viscous texture that will serve as mating plugs; these gland products are transferred to the female during copulation, where they protect the sperm and maintain its viability, but also induce physiological and behavioral changes in the female’s body that increase the chances of successful insemination by the male [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. In honeybees, studies have demonstrated that larval nutrition plays a central role in determining male reproductive quality, while protein intake during adulthood has no effect on sperm quality [ 6 , 58 , 59 , 60 ].…”

Factors Influencing the Reproductive Ability of Male Bees: Current Knowledge and Further Directions

“…The semen of A. mellifera is so effective at keeping sperm alive that the positive effects can last up to 24 h. The presence of proteins in semen and their structural integrity are critical to this effect, which cannot be replicated by ordinary protein substitutes [116]. Moreover, semen fluids are largely responsible for stimulating postmating changes in queen behavior and physiology, e.g., reduced sexual receptivity, reduced attraction to light, reduced mating flight, ovary activation, ovulation, modulation of pheromone production and transcriptional changes in queens [117,118]. Honeybee drone seminal fluid could induce a decline in queen vision by causing substantial gene expression changes in the brain and perturbing the phototransduction pathway to reduce queen promiscuity across mating flights [18].…”