Colony failure linked to low sperm viability in honey bee (Apis mellifera) queens and an exploration of potential causative factors. Predictive markers of honey bee colony collapse. A survey on some factors potentially affecting losses of managed honey bee colonies in Luxembourg over the winters 012. Evaluation of colony losses in Israel in relation to the incidence of pathogens and pests. Global pollinator declines: Trends, impacts and drivers. Approximately 10% of each male’s ejaculate is transferred to the queen’s oviducts where the semen of the different drones is mixed. After ejaculation, the endophallus is broken off inside the queen, acting as a temporary vaginal plug that may prevent sperm leakage, and the drone dies shortly afterwards. During mating, 6–12 million spermatozoa are transferred from the seminal vesicles of the drone into the genital orifice of the queen through the drone’s irreversibly everted endophallus. Earliest studies suggested that the queens copulate with 12–14 drones on average, usually in one or two mating flights, but a recent study suggested that the degree of polyandry might be much higher, so that queens can mate up to 34–77 males. Normally, the queen mates consecutively with several drones in rapid sequence during the mating (nuptial) flight. When a queen approaches a male congregation area, the drones chase her trying to copulate, forming a comet-like swarm in her wake. In the afternoon of days with good weather, drones fly from the colonies to the male congregation areas, with a diameter of around 30–200 m, where thousands of drones from hundreds of colonies may await the arrival of a few virgin queens. Drones mate with the queen during the mating flight at the age of 15–23 days, 21 days on average. Mating is the most significant function of an adult drone, although most of them fail in this task. The two accessory bodies are elongated structures located between the axoneme and each mitochondrial derivative. The mitochondrial derivatives are asymmetrical in length and diameter and lie parallel to the axoneme throughout the sperm flagellum. The sperm flagellum is formed by an axoneme of 9+9+2 microtubular pattern, two large mitochondrial derivatives and two accessory bodies. The nucleus is dense and elongated, with a compact chromatin. The acrosomal complex is formed by a conical and two-layered acrosomal vesicle that covers the perforatorium up to the anterior nuclear end, where the perforatorium is inserted into a deep fossa. The sperm head contains two consecutive parts of equal size: the acrosomal complex followed by a linear nucleus. With a length of 250–270 µm and a width of 0.7 µm, the sperm consists of a relatively small and narrow head region (10 µm long and 0.4–0.5 µm in width ), the transitional centriole adjunct and the flagellum. Honey bee sperm are long and filamentous cells with tapered ends ( Figure 1). To date, it has been applied to study the effects of age, body size, genetics, temperature, nutrition, management, seasonal variations, disease, insecticides, miticides, semen storage in liquid and frozen states, semen handling, sperm competition and physiology. The study of drone sperm quality is also of considerable research interest. Poor semen quality generates poorer quality queens, this being considered one of the main causes of colony loss. It may determine the reproductive success of the queen and, as a consequence, the colony’s survival and level of productivity, as well as the success of artificial insemination (AI, also called instrumental insemination in this species). Since the queen will store viable sperm after insemination for several years, the study of semen quality in this species is especially relevant. A limiting factor of successful reproduction may be sperm quality.
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