''Sphaerularia bombi'' is an

entomopathogenic nematode Entomopathogenic nematodes (EPN) are a group of nematodes (thread worms), that cause death to insects. The term ''entomopathogenic'' has a Greek origin, with ''entomon'', meaning ''insect'', and ''pathogenic'', which means ''causing disease''. Th ...

. It is parasite of

bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related gene ...

s. It infects and sterilizes

gyne The gyne (, from Greek γυνή, "woman") is the primary reproductive female caste of social insects (especially ants, wasps, and bees of order Hymenoptera, as well as termites). Gynes are those destined to become queens, whereas female workers ...

s or potential queens of bumblebees.

Life Cycle

''Sphaerularia bombi'' is a nematode that infects hibernating bumblebees. Bumblebees start seeking out a hibernation site for the winter season during fall and autumn. ''S. bombi'' would cause the infected bee multiple fail attempts to burrow into the ground, and with each fail attempt hundreds of 3rd stage larvae would be discharged from the bee's anal opening. The larvae would eventually develop into the 4th larvae stage, this is the period where the infected bee dies. When a healthy bee finds its hibernation site, the 3rd stage larvae would infect the bee by penetrating it. The bee emerges to the surface during the spring season, and by that time the nematodes has developed into a mature female producing eggs within the bumblebee; 1st larvae stage. The eggs then hatches and molts into the 2nd larvae stage, which then rapidly molts into the 3rd larvae; the 3rd larvae stage is the infective stage for ''S. bombi''. These 3rd stage larvae would be in the bee's hemocoel, midgut, and hindgut.

Morphology

Once in the host, the uterus and other related reproductive counterparts of the female ''S. bombi'' turn inside out, allowing for the uterine cells to stretch out and expand into a sac. The sac, also known as a prolapsed uterus, is composed of an ovary, oviduct, and sperm, and is found all over the body of the parasite. These “bumps” on the parasite's body bulge into bigger sacs to create a larger surface area for absorbing nutrients from the host via

pinocytosis In cellular biology, pinocytosis, otherwise known as fluid endocytosis and bulk-phase pinocytosis, is a mode of endocytosis in which small molecules dissolved in extracellular fluid are brought into the cell through an invagination of the cel ...

. Once absorbed, the nutrients are digested and delivered through the ovary-oviduct to the eggs. Developing eggs from the uterine sac develop into third-stage juveniles once they disperse into the host's hemocoel. Although the eggs develop, there is no apparent growth of the parasite that initially produced the eggs. At this stage, the nematode is nothing but an enormous uterus filled with eggs, with a tiny appendix containing the remaining organs.

Distribution

Canada, France, Germany, Netherlands, New Zealand, Norway, Sweden, USA, Argentina

Life Cycle

Morphology

Distribution

References

Further reading