Coelopa frigida is a species of seaweed fly or kelp fly. It is the most widely distributed species of seaweed fly. It can be found on most shorelines in the temperate Northern Hemisphere. Other species of seaweed flies include Coelopa pilipes.
The fly has a grayish black body and yellow-brown legs.
The fly oviposits in dead kelp that washes up on beaches. This is the only place it lays eggs, and it can do so on many species of kelp and seaweed, including species of Laminaria and Fucus. A female fly lays up to five clutches of 80 eggs each. The larvae feed upon the bacteria coating the dead kelp. The life cycle is about 11 or 12 days long.
"Blooms" of the flies occur at times, possibly when temperatures and amounts of kelp increase.
This fly is sometimes cultured in the laboratory. Its behavior is studied in an effort to understand sexual selection, especially the topic of female choice. Studies suggest that female flies of this species prefer larger males to smaller. The species engages in sexual conflict. Females perform rejection behaviors when mounted by males, and may mate with larger males because larger males are better able to force the mating. As females are more likely to successfully reject smaller males, sexual selection favors larger ones. Mating behaviors are genetically influenced, as evidenced by a preference for smaller males among females of a certain genotype.
This fly is host to the mite Thinoseius fucicola. It provides food for seabirds such as the purple sandpiper (Calidris maritima). It competes with another seaweed fly, C. pilipes, for resources.
- "Kelp Fly". Marine Wildlife Encyclopedia. Oceana.
- Gilburn, AS; Stewart, KM; Edward, DA (2009). "Sex-biased phoretic mite load on two seaweed flies: Coelopa frigida and Coelopa pilipes". Environmental Entomology. 38 (6): 1608–12. doi:10.1603/022.038.0612. PMID 20021755.
- Mather, Kate (June 18, 2011). "South Bay beaches hit by swarms of kelp flies". Los Angeles Times. Retrieved June 18, 2011.
- Cullen, Sally J.; Young, Alison M.; Day, Thomas H. (1987). "Dietary requirements of seaweed flies (Coelopa frigida)". Estuarine, Coastal and Shelf Science. 24 (5): 701. doi:10.1016/0272-7714(87)90108-9.
- Edward, Dominic A.; Newton, Jason; Gilburn, André S. (2008). "Investigating dietary preferences in two competing dipterans, Coelopa frigida and Coelopa pilipes, using stable isotope ratios of carbon and nitrogen". Entomologia Experimentalis et Applicata. 127 (3): 169. doi:10.1111/j.1570-7458.2008.00692.x.
- Burnet, B.; Thompson, U. (2009). "Laboratory Culture of Coelopa Frigida (Fabricius) (Diptera: Coelopldae)". Proceedings of the Royal Entomological Society of London A. 35 (4–6): 85. doi:10.1111/j.1365-3032.1960.tb00672.x.
- MacDonald, C.; Brookfield, J. F. Y. (2002). "Intraspecific molecular variation in the seaweed fly Coelopa frigida consistent with behavioural distinctness of British and Swedish populations". Molecular Ecology. 11 (9): 1637–46. doi:10.1046/j.1365-294X.2002.01559.x. PMID 12207715.
- Gilburn, A S; Foster, S P; Day, T H (1992). "Female mating preference for large size in Coelopa frigida (seaweed fly)". Heredity. 69 (3): 209. doi:10.1038/hdy.1992.118.
- Gilburn, A. S.; Day, T. H. (1994). "Sexual Dimorphism, Sexual Selection and the Formula Chromosomal Inversion Polymorphism in the Seaweed Fly, Coelopa frigida". Proceedings of the Royal Society B: Biological Sciences. 257 (1350): 303. doi:10.1098/rspb.1994.0130.
- Shuker, D. M. (2002). "Mate sampling and the sexual conflict over mating in seaweed flies". Behavioral Ecology. 13: 83–86. doi:10.1093/beheco/13.1.83.
- Blyth, Jennifer E.; Gilburn, Andre S. (2011). "The function of female behaviours adopted during premating struggles in the seaweed fly, Coelopa frigida". Animal Behaviour. 81: 77–82. doi:10.1016/j.anbehav.2010.09.013.
- Summers, R. W.; Smith, S.; Nicoll, M.; Atkinson, N. K. (1990). "Tidal and sexual differences in the diet of Purple Sandpipers Calidris maritima in Scotland". Bird Study. 37 (3): 187–94. doi:10.1080/00063659009477056.