- Pre-copulatory guarding - males prevent rivals from mating, and sequester the female early in the day until the temperature has risen sufficiently to permit copulation and oviposition.
- Post-copulatory guarding - after mating, rival males are still excluded as they can displace existing sperm and replace it with their own. This may include guarding during oviposition (egg-laying) for similar reasons e.g. females are highly receptive after copulation and thus males are guarding against sperm competition, and ensuring theirs retains precedence during sperm storage.
The precise behaviour varies between species and is influenced by factors such as sex ratio, but whatever its precise form, mate-guarding has developed to prevent mating of females by rival males. For more about this behaviour in dragonflies, see for example Corbet & Brooks (2008). In other insect groups it is not always so well documented. Walker (2010) describes, for the first time, mate-guarding in the parasitic Hippoboscidae ('louse-flies' or 'keds'), while Dyte, (1988), Adler & Adler (1991) and McLean (1991) do the same for a few species of flies in the families Dolichopodidae, Tipulidae (crane-flies) and Ephydridae respectively. However, this behaviour is well documented in only a tiny proprtion of the many known fly species, so I was interested to see a pair of the honeybee-mimic hoverfly Eristalis interruptus (at least I think it's this species going by leg colour, overall form, and the pattern of the 2nd tergite in the male - the genus is certainly correct) engaging in mate-guarding behaviour in our back garden.
|Mate-guarding in a pair of Eristalis interruptus hoverflies.|
So, a rarely (if ever) reported behaviour and another example of what can be seen in even a moderate-sized urban garden if it is managed in a wildlife-friendly way. As ever, if you have seen this behaviour in hoverflies, do let me know!
Adler, P.H. & Adler, C.R.L. (1991). Mating behavior and the evolutionary significance of mate guarding in three species of crane flies (Diptera: Tipulidae). Journal of Insect Behavior 4(5): 619-632.
Corbet, P. & Brooks, S. (2008). Dragonflies. HarperCollins, London. [see especially pp. 226-7, 250-6]
Rotheray, G.E. & Gilbert, F. (2011). The Natural History of Hoverflies. Forrest, Tresaith.
Dyte, C.E. (1988). Mate guarding and sex ratio in Hydrophorus oceanus (Macquart) (Diptera: Dolichopodidae). The Entomologist 107: 122-126.
McLean, I. (1991). Mate-guarding in Ephydra riparia Fallen (Diptera: Ephydridae). British Journal of Entomology and Natural History
Dipterists Digest (2nd series) 17(2): 115-116.