Rose bedeguar gall, Bedeguar gall wasp, robin's pincushion, Mossy rose gall, Moss gall
Diplolepis rosae is a gall wasp which causes a gall known as the rose bedeguar gall, bedeguar gall wasp, Robin's pincushion, mossy rose gall, or simply moss gall. The gall develops as a chemically induced distortion of an unopened leaf axillary or terminal bud, mostly on field rose (Rosa arvensis) or dog rose (Rosa canina) shrubs. The female wasp lays up to 60 eggs within each leaf bud using her ovipositor. The grubs develop within the gall, and the wasps emerge in spring; the wasp is parthenogenetic with fewer than one percent being males.
A similar gall is caused by Diplolepis mayri, but this is much less common.
Being so prominent and interesting in appearance, this gall has more folklore attached to it than most. The term 'Bedeguar, Bedegar or Bedequar' comes from a French word, bédégar, and is ultimately from the Persian, bād-āwar, meaning 'wind-brought'. Robin in Robin's pincushion refers to the woodland sprite of English folklore, Robin Goodfellow.
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DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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A week after the egg has been laid, the larva hatches and begins to feed on the leaf bud tissue. This activity stimulates (in a way not yet understood) the development by the host plant of enlarged 'nutritive' cells in the area around the growing larva. These are fed on by the larva and are continually replaced by new cells. Further concentric layers of tissues develop around the core nutritive tissue and come to form the structure known as the bedeguar, complete with the outermost and characteristic fibrous outgrowths that give the gall its alternative name of Robin's pincushion. As the larva feeds and grows within this gall, it probably undergoes five larval instar stages (the growth stages between moults). The final instar stage is reached by late October. The larva ceases feeding. It now passes into the prepupal stage, in which form it overwinters inside the gall. In the following February or March, the prepupa undergoes a final moult and becomes a pupa. Through the thin, transparent skin of the pupa, it is possible to see the fully formed antennae, legs, wings and body segments of the adult wasp. The adults begin to emerge from the old galls, which are still attached to the rose, in May. Emergences may continue through to August.
As stated earlier, the adult wasps which start to emerge from the rose bedeguar will be mostly female, and these females will go on to lay eggs through parthenogenesis. No alternation of generations exists in this species. Males are known, but are very rare. One possible reason for this scarcity is the presence of a bacterium in the genus Wolbachia, which is endosymbiotic in the females' gametes. A female infected with Wolbachia produces only diploid eggs, when in the cells of the ovaries presumably cause the fusion of the pronuclei, which leads to entirely female progeny. When the females were treated with antibiotics, they were then able to produce normal male and female eggs.
