Diplolepis nervosa
(Curtis, 1838)
Spiked Pea Gall Wasp
Diplolepis nervosa is a in the Diplolepididae that induces distinctive spiked pea on wild roses (Rosa ). Like other members of its , it exhibits an with both sexual and parthenogenetic phases. The species is to Europe and has been to North America, where it has become established. The galls it produces are among the most recognizable of rose galls due to their characteristic spiny, pea-like appearance.
Pronunciation
How to pronounce Diplolepis nervosa: //ˌdɪploʊˈlɛpɪs nərˈvoʊsə//
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Identification
The of Diplolepis nervosa are diagnostic: small, spherical, pea-like structures approximately 5–10 mm in diameter, covered with numerous sharp, slender or filaments that give them a bristly appearance. These galls are borne on the leaves and stems of wild roses, typically clustered. The are tiny, approximately 2–3 mm in length, with reduced typical of . Females have a visible for inserting into tissue. The can be distinguished from the related Diplolepis rosae (which produces the smooth, mossy rose gall) by the spiny rather than mossy or smooth gall surface.
Images
Habitat
Found in supporting wild rose , including hedgerows, woodland edges, scrubland, and disturbed ground. The requires access to Rosa species as obligate for development.
Distribution
to Europe; recorded from Belgium, the United , and other parts of western and central Europe. to North America, with established in Canada and the United States.
Seasonality
Sexual emerge in spring from overwintered ; parthenogenetic (agamic) generation females emerge in late summer to autumn. Gall formation is most evident on plants during late spring through summer.
Diet
feed on nutritive tissue within the induced on Rosa . do not feed; they rely on larval reserves and brief nectar feeding if at all.
Host Associations
- Rosa - Obligate; induces on leaves and stems
Life Cycle
Exhibits heterogony (). The sexual produces that mate and give rise to the parthenogenetic generation. The agamic generation consists solely of females that reproduce parthenogenetically and produce the . develop within the gall tissue, which provides both nutrition and protection.
Behavior
Females insert into tissue using their , simultaneously introducing chemical stimuli that induce formation. The developing feeds on the nutritive layer of lining the gall interior, manipulating plant growth to maintain this food source. are short-lived and primarily focused on .
Ecological Role
As a inducer, modifies growth and creates microhabitats that support a of , , and other gall-associated . The galls serve as a food source and shelter for these secondary occupants, contributing to local .
Human Relevance
Of minor economic significance; cause to ornamental roses but rarely threaten health. Occasionally studied in contexts and as a model for understanding plant- interactions and gall mechanisms.
Similar Taxa
- Diplolepis rosaeProduces the mossy rose on Rosa, but galls are larger, irregularly lobed, and covered with moss-like filaments rather than distinct ; galls are often reddish and less spherical.
- Diplolepis mayriAnother European Diplolepis on Rosa; produces different (bullet galls or spiny bedeguar variants), with galls typically more elongated and with different arrangement.
- Diplolepis spinosaAlso produces spiny , but and gall size differ; precise identification often requires gall examination and context.