Antistrophus
rosinweed stem gall wasp
An undescribed species of cynipid gall wasp in the Antistrophus that induces distinctive stem-cluster galls on Silphium perfoliatum (cup plant). Like other Antistrophus , it likely produces only female through , with emerging in fall to lay in plant stems. The galls provide shelter and food for developing larvae.
Pronunciation
How to pronounce Antistrophus: /ænˈtaɪstɹəfəs ˌʌndɪˈskɹaɪbd ˌpɜːfoʊˈleɪətəm stɛm klʌstər ɡæl/
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Identification
Distinguished from other Antistrophus by plant specificity (Silphium perfoliatum vs. S. integrifolium for A. silphii or Lygodesmia juncea for A. lygodesmiaepisum) and gall (stem-cluster formation). The perfoliate leaves of the host plant (cup plant) provide a field identification cue. Galls differ from goldenrod ball galls (Eurosta solidaginis) in being stem-based rather than terminal, and from oak galls in host plant and .
Habitat
Tallgrass prairie and prairie remnants; associated with Silphium perfoliatum in mesic to wet-mesic prairie conditions
Distribution
Northwestern Missouri and adjacent regions with tallgrass prairie ; likely occurs throughout the range of Silphium perfoliatum in the central United States
Seasonality
in fall; gall formation visible on plants during summer growing season
Host Associations
- Silphium perfoliatum - gall inductionStem-cluster galls induced on this plant; undescribed species distinct from A. silphii on S. integrifolium
Life Cycle
Parthenogenetic producing only female ; laid in plant stems, gall formation initiated by larval secretions manipulating plant growth , larval development within gall, inside gall, by chewing exit hole
Behavior
females use ovipositor to inject into actively growing stem tissue; larvae induce gall formation through chemical manipulation of plant rather than direct feeding on existing tissue
Ecological Role
Gall formation creates microhabitat structure on prairie plants; galls may serve as food source for gall- or ; contributes to biodiversity of prairie through specialized plant-insect interaction
Human Relevance
Subject of entomological research on gall wasp and prairie dynamics; contributes to understanding of plant specialization and in Hymenoptera
Similar Taxa
- Antistrophus silphiiAlso occurs on Silphium but specifically on S. integrifolium (wholeleaf rosinweed) rather than S. perfoliatum; galls may differ in clustering pattern and plant leaf differs (non-perfoliate)
- Antistrophus lygodesmiaepisumSame with similar but restricted to Lygodesmia juncea (rush skeletonplant) in loess hilltop prairies; galls described as pea-like on wiry stems rather than clustered on thick perfoliate stems
More Details
Undescribed Status
This represents an undescribed species known from informal designation; formal taxonomic description pending. The 'perfoliatum' epithet in the working name refers to the plant Silphium perfoliatum with its distinctive perfoliate leaves that wrap around the stem.
Conservation Context
Like other prairie- Antistrophus , occurrence tied to remaining tallgrass prairie . plant S. perfoliatum more widespread than Lygodesmia juncea, potentially conferring less imperiled status than A. lygodesmiaepisum.