Rhinocyllini
Genus Guides
2- Bangasternus
- Rhinocyllus(thistle head weevil)
Rhinocyllini is a tribe of weevils within the Lixinae, characterized by their association with thistles (Asteraceae: Cardueae). Members are recognized by their distinctive rostrum structure and have been studied for their potential as agents against thistle . The tribe includes economically significant such as Rhinocyllus, which has been introduced to multiple countries to manage thistle .
Pronunciation
How to pronounce Rhinocyllini: /riːnɔsɪˈlaɪnaɪ/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Rhinocyllini can be distinguished from related Lixinae tribes by the combination of: a moderately long, slender rostrum with inserted near the middle; tibiae lacking uncus (hooked apex); and a body form adapted for boring into thistle flower . The scutellum is usually visible and triangular. These traits separate them from the closely related Cleonini, which typically have more robust rostra and different antennal insertion points.
Images
Habitat
Primarily associated with thistle-dominated including grasslands, rangelands, agricultural margins, and disturbed open areas where plants in the tribe Cardueae (Asteraceae) occur.
Distribution
Native to the Palearctic region, with individual introduced to North America, Australia, South America, and South Africa as agents. Natural distribution centers on Europe, North Africa, and temperate Asia.
Seasonality
activity coincides with flowering periods of thistles, generally late spring through summer in temperate regions. Larval development occurs within thistle flower .
Diet
Specialized feeders on plants in the tribe Cardueae (Asteraceae), with larvae developing inside thistle flower and feeding on thistle foliage, stems, or flowers.
Host Associations
- Cardueae - herbivorethistle tribe within Asteraceae; includes Cirsium, Carduus, Onopordum, and related
Life Cycle
are deposited on or in thistle flower . Larvae feed internally on developing seeds and receptacle tissue, passing through multiple instars. occurs within the flower head. emerge to feed on plant tissues and overwinter, with typically one per year in temperate regions.
Behavior
are thigmotactic, often hiding within thistle flower or among bracts. Females use the rostrum to prepare oviposition sites in flower heads. Larval feeding destroys seeds, reducing plant reproductive output.
Ecological Role
Acts as a seed and herbivore on thistles, capable of significantly reducing seed production. In native ranges, contributes to thistle . In introduced ranges, functions as a agent targeting thistles.
Human Relevance
Widely used in programs against economically damaging thistles, particularly musk thistle (Carduus nutans) and Scotch thistle (Onopordum acanthium). Rhinocyllus conicus has been introduced to at least six countries for this purpose, though its efficacy varies by region and specificity concerns have been raised regarding non-target effects on native thistles.
Similar Taxa
- CleoniniAlso within Lixinae but distinguished by more robust rostrum, different antennal insertion, and typically broader associations beyond thistles; many Cleonini have tibial uncus absent in Rhinocyllini
- LixiniRelated Lixinae tribe with generally larger body size, longer rostrum relative to body, and often associated with different plant groups; antennal club structure differs
More Details
Biological Control History
Rhinocyllus conicus was among the first weevils approved for in North America, released in 1969 against musk thistle. It established widely but effectiveness varies; some have shifted to native thistle , raising questions about specificity and non-target impacts.
Taxonomic Stability
Rhinocyllini has remained taxonomically stable relative to other Curculionidae tribes, though generic boundaries within the tribe have been revised based on phylogenetic studies. The tribe is well-supported in molecular analyses of Lixinae.