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Laboratory and realized host ranges of Chaetorellia succinea (Diptera: Tephritidae), an unintentionally introduced
Joe K Balciunas1, Baldo Villegas
1Exotic and Invasive Weed Research Unit, USDA-ARS, Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710, USA. joe@pw.usda.gov
Environmental Entomology
|August 25, 2007
Summary
The yellow starthistle seed fly (Chaetorellia succinea) is a biological control agent. While it prefers yellow starthistle, it can lay eggs on other thistles, posing a risk to native species.
Area of Science:
- Entomology
- Weed Science
- Ecology
Background:
- Chaetorellia succinea, an adventive fly from Greece, was discovered in California and Oregon in 1999.
- This fly targets yellow starthistle (Centaurea solstitialis), a significant weed in the western US.
- Concerns exist regarding the potential impact of Ch. succinea on native thistles within the Cardueae tribe.
Purpose of the Study:
- To determine the physiological and realized host range of Chaetorellia succinea.
- To assess the risk posed by Ch. succinea to native and other introduced thistle species.
Main Methods:
- Laboratory no-choice and choice tests exposing 14 potential Cardueae hosts to Ch. succinea.
- Field surveys collecting flower heads from 24 potential host species at 111 sites across California.
Main Results:
- In the lab, American basketflower (Centaurea americana) and two introduced thistles were hosts under no-choice conditions.
- Under choice conditions, yellow starthistle was preferred, but some oviposition occurred on the other three species.
- Field surveys confirmed Ch. succinea emerged only from Ce. melitensis and Ce. sulfurea, not American basketflower.
Conclusions:
- While yellow starthistle is the preferred host, Ch. succinea can utilize other Cardueae species.
- American basketflower in the southwestern US may be at risk if Ch. succinea expands its range.
- Current field data suggest limited risk to native California thistles but potential risk to American basketflower in other regions.
