Biology and host specificity of the Chondrilla crown moth, Oporopsamma wertheimsteini (Rebel) (Lepidoptera: Tortricidae)

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Abstract
The tortricid moth Oporopsamma wertheimsteini (Rebel) is a potential biological control agent of Chondrilla juncea, which is a serious introduced weed in Australia. The biology of the moth was studied on wild C. juncea growing in Azerbaidzhan (Iran). It has one generation per year and undergoes two periods of diapause, aestivating as a pupa and hibernating as an egg. The larvae live in cases attached to and feeding on the collar region of C. juncea and may destroy plants with thin stems. Larval infestations are common on C. juncea growing in sandy soils. The braconid Chelonus asiaticus Telenga was recorded as a larval parasite. Host specificity assessment by laboratory tests in France, in which trimmed crowns of various Compositae were exposed to late-instar larvae, suggested that they had a broader host range within that plant family than would be desirable in an organism to be used for biological control. However, tests under both field and glasshouse conditions in Iran indicated that the first-instar larvae select only Chondrilla juncea as hosts. The species was therefore introduced into Australia under quarantine for further host-safety studies.