Environmental Entomology (1981) 10, 691-696

Paul E. Boldt and Gaetano Campobasso (1981)
Biology of two weevils, Ceutorhynchus trimaculatus and Trichosirocalus horridus, on Carduus spp. in Europe
Environmental Entomology 10 (5), 691-696
Abstract: Field studies were conducted at Rome, Italy, on Ceutorhynchus trimaculatus (F.) and Trichosirocalus horridus (Panzer), two candidate insects for the biological control of Carduus thistles in the United States. The biologies of these weevils were similar; teneral adults appeared in the spring and fed for 2 to 3 weeks on leaves of the primary host, Carduus macrocephalus Desfontaines, before estivation in the soil. Both weevils resumed feeding in the fall. Mating and oviposition occurred from November to March. Eggs of C. trimaculatus were laid on the surface and under the epidermis of the leaves, whereas eggs of T. horridus were laid in feeding grooves in the midrib. Larvae of both species fed together in the crowns and buds from December to April, but no cannibalism was observed. More larvae of T. horridus fed in buds than did larvae of C. trimaculatus. Pupation occurred in the soil. Both weevils were univoltine.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
population dynamics/epizootiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Carduus (weeds)		Italy
Trichosirocalus horridus (weed bioagent)	Carduus (weeds)		Italy
Ceutorhynchus trimaculatus (weed bioagent)	Carduus (weeds)		Italy