Seasonal ecology and geographical distribution of Anaphes listronoti and A. victus (Hymenoptera: Mymaridae), egg parasitoids of the carrot weevil (Coleoptera: Curculionidae) in central Ontario
1996
Cormier, D. | Stevenson, A.B. | Boivin, G.
Field surveys were conducted during 3 yr in the Holland Marsh and district marshes to evaluate egg parasitism of the carrot weevil, Listronotus oregonensis (LeConte). Anaphes listronoti Huber was the dominant species in Ontario and was widely distributed in the sampled area. In commercial fields, up to 33% of the carrot weevil eggs were parasitized by Anaphes spp. In an untreated plot, parasitism averaged 68% and reached 94% in high density of carrot weevil eggs. Spring emergence of the parasitoids occurred from the end of April to mid-May, at which time the carrot weevil had begun its oviposition period in wild plants. Parasitoids had to complete between 1.6 and 2.3 generations outside the carrot fields before the appearance of carrot weevil eggs in plants. Parasitized eggs were observed in carrot fields from the beginning of the carrot weevil oviposition until September.
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