Journal of Entomological Science (1999) 34, 101-112

E.R. Mitchell, G.Y. Hu, J.S. Okine and J.E. Carpenter (1999)
Parasitism of diamondback moth (Lepidoptera : Plutellidae) larvae by Cotesia plutellae (Hymenoptera : Braconidae) and Diadegma insulare (Hymenoptera : Ichneumonidae) in cabbage fields after inundative releases of C. plutellae
Journal of Entomological Science 34 (1), 101-112
Abstract: Cocoons of Cotesia plutellae (Kurdjumov) were released for nine consecutive wk along the margins of two commercial cabbage (Brassica oleracea var. bravo L.) fields near Bunnell, Flagler Co., FL, in spring 1996. The larval parasitism of diamondback moth, Plutella xylostella (L.), by C. plutellae and by the native parasitoid Diadegma insulare (Cresson) was evaluated in release fields and in nearby cabbage fields using two methods - sentinel collard (Brassica oleracea var. acephala L.) or sentinel cabbage plants and non-sentinel plants. Total parasitism of diamondback moth larvae on sentinel plants in the release and adjacent fields was 35.7%. There were no significant differences in the level of parasitism by C. plutellae among sentinel plant locations within the release fields. In non-release fields, parasitoids spread as far as 1,500 m from the nearest release site during the release period, but parasitism of larvae on sentinel plants decreased as the distance from the release area increased. Parasitism of diamondback moth larvae by D. insulare was 8.3% in C. plutellae release and adjacent fields, but 14.6% in the nearby fields. Sampling of non-sentinel cabbage plants for diamondback moth larvae demonstrated a total of 37.4% larval parasitism by C. plutellae in the release and adjacent fields, similar to that recorded on sentinel plants. However, C. plutellae were detected only as far as 800 m from the release site on non-sentinel cabbage plants, and total parasitism in the dispersal fields also was very low. Diadegma insulare contributed only 1.1 % parasitism of larvae sampled from non-sentinel plants in all cabbage fields. Cotesia plutellae was more effective than D. insulare in attacking diamondback moth larvae in this study where field populations of diamondback moth were low (<0.1 larva per cabbage plant).
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): James E. Carpenter

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
inundative/inoculative release

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plutella xylostella	Cabbage (Brassica oleracea)	U.S.A. (SE)
Cotesia vestalis (parasitoid)	Plutella xylostella	Cabbage (Brassica oleracea)	U.S.A. (SE)
Diadegma insulare (parasitoid)	Plutella xylostella	Cabbage (Brassica oleracea)	U.S.A. (SE)