Entomologia Experimentalis et Applicata (1998) 87, 225-235

Brook C. Murphy, Jay A. Rosenheim, Robert V. Dowell and Jeffrey Granett (1998)
Habitat diversification tactic for improving biological control: parasitism of the western grape leafhopper
Entomologia Experimentalis et Applicata 87 (3), 225-235
Abstract: In a previous study we demonstrated greater abundance of the parasitoid Anagrus epos (Girault) in grape vineyards located downwind of prune trees that function as overwintering habitats. This study examines whether these higher A. epos numbers translated into higher egg parasitism rates of the grape leafhopper, Erythroneura elegantula (Osborn). Paired commercial wine-grape vineyard plots, one with and one without adjacent prune trees, were studied within a complete block design in northern and central California. A. epos was the key mortality factor affecting E. elegantula eggs. Point estimates of A. epos parasitism rates were significantly greater in vineyards associated with prune trees during the first E. elegantula generation in both 1991 and 1992. No consistent differences in parasitism rates were observed during the second or third generations. The results indicated that prune trees enhance early season parasitism rates. Cumulative estimates of egg parasitism across E. elegantula generations demonstrated that enhanced early-season parasitism resulted in a net season-long increase in the degree of mortality imposed by A. epos on E. elegantula eggs. Two factors were found to influence parasitism rates: the abundance of early-season A. epos adults moving into vineyards and the density of E. elegantula eggs in vineyards. Our results indicate that diversification of vineyards using prune trees supports overwintering populations of a specialist parasitoid and thereby alters host-parasitoid interactions to favor enhanced parasitism in vineyards.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Jay A. Rosenheim

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Erythroneura elegantula	Grapevine (Vitis)	U.S.A. (SW)
Anagrus epos (parasitoid)	Erythroneura elegantula	Grapevine (Vitis)	U.S.A. (SW)