International Journal of Pest Management (1999) 45, 23-28

Mats Lindblad (1999)
Density and mortality of overwintering Oscinella frit and other oscinellids in Swedish grasslands
International Journal of Pest Management 45 (1), 23-28
Abstract: Aiming to assess the mortality of the overwintering generation of Oscinella frit , populations of oscinellid flies and their parasitoids were sampled during five consecutive years, before and after overwintering. Samples were taken in permanent pastures, leys and ryegrass plots in Sweden. Densities of O. frit were higher in pastures than in leys. The percentage of oscinellids parasitized showed little variation among years, but was higher in ryegrass plots (37%) than in pastures (14%). The parasitoid complex was dominated by one species, Rhoptromeris heptoma. The percentage decline in density of unparasitized O. frit from autumn to spring ranged from 5 to 65% during the five studied winters. This mortality was not related to O. frit density in autumn, nor were any weather effects found. My results suggest that the yearly variation in mortality of overwintering O. frit is moderate and that, consequently, during most years it should be possible to predict spring population size based on population estimates made the previous autumn.
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Link to article at publishers website

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
population dynamics/ epidemiology
Research topic(s) for beneficials or antagonists:
population dynamics/epizootiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Oscinella frit	Grasses/turf/rangeland	Sweden
Rhoptromeris heptoma (parasitoid)	Oscinella frit	Grasses/turf/rangeland	Sweden