Journal of Applied Entomology - Zeitschrift für angewandte Entomologie (2002) 126, 101-107

L. Sigsgaard (2002)
A survey of aphids and aphid parasitoids in cereal fields in Denmark, and the parasitoids' role in biological control
Journal of Applied Entomology - Zeitschrift für angewandte Entomologie 126 (2-3), 101-107
Abstract: In 1996 and 1997 a field survey of the abundance and species composition of cereal aphid primary and secondary parasitoids in spring barley, winter wheat and durum wheat was conducted in Zealand, Denmark. The purpose was to create a better understanding of the mechanisms underlying aphid-parasitoid dynamics in the field. Such an understanding can be used when developing biological control methods in cereals. In both years aphid attacks in cereals began in late June and never exceeded the economic threshold. In 1996 the first aphids were found in wheat on 26 June; in 1997 the first aphids were found on 24 June on both crops. The highest densities reached in 1996 were an average of six aphids per shoot in winter wheat and one aphid per shoot in spring barley. In 1997 the highest densities reached were 11 aphids per shoot in winter wheat and four aphids per shoot in spring barley. The aphid population collapsed by the end of July to early August in 1996, but it collapsed by mid-July in 1997. The onset and peak of parasitization were delayed in comparison to aphid infestation. Parasitism was 20-60% by the end of the cropping season in spring barley, and 30-80% in winter wheat and durum wheat in 1996. In 1997 parasitism did not exceed 3-11% in barley and was less than 2% in one winter wheat field but more than 40% in the other winter wheat field sampled. In both years most parasitism was due to Aphidiidae (Hymenoptera). The two dominant species were Aphidius ervi Haliday and Aphidius rhopalosiphi De Stefani-Perez. Hyperparasitism began after primary parasitism and increased progressively during the cropping season. The two years were similar in many respects, including for species composition of aphids and parasitoids. The late start of the aphid infestation may have contributed to the high level of parasitization found in 1996, but in 1997 the aphid infestation period was so short that a parasitoid population did not have time to build up.
(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): Lene Sigsgaard

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

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Aphidius rhopalosiphi (parasitoid)			Denmark
Aphidius ervi (parasitoid)			Denmark