Nachrichtenblatt des Deutschen Pflanzenschutzdienstes (1997) 49, 215-222

Bernd Freier, Holger Triltsch, Maureen Möwes and Verena Rappaport (1997)
Der relative Wert von Prädatoren bei der natürlichen Kontrolle von Getreideblattläusen und die Verwendung von Prädatoreneinheiten
[The relative value of predators in natural control of cereal aphids and the use of predator units]
Nachrichtenblatt des Deutschen Pflanzenschutzdienstes 49 (9), 215-222
Abstract: Under field conditions the effect of cereal aphid predators differs between certain species or predator groups. Calculating predator efficiency a simple addition of predator numbers is not possible. The aim of this paper was to develop and use a suitable approach for the evaluation of the predator community. Results of feeding experiments, gut dissections and trophic interaction studies were analysed and predator specific consumption rates per day at 20 °C were estimated. Considering the proportion of cereal aphids in the predator food relative values for the predators were defined between 1.0 (fertile females of Coccinella septempunctata) and 0.002 (adult spider). On this basis it was possible to quantify the whole predator community, by using so-called predator units (PU) per m². This approach permits complex efficiency analyses of predator occurrence in wheat fields. On an average of all the surveys in 8 winter wheat fields the predator potential amounted 4.3 (season maximum: 17:3) PU per m². Using PU-calculations the average portion of coccinellids was 45 %. At more than 8 PU per m² a stagnation rather than an increase in aphid infestation was observed.
Investigations on coccinellids and computer simulations with the model GTLAUS have shown that not only the predator potential but also other variables, especially prey density and temperature, must be considered to evaluate the particular effect of each predator group.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: German)
Database assignments for author(s): Bernd Freier

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

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Coccinella septempunctata (predator)