Vergleichende Untersuchungen zum Schadpotential der Getreideblattlausarten Metopolophium dirhodum (Wlk.) und Sitobion avenae (F.) in Winterweizen

Abstract

: Investigations on the damage potential of cereal ahpids (Metopolophium dirhodum [Wlk.], Sitobion avenae [F.]) in winter wheat: The damage potential of the cereal aphids. S. avenae and M. dirhodum was investigated in winter wheat. Ears and flagleafs were artificially infested with different aphid densities between EC 65 and EC 83 using ear‐ and flagleaf cages. The aphid densities were adjusted to the initial densities every third day. Aphid damage is related to density and duration of infestation. Therefore the aphid infestation was quantified in terms of aphid days per ear or flagleaf. Yield was measured by calculating drymass, thousand kernel weight (TKW), kernals per ear and nitrogen content. The results show that S. avenae at the ear caused significant higher reduction in drymass and TKW compared to M. dirhodum on the flagleaf. Based on the relationship between aphid infestation and yield (drymass and TKW), the damage factor for S. avenae on the ear was 1.7 times (drymass) and 2 times (TKW) higher compared to M. dirhodum on the flagleaf. There was no clear relationship between aphid infestation and the relative nitrogen content. Zusammenfassung In einem Winterweizenbestand wurde das Schadpotential der Getreideblattlausarten S. avenae und M. dirhodum untersucht. Dazu wurden verschiedene Ertragsparameter erfaßt: Massenertag (TM), Tausendkorngewicht (TKG), Kornzahl je Ähre und Proteingehalt. Ab Mitte der Blüte (EC 65 – EC 83) wurden verschiedene Blattlausdichten in Ähren‐ und Fahnenblattkäfige eingesetzt und in dreitägigen Intervallen kontrolliert. Zur exakten Wiedergabe des Befalls wurde der Blattlausindex (Blattlaustage pro Ähre bzw. Fahnenblatt) berechnet. Es zeigte sich, daß S. avenue an der Ähre zu deutlich stärkeren Ertragsreduktionen (TM und TKG) führte als M. dirhodum am Fahnenblatt. Anhand von Regressionskoeffizienten war das Schadpotential von S. avenue um den Faktor 1,7 (TM) bzw. 2 (TKG) höher im Vergleich zu M. dirhodum. Zwischen dem relativen Proteingehalt und dem Blattlausbefall zeigte sich keine deutliche Beziehung.

Aphids (Homoptera: Aphididae) on Winter Wheat: Predicting Maximum Abundance of Metopolophium dirhodum

“…Substantial annual variation in its maximum abundance indicates that M. dirhodum may in some years become an economically significant pest. The DT density used in this study (10 individuals/tiller) may cause a 6% loss of yield compared with an aphid-free control ( Niehoff and Stäblein 1998 ). This threshold was exceeded in 36 subplots (25%) and 14 yr (57%) of this study.…”

“…For the following practical reasons, the time when 50% of the tillers are at the heading stage was chosen as the time when aphid counts could be used to predict maximum abundance: 1) the timing of the peak in population is unknown, 2) heading stage can be easily determined in practice, and 3) its use resulted in reliable predictions in the case of S. avenae (Honěk et al 2017). For this, we set the ‘damage threshold’ (DT) at 10 aphids/tiller, which causes a 6% loss of yield according to Niehoff and Stäblein (1998) . The maximum abundance was therefore regressed within the mixed effect modeling against the abundance at the time of heading.…”

Factors of between‐ and within‐plant distribution of Metopolophium dirhodum (Hom., Aphididae) on small grain cereals

“…Metopolophium dirhodum is usually the most abundant aphid of cereal stands of Central Europe ( hon ě k , 1987, 1991c; S engonca et al., 1994; B asky , 1996; havlíčková , 1996; praslička , 1996). Because of its abundance M. dirhodum is an important cereal pest although its effect on grain yield is smaller than that of Sitobion avenae (F) (N iehoff and S täblein , 1998). The abundance of M. dirhodum is positively correlated with plant vigour and leaf chlorophyll content ( hon ě k , 1991b; hon ě k et al., 1998).…”

Length of prematurity period in wheat cultivars determines maximum cereal aphid abundance

“…The virus transmission causes a significant damage. In addition, aphids sucking on leaves and ears decrease seed mass and may cause significant damage in years when aphids are abundant (Niehoff & Stäblein 1998;Larsson 2005). Plants are damaged by the removal of assimilates transported to and within ears.…”