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

Abstract

In Central Europe, the most abundant aphid infesting the leaves of small grain cereals is Metopolophium dirhodum (Walker) (Homoptera: Aphididae). Annual variation in its seasonal dynamics was evaluated using a 25-yr series of standardized weekly censuses of winter wheat plots. M. dirhodum made up >50 % of the aphids on the foliage. Date of immigration (8 May–3 July), length of period of population increase (0–9 wk), and date of attaining maximum abundance (28 May–22 July) varied greatly. For the prediction, we regressed maximum numbers/tiller on numbers recorded in the first week after heading. The regression of maximum abundance on nonzero aphid counts revealed a critical number of ≥1.50 aphids/tiller, which if exceeded resulted in a harmful maximum abundance of ≥10 aphids/tiller at the peak. Zero aphid counts resulted in 10% of cases with a harmful maximum abundance. Using this regression for prediction will result in 18% of the recorded cases being false negatives and 9% false positives. Parallel annual variation in the average maximum numbers of M. dirhodum, Sitobion avenae (Fabricius) (Homoptera: Aphididae), and Rhopalosiphum padi (Linné) (Homoptera: Aphididae) indicated the following factors that affected their abundance: temperature in winter and host plant quality. The predictions apply only in areas where M. dirhodum is holocyclic and aphids do not overwinter in wheat stands.

Rapid responses of winter aphid-parasitoid communities to climate warming

“…From late spring to fall, additional species were present, including the parasitoids Aphidius ervi Haliday and Aphidius avenae Haliday (Krespi, 1990;Krespi et al, 1997;Rabasse et al, 1983) and the aphid Metopolophium dirhodum (Walker). These seasonal variations in aphid and parasitoid species occurrence seem to be consistent across Western Europe in cereal crops (Honek et al, 2018;Lumbierres et al, 2007) and reflect thermal niche separation Le Lann et al, 2011). Aphidius avenae parasitoid shows less cold resistance and more heat resistance than A. rhopalosiphi (Le Lann et al, 2011), while the aphid R. padi prefers cooler conditions and is more cold resistant than S. avenae Jarošík et al, 2003;van Baaren et al, 2010).…”

“…The importance of host species in shaping parasitoid response to climate warming must therefore be accounted (Barton and Ives, 2014). Parasitoids and their hosts may also be influenced by microclimatic refuges in the landscape Tougeron et al, 2016), by surrounding plant covers (Damien et al, 2017;Gagic et al, 2012) or by plant quality (Honek et al, 2018).…”

“…Climate warming challenges the coexistence and interactions between ecologically related species, as well as community stability and ecosystem functioning (Tylianakis et al, 2008;van der Putten et al, 2004). In cereal fields, overwintering reproduction in aphid parasitoids plays an important role in suppressing early cereal aphid populations in spring (Honek et al, 2018;Langer et al, 1997;Plantegenest et al, 2001). Increasing number of parasitoid species during winter due to climate warming could enhance aphid natural biological control through increasing already high parasitism rate in winter, even if consequences of niche overlapping between parasitoid species via addition of new species in the food-web are difficult to predict.…”

Rapid Responses of Winter Aphid-Parasitoid Communities to Climate Warming

“…We have shown that both mean minimal temperatures and mean duration of frost events over the winter are predictors of winter aphid abundances and of their variation in occurrence among years. Honek et al (2018) also demonstrated that temperature in winter was an important predictor of maximum abundances of cereal aphids during the weeks following sampling. However, change in mean minimal temperature and duration of frost events only slightly contributed to the trend observed in parasitoid relative abundance changes over the years.…”

“…From late spring to fall, additional species were present, including the parasitoids Aphidius ervi Haliday and Aphidius avenae Haliday and the aphid Metopolophium dirhodum (Walker) (Rabasse et al, 1983;Krespi, 1990;Krespi et al, 1997). These seasonal variations in aphid and parasitoid species occurrence seem to be consistent across Western Europe in cereal crops (Lumbierres et al, 2007;Honek et al, 2018) and likely reflect thermal niche separation (Le Lann et al, 2011;Andrade et al, 2016). The parasitoid A. avenae shows less cold resistance and more heat resistance than A. rhopalosiphi (Le Lann et al, 2011), while the aphid R. padi prefers cooler conditions and is more cold resistant than S. avenae (Jarošík et al, 2003;van Baaren et al, 2010;Alford et al, 2016).…”