I started to find now on different crops near Modena the first aphid populations… it is not too early neither too late… in respect to the last years. However, it seems that in Italy we started to have aphids earlier on our plants in the last years.
Interestingly, a recent papers clearly assessed this trend at an European level using the suction trap network, a valuable tool for monitoring invasive aphid species.
According to the paper published by the Richard Harrington network in the Journal of Animal Ecology, five decades of data have shown that the first flights of all 55 aphid species studied were found to be occurring earlier and 85% of aphids showed increased duration of their flight season. The seasonal timing of these migrations was shown to be statistically linked to a changing temperature – an indication of the impact of a changing climate on pests. Quite surprisingly, aphid abundances generally has been not increasing dramatically with years. Instead, numbers fluctuate widely between years indicating that that there are strong within-season processes that regulate the overall population size.
However, even if the general trend is clear… there are also controversial effects. For example, as also Simon R. Leather wrote in his paper in The Journal of Animal Ecology, aphids Hyalopterus pruni and Aulacorthum solani seem to be becoming less common, and as such, their pest status may change for the better.
Aphids are able to adapt to climate change faster than many other insect groups studied because of their low developmental threshold temperature and high intrinsic rate of increase, but it seems that also their natural enemies adapted to the climate changes or that these trends can be explained by the effect of climate, particularly that related to winter conditions that are still sufficiently cold to overcome the aphid cryodefence.
A further element of interest is related to the frequencies of alata aphids since some aphid species produce few (or none!) alata specimens so that their identification in suction traps scould be difficult. It could be therefore very important to set up plant-based monitoring sites where aphid occurrence on key host plants is run in parallel with existing suction traps.
I read the paper with great interest, but I have not found any data about emerging pests, such as Myzus persicae nicotianae. This subspecies seems to be spreading in some countries (such as Greece) and this particularly concerning for the economic importance of these aphids. Unfortunately, the paper published by Bell and colleagues did not verified this subspecies that can be identified mainly using molecular tools (actually… what about morphometric analyses?). According to an interview to James Bell, these data will be available in the next future….
We’re watching out for new, potentially damaging aphids such as Myzus persicae nicotianae, Diuraphis noxia and Schizaphis graminum sensu stricto, which are important vectors of plant viruses to UK crops.
… in the meanwhile I will continue to check its presece in Italy, where some surprises seems to be present. Stay tuned!
Bell, J., Alderson, L., Izera, D., Kruger, T., Parker, S., Pickup, J., Shortall, C., Taylor, M., Verrier, P., & Harrington, R. (2015). Long-term phenological trends, species accumulation rates, aphid traits and climate: five decades of change in migrating aphids Journal of Animal Ecology, 84 (1), 21-34 DOI: 10.1111/1365-2656.12282
Kati, A., Mandrioli, M., Skouras, P., Malloch, G., Voudouris, C., Venturelli, M., Manicardi, G., Tsitsipis, J., Fenton, B., & Margaritopoulos, J. (2014). Recent changes in the distribution of carboxylesterase genes and associated chromosomal rearrangements in Greek populations of the tobacco aphid. Biological Journal of the Linnean Society, 113 (2), 455-470 DOI: 10.1111/bij.12357
Leather, S. (2015). Onwards and upwards – aphid flight trends follow climate change Journal of Animal Ecology, 84 (1), 1-3 DOI: 10.1111/1365-2656.12314