I have found evidence on various landscape variables such as amount of; arable, crop, cereals, etc. But I wondered if you knew of any evidence on winter wheat specifically? Alternatively, on a single crop type such as spring barley, winter barley, or maybe broader to wheat only or winter only crops? Considering we depend on wheat, I thought this would be interesting to follow up. However, so far it would seem there is little evidence out there. Do you know of some evidence in this area?
Hi Victoria,
I guess you refer to aphid species that attack wheat. Is that correct?
Have you checked this reference?
Modelling the Geographical Range of a Species with Variable Life-History
Sarina Macfadyen, Darren J. Kriticos
I think they partially refer to your question, when they consider mostly the primary host of Rhopalosiphum padi and just touch a little the secondary host (wheat), among other variables. The think here is that they consider an alternating host species. I do not think is a full answer to what you are looking for. But perhaps can help!!!
Maybe if in a particular country there are good figures about aphid infestation over several years, one can make a study by relating the area that has been planted/harvested with wheat and correlate that with aphid infestation. I know in Sweden there are yearly data about the incidence of some wheat aphids, perhaps there are data in the UK as well.
I guess there should be other studies on species that feed only in grasses, like Schizaphis gramiinum or Sitobion avenae, and maybe the following study refers a bit to your question, but still, it is more related to plant resistance:
Biotypic Diversity in Greenbug (Hemiptera: Aphididae): Characterizing New Virulence and Host Associations
JOHN D. BURD AND DAVID R. PORTER
Cheers,
Leo
Hi Victoria
I don't have any specific studies to refer and unfortunately do not have data to substantiate this observation regarding Russian wheat aphid in South Africa on winter wheat, but we notice differences in occurrence of RWA depending on the area planted to wheat .
It seems to me to be a worthy topic of study - possibly with the hypothesis that planted hectares under a certain area is more associated with only localised outbreaks (more difficult for aphids to spread and reach all plantings), and over a much larger area leads to "wall-to-wall" wheat with very easy spread for aphids resulting in large outbreak.
I recall speaking to someone once about this phenomena and if I remember correctly it was for Hessian fly in the USA, but cannot remember exactly.
Anyway - good luck Vicki
Hi Leonardo and Vicki,
Thank you very much. I had not seen the Macfadyen and Kriticos or the Burd and Porter papers previously, they are a great help! I will look into other species and see if there is more evidence on the relationship between pests and amount of crops.
Many thanks,
Victoria
I don't think they have done anything specific on the proportion of cereals in a landscape directly, but Mattias Jonsson et al at SLU in Sweden have done a fair bit of work on landscape matrix in relation to aphid outbreaks and natural enemies.
e.g.
Rusch, A., Bommarco, R., Jonsson, M., Smith, H.G. & Ekbom, B. 2013. Flow and stability of natural pest control services depend on landscape complexity and crop rotation in the landscape. Journal of Applied Ecology, 50, 345-354.
Have a look at Mattias' publications, you might find some more information in there somewhere.
Hi Mark,
I know the one you mention, it is a great paper. Thank you for the advice, will look over it now. Hope all is going well for you.
All the best,
Victoria
HI Victoria
Did you see this paper - it has relevance to the area dependence of crop pest outbreaks. Drechsler M, Touza J, White PCL, Jones G (2016). Agricultural landscape structure and invasive species: the cost-effective level of crop field clustering. Food Security 8: 111-121 DOI 10.1007/s12571-015-0539-5
TRegards, Vicki
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