Hu, Gao ORCID: 0000-0002-1000-5687 , Stefanescu, Constanti ORCID: 0000-0001-8952-7869 , Oliver, Tom H., Roy, David B. ORCID: 0000-0002-5147-0331 , Brereton, Tom, Van Swaay, Chris ORCID: 0000-0003-0927-2216 , Reynolds, Don R. ORCID: 0000-0001-8749-7491 and Chapman, Jason W. (2021) Environmental drivers of annual population fluctuations in a trans-Saharan insect migrant. Proceedings of the National Academy of Sciences, 118 (26):e2102762118. ISSN 0027-8424 (Print), 1091-6490 (Online) (doi:https://doi.org/10.1073/pnas.2102762118)

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Abstract

Many latitudinal insect migrants including agricultural pests, disease vectors, and beneficial species show huge fluctuations in the year-to-year abundance of spring immigrants reaching temperate zones. It is widely believed that this variation is driven by climatic conditions in the winter-breeding regions, but evidence is lacking. We identified the environmental drivers of the annual population dynamics of a cosmopolitan migrant butterfly (the painted lady Vanessa cardui) using a combination of long-term monitoring and climate and atmospheric data within the western part of its Afro-Palearctic migratory range. Our population models show that a combination of high winter NDVI (normalized difference vegetation index) in the Savanna/Sahel of sub-Saharan Africa, high spring NDVI in the Maghreb of North Africa, and frequent favorably directed tailwinds during migration periods are the three most important drivers of the size of the immigration to western Europe, while our atmospheric trajectory simulations demonstrate regular opportunities for wind-borne trans-Saharan movements. The effects of sub-Saharan vegetative productivity and wind conditions confirm that painted lady populations on either side of the Sahara are linked by regular mass migrations, making this the longest annual insect migration circuit so far known. Our results provide a quantification of the environmental drivers of large annual population fluctuations of an insect migrant and hold much promise for predicting invasions of migrant insect pests, disease vectors, and beneficial species.

Item Type:	Article
Additional Information:	© 2021 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY).
Uncontrolled Keywords:	insect migration; population; dynamics; painted lady butterfly; Lepidoptera
Subjects:	S Agriculture > S Agriculture (General)
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Natural Resources Institute Faculty of Engineering & Science > Natural Resources Institute > Agriculture, Health & Environment Department
Last Modified:	10 Jul 2021 01:13
URI:	http://gala.gre.ac.uk/id/eprint/33262

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