Environmental drivers of annual population fluctuations in a trans-Saharan insect migrant - Hu, Gao (Nanjing Agricultural University. Department of Entomology) ; Stefanescu, Constantí (Centre de Recerca Ecològica i d'Aplicacions Forestals) ; Oliver, Tom (University of Reading. School of Biological Sciences) ; Roy, David B. (Uk Centre for Ecology and Hydrology) ; Brereton, Tom (Butterfly Conservation) ; Van Swaay, Chris (Dutch Butterfly Conservation) ; Reynolds, Don R. (University of Greenwich. Natural Resources Institute) ; Chapman, Jason W. (Nanjing Agricultural University. Department of Entomology)