Abstract
Anastrepha ludens (Mexican fruit-fly) is a highly polyphagous fruit fly species (Tephritidae) attacking wild and commercial fruit from Mexico to Panama. Here we report on a recent habitat and host range expansion as A. ludens lately started to attack apples (Malus domestica) in Mexico, a phenomenon likely influenced by global warming. We document natural infestations in apple-growing regions in the States of Nuevo León and Hidalgo, Mexico where A. ludens has started to attack the cultivars 'Golden Delicious', 'Rayada' and 'Criolla'. No infestations were found in the apple-growing region of Zacatlán, Puebla. To determine apple cultivar susceptibility to the attack of this emerging pest, we ran forced infestation assays in enclosed fruit-bearing branches in all three apple-growing regions and studied the metabolome of all fruit. A clear pattern emerged indicating that the cultivar 'Golden Delicious' was the most susceptible, with 'Criolla' exhibiting complete resistance in one location (Puebla). Although A. ludens can develop in this new host, development rates (egg-adult) and adult emergence were affected when compared with the performance in the natural host 'Marsh' grapefruit. Warmer temperatures and specific secondary metabolites of some apple cultivars are likely contributing to the territorial and host expansion of A. ludens.