Testing the ‘plant domestication-reduced defense’ hypothesis in blueberries: the role of herbivore identity

Abstract

Domestication is predicted to reduce resistance of agricultural crops against insect herbivores; however, its impact on herbivores with different feeding modes and evolutionary histories needs investigation. To this end, we conducted greenhouse experiments to explore the effects of domestication of blueberries (Vaccinium corymbosum), a crop native to North America, on the performance of two chewing herbivores [the native Sparganothis fruitworm (Sparganothis sulfureana (Clemens)) and non-native gypsy moth (Lymantria dispar L.)], and one piercing-sucking herbivore [the blueberry aphid (Illinoia azaleae (Mason))]. Lymantria dispar performed better (i.e., larvae gained more mass, damaged more leaves, and had greater survival) on cultivated V. corymbosum than on its wild counterpart. In contrast, domestication had no impact on the native S. sulfureana larval mass, consumption, and survivorship. Domestication increased survivorship, but not offspring production, of the aphid I. azaleae. To examine changes in plant chemistry due to domestication, we measured phenolic and nutrient (macro- and micro-elements) content in wild and cultivated V. corymbosum leaves. Although there were no differences in total phenolic content, two compounds were absent, while two were at lower and one at higher concentration in domesticated than in wild plants. Wild V. corymbosum leaves had higher amounts of phosphorus, sulfur, and sodium than cultivated leaves; the opposite was found for aluminum. While our findings provide support for the ‘plant domestication-reduced defense’ hypothesis, the effects of domestication were dependent on feeding modes and adaptations of the herbivores such that the non-native chewing species was more positively affected than the chewing and the piercing-sucking natives.