Rapid Adaptive Evolution of Ophraella Communa in New Low Temperature Environment

Abstract

\n Low winter temperatures are a severe environmental pressure for newly arriving insect species. Adaptive evolutionary changes in cold tolerance facilitate establishment of these species in new environments. Ambrosia artemisiifolia, a noxious invasive plant, is distributed from southern to northern China. As an effective biological control agent of A. artemisiifolia, Ophraella communa is mainly spread in southern China. Previously, O. communa successfully established stable populations in Beijing (39.98°N, 115.97°E) following introduction from Laibin (23.62°N, 109.37°E) in 2012. This means that O. communa has adapted the cold winter temperatures in Beijing. However, the mechanisms underlying its rapid evolution of cold tolerance remain unknown. We investigated the levels of cryoprotectants and energy reserves in adult O. communa from two latitudes. We found that higher levels of trehalose, proline, glycerol, total sugar, and lipid were accumulated in O. communa from high latitudes. We also identified five potential genes (Tret1a, Tret1b, Tret1-2, P5CS, and GST) responsible for regulating cold tolerance that were highly expressed in high latitudes. These genes were involved in trehalose transport, proline biosynthesis, and glutathione S-transferase activation. These changes in hybridization indicated facilitating adaptation to cold temperatures. Our results demonstrate the genetic basis underlying the rapid adaptation of cold tolerance in O. communa, which indicates its extension in regions of A. artemisiifolia distribution at higher latitudes. This implies that the specialist herbivores can often adapt to a new low temperature environment where their host plant exist by rapid genetic evolution.