Climate as a possible driver of gall morphology in the chestnut pest Dryocosmus kuriphilus across Spanish invaded areas.

The alien cynipid wasp Dryocosmus kuriphilus Yasumatsu, 1951 is a serious pest of chestnuts (Castanea spp.) in Japan, North America and Europe, causing fruit losses while inducing galls in buds. While D. kuriphilus galls have a recognizable and roughly invariable globular shape, their size varies, reaching up to 4 cm in diameter. Among other factors, such variation may depend on different climatic conditions in different attacked areas. Here, we sampled and measured 375 D. kuriphilus galls from 25 localities throughout the Iberian Peninsula, including both cold and rainy northern (Eurosiberian) areas and warm and dry central-southern (Mediterranean) areas, to test the effects of climate and geographical location on gall morphology. The analyses indicate that gall mass and volume follow a pattern that can be associated with a climatic cline. In particular, the Eurosiberian galls were smaller than the Mediterranean galls according to differences in climatic conditions. In the southern areas, the greater insolation regime does not allow the chestnut trees to be distributed at lower altitudes, but the high rainfall and humidity regime of the mountain enclaves allow their presence. These conditions of insolation and precipitation seem to influence the morphological characteristics of the galls of D. kuriphilus.

Phylogenetic relationships of Iberian Aphodiini (Coleoptera: Scarabaeidae) based on morphological and molecular data.

A phylogeny of Iberian Aphodiini dung beetles was reconstructed based on morphological and molecular data. The data set included a total of 84 variable characters from wing venation, mouthparts, genitalia, and external morphology, as well as mitochondrial partial cytochrome c oxidase I (COI), complete tRNA-Leu (UUR), and partial cytochrome c oxidase II (COII) gene nucleotide sequences (1210 positions). Phylogenetic trees based on molecular data were relatively more resolved than those based on morphological characters. The Bayesian analysis of combined molecular and morphological data provided resolution not achieved by each data set separately. Ammoecius and Aphodius are the first lineages that branch off from the tree, followed by Acrossus, Nimbus, and Heptaulacus. The remaining studied taxa are recovered in a more derived clade that lacks internal resolution. Reconstructed trees based on molecular data showed relatively short internal nodes that were weakly supported. Such pattern may reflect a rapid radiation at the origin of the tribe Aphodiini, but also saturation of mutational changes. Several tests were conducted to discern between both competing hypotheses, as well as to assess the effect of incomplete taxon sampling.