Colonization patterns of the red turpentine beetle, Dendroctonus valans （Coleoptera： Curculionidae）, in the Luliang Mountains, China

The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle in order to develop an effective monitoring and management strategy. In this study, the effects of hillside exposure （south- and north-facing）, host-tree locations according to relief （valley, mid-slope, and ridge-top） and tree diameters on RTB colonization were investigated in one valley （3 sites）. The results showed that （i） RTB clearly preferred colonizing pines growing on south-facing hillsides, especially in the valley; （ii） RTB preferred to colonize the pines growing at the valley rather than pines growing at mid-slope or on ridge-top; （iii） RTB preferred to colonize trees with large diameter over small and medium-sized pines; （iv） the attack density of RTBs （measured by pitch tubes/pine） was obviously higher on larger trees standing in the valley than other trees standing at other places. We conclude from RTB colonization patterns, that RTB prefers to attack large trees in the valley, which may be useful in developing a pest-management strategy.

Inheritance of social dominance is associated with global sperm DNA methylation in inbred male mice

Dominance relationships between males and their associated traits are usually heritable and have implications for sexual selection in animals.In particular,social dominance and its related male pheromones are heritable in inbred mice;thus,we wondered whether epigenetic changes due to altered levels of DNA methylation determine inheritance.Here,we used C57BL/6 male mice to establish a social dominance-subordination relationship through chronic dyadic encounters,and this relationship and pheromone covariation occurred in their offspring,indicative of heritability.Through transcriptome sequencing and whole-genome DNA methylation profiling of the sperm of both generations,we found that differential methylation of many genes was induced by social dominance-subordination in sires and could be passed on to the offspring.These methylated genes were mainly related to growth and development processes,neurodevelopment,and cellular transportation.The expression of the genes with similar functions in whole-genome methylation/bisulfite sequencing was also differentiated by social dominance-subordination,as revealed by RNA-seq.In particular,the gene Dennd1a,which regulates neural signaling,was differentially methylated and expressed in the sperm and medial prefrontal cortex in paired males before and after dominance-subordination establishment,suggesting the potential epigenetic control and inheritance of social dominance-related aggression.We suggest that social dominance might be passed on to male offspring through sperm DNA methylation and that the differences could potentially affect male competition in offspring by affecting the development of thenervous system.