Host specificity of phytophagous insects plays a critical role in the maintenance of plant diversity. However, a lack of approaches to identify the larvae of phytophagous insects, which usually have similar morphology, can lead to misinterpretation of their host ranges. Acorn weevils are seed-exploiting parasites of Fagaceae species, a dominant plant group in subtropical evergreen broad-leaved forests (EBLFs). Therefore, variation in their host specificity may profoundly influence plant diversity in this ecosystem. Here, we collected larvae of acorn weevils from 36 655 seeds of Fagaceae species in EBLFs in southeastern China and performed multiple operational taxonomic unit (OTU) delimitation analyses using one mitochondrial (COI) and two nuclear (ArgK and EF1-alpha) genes to reveal species composition of acorn weevils and assess the variation in host specificity among OTUs. We analysed the DNA barcoding sequences from 478 larvae and 4 adults of acorn weevils sampled from 17 common Fagaceae species (five genera) and detected 11 OTUs. Moreover, host range varied drastically among different OTUs, with Curculio bimaculatus being the most generalised. Our results revealed high diversity of acorn weevils and that strong variation in host specificity can even exist among OTUs in the same genus, addressing the need to distinguish different Curculio species before conducting forest management in EBLFs.

PREMISE OF THE STUDY:To quantify the population-level genetic characteristics of Cunninghamia lanceolata (Taxodiaceae), an important timber conifer, we developed 30 pairs of microsatellite primers based on the nuclear genome.METHODS AND RESULTS:Using the streptavidin-biotin capture system, we developed 14 polymorphic and 16 monomorphic microsatellites. Polymorphisms were detected in 14 loci using 94 individual trees that were collected from three C. lanceolata populations in Hubei and Zhejiang provinces and in Chongqing Municipality, China. There were three to 30 alleles per locus, and the observed and expected heterozygosities ranged from 0.0313-0.8333 and from 0.0313-0.9246, respectively. Cross-species amplification showed that two to seven polymorphic loci were functional in three of the five related species that were collected.CONCLUSIONS:Our newly developed microsatellite primers provide neutral molecular markers that are beneficial to future studies of population genetics and germplasm conservation of C. lanceolata.

Premise of the study: To estimate the genetic variation of Rhododendron ovatum (Ericaceae), a monoecious evergreen shrub, 23 microsatellite markers were identified from its nuclear genome. Methods and Results: We developed 16 polymorphic and seven monomorphic microsatellite primers using the biotin-streptavidin capture method. The 16 polymorphic loci were investigated further using 89 individuals sampled from three populations in China. The number of alleles per locus ranged from four to 30, indicating a high level of polymorphism. The observed heterozygosity varied from 0.1034 to 0.9333, while the expected heterozygosity ranged from 0.1016 to 0.9542. Of these polymorphic primers, 12 were found to be functional in R. simsii, a congeneric species of R. ovatum. Conclusions: Moderate to high levels of genetic variation were found in these microsatellite loci, indicating that they can be applied in future studies of Rhododendron genetic structure, contributing to forest management and conservation.