Baryscapus dioryctriae is a pupal endoparasitoid of many Pyralidae pests and has been used as a biocontrol agent against insect pests that heavily damage the cone and seed of the Korean pine. The olfactory system of wasps plays an essential role in sensing the chemical signals during their foraging, mating, host location, etc., and the chemosensory genes are involved in detecting and transducing these signals. Many chemosensory genes have been identified from the antennae of Hymenoptera; however, there are few reports on the chemosensory genes of Eulophidae wasps. In this study, the transcriptome databases based on ten different tissues of B. dioryctriae were first constructed, and 274 putative chemosensory genes, consisting of 27 OBPs, 9 CSPs, 3 NPC2s, 155 ORs, 49 GRs, 23 IRs and 8 SNMPs genes, were identified based on the transcriptomes and manual annotation. Phylogenetic trees of the chemosensory genes were constructed to investigate the orthologs between B. dioryctriae and other insect species. Additionally, twenty-eight chemosensory genes showed female antennae- and ovipositor-biased expression, which was validated by RT-qPCR. These findings not only built a molecular basis for further research on the processes of chemosensory perception in B. dioryctriae, but also enriched the identification of chemosensory genes from various tissues of Eulophidae wasps.

Baryscapus dioryctriae Yang & Song sp. nov. (Hymenoptera: Eulophidae), a gregarious pupal and larval endo-parasitoid of Dioryctria pryeri Ragonot and Dioryctria abietella Denis & Schiffermüller (Lepidoptera: Pyralidae) is described and illustrated. The hosts are serious pests of the cones, seeds, and twigs of Pinus koraiensis Sieb. & Zucc., a predominant forest tree species in the northeastern China. The parasitoid has potential as a biocontrol agent for the pests, as an average parasitism rate of 19.5% has been observed and 87.7 parasitoid adults (range 41–138) emerge from a single host. Detailed photographs of the key characters of the female and male of the new species are provided. Type specimens were deposited in Insect Museum, Chinese Academy of Forestry, Beijing, and the Insect Collection of Jilin Provincial Academy of Forestry, Changchun, Jilin Province, China, as well as China National Insect Collection at Institute of Zoology, Chinese Academy of Sciences, Beijing.

Hazel (Corylus avellana) is easily attacked by Curculio nucum L. To better understand the physiological mechanisms underlying the different resistance of cultivars to C. nucum, we determined the insect-resistant compounds, plant hormones contents, and enzyme activities in the nutshells of three hazel cultivars (DW, B21, and MZ) before (preexisting defense) and after (induced defense) C. nucum chewing. The findings demonstrated that the resistance of three hazel cultivars to C. nucum differed significantly (p < 0.05): the damage rate of MZ with 17.57% was highest, followed by DW (11.23%), and then B21 (7.15%). The contents of insect-resistant compounds (total terpenoid, tannin, total phenol, flavonoids, cellulose, and lignin) varied with hazel cultivars, both before and after C. nucum chewing, except for cellulose and lignin before induction. The level of plant hormones and defense enzyme activities of hazelnut enhanced due to C. nucum induction. Pearson correlation results revealed that the hazelnut damage rate was significantly negatively correlated with jasmonic acid (JA) (R2 = 0.812), SOD (R2 = 0.671), salicylic acid (SA) (R2 = 0.878), and terpenoids (R2 = 0.774), and significantly positively correlated with flavonoids (R2 = 0.696), celluloses (R2 = 0.501), POD (R2 = 0.758), and abscisic acid (ABA) (R2 = 0.978). The hazelnut defense to C. nucum was negatively related to cellulose contents, and not to lignin contents, but was significantly positively related to the ratio of cellulose-to-lignin (R2 = 0.703). Our results suggested that the hazel against C. nucum attack responded by improving plant hormones contents and enzyme activities in the nutshells. A particular cellulose-to-lignin ratio provides the most effective physical structural defense properties in the nutshells.