Aromia bungii (Coleoptera: Cerambycidae) is an economically important wood-boring insect pest of stone fruit trees, particularly Prunus persica, in China. It has entered Japan and several European countries as an invasive species in recent years. It is difficult to control because of the cryptic feeding behaviour of larvae beneath the bark. Identification of repellent constituents from non-host plants has potential for use in management strategies against this beetle. Mentha spicata is cultivated extensively in Hebei Province (China) as a medicinal plant. Firstly, antennal responses of female A. bungii to M. spicata volatiles were evaluated by coupled gas chromatography-electroantennograms (GC-EAD), and then the EAD-active components were tested in semi-field trials. The results showed that A. bungii females were significantly repelled by myrcene, (S)-(+)-carvone, (E)-β-caryophyllene, and borneol compared with the control. The presence of myrcene (100 µL; 90% purity), (S)-(+)-carvone (200 µL; 96% purity), (E)-β-caryophyllene (500 µL; 98.5% purity), and borneol (800 µL; 80% purity) significantly reduced the perching rates of A. bungii females on both peach logs and leaves. Considering cost and commercial availability, we suggest that myrcene, (S)-(+)-carvone, and (E)-β-caryophyllene could be promising repellents against A. bungii females in the field.

Dastarcus helophoroides Fairmaire, a parasitic natural enemy widely used in the biological control of Monochamus alternatus Hope, possesses strong abilities to search for hosts and prey. To enhance the biological control efficacy of D. helophoroides against M. alternatus, this study systematically evaluated the effectiveness of enhancing control through methods such as drilling holes in lure logs and introducing D. helophoroides carrying Pyemotes zhonghuajia or Beauveria bassiana under controlled indoor conditions. The results showed that: (1) Releasing D. helophoroides eggs (after 30 days) and releasing adults (after 120 days) were both effective in controlling M. alternatus, with the best control effects achieved when 50 eggs/m and 3 adults/m were released. The release of adults took longer to show effects but had better results than the release of eggs in the later stages. (2) The location and number of holes drilled in lure logs significantly influenced the efficiency of D. helophoroides in searching for and parasitizing M. alternatus, while the diameter of the holes was not significant. Considering the highest control efficacy and minimizing damage to the tree, the optimal conditions were releasing D. helophoroides adults 2 cm above M. alternatus fecal holes, with 0.4 cm in diameter and 2 holes/m release density, which significantly promoted the invasion of D. helophoroides adults into the borer tunnels and increased the M. alternatus mortality rate. (3) Releasing D. helophoroides adults carrying P. zhonghuajia or B. bassiana significantly improves the control efficacy against M. alternatus. The higher the number of D. helophoroides adults released per log segment and the greater the quantity of P. zhonghuajia or B. bassiana that they carry, the higher the mortality rate of M. alternatus. After 60 days of release, the highest mortality rate of M. alternatus was observed in treatments where D. helophoroides (released at densities of 3 adults per meter of log segment) carried P. zhonghuajia (0.6 million/m) or were sprayed with B. bassiana (3 g/m). The synergistic effect of carrying P. zhonghuajia was evident, but the overall control efficacy of spraying B. bassiana was limited. In summary, optimizing drilling techniques and combining biological release strategies under laboratory conditions can significantly enhance the control efficacy against M. alternatus, providing data support for D. helophoroides future application in forest pest control.

Pinus massoniana Lamb. is an economically important conifer native to China. However, it is highly susceptible to the pine wood nematode (Bursaphelenchus xylophilus, PWN), the causal agent of pine wilt disease (PWD), resulting in substantial ecological and economic losses. To elucidate potential molecular defense mechanisms, 50 NAC (NAM, ATAF1/2, and CUC2) transcription factors (PmNACs) were identified in the P. massoniana genome. Phylogenetic analysis divided these PmNACs into seven subfamilies, and motif analysis identified ten conserved motifs associated with stress responses. Twenty-three genes were selected for expression analysis in various tissues and under exogenous salicylic acid (SA), methyl jasmonate (MeJA), and PWN infection. Six genes (PmNAC1, PmNAC8, PmNAC9, PmNAC17, PmNAC18, and PmNAC20) were significantly up-regulated by both hormonal treatment and PWN infection, implying their involvement in JA/SA-mediated immune pathways. Functional characterization showed PmNAC8 is a nuclear-localized transcription factor with autoactivation activity. Furthermore, transient overexpression of PmNAC8 in Nicotiana benthamiana induced reactive oxygen species (ROS) accumulation and necrotic lesions. Collectively, these results elucidate NAC-mediated defense responses to PWN infection in P. massoniana and identify candidate genes for developing PWD-resistant pine varieties.