Objective The aim of this study is to evaluate the potential resistance level of pine forests in Aba Prefecture to pine wilt disease, providing a scientific basis for the establishment of a preventive technical system to cope with the risk of future pest invasion.

Methods A total of 144 samples (72 pine wood and 72 pine needle samples) from forest areas in Li County and Jiuzhaigou County were collected, 36 samples from Li County (18 pine wood and 18 pine needle samples) were treated via trunk injection with 5% abamectin emulsifiable concentrate (treatment group), while another 36 samples received no treatment (control group). The same treatment and control groups were established for the samples from Jiuzhaigou County, resulting in a total of 72 samples in the treatment groups and 72 samples in the control groups. Diseases and pests data were derived from evaluative datasets. The water content, resin content, chlorophyll content and the contents of four volatile terpenes (α-pinene, β-pinene, D-limonene, and α-caryophyllene) of the samples were determined using National Standard Methods of China combined with gas chromatography. Principal component analysis was used to screen key resistance indicators, and systematic clustering was employed to classify resistance levels.

Results  (1) The core resistance indicators, namely resin content, needle α-pinene content, needle β-pinene content, and needle chlorophyll content, exhibited a cumulative contribution rate of 78.62%. The high resistance thresholds for the treatment group were revealed as follows: resin content ≥18 mg·kg⁻¹, needle α-pinene content ≥800 mg·kg⁻¹, needle β-pinene content ≥200 mg·kg⁻¹ and chlorophyll content ≥1.5 mg·g⁻¹, with the mean values of each indicator being significantly higher than those of the control groups (P<0.05). (2) The 144 samples were classified into four resistance levels: high resistance (8.33%), moderate resistance (41.67%), susceptible (45.18%), and highly susceptible (4.82%). The proportion of high-resistance samples in the treatment group (27.78%) was significantly higher than that in the control group (5.56%), while the proportion of susceptible and highly susceptible samples (16.67%) in the treatment group was significantly lower than that in the control group (44.45%). (3) Based on the resistance classification and the efficacy of chemical treatments, a technical system integrating “graded monitoring, chemical induction, Monochamus alternatus control and stand optimization” was established. This system increased the resin content in susceptible stands by 32.6%～45.8%, reduced the population density of M. alternatus by 68.3%, and decreased the risk assessment results derived from core resistance indicators by 72.5%.

Conclusion This study identified the core indicators and thresholds for the resistance of pine forests in Aba Prefecture to pine wilt disease, confirmed that treatment with 5% abamectin emulsifiable concentrate significantly enhanced pine resistance, and established a preventive monitoring and pre-control technical system. The results provide scientific support for preventing the invasion of pine wilt disease and protecting the pine forest resources in Aba Prefecture.