Cuticular Hydrocarbons of Six Geographic Populations of Ips subelongauts in Northeastern China: Similarities and Evolutionary Hints
by
Yuge Zhao
1,†, 
Chao Wang
3,†,
Xinmeng Liu
1,
Xu Lin
1,
Dongdong Chu
2,
Junyi Ding
1,
Xiangbo Kong
2,* and
Dafeng Chen
1,* 1
State Forestry and Grassland Administration Key Laboratory of Silviculture in Downstream Areas of the Yellow River, College of Forestry, Shandong Agricultural University, Tai’an 271018, China
2
Key Laboratory of Forest Protection of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
3
College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271018, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work as first authors.
Insects 2025, 16(4), 384; https://doi.org/10.3390/insects16040384
Submission received: 12 March 2025
/
Revised: 29 March 2025
/
Accepted: 1 April 2025
/
Published: 3 April 2025
(This article belongs to the Special Issue Beetles in Integrative Entomology: Biology, Taxonomy, and Conservation)
Simple Summary
The Ips bark beetles are serious wood-boring pests. Accurate and convenient identification of these pests is crucial for forest protection. This study characterizes the cuticular hydrocarbons (CHCs) of I. subelongatus in northeastern China, revealing both similarities and differences among populations. The phylogenetic tree constructed using CHCs can distinguish I. subelongatus from other bark beetle species, aligning with the nucleic acid-based phylogenetic tree. CHCs are expected to serve as a chemotaxonomic marker for I. subelongatus.
Abstract
The Asian larch bark beetle, I. subelongatus Motschulsky, is a severe pest of various Larix species in its natural range. This study reports the degree of similarity among cuticular hydrocarbon (CHC) profiles of six populations of I. subelongatus in northeastern China. Thirty individual or isomeric mixtures of hydrocarbons were identified by solid-phase microextraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS). The hydrocarbon components consist of straight-chain alkanes, alkenes, and methyl-branched hydrocarbons with carbon chain lengths ranging from 24 to 31. Among these, four CHCs (n-C25, 9-C27:1, n-C27, and 3-meC27) can serve as chemotaxonomic markers to identify I. subelongatus. No qualitative differences were detected between males and females in any of the six populations, but significant quantitative differences were observed in some CHCs. Phylogenetic analysis based on CHC profiles showed only minor differences compared to analysis based on partial mtDNA COI sequences regarding bark beetle species affinity. These results establish a rapid chemotaxonomic method and provide a basis for further investigations into the functions of CHCs in I. subelongatus.
