Physiological Adaptation Strategies of the Interaction Defense Between Larvae of <em>Megastigmus sabinae</em> and the Host <em>Juniperus przewalskii</em>

作者：Huike Yao, Jianxin Zeng, Yahui Li, Dong Lv, Min Chen · 发表于：Preprints.org · 年份：2025 · DOI：10.20944/preprints202510.0439.v1 · 被引用次数：1 · 研究领域：Forest, Soil, and Plant Ecology in China

Juniperus przewalskii Komarov, an endemic conifer in the high-altitude mountains of the Qinghai-Tibet Plateau, develops its cones in a synergistic manner with the oligophagous pest Megastigmus sabinae Xu et He (Hymenoptera: Torymidae), forming a highly specialized interaction system. However, the physiological adaptation mechanisms underlying this interaction remain unclear. Feeding by M. sabinae larvae significantly induced defense responses in J. przewalskii cones. During the early instars (2nd~3rd) of M. sabinae larvae, infested J. przewalskii cones upregulated cone protein content (48.91%; 3rd instar), significantly enhanced peroxidase (POD) activity (71.10%; 2nd instar), and specifically enriched coumarins and cinnamaldehyde derivatives (2nd instar) to increase M. sabinae larvae metabolic costs. In later instars (4th~5th) of M. sabinae larvae, the infested cones downregulated starch content (29.69%; 4th instar), reduced phenylalanine ammonia-lyase (PAL) activity (57.34%; 4th instar), and accumulated steroid derivatives to suppress larvae development. Conversely, M. sabinae larvae demonstrated unique adaptive strategies: pre-activating glutathione S-transferase (GST) as an antioxidant defense system during early instars and significantly elevating three digestive enzyme activities in later stages to overcome host multi-layered defenses. Juniperus przewalskii counters pest infestation through dynamic nutrient modulation, temporal activation of protective enzymes, and a mul...