Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, Kórnik, 62-035, Poland.
Faculty of Biological Sciences, University of Zielona Góra, Szafrana 1, Zielona Góra, 65-516, Poland.
J Plant Res. 2023 Jul;136(4):527-534. doi: 10.1007/s10265-023-01462-8. Epub 2023 May 3.
Oaks serve as host plants for numerous insects, including those forming galls. Galls induced on oaks are completely dependent on leaf resources. Many other folivores damage veins of leaves, which may result in cutting galls off from sources of assimilates, nutrients and water. We hypothesised that the disruption of the continuity of leaf vascular tissues stops gall development, leading to the death of the larva. Leaves of sessile oak (Quercus petraea) with Cynips quercusfolii galls in the initial stage of development were marked. The diameter of the galls was measured, and the vein on which the gall was present was cut. Four experimental treatments were established: control - with no cutting, cutting the vein distal to the gall relative to the petiole, cutting the vein basal to the gall and cutting both sides. The average survival rate (live galls at the end of the experiment including healthy larvae, pupae or imagines inside) - was 28.9%. The rate varied depending on the treatment and was 13.6% in the treatment with the vein cut on both sides and about 30% in the remaining treatments. However, this difference was not statistically significant. The growth dynamics of galls are highly dependent on the experimental treatment. The largest galls grew in the control treatment, and the smallest galls were in the treatments with the veins cut on both sides. Unexpectedly, even cutting veins on both sides did not result in the immediate dieback of the galls. The results suggest that the galls are very strong nutrient and water sinks. The functions of the cut vein are likely taken over by other lower-order veins, allowing nourishment of the gall to complete larva development.
橡树是许多昆虫的宿主植物，包括形成虫瘿的昆虫。在橡树上诱导的虫瘿完全依赖于叶片资源。许多其他食叶动物会损伤叶脉，这可能导致虫瘿与同化产物、养分和水分的来源切断。我们假设破坏叶片维管束的连续性会阻止虫瘿发育，导致幼虫死亡。对处于发育初期的栓皮栎（Quercus petraea）带卷叶虫瘿的叶片进行标记。测量虫瘿的直径，并切割存在虫瘿的叶脉。建立了四个实验处理：对照-不切割、相对于叶柄切割虫瘿远端的叶脉、切割虫瘿基部的叶脉以及切割两侧。平均存活率（实验结束时仍存活的虫瘿，包括内部健康的幼虫、蛹或成虫）为 28.9%。存活率因处理而异，两侧叶脉切割处理的存活率为 13.6%，其余处理的存活率约为 30%。然而，这种差异没有统计学意义。虫瘿的生长动态高度依赖于实验处理。最大的虫瘿在对照处理中生长，最小的虫瘿在两侧叶脉切割处理中。出乎意料的是，即使两侧叶脉都被切割，虫瘿也不会立即枯萎。结果表明，虫瘿是非常强大的养分和水分汇。被切割的叶脉的功能可能被其他低级叶脉接管，从而使虫瘿能够完成幼虫的发育。
