A broad spectrum of host plant responses to the actions of the gall midge: case study of Robinia pseudoacacia L. and Obolodiplosis robiniae (Haldeman)

Abstract

This study aims to provide insights into plant-insect interaction during the formation and development of open gall structure on the leaves of Robinia pseudoacacia during gall formation by Obolodiplosis robiniae. This was the first time such far-reaching studies were performed at a biochemical and anatomical level. The gall wall is created from a few thick cells covered with epidermis. This parenchymatous nutritive tissue is rich in starch. Sclerenchyma only occurs around the vascular bundles as a result of the lignification of the parenchyma of the bundle sheaths. The level of reactive oxygen species (ROS) in the new structure was reduced and catalase activity was inhibited, which suggests another pathway of ROS decomposition – e.g. by ascorbate or glutathione peroxidase. The gall structure was combined with an increasing level of protein and non-protein thiols. Phenols seems to be a good protective factor; whose level was lower in infected leaflets. Levels of MUFA (monosaturated fatty acids) and SFA (saturated fatty acids) rose, probably as source of food for insects. The amount of fatty acid is positively correlated with the plant response. We detected that non infected leaflets produced C6:0 (hexanoic acid) and C8:0 (octanoic acid) fatty acids connected with odor. Changes in gall color as they develop are connected with photosynthetic pigments degradation (mainly chlorophylls) where the pathway of astaxanthin transformation to fatty acid is considered to be the most important process during gall maturation. Nutritive tissue is composed mainly of octadecanoic acid (C18:0) – a main source of food for O. robiniae.

The gall midge Obolodiplosis robiniae Haldemann (Diptera Cecidomyiidae) new invasive alien species in Europa – Review

“…However, most gallic species systematically belong to only four families of insects of three orders: Hemiptera (Adelgidae), Diptera (Cecidomyiidae) and Hymenoptera (Cynipidae and Eulophidae) (Csóka et al, 2017;Mirumian and Skuhravá, 2022). Galls are irregular growths of attacked plants caused by the plant's reaction to hormones and chemicals secreted by the larvae of these species (Molnár et al, 2009;Oates et al, 2016;De Araújo et al, 2017;Staszak et al, 2023). The galls provide feeding conditions for the larvae and protection against insecticides used in chemical treatments and against the attack of many zoophagous species (Molnár et al, 2009;Csóka et al, 2017).…”

Invasive leaf-mining moths (Lepidoptera, Gracillariidae) in Ukraine: ecology, degree of invasion

“…The protective enzymatic antioxidant system in the cell comprises a series of enzyme systems including peroxidases (BPODs) actively involved in the mechanisms of plant adaptation to both abiotic and biotic influences [9,17,25]. Being regulated a number of processes directly or indirectly related to plant resistance to insect pests, peroxidases can be induced in a number of plants in response to insect attack, and they act as an important component of the direct plant response to damage [26,27].…”