Phytochemical screening, GC-MS profiling of invasive cocklebur (Xanthium strumarium)-insect-pathogen interaction and simulated volatile chemical signaling at Northeast China

Invasive cocklebur (Xanthium strumarium) is characterized by its excellent genetic and ecological plasticity, ability to spread in agriculture crops. There is a dire need to locate useful management strategies to control this invasive weed at diversified latitudinal gradients. In ecology, there is weak evidence that the damage caused by the natural enemy varies with latitudes. Therefore, we investigated this evidence with the help of transect quadratic ecological sampling method which was conducted randomly at ten different sites of Northeast China. Overall, significantly high infestation of gall-forming insect (Epiblema strenuana) was observed on Xanthium leaves (21.16%) at 41.51279°N, followed by 40.2241°N latitude. Similarly, there was a significantly high abundance of Epiblema infestation (7.3) with high damage (3.88%) at 41.51279°N and 40.12749°N latitude. Likewise, the fungal abundance (5.6) of rust i.e. Puccinia xanthii (presenting 16.23% attack) was dominated significantly at 41.51279°N. Hence, high pathogen infection rate (8.97%) was detected at 40.2241°N. On the other hand growth parameters, i.e. plant height (cm), stem diameter (mm) vary with latitude and longitudinal trends. In our experiment, of plant natural enemy interaction provides the evidence-based indication the Epiblema abundance, was diversified at 41.51279°N, and P. xanthii infection was most frequent at 40.22411°N latitudes. This study provides an evidence-based indication that natural enemy pressure varies with latitude, however this investigations gave valuable information that insect and phytopathological fungus having biological control potential against Xanthium strumarium invasive weed. Secondly, phytochemical qualitative and chemical signaling through Gas Chromatography-mass spectrometry (GC-MS) executed the presence of flavonoids, phenols, saponins, alkaloids, terpenoids, nitrogen (N), sulpher (S), silicon (Si) containing compounds in both treated and controlled leaves that defend against Puccinia xanthii. Fascinatingly, all X. strumarium populations collected from different latitudes possess similar compositions. In interaction mechanism, plant known to omit volatile organic compounds in response to attack of natural herbivores. The leave chemical profiling suggested that the influence of fungus attack on invasive weed brought different changes in chemical infrastructure of leave and these chemicals also play a vital role in the food web. After attack of these biological control agents, plants exhibits passionate compound reprogramming within the leaf naturally that act upon in defense systems.Author summaryThe study was conducted to observe the environmental impact on the trend of insect, invasive weed and pathogens.There was a significant dominance of gall-forming insect on invasive Xanthium weed at all locations.Puccinia xanthii infected more than 16% plantationPlant growth had significant variation at various longitudes and latitudes.The abundance of insect was positively linked with different environmental factors and Xanthium plant.The results of GC-MS suggested that Puccinia xanthii infected (treatment) leaves covered maximum area (%) compared to control treatments due to breakdown of the chemical compounds that proved our hypotheses that volatile organic compounds altered infrastructures of the leave chemistry that led to activeness of plant defensive chemicals resulted invasion success.