author(s)
RK Gupta, Kamlesh Bali, Suheel Ahmad Ganai and R Kour

abstract
Invasive weeds establish in communities because they are better competitors than natives in absence of their natural herbivores. However, native arthropods may also evolve to adapt and harbor the invader affecting its dominance. Hence native arthropod fauna associated with Parthenium hysterophorus L. was studied and their role for weed suppression was assessed. A random survey undertaken in Jammu and Kashmir, India showed the presence of twenty one resident arthropods species harbouring this weed. Among these, three were of exotic origin already introduced in India while the remaining were native species. Therefore, we preferred the term resident arthropods. The most devastating polyphagous pests like Spilosoma obliqua, Phenacoccus solenopsis, Pseudococcus comstocki and Tetranychus uriticae completed their life cycle on the weed host without any significant reduction in their fitness attribute such as body weight and fecundity. The relationship between population of weed and resident insect was density dependent. Therefore, it is assumed that increasing abundance of resident insect will restrict and reduce the weed population in coming years. Potential effect of these arthropods additionally uncovered that many of them could stifle this weed in term of reduction of the floral capacity and seed bank The yield infestation relationship was best explained by log linear equation with highly significant relationship and coefficient of determination exceeding 90.0 per cent in case of all the four major insects. With every unit increase in population of S. obliqia, P. solenopsis, P. comstocki and T. uriticae, flowers reduction of this weed decreased to the extent of 1.76, 1.33, 0.77 and 0.77 per cent, respectively. Further, in a field trial conducted over the five successive years, we found that herbivory by native insects became significant only in the third years onwards with reduced weed biomass (57.54%) and soil seed bank (36.95%) at the end of 5^th year when compared to insecticide treated plots (without herbivory). Our findings suggest that although these herbivores cannot be advocated for applied biological control, yet their ability to evolve and to restrict the invasive weed in nature cannot be ruled out.