Biocontrol measures to manage Parthenium hysterophorus: Current paradigms, scope and relevance

Parthenium hysterophorus, a noxious weed of tropical America, had relocated to Indian plains and rapidly encroached on north-western Himalayas Mountain regions. Earlier, the plant was primarily found in wastelands, but it now thrives in cultivated fields, pastures, and roadsides. Parthenium weed threatens human and animal health, destroys vegetation, lowers the diversity of native plant groups and causes significant financial damage to individuals and their significance in numerous nations worldwide. Parthenin, a sesquiterpene lactone found in P. hysterophorus, is harmful to livestock and poses a serious health risk to people, e.g., dermatitis and skin rashes, emaciation, tissue rupturing, internal organ haemorrhages and death are the hazardous side effects. Several studies are being conducted to determine the most efficient and reasonable method to control this harmful weed worldwide, including physical, chemical and biological ones. The study revealed that biocontrol of P. hysterophorus was a cost-effective, safe and viable technique and poses no threat to non-target organisms, environment and biodiversity, e.g., some allelopathic plants are used to curb the growth of congress grass. The combined effects of biocontrol agents like insects, fungi, nematodes, snails, slugs, and competitive plants decrease the density and vigour of congress grass and increase its production. The work done over the past 20 years on screening and evaluating both insect and fungal agents and the actual and potential employment of natural enemies as traditional biological control agents has been discussed. The study concludes that biological control, because of its affordability, environmental safety and sustainability, could be a significant constituent of an effective strategy for managing weed.