Be aware of a new threat Parthenium hysterophorus L: A serious headache

by: Subodh Khanal, Conservation Ecologist

Preferred Scientific Name
• Parthenium hysterophorus L.

 Preferred Common Name
• parthenium weed Other Scientific Names
• Argyrochaeta bipinnatifida Cav.
 • Parthenium lobatum Buckl.
 • Villanova binnatifida Ortega

International Common Names
• English: barley flower, bastard feverfew, broomweed, congress grass, congress weed, dog flea weed, mugwort, Santa Maria feverfew, whiteheads, wormwood
 • Spanish: ajenjo cimarron, amargosa, camalote, escoba amarga, hierba amargosa, istafiate, requeson
• French: parthenium matricaire
 • Portuguese: mentruz

 Local Common Names
• Brazil: coentro-do-mato, fazendeiro, losna-branca
 •Caribbean: feverfew
 • Cuba: cofitillo
 • Ethiopia: arama-kuba, arama-sorgo, biyabassa, chebchabe, dayessa, faramssissa, kalignole, qinche, terekabi
 • India: carrot weed, chatak chandani, gazar ghas, osadi
 • Jamaica: whitetop
 • Pakistan: babyflower, gandhi booti, lewanai bhang
 • USA: false ragweed, ragweed parthenium
 • Nepal: gajar ghar, congress jhar, maobadi jhar

 General information:

•  is an aggressive ubiquitous annual herbaceous weed with no economic importance 
•  Commonly known as ‘altamisa’, carrot grass, bitter weed, star weed, white top, wild feverfew, the “Scourge of India” and congress grass. 
•  In Bardia and adjoining region it is also called as Maobadi grass.
•  believed to have been introduced into India as contaminants in PL 480 wheat (Public Law 480 passed in 1954 to give food grains to developing countries for eliminating starvation and malnutrition) imported from the USA in the 1950s. 
•  And from India it is believed to come into Nepal. 
•   Many people confuses it with artemesia (tite pati) and use it for various purpose which may be very harmful practice. 

 Chemical analysis of P. hysterophorus

•  all its parts including trichomes and pollen contain toxins called sesquiterpene lactones (SQL). 
•  Maishi et al. (1998) reported that P. hysterophoruscontains a bitter glycoside parthenin, a major sesquiterpene lactone. 
•  Other phytotoxic compounds or allelochemicals are hysterin, ambrosin, flavonoids such as quercelagetin 3,7-dimethylether, 6-hydroxyl kaempferol 3-0 arabinoglucoside, fumaric acid. P-hydroxy benzoin and vanillic acid, caffeic acid, p courmaric, anisic acid, p-anisic acid, chlorogenic acid, ferulic acid, sitosterol and some unidentified alcohols 
•  Parthenin, hymenin and ambrosin are found to be the culprits behind the menacing role of this weed in provoking health hazards
•  Gupta et al. (1996) identified a novel hydroxyproline-rich glycoprotein as the major allergen in P. hysterophorus pollen. 
•  Chhabra et al. (1999) discovered three ambrosanolides from the chloroform extract of this weed. The structure is similar to inject juvenile hormone.

Health hazards to humans and livestock

• Affecting food and fodder crops, since the pollen and dust of this weed elicit allergic contact dermatitis in humans (Gunaseelan 1987; Morin et al. 2009).
•  Parthenium hysterophorus has been reported to cause with watery eyes, swelling and itching of the membranes of the mouth and nose, constant coughing especially at night, continually running nose and sneezing, itching of the roof of the mouth and fatigue.
•  This weed is considered to be a cause of allergic respiratory problems, contact dermatitis, mutagenicity in human and livestock. 
•  Dermatitis is a T cell-mediated immune injury and the disease manifests as itchy erythematous papules and papulovesicular lesions on exposed areas of the body 
•  Effects have been related to cytotoxicity of the sesquiterpene lactone parthenin (Narasimban et al. 1984).
•  Persons exposed to this plant for prolonged period manifest the symptoms of skin inflammation, eczema, asthma, allergic rhinitis, hay fever, black spots, burning and blisters around eyes.
• Parthenium hysterophorus also causes diarrhoea, severe papular erythematous eruptions, breathlessness and choking (Maishi et al. 1998). 
• Exposure to P. hysterophorus pollens causes allergic bronchitis (Towers and Subba Rao 1992).
•  Ramos et al. (2001) assessed the mutagenic potential of a crude extract of P. hysterophorus in theSalmonella/microsome (Ames) assay and the mouse bone marrow micronucleus test. 
• Eczema herpeticum is reported to complicate parthenium dermatitis. Sriramarao et al. (1993) 
•   Exposure to P. hysterophorus also causes systemic toxicity in livestock (Gunaseelan 1987). 
• Alopecia, loss of skin pigmentation, dermatitis and diarrhoea has been reported in animals feeding on P. hysterophorus. Degenerative changes in both the liver and kidneys and inhibition of liver dehydrogenases have been reported in buffalo and sheep (Rajkumar et al. 1988). 
• The milk and meat quality of cattle, buffalo and sheep deteriorate on consumption of this weed (Lakshmi and Srinivas 2007) and is not recommended to drink. 
•  Significant reduction in rat WBC count after oral treatment of Parthenium extract signifies its immune system weakening ability (Yadav et al. 2010)

Reducing agricultural and pasture productivity

•   Singh et al. (2003) explored the allelopathic properties of unburnt (UR) and burnt (BR) residues of P. hysterophorus on the growth of winter crops, radish and chickpeas.
•  BR extract was more toxic due to its highly alkaline nature. Growth studies conducted in soil amended with UR and BR extracts revealed phytotoxic effects towards test crops, UR being more active than BR unlike crude extracts
• Parthenin has also been reported as a germination and radicle growth inhibitor in a variety of dicot and monocot plants and it enters the soil through the decomposing leaf litter (Gunaseelan 1998). 
• Burning of P. hysterophorus in fields reduced germination, biomass growth, plumule and radicle length of Phaseolus mungo (Kumar and Kumar 2010). 
•  Poor fruiting of leguminous crops and reduction in chlorophyll content of crop plants were observed in P. hysterophorus-infested fields (Lakshmi and Srinivas2007). 
•  Parthenium hysterophorus played role as alternate host for crop pests functioning as an inoculum source. This weed has been reported to serve as a reservoir plant of scarab beetle, a pest of sunflower. 
•  Parthenium hysterophorus invasion causes changes in above-ground vegetation and below-ground soil nutrient contents, disturbing the entire grassland ecosystem in Nepal as reported by Timsina et al. (2010). 
•  Parthenium hysterophorus is a serious invasive weed of pasture systems, reducing pasture productivity 90% (Evans 1997). 
•  Crop production is drastically reduced owing to its allelopathy. Also aggressive dominance of this weed threatens biodiversity. Biodiversity loss due to P. hysterophorus 
•  potential to disrupt the natural ecosystems 
•  It has been reported to be causing a total habitat change in native Australian grasslands, open woodlands, river banks and flood plains (Lakshmi and Srinivas 2007). 
•  These weeds rapidly invade new surroundings often replace the indigenous species and pose a serious threat to biodiversity in India. 
•  The more vigorous mode of reproduction and the possession of an array of secondary metabolites give the weed the status of invasive alien species. 

 Control:

• Mechanical, chemical and biological control strategies have been proved futile individually to curb proliferation of P. hysterophorus. 
•  public awareness has to be developed and participatory approach to control the invasive weeds should be adopted. 
•  need to encourage the research on the utilization potential of this weed and to evaluate its efficacy on field trials 
•  joint efforts of researchers, farmers, governmental and non-governmental agencies. 
• Nanomedicine, biopecticide, green manure potential, agent for bioremediation of toxic metals and dyes, herbicide, cheap substrate for enzyme production and source of biogas are some of the recently discovered implications of P. hysterophorus. 
•  Eradication of P. hysterophorus by burning, chemical herbicides, eucalyptus oil and biological control by leaf-feeding beetle, stem-galling moth, stem-boring weevil and fungi have been carried out with variable degrees of success.