Biological control of Congress Grass in NE India using Mexican Beetle
- A report -

Prof N Irabanta Singh & Dr Sushil Kumar *

Parthenium hysterophorus at Salem, Tamil Nadu :: Pix - Wikipedia/Thamizhpparithi Maari

Introduction: The congress grass ( Parthenium hysterophorus L. ) has been considered as one of the worst weeds responsible for causing health hazards in human being and animals besides loss to crop productivity and plant biodiversity. This weed is of global significance occurring in Asia( Bangladesh, India, Israel, Pakistan, Nepal, Southern China, Sri Lanka, Taiwan and Vietnam), Africa ( Ethopia, Kenya, Madagascar, Mozambique, South Africa, Soralie, Swizerland and Zimbabwe), Australia and Pacific ( New Califonia, Papua, New Guinea, Seychells and Vanuatu).

It was first reported in India in 1955 and now occurs throughout the country including North East India. The senior author had surveyed areas infested with Parthenium hysterophorus L. along the railway tracts and roadside of National and State highways in the North Eastern State of India. Parthenium was found to be grown luxuriantly in all the selected National and State Highways of North East India (Singh,2012).

Biological Control: It does not advocate complete eradication of the unwanted organism, but rather mean to maintain its population at lower than average that would occur in the absence of the bio-control agents. Biological control of Parthenium through insects has gained momentum in India in 1980s with publication of more reports about the indigenous biogents infesting Parthenium. Among the number of biological control agents, leaf feeding beetle, Zygogramma bicorolata Pallister (Coleoptera: Chrysomelidae) has proved to be effective in controlling Parthenium.

Mexican beetle: The Mexican beetle (Zygogramma bicolorata Pallister ( Coleoptera: Chrysomalidae) is a host specific leaf feeding beetle and proved successful for control of Parthenium hysterophorus L. The beetle was imported by Indian Institute of Horticultural Research (IIHR), Bangalore from Mexican substation of Commonwealth Institute of Biological Control ( CIBC). The safety to this beetle to the cultivated crop land was confirmed by detailed host specificity test under quarantine measure and considered as monophagus. The adult and larvae both feed the apical meristem and newly emerging Parthenium leaves.

Release of Mexican beetles in North East India:

Under Department of Biotechnology, Govt. of India's Twinning R & D Programme on Parthenium Management in NER, the present writers along with their research scholars releases 35,000 beetles in N.E. region during August and September, 2015. The details are given below in Table I:

Table I : Mexican Beetles released in different states of the North East India for the management of the Congress grass (Parthenium hysterophorus L.)

Post Released Impacts on Parthenium

On 3rd September, 2015, the senior writer along with Dr. L Kumar, R.A, attached to the Directorate of Weed Research ,Jabalpur released about 500 beetles on the roadside way to Tezpur University, Assam on their way to Itanagar, Arunachal Pradesh. While returning from Itanagar on 5th Sept., 2015 , the team revisited the same place and observed the beetles start mating and could observed two or three eggs on back side of Parthenium leaves.

Another observation was made on 7th Sept., 2015 at places where Mexican beetles were released on Parthenium growing area of Imphal East, Imphal West Districts, Manipur. It was observed that the eggs laid by Zygogramma bicolorata were at IIIrd and IVth instar stages. On the 10th September the IVth instar larvae start penetration into the soil for pupation. It will take about two weeks for emerging as an adult beetles. So, it is expected that the beetles will successfully multiply in the Parthenium growing areas of the NE India.

Discussion and Future Prospect

From our field observations, it was clear that the Mexican beetles ( Zygogramma bicolorata) Pallister can acclimatized in the climatic condition of NE India. As such we can utilized Mexican beetles for biological control of Parthenium in the rigion. Our field observation reveals complete invasion of road median flora by Parthenium resulting complete change over of the plant biodiversity in the National and State Highways of NE India.

Further, National Highway from Guwahati to Barapani, Meghalaya was completely changed by permanent absence of Parthenium on the either side of the Highway. These places were earlier found presence of Parthenium. But due to 4 lane road expansion from Guwahati to Silchar , Parthenium plants was absent.

Another peculiarity is absence of Parthenium in the Itanagar region of Arunachal Pradesh. Even at the Inter State bus stop at Itanagar, presence of Parthenium was not observed. This might be due to frequent land slide from Banderdewa to Itanagar. Moreover, due to frequent rainfall Parthenium seeds might have been washed down. However, thick population of Parthenium on either sides of the road were recorded at Banderdewa (Assam- Arunachal Pradesh border).

Conclusion:

It is expected that the Mexican beetle (Zygogramma bicolorata) Pllister, if released in huge quantity, will successfully multiply in the Parthenium growing areas in North East India and thereby control biologically further spread of Parthenium in NE India .