Title: Scientists send weevils after water hyacinth
[234next.com 22 Aug 2010, by Emmanuel Ogala] -- Researchers have released
two species of weevils to eat up the water hyacinth in River Mono, Republic of
Benin. The weevils - Neochetina and N. Bruchi - are special species of weevils
that feed on water hyacinths only. Obinna Ajouno, a scientist with the
International Institute of Tropical (IITA) who is also a member of the research
team, said the two biological agents have proved to be effective control agents
of the water weeds.Water hyacinth (Eichhornia crassipes) often grows as
floating plants or mats, as islands of plants floating freely on the water, or
mixed with other vegetation on river banks.
It is expected that the project, if adopted in Nigeria, will tackle the
devastation caused by the water weed and free waterways for fishing and
transport. It will also drastically reduce the cost of removing water hyacinths
from Nigerian waterways, which is estimated to cost the country up to N1 billion
annually.
The released weevils were mass produced by the Department of Agriculture in
Porto-Novo, using start-up colony supplied by IITA, which also provided
technical assistance.
"Previous efforts by IITA and partners using bio-control agents against water
hyacinth, yielded success on the Oueme River eight years ago," Mr Ajouno said.
"However, the use of the weevils is the first of its kind. We are confident this
approach will produce results."
The project is part of the ongoing African Development Bank (AfDB), funded
ECOWAS integrated project for the control of aquatic weeds involving physical
removal, utilisation and biological control methods.
Participants in the project, which was initiated on July 30, 2010, included
the Department of Agriculture, the National Coordination Unit of the Benin
ECOWAS Water Weeds Project, the local communities and IITA.
Godwin Atser, the West African public communications officer of IITA said the
success of the project will rub off on other ECOWAS water ways including
Nigeria.
"In nutrient-rich waters such as in polluted ponds or lakes, it can grow so
quickly that the surface covered by the mats doubles every four to seven days,"
Mr Ajouno said.
Destructive weeds
The aquatic weed poses serious socioeconomic and environmental problems to
millions of people in riparian communities and limits development. For instance,
the Nigerian government budgeted N400 million in the 2009 budget to clear the
water hyacinth in Port Harcourt waterways only.
The weed obstructs electricity generation, irrigation, navigation, and
fishing; increases water loss resulting from evapo-transpiration; and
facilitates proliferation of such diseases as bilharzia.
In Sudan alone, a partial evaluation of socioeconomic costs of water hyacinth
estimates that annual water loss from evapo-transpiration over 300 km2 of canal
would be enough to irrigate more than 400 ha. Effects on navigation in the Nile
include 50 per cent higher running and maintenance costs and 30 per cent more
use of fuel.
The cost of chemical control alone, over 15 years, would have been in excess
of $19 million, according to the International Development Research Centre
(IDRC). Until 2000, the Mono River which borders Togo was free of water
hyacinth. Researchers are of the view that the weed might have been infested
through human activities. But Mr Ajouno says the impact of these biological
agents-(weevils) - in the Mono River system in the years ahead will be monitored
by regular field visits involving the collaborating institutions.