HERBAL WAY TO COMBAT MOSQUITO By Melati Mohd Ariff

KUALA LUMPUR, Sept 24 (Bernama) - Despite rapid advances in medical
sciences during the past decades, mosquito-borne diseases like dengue, Japanese
encephalitis (JE), 'filiarisis', malaria and chikungunya continue to haunt
mankind.

This is due to the reason that the mosquito vectors as well as causative
agents like bacteria and fungi have developed resistance against the pesticides
and anti-microbial drugs.

Anti-microbial drugs that either kill microbes or prevent their growth.

"Dengue, which has spread across the globe, is caused by the breeding and
adaptation of the Aedes agyptii and Aedes albopictus mosquito.

"This is the reason why dengue is still rampaging in Asia", Forest
Research Institute of Malaysia's (FRIM) Dr Nor Azah Mohamad Ali told Bernama
here recently.

Dr Nor Azah is a senior researcher with medicinal plants programme at
FRIM's Forest Biotechnology Division.

According Dr Nor Azah the best move to curb the breeding of the mosquito is
to destroy its larva or through the use of insect repellents.

She said even though the chemicals are effective, some could be hazardous
apart from being ozone-depleting and continuous use could turn the mosquito
vectors resistant to insecticides.

Dr Nor Azah suggested the possibility of using herbs and spices, whose
essential oils are able to repel insects, be used in insecticides.

"As aroma play an important role towards controlling the insect's
behaviour, essential oils can be used as insect repellents," she said.

From FRIM's research, a number of essential oils demonstrates repellent
properties against the Aedes agyptii mosquito.

She said essential oils from other plants, reported to be able to repel
insects are that from geranium (Pelargonium citrosum), sandalwood (Aquilaria
malaccensis) and Sweet Basil (Ocimum spp).

"There are other aromatic species that can be found in the Malaysian
forest or that cultivated in parks for their medicinal properties and culinary
reasons. Essential oils from these species are also preferred by the essential
oil industry," said Dr Nor Azah who has been with FRIM since 1987.

Since the early 1990s, FRIM has carried out research on the potential for
their extracts to be used for various purposes.

"Our research is focused on the extraction process. We also make trips to
the jungle for random sampling of plants that contain essential oils.

"FRIM's efforts are among the earliest research work on essential oils in
Malaysia," she said.

According to Dr Nor Azah, since 1994, the research centered on the
production of essential oils that emit strong aroma.

"We found out that essential oils contain natural therapeutic properties
that can be used to repel insects apart from being used as deodorants," she
said.

When FRIM set up its medicinal plants division in 1995, the research work
is geared towards bioactivity work. Then, dengue was a frequent occurrence, she
said.

Dr Nor Azah said the use of various repellents to kill Aedes mosquito
could inevitably turn the insect to be resistant to such chemicals.

She said further research work is needed on scent-producing plants, which
can be utilised for the making of insect repellents and aromatic agents.

She said from studies held at FRIM, it was found that aroma-producing
plants exhibited their potential in repelling mosquito when tested on
Aedes aegyptii via the American Society Testing and Materials (ASTM) standard
E951-85.

Dr Nor Azah said the most effective essential oils discovered so far are
that from the citrus plants.

"Mosquito is repelled by certain aromas from essential oils. Our aim now
is to find the essential oils that can kill or knock down this insect," she
said.
She said the research conducted at FRIM is to also know more about these
therapeutic effects on, among others, the human skin.

"All ingredients, no matter how natural they are, would have side effects
if excessively used. Essential oils are not ideal for direct use (and) they
should be blended in the form of creams or lotions.

Dr Nor Azah also cautioned that some essential oils might cause allergies
to pregnant women.

Among the success chalked by FRIM on its research over essential oils is
the discovery of 'Deesrept' which contains one or a blend of essential oils
from the citrus family.

"This essential oil can be included in creams and lotions," she said.

Dr Nor Azah said the essential oil was extracted via hydro-distillation and
chemically purified to retain its quality.

"This natural herbal-based product comprises the essential oil that acts as
mosquito repellent apart from having aromatherapy effect.

"This aroma is really refreshing and helps us to unwind. FRIM's research
showed that this essential oil product is able to repel the mosquito to the
extent of killing it," said Dr Nor Azah.

This products could also be used as body sprays or air fresheners, she
said, adding that a Bumiputera firm is working on commercialising the product.

She said further research is needed to ensure non-toxicity and optimum
efficiency of the essential oils.

According to Dr Nor Azah, FRIM would carry out more research, as there are
still more of the 'untapped' medicinal plants in the country's forests.

Public awareness on alternative products for repelling mosquito is high
but there are only few of such products in the market due to limited resources
of raw materials, she said.