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Archives (2003)
Fighting potato whitefly
the indigenous way
by Rita T. De la Cruz |
October-December
2003
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 For
a small insect like the whitefly, the damage that it inflicts
on crops is hard to imagine. They are often found in the leaf
undersides. As their name implies, they are white, powdery,
and soft-bodied insects. They measure about .5 to 1 inch.
Both early and adult stages are destructive to the plants.
They suck the sap of the plants and transmit viruses. Whiteflies
are prolific insects. The female whitefly can lay 25 eggs
in a day. Its life span could extend up to 36 days depending
on the temperature.
Whitefly infestation has become a major problem
in the Philippines, particularly in Region 10, since year
2000 when potatoes are grown throughout the year. The presence
of the whiteflies peaks during the dry season. The use of
insecticides is no longer effective as it encourages the build-up
of whitefly population. Due to lack of effective means to
control whiteflies, most farmers still resort to insecticides
that are both hazardous to human health and the environment.
The whitefly does not only attack potatoes but other commercially
important crops like squash, tomato, beans, cutflowers, and
ornamentals.
A group of researchers from the Northern Mindanao
Integrated Agricultural Research Center (NOMIARC) of the Department
of Agriculture (DA) saw the urgency to solve the problem.
According to them, whitefly management depends greatly on
the severity of damage to the crops and at what particular
stage they attack.
IPM experts and researchers have long recognized
the use of indigenous botanicals as alternative means to control
pests and insects. They are readily available, cheap and safe
to humans and the environment.
Botanical insecticides are derived from the
extracts of plants with active ingredients that are poisonous
to certain pests and insects. Even before the use of synthetic
insecticides, botanical insecticides have been used for centuries
and found to be useful and effective.
Botanical insecticides are processed into different
forms such as crude plant material, extracts or resins. The
crude plant material is usually ground in powder form and
applied in full strength or diluted with extenders like talcs
or clays among others. Another form is through extraction,
wherein the extract could be sprayed directly on the plants,
or through chemical preparation, which involves isolating
the active ingredient from plants.
Researchers from NOMIARC tried, tested, and
evaluated the efficacy of 13 types of indigenous botanicals
as potential insecticides against whitefly. Among these indigenous
botanicals are: madre de cacao leaves, eucalyptus leaves,
sunflower leaves, tobacco leaves, neem leaves, lagundi leaves,
adelfa leaves, dulaw rhizomes, panyawan vines, neem seeds,
atis seeds, hot pepper fruit, and tubli roots.
 Specifically,
the purpose of the study is to determine the level of effectiveness
of these indigenous botanicals in controlling whiteflies.
Evaluations were done using two conditions: laboratory and
screenhouse. The researchers also determined the influence
of these botanicals on crop yield.
Results of the experiment showed that certain
botanicals were able to reduce the population of the whiteflies.
Among the 13 plant extracts tested, four were evaluated to
be the most toxic against the whiteflies with fast-acting
effect both in the lab and screenhouse conditions. These are:
tobacco, hot pepper, dulaw rhizomes, and tubli. These botanicals
were transformed into plant extracts and used as sprays at
5% concentration.
Neem tree has an active ingredient called azadirachtin,
which can be extracted, from its seeds and leaves. This active
ingredient is responsible for killing whiteflies especially
during their earlier days. It repels the insects and deters
their feeding and growth process.
The nicotine in tobacco leaves is the toxic
ingredient that poisons the insects. It has a fast-acting
effect that disrupts the nervous system of the insect once
ingested. It is also helpful in fumigating pest-infested greenhouses
as it kills other soft-bodied insects. Aside from insects,
extracts of tobacco are also effective in controlling nematodes.
Tubli has rotenone, an active ingredient extracted
from its roots. It poisons the stomach of insects causing
them to lose appetite and die in a few hours after ingestion.
The substance is also deadly to fish. At a given concentration,
the extract of eucalyptus is effective in controlling the
bud infestation of whiteflies.
Meanwhile, the botanicals that lowered the
population of whiteflies with relatively slow-acting effect
are: neem leaves, neem seeds, madre de cacao, panyawan and
sunflower. Botanicals with the biggest return of investments
include those with 5% crude extracts from neem leaves, panyawan,
tobacco, sunflower, and hot pepper. 
Source: Evaluation of indigenous botanical
insecticides for the control of whitefly under greenhouse
condition by B.F. Tatoy, F.N. Abragan, F.C.Makabugto, J.B.Salvani,
C.T. Apiag, L.A. Ramos. DA-NOMIARC, Dalwangon, Malaybalay
City
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