Journal of Tea Science Research. 2015, Vol. 5, No. 8, 1-7
2
thousands of eggs (Ahmed, 2005). Red spider mites
are responsible for depredation of yield and debilitation
of tea plants causing considerable crop loss. It has
been estimated that 9.57% crop loss occurred due
to this pest (Ali et al., 1994). Most of the valley circles
reported severe infestation of red spider mites, which
are more prevalent and alarming round the year for the
tea industry (BTB, 2014). The larvae, nymphs and
adult mites cause the damage. When the infestation is
severe in hot and dry weather, the whole leaf changes
to a bronze color as a result of feeding on chlorophyll
of leaves and the infested plants defoliate (Sana, 1989).
It may also be mentioned here that the red spider mite
prefers mature leaves, and young leaves are not
normally attacked, but in severe outbreaks when the
growth of the bushes checked, particularly under
conditions of drought, both young and mature leaves
may be equally attacked. Thus, drought accelerates the
mite infestation in tea plantation. Nowadays, drought
is a common phenomenon and therefore, infestation of
red spider mite is emerging threat to the tea industry
of Bangladesh.
To combat this mite problem different groups of
pesticides have been used in the tea fields since 1960.
Pesticides such as Sulphur, Ethion, Quinalphos,
Propargite, Abamectin, Dimethoate, Fenvalerate,
Fenpropathrin, Fenazaquin, Bifenthrin, Hexythiazox,
Spiromesifen and Fenpyroxymate etc. are the
commonly used miticides for the control of red spider
mite in tea plantation in Bangladesh (Mamun et al.,
2014). Indiscriminate use of chemical pesticides may
render the tea unsuitable for consumer & trade due to
residual effect and increase the cost of pest
management by developing resistance in the pest.
In order to search an environmentally safe alternative,
scientists considered the pesticides of biological origin
in the place of synthetic pesticides. Replacement of
synthetic insecticides by bio-rational insecticide is a
universally acceptable and practicable approach
worldwide (Rathi and Gopalakrishnan, 2006). Current
trends in eco-friendly insect pest-management
practices emphasize on the preparation and
application of new botanical and microbial
pesticide formulations, mass rearing techniques
for biocontrol agents, evaluation of fie ld
bio-efficacy and conservation of biological agents,
cultural control measures, genetic techniques in pest
and vector management, and pheromone attractants and
repellents (Mamun and Iyengar, 2010). In this context,
biopesticides are being considered as environmentally
safe, selective, biodegradable, economical and renewable
alternatives for use in IPM programmes in tea.
Biopesticides are natural plant products and may be
grown by the planters with minimum cost and
extracted by indigenous methods. Biopesticides are
secondary metabolites, which include alkaloids,
terpenoids, phenolics etc. It is estimated that the plants
may contain as many as 4000,000 secondary
metabolites. Botanical products are environmentally
safe, less hazardous, economic and easily available.
Certain products derived from indigenous plants are
used for tea pest control. The pool of plants possessing
insecticidal substances is enormous (Kabaru and
Gichia, 2001). Today, over 2000 species of plants are
known to possess some insecticidal activity (Jacobson,
1989). As many as 2121 plant species have been
reported to possess pest control properties; 25 of these
plants species possess the characteristics required for
an ideal botanical insecticide and are therefore more
promising for use in organic pest control programmes
(Radhakrishnan, 2005). Botanicals like neem,
ghora-neem, mahogoni, karanja, adathoda, sweet flag,
tobacco, derris, annona, smart weed, burweed, datura,
calotropis, bidens, lantana, chrysanthemum, artemisia,
marigold, clerodendrum, wild sunflower and many
others may be grown by planters with minimum
expense and extracted by indigenous methods
(Mamun and Ahmed, 2011). These botanical materials
can be used as an alternative to chemical pesticides.
This will be very helpful in minimizing the undesirable
side effects of synthetic pesticides. A few works have
been done on some indigenous plant extracts for the
control of red spider mite in tea. But no work has been
done on commercially formulated plant products
against red spider mite in tea in Bangladesh. Based on
the foregoing, the present study was undertaken to
evaluate the some plant origin comme rcial
biopesticides i.e. Bio-Cawach (
Pongamia pinnata
),
Karanza (
Azadirachta indica
+
Pongamia pinnata
),
Miticon (various herbs i.e. alkaloids and salt of fatty
