Bt Research 2015, Vol.6 No.2 1-10
ISSN 1925-1939
1
Research Article Open Access
Efficiency of
Bacillus thuringiensis
subsp.
kurstaki
in crude solid fermented
matter against the coconut pest,
Aceria guerreronis
Robinson Babysarojam Smitha
1
, Prakasan Priji
1
, Sreedharan Sajith
1
, Niravath Ramani
2
and Sailas Benjamin
1
1 Enzyme Technology Laboratory, Biotechnology Division, Department of Botany, University of Calicut, Kerala - 673 635, India
2 Acarology Division, Department of Zoology, University of Calicut, Kerala - 673 635, India
Corresponding author email
Bt Research, 2015, Vol.6, No.2 doi: 10.5376/bt.2015.06.0002
Received: 14 Dec., 2014
Accepted: 23 Feb., 2015
Published: 5 Mar., 2015
© 2015
Smitha et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Smitha et al., 2015,
Efficiency of
Bacillus thuringiensis
subsp.
kurstaki
in crude solid fermented matter against the coconut pest,
Aceria
guerreronis
, Bt Research, Vol.6, No.2, 1-10
(doi
Abstract
The coconut palm appears to be virtually the only host of coconut mite,
Aceria guerreronis
Keifer. This serious and
exponentially multiplying mite has not succumbed to any control treatments yet, due to its microscopic structure and cryptic life. For
the first time, it was explored whether
Bacillus thuringiensis
subsp.
kurstaki
(
Btk
) could be used as an efficient bio-control agent to
combat this mite. In a biphasic fermentation strategy for the overproduction of
δ-
endotoxin, the conventional Luria-Bertani (LB)
medium was supplemented with 10% (w/v) potato flour. After initial submerged fermentation of this modified medium for 12 h, the
wet and crude solid pellet (
i.e.,
without free solution) with
Btk
embedded in it was incubated further up to 48 h under solid-state
fermentation for obtaining crude fermented matter. A bio-assay set-up was standardized for
A. guerreronis
on tender coconut button.
The probit value (lethal dose) of solid-fermented matter (obtained from potato flour supplemented LB) was 1.64 µg/cm
2
with 18 folds
more efficiency than the LB control. Preliminary field trial showed that one time application of crude solid-fermented matter in the
leaf pockets of the infested coconut palms - prior to monsoon - could be efficient to combat the mite permanently, if all palms in a
plantation receive a simultaneous treatment.
Keywords
Aceria guerreronis, Bacillus thuringiensis,
mite, solid-state fermentation,
δ-
endotoxin, pest biocontrol
Introduction
The coconut palm (
Cocos nucifera
L.) (Arecales:
Arecaceae) - commonly referred to as “Tree of Life”
as well as “Kalpa Vriksha” - provides livelihood to
millions of people across the world (Persley 1992;
Smith 1998). Globally, coconut occupies an area of 12
million hectares with a total production of about 56
billion nuts per annum. India, Indonesia, the
Philippines and Sri Lanka are major coconut-growing
countries; they together contribute over 78% of the
total world production (Persley, 1992). This crop is
attacked by various pests, of which,
Dynastes tityus
(rhinoceros beetle),
Rhynchophorus ferrugineus
(red
palm weevil),
Opisina arenosella
(leaf-eating
caterpillar),
etc
. are important. Of late, incidence of
coconut nut infesting eriophyid mite, the microscopic
Aceria guerreronis
Keifer (Acari: Eriophyidae)
bearing the vernacular (Malayalam) name
Mandari
has become a critical problem across the world (Levin
and Mammooty, 2003; Lawson-Balagbo et al., 2008).
Studies on the geographic pattern of morphological
variations among populations of this coconut mite
from different countries and continents would provide
some bio-geographic information, and it can be
concluded that
A. guerreronis
is of American origin,
which was introduced to Asia from Africa, or from the
same source as that of the African populations (Navia
et al., 2006).
A. guerreronis
has a history as a pest of coconut since
three decades as of now. The mite, since its detection
and description from the Guerrero state of Mexico has
been known to invade several countries in the world.
In coconut, initial colonization by
A. guerreronis
requires only one gravid female, the arrival on the
button of which is sufficient to establish population to
induce further infection to other nuts of the
inflorescence, and even a plantation in a short time
