International Journal of Marine Science 2015, Vol.5, No.57: 1-5
4
commune
,
Oscillatoria fremyii
,
O
.
geminata
,
O
.
sancta
,
Phormidium corium
,
P
.
tenue
,
Spirulina major
and
Skeletonema costatum
were able to reach adult but
growth was slow. The wing length of adult emerged
from larvae fed with all cyanobacteria isolates except
Chroococcus turgidus
and
Oscillatoria geminata
comparatively shorter than the control but significant
variation was not found. Rashed and El-Ayouty (1991)
reported that some green algae produce substances that
inhibit larval development and delay the development of
the surviving larvae to the adult stage. The delay in
the development of mosquito larvae fed with
Chlorococcum
sp. and
Scenedesmus quadricauda
was
observed by Ahmad et al. (2004). Feeding of
Aedes
aegypti
on
Anabaena circinalis
and
Oscillatoria
agardhii
causes lesions in the midgut epithelial cells
of the larvae (Abdel-Hameed and Kiviranta, 1993;
Saario et al., 1994).
Conversely, larvae fed on
Chaetoceros calcitrans
showed enhanced development and no mortality was
seen. All larvae developed normally to the adult stage
and growth was rapid than the control. Similar
observation was also made by Ahmad et al. (2001) in
larvae of
Aedes aegypti
fed with
Ankistrodesmus
convolutus
.
Rey et al. (2009) studied the effect of phytoplankton
such as
Skeletonema costatum
,
Chlorella pyrenoidosa
,
C. vulgaris
,
Scrippsiella
sp.,
Nitzschia kuetzingiana
,
N.
palea
,
Akashiwo sanguinea
,
Entomoneis
cf.
delicatula
,
Thalassiosira weissflogii
,
Melosira lineata
,
Microcystis
aeruginosa
,
Pandorina morum
,
Prorocentrum micans
and
Scenedesmus quadricauda
on development and
survival of the mosquito larvae
Aedes aegypti
using
log-growth phase and senescent-phase cultures. They
observed that larvae exposed to
Microcystis
aeruginosa
producing microcystin toxin had significantly
longer development times than the controls or those
grown with non-toxic strain and larvae exposed to the
dinoflagellate
Akashiwo sanguine
showed significantly
higher mortality than the controls. At cell lyses, during
the senescent phase, many compounds are released in
culture medium and some of these compounds may
play a nutritive role for the larvae. But toxic
compounds may also be released at lyses. Production
and release of exudates by algal cells are also
influenced by the physiological status of the cells
(Subbarao, 2006; Amsler, 2008).
The mosquito larvicidal activity of transgenic cyanobacteria
species was studied by many researchers. The constitutive
expression of high mosquito larvicidal activity by
transgenic
Anabaena
sp. strain PCC 7120 with
combinations of two δ-endotoxin genes (
cryIVA
and
cryIVD
) and regulatory gene
p20
of
Bacillus
thuringiensis
subsp.
israelensis
against
Aedes aegypti
was reported by Xiaoqiang et al. (1997). The
cyanobacterium,
Agmenellum quadruplicatum
PR-6
transformed with
cryIVD
behind its own strong
phycocyanin promoter,
P
cpcB
, produced inclusion
bodies and was mosquitocidal, but the onset of
toxicity with
Culex pipiens
larvae was delayed
(Murphy and Stevens, 1992). Using tandem promoters
for expression of
cryIVB
in
Synechococcus
sp. strain
PCC 7942 increased the mosquitocidal activity, but
the activity remained relatively low against
Culex
restuans
(Soltes-Rak et al., 1993).
5 Conclusions
The present study demonstrates ecological importance
of marine phytoplankton in the control of mosquito
Culex quinquefasciatus
. The study showed that some
species may serve as nutritious food for mosquito
larvae, whereas others are harmful. Among the twelve
species,
Nannochloropsis oceanica
(planktonic green
alga) showed effective larvicidal activity. The death of
the larvae might be due to the poor digestibility of
Nannochloropsis
cells. In future, such phytoplankton
can be used for the development of natural pesticides
against larvae of disease transmitting mosquitoes.
Author’s contributions
SVR designed and carried out the experiments. MR
participated in the design of the experiment and also
helped to draft the manuscript. All authors read and
approved the final manuscript.
Acknowledgements
The authors are thankful to the Ministry of Earth
Sciences, Government of India, New Delhi for the
financial assistance and Dr. C. Krishnaiah, Co-ordinator,
OASTC, Mangalore University for his help during the
study period.
References
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Algae
Oscillatoria agardhii
to the Mosquito
Aedes aegypti
and the
Shrimp
Artemia salina
, World Journal of Microbiology and
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Chlorophytes on Larval Survival, Development and Adult Body Size of
