The
objective of this study was to determine the larvicidal effects of
entomopathogenic fungus Metarhizim anisopliae against degue, chikunguniya and
filariasis disease vectors. The fungus was cultivated in the complete brothmedia and the extracelluar metabolites were filtered by using Whatman no.1
filter paper. Further, the filterd metabolites were conducted for its
larvicidal efficacy against all instars of Ae. egypti and Cx. quenquefacistus,
at five different significant concentrations (2.35, 2.65, 2.83, 2.95 and
3.05ppm). Larvae of Cx. quenquefacistus were found more susceptible than larvae
of Ae. aegypti. The hightest LC99 value (663.74ppm) was resulted in the first
instar of Cx. quinquefasciatus while the lowest LC99 value (309.02ppm) was
found in third instar of Ae. aegypti. The findings of this preliminary study
gives overview idea about the different larvicidal properties of the metabolites
of M. anisopliea. Additionally it will help us to find specific larvicidal
compound for mosquito borne disease control applications
Culex and Aedes are major vectors of zoonotic diseases in
tropics. It causes morbidity of millions of persons resulting in loss of
mandays causing economic loss. Culex quinquefasciatus, a vectore of lymphetic
filariasis, is widely distributed. On the other hand, Aedes aegypti is a vector
of dengue, chikunguniya, yellow fever and that carries the arbovirus responsible
for these diseases is also widely distributed in the troical and subtropical
zones. In Indian scenario, almost the entire country is endemic to the mosquito
borne diseasses due to favorable ecological conditions. To prevent
mosquito-borne diseases and improve public health, it is necessary to control
them. Mosquito in the larval stages are attractive target for pesticides
because mosquitoes breed in water, and thus it is easy to deal with them in
this habitat.
Numerous chemical larvicides are known to have toxic effects
beyond their target pests including toxic effects to animals and human. The
opportunity to substitute safer, more selective and biodegradable biocontrol
agent can provide important ecological benefits. The use of microbial larvicides
could decrease our dependence on chemical insecticides. The entomopathogenic
fungus life cycle is associated with the synthesis and secretion of different
active metabolites, including extracellular enzymes and low molecular weight
compounds (toxins). These toxic byproducts mainly help the organisms to
withstand and protect themselves from invading pathogens. In general fungi
produce a wide range of secondary metabolites with diverse biological activites
like antibiotics, cytotoxic substances, insecticides compound that promote or
inhibit growth, attractor, repellent etc