The present study recorded a total of 45 species of Odonata, of which one species, Ischnura mildredae, was recorded for the first time from West Bengal in India. Thirty-eight species were found in Tamluk Municipality as compared to 21 species in Haldia Industrial Belt (IB), with 14 species common to both the localities. Index of similarity revealed that the two localities were slightly dissimilar in odonate faunal composition as only 47% of species were shared. In both the localities, Anisoptera was more abundant, comprising over 69% of the total odonates. Libellulidae was the most abundant Anisopteran family in both the localities, comprising over 66% of the total odonates. Coenagrionidae was the most abundant Zygopteran family in both the localities. Thirteen species of Anisoptera and 11 species of Zygoptera were found only in Tamluk whereas two species of Anisoptera and five species of Zygoptera were found only in Haldia IB. Crocothemis servilia, Pantala flavescens, and Ceriagrion coromandelianum were the dominant species in Tamluk while Brachythemis contaminata and Orthetrum sabina were the dominant species in Haldia IB. Based on the values of Shannon index, Tamluk was considered unpolluted (=3.16) and Haldia IB moderately polluted (=2.43). Higher equitability index (J=0.87) and very low dominance index (0.06) in Tamluk indicated homogeneity in community composition and relatively stress-free equitable environment. The present investigation suggests that Odonata can be used as bioindicators of industrial pollution.
Background and Objectives:
In recent years, resurgence of mosquito-borne diseases has become a serious health problem in India. In the present study,
Stigmatogobius sadanundio
, a common indigenous fish, has been tested for its biocontrol potentiality for controlling
Culex quinquefasciatus
larvae. This small larvivorous fish can consume large number of
Culex
larvae even in the presence of alternate prey. This is the first report on the mosquito control ability of this fish.
Materials and Methods:
Experimental fishes were captured from tidal canals of Rupnarayan River in Purba Medinipur district, West Bengal. Mosquito larvae, pupae, and chironomid larvae were collected from Tamralipta municipality drainage system. Predation efficacy of the fish was evaluated on
C. quinquefasciatus
larvae and pupae as well as on
Chironomus ramosus
larvae which were collected from the drainage system of Tamralipta municipality and reared in the laboratory maintaining similar water parameters. Prey were offered to the fish separately and in paired combination to study its dietary preference.
Results:
S. sadanundio
is a diurnal predator consuming significantly large number of prey during daytime. It prefers mosquito and chironomid larvae over mosquito pupae. The rate of predation was very high during 1
st
h of predation. It consumed more chironomid larvae in the presence of mosquito larvae during daytime but consumed large number of mosquito larvae as compared to other larvivorous fish.
Conclusion:
S. sadanundio
, an indigenous fish, is an effective biocontrol agent for the larvae of
C. quinquefasciatus
in laboratory condition. Even though the presence of alternate prey chironomid larvae influences the predation rate, it consumed large number of mosquito larvae. However, careful controlled field trials must be conducted before this fish is used as a biocontrol agent.
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