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Functional responses of Laccotrephes griseus (Hemiptera: Nepidae) against Culex quinquefasciatus (Diptera: Culicidae) in laboratory bioassay

Author(s): Anupam Ghosh & Goutam Chandra

Journal: Journal of Vector Borne Diseases
ISSN 0972-9062

Volume: 48;
Issue: 2;
Start page: 72;
Date: 2011;
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Keywords: Bioassay | coefficient of attack rates | food breadth | handling time | niche width | selectivity index

Background and objectives: In integrated vector management programmes, major emphasis is given on theapplication of biocontrol agents. In the present study, the hemipteran water bug, Laccotrephes griseus(Hemiptera: Nepidae) was evaluated to establish its functional response against the immature Culexquinquefasciatus Say in the laboratory.Methods: Adult water bugs (L. griseus) were collected from different ponds in Bankura, West Bengal, India.Predation rate was determined in semi-field conditions. Functional response, regression equation analysis andrate of predation were also determined in the presence of an alternative prey.Results: The long-term predation experiment (up to 30 days) revealed that L. griseus is a very good predatorof mosquito larvae. The functional curve analysis of L. griseus exhibited a Type II functional response. Theirhandling times and coefficient of attack rates were 29.37 min and 2.17 respectively. Regression equationsshowed that consumption rate was directly proportional to prey and predator densities and inversely proportionalto the search area. The selectivity index, niche width and food breadth were also determined.Interpretation and conclusion: The present study revealed that L. griseus can consume a good number ofmosquito larvae in the laboratory conditions. The long-term bioassay also indicates their predatory responseagainst mosquito larvae in the semi-field conditions. The result of selectivity index, niche width and foodbreadth were also highest for Cx. quinquefasciatus. In these respects, the water bugs L. griseus are indicativeof their release in the aquatic habitat where Cx. quinquefasciatus is the most dominant mosquito species.
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