Bradinopyga geminata (Anisoptera: Libellulidae) as a predator of Aedes aegypti immatures (Diptera: Culicidae)

Authors: A. Venkatesh and B.K. Tyagi

Predatory potential of 12th instar larvae of Bradinopyga geminata on Aedes mosquito immatures was observed, by exposing two different prey-predator combinations (Prey: Predator; 200:1 and 1000:5). One and five 12thinstar larvae of B. geminata were provided with 200 (SET A) and 1000 (SET B) I, II, III & IV instars of Aedes aegypti larvae as prey, for a period of 24 hr in plastic containers containing 1 and 5 litres of water respectively. The number of Ae. aegypti larvae consumed by B. geminata larvae were noted through one day, at an interval of 3 hours. To maintain the prey density, same number of larvae was replenished. In the daily feeding rate experiment the consumption showed a peak during the 9thhour, irrespective of the instar stages. Predation rate of B. geminata was more for I instar, The predatory impact values for I instar in both Set A and B were 4.12+0.05 and 3.6+0.02 respectively, and were significant (P<0.01). The comparative clearance rate for Set A and B was highly significant for the first instar (P<0.01). This study revealed that B. geminata larvae is an efficient predator of mosquito larvae. The rate of consumption was dependent on the size of the prey and the density of the predator. The predatory impact of B. geminata was more for the first instar Ae. aegypti, owing to its size and energy requirements. To conclude, B. geminata is an efficient bio-control agent for container breeding Ae. aegypti and can be an effective tool in the integrated vector control programme.

 

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