1. We have studied the numerical and functional responses of campanulate morphs of Asplanchna intermedia fed five species of rotifer (Brachionus rubens, B. patulus, B. calyciflorus, Hexarthra mira and Filinia longiseta). The vulnerability of the prey varied with their morphology and mode of swimming. 2. To test the numerical and functional responses, prey species differing in their morphology and mode of swimming were provided. Responses were also tested with mixtures of evasive and non‐evasive prey provided in three different ratios. 3. A. intermedia showed a type II functional response to all the prey species provided. 4. The population growth rate of A. intermedia on the various prey species provided ranged from a minimum of –0.24 to a maximum of 0.68. There was a significant correlation between the capturability of a prey species and the population growth rate of the predator feeding on it. The capturability of a prey species also has a significant influence on the maximal predator density but not on the time taken to reach it. 5. Observations from a field study undertaken over a 10‐month period to study the prey preferences of A. intermedia in nature were corroborated by the laboratory findings.

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The cyclopoid copepod Mesocyclops thermocyclopoides, a dominant invertebrate predator in many shallow ponds and temporary water bodies in northern India, feeds on cladocerans, rotifers, ciliates and when present, on mosquito larvae also. We studied in the laboratory the prey consumption rates of the copepod on first and fourth instar larvae of two species of mosquito (Anopheles stephensi and Culex quinquefasciatus) in relation to their density. We also studied its prey selectivity with mosquito larvae in the presence of an alternate prey (the cladocerans-either Moina macrocopa or Ceriodaphnia cornuta) in different proportions. With either mosquito species, the copepod actively selected Instar-I larvae, avoiding the Instar-IV larvae, and with either instar, selected Anopheles stephensi over Culex quinquefasciatus. When prey choice included the cladoceran as an alternate prey, the copepod selected the cladoceran only when the other prey was Instar-IV mosquito larvae. Our results point to the potential and promise of M. thermocyclopoides as a biological agent for controlling larval populations of vectorially important mosquito species.

The Combined Effects of Food and Temperature on the Life History Parameters of Brachionus patulus MULLER (Rotifera) key worda: Rotifera, Brachionw patulus, food, temperature, life history parameters AbstractThe combined effects of different levels of temperature (15". 25" and 35 "C) and food Chlorella (1,2 and 4 x 106 cells/ml) on the life history parameters (lifespan, life expectancy, net reproductive rate, intrinsic rate of increase, developmental time, and generation time) of a laboratory population of the rotifer Brachionus patulua were investigated. Both food and temperature, independently and in interaction, significantly influenced nearly all the parameters. The reproductive performance was a direct function of the food level, but the magnitude of food effect was temperature-dependent. The observed temperature x food interaction effects are explained in terms of the energetics of resource apportionment between metabolism and reproduction. 252 226 226 229 231 231 232 235 235 237 238 238

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