Midge Chironomus Tentans Research Articles

Effect of TFM and Bayer 73 on in Vivo Oxygen Consumption of the Aquatic Midge Chironomus Tentans

Exposure of fourth instar larvae of Chironomus tentans to 2.0-8.0 mg/liter of TFM (3-trifluormethyl-4-nitrophenol) for 6 hr at 22 ± 0.5 C in soft water resulted in a significantly increased rate of larval oxygen consumption compared to that of control larvae, as measured with the Warburg respirometer. Maximum stimulation of oxygen consumption occurred with 8.0 mg/liter of TFM, and 1.0 mg/liter of TFM had no measurable effect on basal respiration. When hardness of exposure water was progressively increased, the effect of TFM on oxygen consumption was diminished. Bayer 73 (5,2′-dichloro-4′-nitrosalicylanilide) stimulated oxygen consumption at 0.75 and 1.0 mg/liter, had no significant effect at concentrations less that 0.75 mg/liter, and inhibited oxygen consumption at concentrations of 1.20 mg/liter or greater. Mixtures of TFM and Bayer 73, in the ratio of 98:2, had no greater effect on oxygen consumption than TFM alone.

A new method for culturing Chironomus tentans Fabricius larvae using burlap substrate in fertilized pools

A new system of culturing larvae of the midge Chironomus tentans was tested. The culture technique consisted of placing pieces of burlap, hung from poles like curtains, in 2 m × 1 m × 0.5 m pools. The pools were fertilized weekly with a standard dosage of 1 kg of fresh horse manure and were provided with intermittent water circulation. This system has the advantage for use in fish culture of permitting the fish, rather than the culturist, to harvest larvae from the substrate. The burlap simply is suspended in the fish pond and the fish allowed to graze. The method was tested on several species of fish with positive results. The effect on yield of midge larvae of a number of environmental variables was tested in the pools. The results were: 1. (1) Rates of fertilization one-tenth and ten times the standard rate resulted in lower production. 2. (2) Fertilization with chicken manure yielded results similar to those obtained with horse manure. 3. (3) When the burlap curtains were densely bunched, both total yield and yield per unit area were decreased. 4. (4) Covering the pools with wire screen lowered production. 5. (5) Yield was lower when there was no water circulation. 6. (6) Yield in pools 1 m deep was nearly twice that in pools 0.5 m deep. 7. (7) A weekly addition of 125 mg of FeSO 4 greatly increased production, but a dosage ten times that amount decreased production. Average yield of the best pools (11 g/m 2 per week) was a fraction of the maximum yields reported for some midge culture systems, but the authors believe that this can be substantially improved and that the new technique will prove feasible and convenient for use in practical fish culture.