I know that there are avaialble some respiration chambers for insects but I was wondering if chambers used for small fruites can be adequate for the scope.
This simple method can be used to measure the respiration rate of the insects. A number of insects or larvae are weighed and placed in a small mesh bag allowing for gas exchange. The samples are attached freely in a 500 ml conical flask containing 50 ml of Ba (OH) 0.1N standard and close the flask with sealed plastic sealed gaskets, which should be carried out quickly. The samples are left for two hours and then extracted from the beaker. The barium hydroxide solution is then titrated with standard 0.1N hydrochloric acid and phenophthalene is present until the pink color disappears.
Respiration rate is estimated at (mgco2 / kg / h) and is calculated as follows:
A- B 1
Respiration rate = -------------- x 1.1 x --------------
Sample weight(kg) Time (h)
A = volume (ml) of HCl used to neutralize barium hydroxide for the blank sample of any model (Blank).
B = volume of the HCl (ml) consumer as a result of the parity with the remaining barium hydroxide in the solution of the sample containing the model.
I could recommend you a closed system method, similar to the one we use to estimate respiration in vegetables. You can determine the change in CO2 concentration inside a glass hermetic chamber with a coupled rubber septum at constant temperature. You should take a gas sample of 1-5 cm3 with a syringe from the chamber headspace to determine the concentration by gas chromatography with a thermal conductivity detector. The respiration rate can be calculated as follows:
rCO2 = (V/W)*( yCO2t1 - yCO2t2) / Δt
where rCO2 is the respiration rate at time t, Δt is the time elapsing between two successive measurements, yCO2t1 is the CO2 mole fraction determined in the first measurement and yCO2t2 is the CO2 mole fraction determined in the subsequent measurement, respectively. V is the chamber free volume and W is the sample weight. You can run the test during 10-30 min avoiding excessive CO2 accumulation and O2 depletion to don't induce stress in the insects (maximun 2-3 % of CO2 and minimum 15-16 % of O2, i guess). Finally, you will need to calibrate the chromatograph to estimate the CO2 concentration.
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