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Table 3 CO2 production and O2 consumption of black soldier fly larvae (5th–6th instar) fed on chicken feed for three subsequent days or during starvation for one day1

From: Growth efficiency, intestinal biology, and nutrient utilization and requirements of black soldier fly (Hermetia illucens) larvae compared to monogastric livestock species: a review

Gas exchange Ambient temperature, °C Changes in larval BW in relation to starting BW, % Gas exchange on measurement db, μL/mg BW/h
Experiment (Fed)c 27.5 + 119.6 1 2 3 SE
CO2 production    2.21 1.88 2.33 0.17
O2 consumption 1.71 1.71 2.17 0.13
RQd    1.29 1.09 1.07 0.10
Experiment (Starved)e 32 − 15.4     
CO2 production    0.53 0.03
O2 consumption 0.71 0.03
RQ    0.75 0.01
  1. aAll larvae were measured in vessels with 23 cm2 surface area, a volume of 536 mL placed inside respiration chambers. The ventilation rate was 37.2 L fresh air/h per respiration chamber. The respiration chambers were placed inside a climate controlled closet (3 chambers per closet) kept at the indicated temperatures in the dark. Continuous measurement of gas exchange was performed at 21 min intervals using open-circuit indirect calorimetry. CO2 and O2 concentrations were measured by infrared absorption and paramagnetic gas analyzers (Maihak AG, Hamburg, Germany), respectively. CO2 and O2 concentrations were multiplied with air flow in and out of the chambers and normalized to BW and time to obtain CO2 production and O2 consumption. We thank Hermetia Baruth GmbH for their cooperation in setting up a black soldier fly colony
  2. bGas exchange data was related to the mean BW at d 3 (fed) of the respiration measurement period or the mean of start and end BW of the 1 d respiration measurement period (starved)
  3. cFed status (n = 6) = 150 larvae at 14.5 d after hatching with a mean BW of 108.4 mg at start of the measurements were fed on 114 g chicken feed substrate. The vessels were filled one d before the start of the experiment with 34.2 g chicken starter feed and 79.8 g of water (30% feed:70% water (w/v)). After 3 d the gas exchange measurement was stopped and the larvae were isolated from the frass, counted, cleaned with tap water, and dried with paper towels. Afterwards, their wet BW was determined
  4. dRQ = Respiratory quotient: CO2 production (μL)/O2 production (μL)
  5. eStarved status (n = 6) = 150 larvae at 18 d after hatching. The larvae were grown until 18 d, transferred to the insect vessels on d 18 at a mean BW of 193.3 mg, and measured in the respiratory chambers for one d without feed. The wet BW was determined as above