Dry Insect Research Articles

Estimating the dynamics of greenhouse gas emission during black soldier fly larvae growth under controlled environmental conditions

Edible insects are considered a sustainable alternative protein source. Several studies have indicated that greenhouse gas (GHG) emissions from insects are generally low. These data were usually recorded in closed static chambers, which did not reflect the actual rearing conditions. On the other hand, open respiration chambers need high amounts of substrate and insects, making the analyses time consuming and expensive. In the present study, a novel small-scale open gas exchange recording system for evaluation of GHG emissions from insects is presented. The device consists of four independent respiration chambers, each one equipped with a pump for supplying air, a flow meter and a septum for sampling the flowing air. A validation experiment was carried out using black soldier fly larvae as model organisms and moistened chicken feed (dry matter 40%) as rearing substrate. Three independent runs were conducted, each with two replicates, using 200 neonates larvae and 300 g of substrate. Moistened chicken feed (300 g) without larvae was used as control. Throughout the 12 days rearing period, gas sampling occurred every 12 h. Data interpolation considering a linear tendency between two successive sampling points was applied and overall amounts of gases were quantified as area under the curve. Irrespective of the run, CO2 emissions in the insect-substrate systems increased during the initial 7 d of experiment, consistently followed by a rapid decrease. Multiple cross correlation analysis showed high reproducibility (r ≥ 0.9), while significant differences in the CO2 emissions between insects-substrate system (range 7.76–11.88 g g−1 dry insects) and sole substrate (range 0.20–0.33 g g−1 initial dry substrate) were observed. Very limited N2O (≤1.13 mg g−1 dry insects) and CH4 (≤1.33 mg g−1 dry insects) emissions were detected in this experiment, indicating that the performed black soldier fly larvae rearing did not result in significant production of these GHGs. Overall, the experiment showed that the novel device may be particularly suited for quick and reliable estimation of GHG emissions from edible insects.

DNA Extraction from Dry Museum Beetles without Conferring External Morphological Damage

BackgroundA large number of dry-preserved insect specimens exist in collections around the world that might be useful for genetic analyses. However, until now, the recovery of nucleic acids from such specimens has involved at least the partial destruction of the specimen. This is clearly undesirable when dealing with rare species or otherwise important specimens, such as type specimens.MethodologyWe describe a method for the extraction of PCR-amplifiable mitochondrial and nuclear DNA from dry insects without causing external morphological damage. Using PCR to amplify ≈220 bp of the mitochondrial gene cytochrome c oxidase I, and 250–345 bp fragments of the multi-copy, nuclear 28s ribosomal DNA gene, we demonstrate the efficacy of this method on beetles collected up to 50 years ago.ConclusionsThis method offers a means of obtaining useful genetic information from rare insects without conferring external morphological damage.