The key innovation is that the insect is dissected while submerged in a saline solution.
After it has been euthanized and secured to a foam pad at the bottom of a tray filled with the solution, the mealworm is dissected using microsurgical instruments and a binocular dissecting microscope.
“We recreated the insect’s natural internal environment,” said Rosa-Teijeiro. “Its organs are normally bathed in hemolymph, which is its blood. Immersion keeps the tissues hydrated, improves their visibility and makes the results (of the dissection) reproducible, whereas dissection in the open air would lead to rapid drying and tearing.”
The procedure demands precision and patience: the insect is tiny, its exoskeleton rigid, and its internal organs fragile.
“Once the insect has been immobilized, we remove the elytra—the rigid wings that form the characteristic dorsal shield of beetles—and then gently lift a flap of chitin (a biopolymer) to expose the entire abdominal cavity,” said Rosa-Teijeiro.
“It’s like lifting the lid off an extremely fragile box. The organs are then isolated one by one in a specific order and documented step by step with annotated photographs.”
It took the researchers about two months, working part-time, to develop a reproducible protocol. As the method uses only standard laboratory equipment, the tools are therefore readily available, but mastering their use involves a considerable learning curve.
“It takes a few days to get used to working while looking through a binocular microscope,” noted Rosa-Teijeiro. “We usually like to see what our hands are doing.”