Clear Resin Casting of Arthropods for Use in Education, Outreach, and Research

The goal of this protocol is to embed insects and other arthropods in resin, creating an optically clear amount which is visible from all six sides. And this is to educate both students and members of the public. Soft-bodied or fragile insects are more difficult to retain their morphological features and minimize air bubbles while embedding in resin.

To begin, remove the ticks from 70%ethanol. Place adult and nymphal ticks removed from ethanol between two microscope slides and apply gentle pressure to both sides to remove excess ethanol from the body. Transfer the tick onto a flat surface and allow it to dry for at least five minutes before placing it into resin.

Place larvae or pupae from a mosquito colony or field-collected samples into water inside an emergence chamber. After eclosion, place the mosquitoes in the freezer to kill them. Then remove the mosquitoes from the freezer and leave them at room temperature for at least five minutes before embedding in resin.

When ready to embed in resin, collect the newly emerged adult mosquitoes from the top compartment of the emergence cup. Next, remove mosquito or other Diptera larvae from ethanol and soak them in resin catalyst for at least 20 minutes before embedding them in resin. For other arthropods, determine whether to follow the tick or mosquito preparation steps based on the fragility of external features.

Create labels with required information, such as scientific names and lifecycle stages. Print the labels on transparency sheets using a laser printer, not an inkjet printer, and cut the printed labels to the appropriate size. Use a size-eight font in Times New Roman italicized for general specimens, and for lifecycles or larger-bodied specimens, apply a size 12 font in Times New Roman italicized.

For teaching collections, incorporate one square centimeter QR codes on the labels that link to a website with species information when scanned with a smartphone. Put on nitro gloves before handling uncured resin or catalyst. Place a wooden block into the pressure pot to elevate the surface for positioning the silicone molds.

Measure approximately 60 milliliters of resin into a plastic cup and pour the resin into a plastic bowl. Place the bowl in a water bath set at 32 degrees Celsius for 5 to 10 minutes. Add 12 drops of catalyst equivalent to approximately 540 microliters to the warmed resin in the plastic bowl.

Then, use a plastic spoon to slowly and carefully mix the resin and catalyst together for about one minute. Now, pour the resin and catalyst mixture into a silicone mold that is placed on a wooden block Inside the pressure pot. Wait for approximately 5 to 20 minutes until the resin becomes tacky and begins to harden before inserting the specimen.

Next, place the specimen at the center of the first resin layer, ensuring that diagnostic features, such as sphericals or appendages, are properly oriented for clear visibility. Then, position the printed label on the first resin layer close to the specimen as desired. Prepare a second resin catalyst mix as demonstrated earlier and slowly poured over the specimen along the inner edges of the mold, filling the remaining space.

Adjust the position of the specimen's appendages, such as legs, wings, or an antennae, as needed before the resin fully cures. Close the pressure pot lid securely. Apply pressure until the gauge reads 60 pounds per square inch and cure for approximately 24 hours.

After curing, release the pressure from the pot and carefully remove the molds. Take the hardened resin blocks out of the silicone molds and allow them to rest at room temperature until further processing. Using a bandsaw, cut the resin blocks to the desired dimensions and sand all six sides of each resin block using a disc sander.

Repeat sanding on all sides with a 4 by 30 inch 600-grit belt sander, then with a 1 by 30 inch 2, 000-grit belt sander. Next, gently press a red aluminum oxide buffing polish stick against the spinning buffing wheel for a few seconds. Then, hold the resin block against the buffing wheel at a 45-degree angle to begin polishing.

Use a cloth or fabric to wipe off excess polish from all sides of the resin block. Repeat the polishing steps using a second buffing wheel and a white diamond polish, and continue polishing until the colored overcast from the red polish is completely removed. Successfully embedded specimens were surrounded by clear and colorless resin, with all sides smooth and the specimen clearly visible from any angle of the resin block.

Features important for identification, such as color patterns, scale, shape, and size, and other anatomical details, were visible So many educational and extension programs, we require these insects to be able to educate students and the public. The challenge is you can't purchase these. There's no commercial sources.

And so following this protocol allows people to use equipment and some resources to be able to generate these high-quality specimens. So having these insects embedded in arthropods has a lot of value by training professionals in different disciplines to be able to identify these insects morphologically. But also when members of the public can identify them, that adds a lot of value through different community-based programs.

So this protocol to embed insects in resin has already evolved a lot in the last several years here at Texas A&M University. We consider this a living protocol, and we anticipate this protocol to continue to evolve and change with new tools and technologies.