HEXAPODA
(insects and other 6-legged organisms)

Hand Sanitiser Gel is a useful temporary mountant for examination and photographic purposes, of both macroscopic and microscopic subjects. The gel is sufficently viscous to hold an insect in place, once it has been positioned. It also self-supporting and doesn’t flow (so only needs a base, not a full container).

It can also be used as a long term preservative if the container is properly sealed (eg Super Glue).

Initial testing of a water-based sanitiser (Sainsbury’s Sensitive Antibacterial Handwash) found it to be slightly cloudy in use. An alcohol-based formulation (eg Carex, Purell) worked much better and the remaining notes relate to such products.

Despite the high alcohol content immersion in the gel is not an effective way of killing insect specimens. They should first be killed in the normal way eg freezing, by dropping in alcohol or hot water, or by ethyl acetate vapour.

Freshly killed insects can be transferred directly to the gel, then examined or photographed. For photography it’s best to have an optically flat surface, either by placing the gel in a cuvette or by floating a coverslip. For examination, at least at low magnification, the surface of the gel is often adequately flat.

Miscibillity With Other Reagents:

The gel is miscible with ethyl acetate, water and acids (eg white wine vinegar, lactic acid).

Melzer’s Iodine is also miscible so it might be useful to slow movement in slide preps of fungal spores scraped from spore prints.

Surprisingly the gel goes cloudy with 70% IMS, but not with unadulterated ethanol. It similarly goes cloudy with Euparal and Berlese’s fluid (although the latter later clears). Isopropanol may work but was not tested.

Alkaline solutions (10% KOH) are immiscible. Residues go cloudy, while stronger concentrations dissolve the gel.

General use:

Smaller specimens need a slide and coverslip, ideally with some sort of spacer (eg plastazote strips) to hold the coverslip up. Put a generous dollop of gel on the slide and place the insect on top. Push it into the gel, gently stroking the surface of the legs with a needle to remove air bubbles as you push them under. Make sure the subject is entirely immersed. Arrange the appendages symmetrically to your taste. Add an extra blob of gel so that the surface rises in the middle - this avoids air bubbles when you add the coverslip. Add the coverslip and gently press it down.

For larger specimens make a sandwich between two microscope slides (double-width slides are easier to handle, if you can get them). The mount can then be turned over to examine the underside.

For oblique views, use a deeper container with a glass coverslip on top.

Protocol for Genitalia Preps:

Genitalia preps to be macerated in hot KOH solution as usual, then left overnight in acid (white wine vinegar or lactic acid) to neutralise all traces of KOH, before transferring to the gel. Beware that any residual water on the specimen will dilute the gel, so perhaps transfer via a small dab of gel to wash it.