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Micron scale insect anatomy

Description: The image quality and resolution of the Phenom™ were sufficient to show micron scale features of insect anatomy.

Recommended Product: Phenom G2 Desktop Scanning Electron Microscope

Executive Summary

The samples imaged were air-dried insects (ant, fruit fly, mosquito) and a tick (Arachnids). A number of structures were imaged to create a single classroom presentation in insect anatomy for North Shore Community College in Massachusetts, and as part of a broader series of classroom presentations directed at grades 9-12, physics, chemistry and biology, at Newburyport High School. The specimens were collected from readily available and indigenous species such as the tick, fruit fly, ant and mosquito. The images showed the students not only specific anatomical detail and inter specie variations but how detailed and complex these structures can be at very small scale.
Figure 1. Cartoon of insect anatomy for reference purpose
Figure 1. Cartoon of insect anatomy for reference purpose

Sample information

The insects imaged were the tick, fruit fly, ant and mosquito. These were chosen based on their availability, ease of sample preparation, and size (e.g. a grass-hopper or praying mantis are too large to put into the SEM without breaking them apart). Apart from ordering live drosophila the insects were collected by ‘field work’.

Sample Preparation

The samples were prepared as follows:

  • Collect dead insects or in the case of live drosophila, mortally anesthetize with a cotton ball soaked in acetone or fingernail polish remover.
  • Attach to stub using carbon paint.
  • Where possible, several samples were of the same insect were attached to a single stub in different body orientations; e.g. lying on the front or side or back.
  • Sputter coat with gold.

Imaging

Imaging was performed using a desktop SEM, the Phenom™. The microscope is very easy to use via a touch screen and no special training is needed to operate the system. The user interface has the simplicity of a digital camera.

Conclusions

The image quality and resolution of the Phenom were sufficient to show micron scale features of insect anatomy. The sample preparation was minimal and easy. The dried and coated samples are robust with respect to long term (2 months+) air storage. Insects are particularly ‘fun’ to use in a live SEM classroom presentation as navigation around the insect is intuitive and interesting, and the entire sample can be easily fit inside the Phenom.

Comparison and preparation techniques

Images of uncoated insects have been obtained in the SEM; however the coated images have better resolution and more uniform contrast to brightness ratio.

Success and recommendations

This project was deemed a success by the author because of ease of sample preparation, speed of data produced, and quality of images produced to demonstrate micron scale insect anatomy. The recommendation was that it is very useful to have an off line program that stitches multiple images into a single panorama image. The single composite image of the tick was created using such an offline auto stitching software program from the University of British Colombia UBC.

Figure 2. Ant Mandible: 462 micro m FOV
Figure 2. Ant Mandible: 462 µm FOV
Figure 3. Ant Mandible, inverted: 462 micro m FOV
Figure 3. Ant Mandible, inverted: 462 µm FOV
Figure 4. Ant Tarsus and Claw: 462 micro m FOV
Figure 4. Ant Tarsus and Claw: 462 µm FOV
Figure 5. Ant Leg Joint: 110 micro m FOV
Figure 5. Ant Leg Joint: 110 µm FOV
Figure 6.
Figure 6.
Figure 7. Fruit Fly Compound Eye: 462 micro m FOV
Figure 7. Fruit Fly Compound Eye: 462 µm FOV
Figure 8. Fruit Fly Compound Eye: 39 micro m FOV
Figure 8. Fruit Fly Compound Eye: 39 µm FOV
Figure 9. Fruit Fly Ocelli (simple eye): 567 micro m FOV
Figure 9. Fruit Fly Ocelli (simple eye): 567 µm FOV
Figure 10. Fruit Fly Tarsus and Claw: 101 micro m FOV
Figure 10. Fruit Fly Tarsus and Claw: 101 µm FOV
Figure 11. Fruit Fly Wing: 1.2 mm FOV
Figure 11. Fruit Fly Wing: 1.2 mm FOV
Figure 12. Fruit Fly Wing: 100 micro m FOV
Figure 12. Fruit Fly Wing: 100 µm FOV
Figure 13. Fruit Fly abdomen with spiracles: 462 micro m FOV
Figure 13. Fruit Fly abdomen with spiracles: 462 µm FOV
Figure 14. Fruit Fly spiracle: 51 micro m FOV
Figure 14. Fruit Fly spiracle: 51 µm FOV
Figure 15. Butterfly wing: 48 micro m FOV
Figure 15. Butterfly wing: 48 µm FOV
Figure 16. Wing wasp: 320 micro m FOV
Figure 16. Wing wasp: 320 µm FOV
Figure 17. Mosquito Wing: 179 micro m FOV
Figure 17. Mosquito Wing: 179 µm FOV
Figure 18. Tick spiracle: 1.4 mm FOV
Figure 18. Tick spiracle: 1.4 mm FOV
Figure 19. Mosquito Proboscis: 287 micro m FOV
Figure 19. Mosquito Proboscis: 287 µm FOV
Figure 20. Tick, inverted, composite of multiple SEM images
Figure 20. Tick, inverted, composite of multiple SEM images



Micron scale insect anatomy app note