The old adage, "you are what you eat" takes on a different twist with insects. When arthropods came on the scene, the main new adaptation they had compared to supposed worm-like ancestors was jointed appendages, including the complex workings of the insect mouth. The same basic moveable pieces of machinery that make up the insect mouth have been modified in several key ways to allow the insects to specialize on certain food types. Consequently, if you see a certain type of damage on a leaf, for example, whole groups of insects are either implicated or exonerated. Specialization can also be a trap - if your exact food is not around, you go hungry!
- Identify the 4 major kinds of insect mouthparts and how they work.
- Learn about "niches" open or closed to insects because of mouthparts.
- Discuss ramifications of feeding habits to pest status and pest management.
- Paper plates
- Peanut butter
- Honey or jelly
- Straw cut in half
- Small soft drink cups with lids with slits for straws
- Long-necked wide-mouth bottle
- Soft rubber or plastic tubing (long enough to reach bottom of bottle)
Timeline: 20 minutes
1. Set out on table:
a. small cup with water with "to-go" lid
b. one long-necked bottle with a little water in bottom
c. 2 paper plates:
- one with honey, jelly or pudding on it;
- one with peanut butter holding a cracker up on edge
2. Get 4 volunteers to form the insect team
3. Instruct each person to put their hands behind their backs and assign each an insect type and the associated mouthpart, e.g.
Tobacco hornworm caterpillar - (chewing) Allowed only to use teeth.
Squash bug - (piercing/sucking) Allowed only to use straw.
Housefly - (sponging/lapping)Allowed only to use tongue.
Butterfly - (siphoning) Allowed only to use tube.
4. Instruct the team to go after the kind of food they can eat on the table in front of them.
5. Ask them questions to promote concepts:
(Housefly! Can you eat leaves? Caterpillar! Can you drink water from the cup?)
Data collection: None
Significance of different feeding equipment: Allow different insects to specialize on different parts of the same resource. Example: One flowering bush may have butterflies sipohoning nectar, aphids piercing the veins of leaves to suck sugars, ants feeding on the aphid honeydew, a leaf miner fly larvae tunneling in the leaf tissue, a Japanese beetle chewing the whole leaf, a stem borer beetle larva inside the stem, and root feeding fly maggots chewing on tender root tissues. Ask students to name insects they know and try to figure out what kind of mouthparts they have.
Ramification to pest status and IPM: Many. One example is, using an insecticide that acts as a stomach poison will not harm a sucking insect. Know the pest, what the damage looks like and act accordingly. Some piercing insects are vectors of disease - damage is due to spread of viruses.