Everything you wanted to know about Manduca

What do Manduca eat?

Larval Manduca is a pest on tobacco, potatoes, tomatoes, peppers and other plants in the plant family Solanaceae.  Adults feed on nectar.

How do Manduca see?

Manduca and insects like the fly pictured on the left have special eyes called compound eyes.

This fly has about 40,000 eyes on each compound eye. Having lots of small eyes allows insects to sense movement much better than humans can. However, they don’t see things as clearly as we do.

If we had eyes that worked like insects, but wanted to see like we do, we would look like the man pictured on the right. This is because the insect eye does not see as clearly as we do.

The picture on the left below shows how we see these flowers. We can see each petal and leaf very clearly. The picture on the right shows the same flowers through insect’s compound eyes. Insects do not need to see things as clearly as we do because they are more worried about being eaten! Seeing the movement of an attacking predator is far more important for their survival.

 

 

 

How we see a flower… How an insect sees the same flower…
   
Insects look at the world differently. They see in the blue region of light much better than we do. Compare the center of the yellow flower to the center of the blue flower. The blue flower has a very dark center that attracts certain insects. To the insect, the flower also looks like it has arrows pointing to the center where the nectar and pollen are located. These mini landing strips show the insect where the nectar is stored. Nectar is the sweet juice the flower produces to attract insects so they will help pollinate the flower. Pollination is the way that flowers can spread.
 

How do Manduca breathe?

Insects do not breathe like us. Instead of using lungs, insects use long tubes called the trachea to carry oxygen. Air enters through the spiracles. Spiracles do the same thing that our noses do, except there are a lot more of them. In fact, a Manduca larva has nine spiracles on each side.

Trachea are like the slinky toy that can bend and fold into just about any shape the insect takes. Trachea get smaller the closer they get to the cells.

How does Manduca blood circulate?

The hemolymph, or blood is pumped from the back to the front by the heart.

Insect blood circulation can be modeled using an elongated balloon. Squeezing one end of the balloon causes expansion at the other end.

By working hand over hand the distance of the balloon, and imagining the air inside the balloon as Manduca blood, will demonstrate how the blood is moved by the chambered pumps.

What kind of insects are Manduca?

Manduca belong to a moderately large family of moths known as Sphingids (formal family name = Sphingidae). The name Sphingidae refers to the Sphinx-like pose the larva takes when disturbed.

The Sphingidae and other families of moths and butterflies belong to a larger grouping termed an Order, in this case Lepidoptera.

Butterflies and moths are part of yet a larger grouping termed a Class, in this case Insecta. Insects belong to a large Phylum called Arthropoda.

Arthropoda includes the insects, spiders, crabs, lobsters, mites, millipedes, centipedes and the extinct Trilobites.

How fast can they grow compared to humans?

If humans grew like a Manduca, we would be giants! For example, the average human baby weighs 6 lbs. If that baby grew like a Manduca, by the time it was full grown at age 18, it would weigh 60,000 lbs or about 30 tons.

Are Manduca pests?

Manduca remained a serious pest for farmers until the 1950’s when DDT was introduced; that pesticide eliminated the insect as a serious pest on any crop. Today, Manduca is still a pest for commercial growers, but it is no longer as damaging as it once was. The use of parasitic wasps as well as the development of insect resistant crops have reduced this species to the status of a minor pest.

Over the past 30 years, Manduca has taken on another role, that of a “model” for studying insect physiology, biochemistry, and molecular biology. Its large size and its ease of rearing makes Manduca one of the most studied species of the insect world.