Mechanics of Flight

Question 1

What are the advantages of flight?

Answer 1

• forage better for food + oviposition sites
• search for mates better
• short + long range dispersal
• escape from predators

Question 2

When do insects produce power?

Answer 2

in their downstroke

Question 3

What are direct flight muscles?

Answer 3

muscles attached directly to the wings

Question 4

What are some direct flight muscles? what do they do?

Answer 4

• basalar muscles -upstroke
• subalar muscles - downstroke
• synchronous muscle

Question 5

What do the direct flight muscles do?

Answer 5

• provides power in primitive insects
• allows wings to be controlled independently
• orient wing angles

Question 6

What are indirect flight muscles?

Answer 6

attached to tergum, sternum and phargma

Question 7

What do indirect flight muscles do?

Answer 7

• contraction causes deformation of the “box”(pterothorax), elasticity of the thorax restores the shape, conserving energy

Question 8

What are some indirect flight muscles? what do they do?

Answer 8

• tergosternal muscles contract = upstroke

- dorsolongitudinal muscles contract = downstroke

Question 9

What are the three ways in which flight can be powered?

Answer 9

• Direct flight muscles
• Indirect flight muscles
• Click mechanism

Question 10

What is the click mechanism?

Answer 10

Since wings are only stable in full up or full down positions, thoracic elasticity snaps the wing to the alternate stable position when it is in the intermediate stage. - sudden tension release causes next set of muscle contractions

Question 11

What does the click mechanism result in?

Answer 11

the oscillation of muscle groups contracting at higher frequencies than those of nerve impulses; muscles only require periodic nerve impulses to maintain flight

Question 12

Since muscles are asynchronous in relation to the click mechanism, how are they kept synchronized?

Answer 12

by the rigidity of the thorax

Question 13

Since insect flight muscle is extremely metabolically active, what does it require?

Answer 13

• enlarged mitochondria

- direct tracheal supply of O2

Question 14

What are some fuels for insect flight? Which insects use it?

Answer 14

• carbohydrates - diptera, hymenoptera, cockroaches
• lipids - orthoptera, lepidoptera
• amino acids - flies, beetles

Question 15

What do some orthoptera and lepidoptera species do in terms of flight fuel?

Answer 15

begin using carbohydrates within their flight muscles and then switch to lipds to mobilize reserves from the fat body

Question 16

What is the glycerol-3-phosphate shuttle?

Answer 16

a mechanism for re-oxidation of NADH produced during glycolysis which permits a high rate of oxidation in flight muscles

Question 17

What does the glycerol-3-phosphate shuttle permit?

Answer 17

• complete oxidation of glucose to CO2 + H2O without lactate accumulation
• Transfer of NADH (which cant permeate mitochondrial membranes) into the mitochondria by reducing it to equivalents before transporting