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What are the advantages of flight?

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


When do insects produce power?

in their downstroke


What are direct flight muscles?

muscles attached directly to the wings


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

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


What do the direct flight muscles do?

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


What are indirect flight muscles?

attached to tergum, sternum and phargma


What do indirect flight muscles do?

- contraction causes deformation of the "box"(pterothorax), elasticity of the thorax restores the shape, conserving energy


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

- tergosternal muscles contract = upstroke
- dorsolongitudinal muscles contract = downstroke


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

- Direct flight muscles
- Indirect flight muscles
- Click mechanism


What is the click mechanism?

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


What does the click mechanism result in?

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


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

by the rigidity of the thorax


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

- enlarged mitochondria
- direct tracheal supply of O2


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

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


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

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


What is the glycerol-3-phosphate shuttle?

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


What does the glycerol-3-phosphate shuttle permit?

- 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