8 - Feeding (2)

Question 1

Why does optimal performance & fitness require balanced nutrient levels?

Answer 1

1. An imbalance can be energetically costly –> organism may have to keep eating to obtain enough of a rare component
2. Nutrient excess can be toxic
3. Conversion of carbohydrates to protein can be metabolically costly

Question 2

Intake nutritional target can changed with?

Answer 2

1. Activity levels
2. Development (stage or age)
3. Reproduction
4. Feeding mode

Question 3

Carnivorous insects nutrient needs

Answer 3

• higher amino acid (protein) and lipid relative to carbohydrates (low digestibility of animal carbohydrates)

Question 4

Herbivorous insects nutrient needs?

Answer 4

Amino acid = carbohydrates or, amino acid < carbohydrates (phloem-feeders).
- Phloem feeders are often associated with presence of symbiotic bacteria (to provide additional proteins which are not present in their food)

Question 5

Holometabolous species def

Answer 5

Complete metamorphosis: eggs, instars, pupae, adults
(e.g. butterflies)
(SLIDE 8 graph)

Question 6

Hemimetabolous species def

Answer 6

No pupal stage; they go from eggs, instars to adults; wings develop externally
(e.g. termites, locusts)
SLIDE 8 GRAPH

Question 7

Plant eating insects with symbionts ratio

Answer 7

Low P:C ratio

Question 8

Plant eating insects without symbionts ratio

Answer 8

P:C ratio close to 1

Question 9

Carnivores ratio

Answer 9

High P:C ratio

Question 10

Methods of studying feeding behaviour and diet

Answer 10

1. Comparative physiology (mouthparts and adaptations)
2. Lab and in situ observations
3. Food preference with food choice
4. Gut content analysis
5. Stable isotope analysis

Question 11

Major insect mouth type functional groups

Answer 11

1. Chewing
2. Piercing and sucking
3. Siphoning
4. Sponging
5. Chewing and lapping

Question 12

Chewing insect example

Answer 12

Grasshopper

Question 13

Piercing and sucking inset eg

Answer 13

Mosquito

Question 14

Siphoning insect eg

Answer 14

Butterflies and moths

Question 15

Sponging insect eg

Answer 15

House flies and fruit flies

Question 16

Chewing & lapping insect eg

Answer 16

Honeybees

Question 17

Major structures of chewing insects mouth

Answer 17

1. Labrum
2. Mandible
3. Maxillae
4. Labium

Question 18

Stable isotope analysis def/ method

Answer 18

• Using rations of Carbon and Nitrogen isotopes from tissue
• Determine an organism’s position relative to other organisms in a trophic web
• Determine the source of the food chain

Question 19

What is stable isotope analysis based on?

Answer 19

• Range of signatures (diet type & variability)
• Overlap of signatures(niche overlap)

Question 20

Decays of stable isotope..

Answer 20

• Nitrogen decays as we move up the trophic web
• Carbon decays as we move to more marine or C4 sources

Question 21

Interesting way of classifying insect feeding (When, who & what?)

Answer 21

• Dow (1986)
• animal-plant axis
• solid - liquid axis