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BIOL 327 > Lecture 9: Dietary Utilization by Insect (Quantitative Nutrition) > Flashcards

Lecture 9: Dietary Utilization by Insect (Quantitative Nutrition) Flashcards

1
Q

Identify two ways in which insect nutrition is studied
Insect nutrition can be studied in two ways

A

Determine the essential nutrient that is needed for growth and development

Determine the efficiency of converting ingested food into their own biomass

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2
Q

Determine the essential nutrient that is needed for growth and development

A

This includes feeding an insect a nutrient at a time and monitoring the growth and development for a period of time

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3
Q

Determine the efficiency of converting ingested food into their own biomass

A

For this, we would need to determine the ecological constraints (Eg. sometimes insects can find food whereas sometimes they cannot, specialists would have to find the same food every single time)

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4
Q

Methodology of Studying Insect’s Nutrition

(3)

A

Weight the insect BEFORE and AFTER feeding

Weight the diet BEFORE and AFTER feeding

Weight the frass (poop) of the insect

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5
Q

What information does the methology of studying insect nutrition provide us with?

(5)

A

a. RGR (relative growth rate)

b. RCR (Relative consumption rate)

c. ECD (efficiency of conversion of digested food)

d. ECI (efficiency of conversion of ingested food)

e. AD (approximate digestibility)

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6
Q

RGR

Definition + Equation

A

Relative growth Rate

Weight (mg) gained per day / average larval weight (mg)

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7
Q

RCR
Definition + Equation

A

Relative Consumption Rate

Mg ingested per day / Average larval weight (mg)

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8
Q

ECI

Definition + Equation

A

Efficiency of conversion of ingested food

[ weight (mg) gained / mg food ingested ] x 100

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9
Q

ECD

Definition + Equation

A

Efficiency of conversion of digested food

[ weight (mg) gained / (mg ingested - mg frass) ] x 100

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10
Q

Why is it that ECD can never be 100%

A

ECD can never be 100% because energy is loss throughout

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11
Q

AD

Definition + Equation

A

Approximate digestibility (amount of food that is absorbed)

[ mg ingested - mg frass ] / [mg ingested ] x 100

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12
Q

Shortcut Nutritional Parameters (3)

A

RGR = ECI x RCR

ECI = AD x ECD

1 - ECD = Metabolic Cost

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13
Q

Highest RGR

Eg (2)

A

Forb feeding (leaves / herbs feeders) Hemiptera and Lepidoptera

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14
Q

Lowest RGR

Eg (2)

A

Eg. Aquatic Detritivores (eg. Stonefly, mayfly naiads)

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15
Q

HIghest RCR

Eg (2)

And how come these insects are the highest RCR?

A

Tree feeding Hymenoptera

Forb feeding Lepidoptera

This is because these insect eat twice their body weight

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16
Q

Lowest RCR

2 Eg + Explanation

A

Predatory insects (these insect would not be able to get food all the time, limited prey)

Wood feeding insect (may not contain the enzyme cellulose)

17
Q

Highest ECI (%)

Eg (2)

A

Eg. Seed- feeding Hemiptera (these insects feed on protein rich seeds)

Eg. Blood feeders (Diptera)

18
Q

Lowest ECI (%)

Eg (2)

A

Eg: Aquatic Detritivores (Mayflies naiads, Stoneflies naiads, Dragonflies naiads)

Eg. True feeding Hymenoptera

19
Q

Highest ECD (%)

Eg (2)

A

Eg. Seed-feeding Hemiptera

Eg. Blood feeders (Diptera)

20
Q

Lowest ECD (%)

Eg (2)

A

Eg. Ants - perform a number of activities, are very active and always moving

Eg. Stored grain feeders

21
Q

Highest AD (%)

Eg (2)

A

Eg. Forb feeding Coleoptera

Eg. Predatory Insects

22
Q

Lowest AD (%)

A

Eg. Dung feeding insects (do not obtain much nutrient because there are low nutrient in feces)

23
Q

Major Requirements for Optimal Growth

(3)

A

All insects need nitrogen in the forms of amino acid and protein as nitrogen is important for the exoskeleton of an insect

Plants can provide 0.03% - 7.0% of nitrogen for plant eating insects

Whereas insect that prey on other insects will provide about 7-14% nitrogen

24
Q

Relationship b/t Nitrogen and RGR + ECI

(2)

A

There is a positive correlation b/t RGR and ECI with Nitrogen

This indicate that as nitrogen increases so does RGR and ECI

25
Q

Other Major Nutrient Requirements for Insects

(1) + 2 Description

A

Water

  • Is a major factor for larval growth
  • There is a strong positive relationship between water and ECI and RGR particularly in the Lepidoptera
26
Q

Physiological efficiency model

A

As nitrogen and water increases, this leads to the increase in growth rate (RGR) and AD (absorption of food)

27
Q

Bernays Studies based on the amino acid of Locust

(2)

A

Found that ONLY phenylalanine had a significant effect on the diet of Locust

Concluded that phenylalanine increase 30% of its weight and 25% increase in ECI

28
Q

Conclusion of Bernays Studies on Locust

(2)

A

Found that phenylalanine is very important for forming the integument of an insect

As locust have large integument therefore would require more phenylalanine whereas smaller insect do not require as much

29
Q

Determine the effect of water on ECI

(2)

A

Found that there is a higher water content in forbes rather than tree therefore the ECI value is higher in forbes

This indicate that high water content yields high ECI

30
Q

What happens when nutrients are lacking in the diet?

(2)

A
  • When there is an increase in consumption rate (RCR) this means insect would want to get more in order to obtain the right nutrient
  • When there is a decrease in consumption rate (RCR), this means the growth rate would decrease.
31
Q

Are holometabolous insects more efficient than hemimetabolous ones?

A

Conclusion found that since hemimetabolous develop external wings therefore their cuticles % is larger than holometabolous

32
Q

Nutrient Self- Selection: Can insects select a nutritionally optimal diet if given a choice?

A

Found that “Self-selectors” had lower RGR, ECI and RCR than control larvae

33
Q

Why do “Self-selectors” grow slower?

A

This is because these self-selectors waste time and energy switching foods

BIOL 327 (13 decks)

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