NutritionNutrition

• Range of diets eaten*

• Nutritional requirements• Nutritional requirements

• How does an insects gain the required nutrients

Nutrient NutrientNutrient demand

Nutrient supply

balanceE l i

P i ti h iF di t Pl t/A i l

EvolutionaryDay to day

Pre‐ingestive choicesmeal type and size

Post‐ingestive processing

Feeding type:  Plant/Animal associated morphology and 

physiology

morphology of mouthparts/gutselective absorption/excretion        

Life history stage:  Reproductive/nonreproductive

Dietary history: last meal(s)

2

Dietary history:  last meal(s)

Nutritional requirements

Nutrition = chemicals required for growth, tissue maintenance, reproduction and all other life activitiesreproduction and all other life activities

Is the outcome of ingestion, digestion, absorption, metabolism and excretion

• Ingested

• Synthesized by the insect

• Symbionts

3

Macronutrients― Nitrogen (10 a.a.): proteins and amino acids

― Energy source ‐ carbohydrate, fat, protein

― Fatty acids

― Sterols (cholesterol or plant sterols)

Micronutrients― Vitamins (vitamins B’s, A, C & E)

― Mineral ions

NitrogenNitrogen

Amino acids Proteins HH

H

OAmino acids Proteins

HN C C

O

O

R• Structural purposes

• Enzymes

• Transport and storage

• Receptor molecules

• Cuticular sclerotization (aromatic amino acids)

NitrogenNitrogen

Amino acids Proteins HH

H

OAmino acids Proteins

HN C C

O

O

RNeed 20 amino acids

10 i id ti l‐ 10 amino acids essential 

‐ the other 10 can be synthesized

= TRANSAMINATION (transfer of an amino acid group from a pre existing amino acid= TRANSAMINATION (transfer of an amino acid group from a pre‐existing amino acid

Chapman, 1998

CarbohydratesCarbohydrates

Fats

Carbohydrates Fats

• Chitin

Amino acids

• Energy 

• (CH2O)n

• Simple carbohydrates  (mono & di‐saccharides)e.g. glucose, fructose, sucrose (gluc + fruc), maltose (gluc+ gluc)

• Complex carbohydrates (polysaccharides) e.g. glycogen, starch, cellulose

LipidsLipids

• Fatty acidsFatty acids

• Phospholipids

• Sterols

• Fatty acids  ‐ CnH2n+1COOH

• Two forms saturated (no double bonds) and• Two forms ‐ saturated (no double bonds) and 

‐ unsaturated (1 or more double bonds)

C ll b• Cell membranes 

• Moulting and Reproduction

• Energy storage e.g. Long distance migration (flight)

SterolsSterols

Ch l l A i lCholesterol Animals

Plant/Fungal Sterols Plant/fungus or from symbionts

• Affects development and morphologyp p gy

• Precursors of the steroid hormones 

d— e.g. ecdysone

• Cellular membranes 

— Essential structural components (provides support and rigidity)

MicronutrientsMicronutrients

VitaminsVisual 

pigments reproduction

• Fat soluble (e.g. provitamin A, vitamin E)

• Water soluble (e.g. B‐vitamins) Can not be synthesizedEnzyme cofactors

Ascorbic acid

Nucleic acids

Enzyme cofactors

Inorganic compounds

• e.g. Sodium, potassium, calcium, magnesium, chloride and phosphate

Metals

• Iron, zinc, magnesium

Nutrient balance mattersNutrient balance matters

Nutrient demand Nutrient supplybalance

Evolutionary

Day to dayDay to day

Nutrient balance matters

Example:  Australian plague locust5th instar

0.7

5th instar

/day)

0.5

0.6 Optimal P:C ratio

 ingested

 (µg/

0 3

0.4

Decreased growth rate

Carboh

ydrate

0.2

0.3

• nutrients diluted

• suboptimal ratio P:C

0 0 0 1 0 2 0 3 0 4 0 50.0

0.1

p

Protein ingested (µg/day)

0.0 0.1 0.2 0.3 0.4 0.5

Nutrient balance mattersNutrient balance matters

Between macronutrients 

‐ protein versus carbohydrate

Chapman, 1998

Nutrient composition of diet

idrate/lipi

rboh

ydr

Diet

Car

Insect

14Protein

Nutrient composition of dietd d

te/lipid

ate/lipid

ohydra

bohydra

Carb

diet Carb diet

insect insect

15

Protein Protein

Nutrient balance mattersNutrient balance matters

Between macronutrients 

‐ protein versus carbohydrate

Within macro nutrients

– amino acid balance

Chapman, 1998

Nutrient balance matters

Nutrition = chemicals required for growth, tissue maintenance, reproduction and all other life activitiesreproduction and all other life activities

Is the outcome of ingestion, digestion, absorption, 

NUTRITION = IN OUT

metabolism and excretion

NUTRITION = IN – OUT

Pre‐ingestive

Pre – ingestive balancing

Choose

• What to eat

• Amount – meal size

• Frequency – meal frequencyq y q y

Foods contain all the necessary chemicals but not in the correct balance

Which nutrients to regulate?Which nutrients to regulate?

Nutrient requirements

‐ multiple nutrients

Carbohydrate requireANDProtein

drate

inq

Carboh

yd

Protei

‐ nutrient interactions drate

Carboh

yd

Protein

a) Balanced foode

)hydrate

•

Carbo

moves along a railmoves along a rail

Protein

Nutrient dilution

• Diluted 5‐fold range

B . Nutrient

400

450dilutionManipulation:

OUTCOME• Diluted, 5 fold range

300

350

400

35 35mg)4

BEHAVIOUR

200

250

300

7:7 14:14

21:21

28:28

35:35

e eaten (m

3

(g)

BEHAVIOUR

150

200

bohydrate

2

od eaten

 (

50

100

Car

1 Foo

Protein eaten (mg)

0 50 100 150 200 250 300 350 400 450

00 7:7 14:14 21:21 28:28 35:35

Food composition (%P:%C)

g/day)

0.6

0.7

b) Multiple foodsate ingested

 (µg

0.3

0.4

0.5

b) Multiple foods

Carboh

ydra

0.0

0.1

0.2

ACTIVE REGULATION in response to dietary

Protein ingested (µg/day)0.0 0.1 0.2 0.3 0.4 0.5

0.0 response to dietary manipulation

drate

Carboh

ydC

Protein

Powerful test of target defence

• Undefended • Defended – active regulationg

e e

ohydrate

ohydrate

Carbo

Carbo

Protein iProtein Protein

African migratory locust ‐ Locusta

350

40014:28 or 7:14% P: %C

g)

250

300

aten

 (mg

200

250

28:14 or14:7

(c;d)(c;c)

ydrate ea

100

150

(d;d)

(d;c)Carboh

yManipulation:Two synthetic foods each,% P, C and bulk different

0

50

0 50 100 150 200 250 300 350 400

Protein eaten (mg)

Nutrient requirements

Can meet nutritional requirements

Pre‐ingestive But life not that easy• What is eaten

• Meal size

• Meal frequently  Host range for many insects restricted

Nutrient requirements

Growth and Rate of Development

0.7 Decreased growth rate

i dil d

/day)

0.5

0.6 Optimal P:C ratio

• nutrients diluted

• suboptimal ratio P:C

 ingested

 (µg/

0 3

0.4

‐ Performance unaffected over a 

Carboh

ydrate

0.2

0.3

range of P:C ratios‐ Similar body compositions

0 0 0 1 0 2 0 3 0 4 0 50

0.1

Protein ingested (µg/day)

0.0 0.1 0.2 0.3 0.4 0.5

ForagingAcquiring the correct blend of nutrients

Nutrient demand Nutrient supplybalance

NUTRITION = IN – OUTNUTRITION = IN – OUT

- not absorbed Examples

h l i l- losses via post

absorptive processing

• morphological

• physiological

Example:   morphological

NUTRITION = IN – OUT - not absorbed

Modification  of  gut

Phloem feeders:e.g. aphids, psyllids, scale insects

phloem = sugar & water > nitrogen

Filter chamber: modified gut to allow water and simple sugars to bypass midgut 

28

29

Gullan and Cranston, 2005

NUTRITION = IN – OUT

b b d l

NUTRITION IN OUT

Nutrition  = ingestion  – not absorbed  – losses via post absorptive  processing

AbsorbedIngestedg

F tForegut Midgut Hindgut

Oral cavity

Malpighian

Caeca

p gtubules

Post – ingestive balancing

• Pre‐absorptive

― Differential release of digestive enzymes(Clissold et al. 2010)

― Change in alimentary canal morphology(Raubenheimer and Bassil 2007)

― Altered transporters?

• Post‐absorptive 

— Metabolism/ExcretionDeamination of amino acids (change N‐compounds to C‐compounds),  excrete excess N

Dietary induced thermogenesis (removal of excess C‐energy)

E ti f i i iExcretion of inorganic ions

Example:   physiological

Diff ti l l fNUTRITION = IN – OUT - not absorbed

Differential release of enzymes

Herbivores (& Carnivores)

e.g. Locusta migratoriag g

extraoral digesters??

32

Example:   physiological

Locusta migratoria Protein Carbohydrate

NUTRITION = IN – OUT - not absorbed g

Ingested

ate

pCPc pC Pc pC

Chymotrypsin Amylase

Carboh

ydr

Pc

Protein

Pc pC Pc pCClissold et al. 2010

Example:   physiological

4

Locusta migratoria

g) 3

Protein conditioning

tio in

the

gras

ses

Protein Carbohydrate

sim

ilate

d (m

g 3

Carbohydrate:car

bohy

drat

e ra

ti

ohyd

rate

ass 2

Carbohydrate conditioning

Aver

age

prot

ein:

c

Pc pC Pc pC

Car

bo1

A

P t i i il t d ( )

0 1 2 3 40

34

Protein assimilated (mg)

Clissold et al. 2010

Example:  physiological / behavioural

NUTRITION = IN – OUT post absorptively removed

Protein ‐ demainate and excrete N,

th CHO b kbuse the CHO backbone as energy

C‐based (carbohydrate and lipid)

‐ increase metabolic rate

35

Example:  morphological / physiological

NUTRITION = IN – OUT

Symbiontst i t ll l i i• extra‐ or intracellular microorganisms

(bacteria, yeast, protists, fungi).  ( , y , p , g )

• Contribute to the insects nitrogen (a.a. synthesis), 

vitamin, sterol and/or carbohydrate economy

36

Post‐ingestive balancing

can only do so much

What happens when insects are forced to eat a suboptimal diet?

can only do so much

0 7

sted

 (µg/day)

0.5

0.6

0.7

bohydrate inge

0.2

0.3

0.4

ohydrate

Protein ingested (µg/day)

Car

0.0 0.1 0.2 0.3 0.4 0.50.0

0.1

Carbo

Protein

250

E D fi it

mg)

200Excess vs Deficit

RulesExcess > DeficitExcess Deficit

inge

sted

(

150

Excess = DeficitExcess < Deficit

rboh

ydra

te

100

Car

50

P t i i t d ( )0 50 100 150 200 250

0

Protein ingested (mg)

Specialist feeder Generalist feederSpecialist feedere.g. Locusta migratoria,

f di i li t

Generalist feedere.g. Schistocerca gregaria,

f d d f bgrass feeding specialist feeds on grasses and forbs

Same intake targets

Compromise between P and C different

E D fi i E D fi iExcess < Deficit Excess = Deficit

Reg lation of n trient intake req iresRegulation of nutrient intake requires

1) Assessment or knowledge of the nutrient composition of foods

• directly by tasting 

• learning

2) K l d f th t iti l t t f th i t2) Knowledge of the nutritional status of the insect

• haemolymph composition

• status of nutrient reserves e g fat stores• status of nutrient reserves e.g. fat stores

3) A method of comparing food and state3) A method of comparing food and state

• Controlled by the sensitivity of peripheral taste receptors which are 

regulated by metabolic and physiological feedbacksregulated by metabolic and physiological feedbacks 

• learning from previous experience

Summary

Diet choice Assimilation allocated to growthCosts ofNutrient requirements

Age Previous history

Environment

Costs ofMetabolic requirementsDiet processing and digestionBehaviourEnvironment

‐ phagostimulants‐ deterrents

Predators/microhabitat/etcExcretion

Selective egestion of 

IngestionMeal size

overeaten compounds

DigestionProcessing

Ease of extractionMandible sharpness

Food retention timeSelective uptake – differential release of nutrients

41

Summaryy

Nutrition

what insects need

how do insects balance demand and supplyhow do insects balance demand and supply 

Further readinggChapman, 1998; Ch 4

Chapman & de Boer 1995, Ch 9p ,

Chown & Nicolson, 2004 Ch 2

Nation, 2008; Ch 3

ReferencesChapman, R. F., 1998. The insects. Structure and function. 4th edition, Cambridge University Press, UK

Chapman, R. F. & de Boer, G. F. 1995 Regulatory mechanism in insect feeding. Chapman & Hall, USA

Chown, S. L. & Nicolson, S. W. 2004 Insect physiological ecology. Oxford University Press, UK

Clissold, F. J., Tedder, B. J., Conigrave, A. D. & Simpson, S. J. 2010 The gastrointestinal tract as a nutrient‐balancing organ. Proceedings of the Royal Society B: Biological Sciences 277, 1751‐1759.

Gullan,  P. J. & Cranston, P. S., 2005. The Insects. An outline of entomology. 3rd edition, Blackwell Publishing Ltd,  UK

Nation, J. L. 2008 Insect physiology and biochemistry, 2nd edition, CRC Press, NY, USA

Additional reading

Behmer S T 2009 Insect herbivore nutritient regulation Ann Rev Entomol 54 165‐187

Additional reading ‐

Behmer, S. T. 2009 Insect herbivore nutritient regulation. Ann. Rev. Entomol. 54, 165 187.

Raubenheimer, D. & Simpson, S. J. 2004 Unravelling the tangle of nutritional complexity. In Yearbook 

of the Wissenschaftskolly zu Berlin.

Raubenheimer, D., Simpson, S. J. & Mayntz, D. 2009 Nutrition, ecology and nutritional ecology: 

toward an integrated framework. Funct. Ecol. 23, 4‐16.

Simpson, S. J. & Raubenheimer, D. 1996 Feeding behaviour, sensory physiology and nutrient 

feedback:  a unifying model. Ent. Exp. Appl. 80, 55‐64.

Simpson S J & Raubenheimer D 2000 The hungry locust Advances in the Study of Behavior 29 1‐Simpson, S. J. & Raubenheimer, D. 2000 The hungry locust. Advances in the Study of Behavior 29, 1

44.

Simpson, S. J., Sibly, R. M., Lee, K. P., Behmer, S. T. & Raubenheimer, D. 2004 Optimal foraging when 

regulating intake of multiple nutrients. Anim. Behav. 68, 1299‐1311.