Equations (Lecture 9) Flashcards
RGR
Definition + Equation
Relative Growth Rate
Weight (mg) gained per day / Average larval weight (mg)
RCR
Definition + Equation
Relative Consumption rate
mg ingested per day / Average Larval weight (mg)
ECI
Definition + Equation
Efficiency of Conversion of Ingested food
[Weight (mg) gained / mg food ingested ] x 100
ECD (Alternate name)
Definition + Equation
Efficiency of conversion of digested food
(aka net dietary utilization)
[ weight (mg) gained / (mg ingested - mg frass) ] x 100
AD (Alternative name)
Definition + Equation
Approximate digestibility
(AKA assimiliation efficiency)
mg ingested - mg frass / (mg ingested) x 100
Shortcut Nutritional Parameters (3)
RGR = RCR x ECI
ECI = AD x ECD
1 - ECD = metabolic cost
Highest RGR (2)
Forb feeding (leaves / herbs feeders) Hemiptera and Lepidoptera
Lowest RGR
Aquatic Detritivores (eg. Stonefly, mayfly naiads)
Highest RCR
(2)
Why do these insect have High RCR ?
Tree feeding, Hymenoptera, Forb feeding Lepidoptera
b/c they eat twice their body weight
Lowest RCR
(2)
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)
Highest ECI (2)
Eg. Seed- feeding Hemiptera (these insects feed on protein rich seeds)
Eg. Blood feeders (Diptera)
Lowest ECI (2)
Eg: Aquatic Detritivores (Mayflies naiads, Stoneflies naiads, Dragonflies naiads)
Eg. Tree feeding Hymenoptera
Highest ECD (2)
Eg. Seed-feeding Hemiptera
Eg. Blood feeders (Diptera)
Lowest ECD (2)
Eg. Ants - perform a number of activities, are very active and always moving
Eg. Stored grain feeders
Highest AD (2)
Eg. Forb feeding Coleoptera
Eg. Predatory Insects
Lowest AD (%)
Eg. Dung feeding insects (do not obtain much nutrient because there are low nutrient in feces)
Positive Relationship in Water
There exists to be a positive correlation b/t water content and ECD and ECI
Positive relationship in N
There exists to be a positive correlation b/t dietary Nitrogen and RGR and ECI
Physiological Efficiency Model
As nitrogen increase and water increase, this leads to an increase in the growth rate (RGR) and AD
Bernays demonstrated that Phenylalanine added at a rate of 1mg/day in the diet of the locust caused
(2)
69% weight gain in the integument of the locust
79% of the phenyl alanine was incorporated into the integument
RCR on nutrient deficient diet
Consumption rate (RCR) of the insect increase on a nutrient deficient diet
Holometabolous (eg. armyworm) insects are more efficiency in conversion of digested food to their biomass than a hemimetabolous insect (grasshopper)
Why
This is because the hemimetabolous insects contribute more towards their integument since they develop external wings
