W9: Invertebrate Physiology (Physiology Overview 3) [Dr. Blair] Flashcards
Nutrition attributes? (3)
- Underpins survival, growth, metabolism, reproduction & immunity.
- Without proper nutrition, one can’t out exercise a bad diet.
- Needs macronutrients, minerals & vitamins.
Egs of Macronutrients? (3)
- Carbohydrates.
- Proteins.
- Fats.
Carbohydrates?
= energy source (activity).
Protein?
= essential for development.
Fats?
= energy store via adipose.
Minerals?
= important for enzyme function.
Vitamins?
= important for metabolic processes.
What do you need to obtain macronutrients, protein & fat? (2)
- A specialised gut.
- Microbial symbionts.
How do insects “attempt” to gain adequate nutrition?
They feed on “all’ organic matter.
2 Strategies of Nutrition?
- Specialist.
- Generalist.
Specialist attributes? (3)
- Niche partitioning.
- Co-evolved.
- Feed on specific organic matter.
Generalist?
= able to feed on any food available & is not really specific regarding what it eats.
Pros of being a specialist? (2)
- Reduced competition.
- Efficient use of resource (specialised whole digestive system for food choice).
Con of being a specialist?
Limited resource use.
Pros of being a generalist? (2)
-Flexible diet.
- Wider resources available.
Cons of being a generalist? (2)
- Increased competition.
- Less efficient at resource use.
Eg of a Specialist?
Monarch butterflies.
Eg of Generalis?
Honeybees.
Monarch butterfly attributes? (2)
- Larvae feed exclusively on Milkweed plants.
- Use toxins for themselves.
Honeybees?
Forage on a wide variety of plants (various floral sources).
Factors that underpin nutrition? (5)
- Survival.
- Growth.
- Metabolism.
- Reproduction.
- Immunity.
What happens if an insect (or you) has poor nutrition (malnutrition)? (5)
- High mortality & short lifespan (survival).
- Slow development (growth).
- Impaired processes (metabolism).
- Low egg production & low fertility (reproduction).
- Low immunity & high infection (immunity).
“Categories”/Strategies in which insects avoid malnutrition? (3)
- Behavioural.
- Physiological.
- Diapause.
How do insects avoid malnutrition: Behavioural? (3)
- Selective feeding.
- Timing of feeding.
- Compensatory feeding.
How do insects avoid malnutrition: Physiological? (2)
- Nutrient conversion.
- Downregulate metabolism.
Diapause?
= a period of suspended development in a insect during unfavourable environmental conditions.
Diapause attributes? (6)
- Dormancy (“hibernate”).
- Decreases MR.
- Suspends development.
- In line with food quality, temperature & photoperiod.
- Common in areas away from the equator.
- Increases resistance to stressors.
Egs of stressors that insects might experience that might cause them to go into diapause? (3)
- Cold stress.
- Heat stress.
- Dessication.
Types of diapause? (2)
- Obligatory diapause.
- Facultative diapause.
Obligatory diapause attributes? (2)
- Occurs in every genration, regardless of environmental conditions.
- Common in univoltine insects.
Facultative diapause attributes? (2)
- Occurs only when environmental conditions are unfavourable.
- Common in multivoltine insects.
Univoltine insect?
= insect that has 1 generation/year.
Multivoltine insect?
= insect that has more than 1 generation/year (many generations/year).
Eg of a univoltine insect?
Burrowing bees.
Eg of a multivoltine insect?
Mosquitos.
Why do insects rely on multiple cues to start/stop diapause (particularly facultative diapause)?
To ensure that they have a safety buffer through multiple cues, so that an insect can be certain that it has adequate resources available.
What underpins the growth & development of insects?
Insect life cycles.
Types of insect life cycles? (2)
- Hemimetabolous.
- Holometabolous.
Hemimetabolous attributes? (6)
- Hemi = incomplete.
- Incomplete/semi metamorphosis.
- Wing buds present.
- In exopterygota.
- Partial change (baba looks similar to adult).
- Babies are called nymphs.
Holometabolous attributes? (6)
- Holo = complete.
- Complete metamorphosis.
- Imaginal wings/developed wings in adulthood (present in adults).
- In endopterygota.
- Complete change (baba looks completely different from adult).
- No wings present in babies.
Egs of hemimetabolous insect? (2)
- Cockroaches.
- True bugs.
Egs of holometabolous insect? (2)
- Butterflies.
- Flies.
Hemimetabolous insect development stages? (3)
Egg
|
Nymph (juvenile)
|
Adult
Holometabolous insect development stages? (4)
Egg
|
Larvae
|
Pupa (Chrystalis)
|
Adult
Imaginal disc?
= cells that will differentiate into adult organs (developed wings) present in the larvae’s body.
The physiology of growing up (Insect development) attributes? (2)
- Influenced by genetics, hormones & the environment.
- Generally, it’s:
Egg
|
Juvenile
|
Pupa
|
Adult
Egg attributes? (2)
- Embryo in a protective shell.
- Most insects are oviparous.
Oviparous?
= to lay eggs.
Juvenile attributes? (3)
- Either called Larva/Nymph/Instar/Maggot.
- Go through several molts as they grow.
- Focus on feeding/growth.
Pupa attributes? (4)
- Occurs in holometabolous insects.
- Metamorph is inside a protected casing.
- Larval tissues are reorganised.
- Imaginal discs are “activated’.
Adult attributes? (3)
- No further molts.
- Wings formed (optional).
- Functional reproductive system.
Insect development: Hormones attributes? (3)
- In both life cycle types.
- Types exist.
- Spike when change of stage occurs.
Insect development: Hormones types? (2)
- Ecdysone (ECH).
- Juvenile hormone (JH).
Ecdysone (ECH) attributes? (4)
- Triggers molting.
- ECH causes molting.
- ECH shedding of the cuticle.
- Ecdysis.
Ecdysis?
=
Juvenile hormone attributes? (3)
- Controls molt type.
- High JH retains the juvenile stage (instar molts).
- Decline in JH causes a transition to an adult.
Explain the Insect development: Hormones graph? (6)
- x-axis = Life stage of insect.
- y-axis = Hormone concentration.
- During embryo stage, both ECH & JH are high, and embryogenesis is occuring.
- During larva stage, when ECH is low, JH is high, and peaks in ECH causes molting throughout this stage.
- During pupa, JH drastically remains low and ECH peaks twice, first during pupariation & second durng metamorphosis (highest ECH), after that ECH decreases.
- During adult stage,
both ECH & JH are low, with JH slightly above ECH.
Insect development: Environment? (4)
- Environmental influence.
- High temperatures = fast development.
- Low temperatures = slow development.
- Phenotypic plaasticity.
Environmental influence?
= when the rate of growth & development depends on temperature, humidity & food availability.
Phenotypic plasticity?
Some insects tend to alter development due to environmental conditions.
Eg of phenotypic plasticity?
Planthopper nymphs.
Explain Planthopper nymphs? (23
- Planthopper nymphs become winged adults if:
(1) Nutrient levels decrease.
(2) Population density increases.
- They only develop wings in these instances to get better resources.
- Planthoppers feed on water hyacinth, which occurs as a result of eutrophication.
Super summary? (3)
- Nutrition (governs growth & development; malnutrition avoidance strategies).
- Life cycle (hemimetabolous & holometabolous).
- Development (egg-juvenile-pupa-adult; roles of hormones; plasticity).
