insect defences part 1

Question 1

what is considered the first line of defence from predators

Answer 1

Hiding which employs a range of cryptic approaches such as mimesis and camouflage

Question 2

what is meant by a cryptic approach

Answer 2

A cryptic approach in insect defense refers to a strategy employed by certain insects to avoid detection or recognition by potential predators. The word “cryptic” comes from the Greek word “kryptos,” meaning hidden or concealed.

Question 3

what is meant by the term deimatic display which is emplyed as a secondary line of defence in insects

Answer 3

goal of startling or intimidating potential predators. The term “deimatic” is derived from the Greek word “deimos,” meaning fright. The primary purpose of a deimatic display is to startle or deter a predator momentarily, giving the prey an opportunity to escape.

Question 4

what are the prey defence strategies and relate them to time costs

Answer 4

1) Fight
2) Run
3) Hide

= as you go down the list time costs decrease

Question 5

outline predator foraging strategies and relate them to energy costs

Answer 5

1) active search
2) Trap
3) sit and wait

= as you go down the list energy costs decrease

Question 6

give some examples of visual defences used by insects

Answer 6

colour and pattern evolved as part of a predator avoidance strategy

1) crypsis= disruptive colouration and countershading
2) mimicry = appearing like another organism
3) mimesis = appearing like an inedible object
4) aposematism = warning colouration
5) deimatic display = sudden display of bright colours or eye spots
6) deflection marks = small eyespots

= there can be overlap between the different types of visual defence

Question 7

give examples of species which show crypsis in terms of disruptive coloration and countershading

Answer 7

colouration
1) lime hawkmoth
2) angle shades

countershade
1) Hummingbird hawk moth
2) smoky wave

Question 8

give an example of species which show mimicry/mimesis

Answer 8

1) orange tip butterfly

Question 9

give an example of a spp which uses deimatic displays

Answer 9

1) peacock butterfly
2) eyed hawkmoth
= use of eyespots

3)Large yellow underwing
= colour

Question 10

give an example of spp which use deflection marks

Answer 10

1) small heath
2) purple hairstreak
3) elephant hawkmoth

Question 11

give an example of a species which uses aposematism

Answer 11

1) cinnabar
2) 6-spot burnet
3) red and black from hopper

Question 12

give some examples of spp which use batesian mimicry

Answer 12

1) large red belted clearwing
2) bee hawk moth

Question 13

give an example of spp which use mullerian mimicry

Answer 13

1) hornet
2) buff-tailed bumble bee

Question 14

what is the difference between mullerian and batesian mimicry

Answer 14

Müllerian mimicry occurs when two or more harmful or unpalatable species evolve to resemble each other.

Batesian mimicry occurs when a harmless or palatable species evolves to resemble a harmful or unpalatable species

Question 15

what are chemical defences

Answer 15

defencive compounds of some type prodcued in nearly all insects (allelochemicals)
= vary in size and volatility, chemical class and mechanism of action
= can contain substances which increase effectiveness

Question 16

how may defence compounds be delivered

Answer 16

1) exist passivley in haemolmph and urticating hairs

2) be secreted from limbs

3) be activle yejected or exploded from the body

4) occur as venom and administered via sting

Question 17

outline passive toxins in terms or urticating hairs

Answer 17

= may have setae/spines along the body containing toxins from poison gland cells
- hairs fracture when touched and toxins spill out onto the body surface causing stinging or dermatitis erucism

Question 18

outline chemical defences secreted from limbs

Answer 18

= common in coleoptera such as ladybirds or bloody nosed beetle
- usually secrete toxic oily haemolymph from leg joints
- haemolymph taste is bitter so predator spits out insect
aka reflex bleeding

Question 19

outline the chemical defence which invloves activley ejecting

Answer 19

• Bombardier beetles eject mixture of
  boiling-hot toxic chemicals, including
  p-benzoquinones, hydrogen peroxide
  and enzymes, from special glands in
  posterior
• Some Isoptera (Nasutitermitinae)
  possess hose-like projections on head
  that produce sticky fluid from glands
• Abdomen tips of Formicinae ants
  adapted for spraying formic acid (lost
  stingers)

Question 20

outline venom in terms of chemical defences in insects

Answer 20

Stings evolved from ovipositor in some
Aculeata (Apocrita: Hymenoptera)
* Eusocial species display altruistic
behaviour in defence of colony (loss of
stinger causes death)
* Venom contains cocktail of enzymes to
produce immediate pain, inflammation and
tissue breakdown
* Releases alarm pheromone
* Barbed stinger gets lodged in flesh and
continues to pump driving stinger further in
and releasing venom

Question 21

outline some behavioural defences

Answer 21

1) avoidance
2) grooming
3) basking in sun = elevates body temp killing pathogens which cant survive above 30 degrees, UV radiation kills many microbes

Question 22

what is thanatosis

Answer 22

aka death feigning
= tonic immobility and is an anti-predator tactic not needing movement
= insect may fall to the ground or tuck in legg/antennae
= common in beetles
= elicited by contact, restraint and substrate vibrations

Question 23

what is faecal defence

Answer 23

Physical or chemical defence against natural
enemies
o Tortoise beetle (Chelymorpha alternans)
covers itself for protection
o Termites (Coptotermes formosanus)
incorporate faeces into nest wall to avert
pathogens
* Predator-prey interactions
o Anti-feedant by pine weevil (Hylobius abietis)
* Habitat location – cockroaches use faeces to relocate and return home
* Mate attraction by beetles, Hylotrupes bajulus

Question 24

outline some physical defences

Answer 24

• Modified mouthparts and spiny legs
  can be defensive
• Some cuticular horns or spines can
  be used to deter predator.
• Body shape can be used to prevent
  dislodging from their hosts.
• Many insects make retreats