Module 3 Flashcards
Insect nervous system is made of
Neurons
Types of neurons
Sensory neurons
Motor neurons
Interneurons
Dendrite
Receives stimuli
Cell body
Receives action potential from dendrite
Axon
Moves signal to another neuron or tissue
Synapse
Neuron signals are passed through neurotransmitters
PNS
Receives info and sends to CNS
CNS
Where info is processed
Has brain and ventral nerve chord
Sensory receptors are found in places like
Antennae and compound eyes and feet
Part of PNS
Trichoid sensillum
PNS receptor that detects movement (mechanoreception)
Seta (hair structure) moves and generates action potential sent to CNS
Chemoreception
Sita is holes that allow chemicals in and these chemicals dissolve in the neuron and this is connected to CNS
Types of trichoid sensilla that detect chemoreception
Contact chemoreceptors (detect substances in fluids)
Olfactory chemoreceptors
(detect substances in the air)
Insect nerv chord is
Ventral
Ganglia
Located along the CNS and are connected to CNS by connectives
Derived insects ganglia amount vs ancestors is
Less because they are more fused
Insect brain
3 distinct pairs of ganglia with different functions
Largest part of brain
Receives inputs from PNS and other structures in the brain
Contain mushroom bodies
Mushroom bodies
Sort information
2nd part of brain
Receives input from antennae and transmit this info to higher processing sectors to influence behaviour
Third part of brain receives input from
Rest of body
Mostly foregut and labium
Subesophageal ganglion
Control mouthparts and is bridge between nervous system and the rest of the nervous system
Neurosecratory cells
Release insect hormones and neurohormones
Neurohormones
Promote further hormone production in endocrine
Ecdysteroid and juvenile hormones affect
Processes in the body that allow development like moulting
Neurohormones stimulate the release of ecdysteroid hormones by
Prothoracic glands
Neurohormones are released by
Corpora Cardiaca
Juvenile hormone is released by
Corpora Allata
Axonic poisons
Affect axon signal movement
Insects begin twitching and lose mobility
DDT
Colourless and odourless chemical used against insects
Ended up being toxic and an environmental poison during WW2
Synaptic poisons
Forces and increase in synapses
Results in tremors restlessness and eventually death
Internal fertilization protects
Gametes
Internal fertilization have led to the development of
Courtship behaviours
Communication of sexes is used through
Visual signals
Auditory signals
Pheromone signalling
Pheromone
Chemical signal that when received, changes the behaviour of target
Used for communication
Singing in insects
Louder signalling is more preferred because it can represent fitness
Butterflies use
Visual cues
Fireflies use
Light communication
Males do courtship behaviours like
Dances
Rhino beetles
Have exaggerated horns to attract females
Male competition
Does not always end in a fight- sometimes the less fit one will back off
Aphrodisiacs
Makes the stimulate sexual receptivity
Multi-modal communication
Chemical and visual cues are both used
Example is butterflies
Nuptial gift
Allows female to assess male fitness
Also can distract female so male can transfer sperm
Often provide nutrition to female
Spermatophylax
Gift from male given to female with both nutrients and sperm
Sexual cannabilism
Male gives female nutrients after mating
Males do courtship because
Females have more investment in offspring
Reproductive system is found in
Abdomen
Repro system is designed for
Sperm receive and storage and manipulation as well as eggs
Females have
Two ovaries
Each has one or more ovarioles which is where the egg is made
Egg has
Yolk on inside and chorion on outside
Oogenesis
Egg production
Egg moves from ovary to
Genital chamber through oviduct
Spermatheca
Holds sperm and gland inside keeps sperm viable
Accessory gland
Makes glues that allows the egg to stick to surfaces during oviposition
Ovipositor
Where the egg travels through to be laid
Egg is layed
When egg is in early development
Egg is protected and yolk is used for nutrients
Sperm production happens in paired
Testes
Sperm travels from testes to
Seminal vesicle through vas deferens
Sperm is sent into the female through the
Ejaculatory duct
Male accessory glands help
Protect and deliver sperm
Can also help make nuptial gifts
Can also make females less attracted to other males or not allow other males to enter repro tract
Traumatic insemination
Male penetrates a new hole into female and lays egg in blood
Sexual conflict
Males and females copulation has conflict
Water strider copulation
Male mounts female on the water and female has to support the male
can be 4 minutes to 7 hours long
Redbacked water strider
Females have a blockage to males appendage
Male redback water strider response
Calls a predator and makes the female choose between death and an energy costly copulation
Most insects repro
Sexually
Oviparity
Females deposit eggs externally
Oviposition
Egg moving from body to outside environment
Females create
Large amount of offspring
Chorion
Prevents water loss
Male giant waterbug
Female lays eggs on the male forewings and male protects the eggs and make sure they get oxygen
Ovoviviparity
Keeping the eggs inside the body for protection
Hatching can happen in the female
Viviparity
Live birth
Embryo is developed in female but different from ovoviviparity because the egg does not get nutrients from yolk but the female itself
Restricts the amount of young the female can have
Parthenogenesis
Asexual reproduction
Example is aphids where the children are genetic copies of mothers
Aphid reproduction goes nonstop until
Conditions deteriorate due to cold
Females then make males because genetic variation is more important than simply increasing numbers
Holocyclic
During different periods the female can reproduce sexually and asexually
Males in insects like bees and ants are
Unfertilized and haploids
Paedogenesis
Juveniles reproduce
Can be sexual or asexual
Paedogenesis forms a
Complex life cycle
Adults are only produced in certain conditions
Repro is done by larvae
Polyembryony
One egg splits into many
Done in parasitic insects
Allows the female laying the eggs in the host to have little energy cost (also lowers predation)
Embryos receive nutrients from host
Hermaphroditism
Both male and female sex characteristics are available
but insect still mostly chooses sexual repro
Mating disruption
Exploits phéromone type mating
Stops reproduction
Meant for pest management
Uses manmade pheromones to disrupt mate finding process
Mating disruption only works when pest population is
Low because if it is high then the male will find the female by chance anyways
Mating disruption is high cost and only used when
There is no other option or if the crops are high value
Gypsy moth
Very invasive species whose spread has been reduced due to mating disruption
Sterile insect technique (SIT)
Releases large amount of sterile individuals into pest population
Uses a large amount of sterile individuals so a lot of resources are needed
Sterilization happens through
Ionizing radiation
Genetic manipulation
RNA manipulation.
For SIT to be effective
The amount of mating with sterile individuals must be greater than non-sterile mating.
This means that sterile population management must be maintained
SIT is worth it due to its cost because it is
Effective and does not use chemicals
