VL 4 Flashcards
What is sensory ecology?
Sensory ecology is the study of how organisms obtain, process and respond to information from their environments
What is a proximate cause?
An immediate underlying cause based on the particular features of an individual organism and its environmet
What is an ultimate cause?
The evolutionary, historical reason why the insect is the way it is and has a particulat set of behaviors
two types of directed response to a stimulus
Endogenous: arisin gfrom within
Exogenous: arising from the external
Innate or inheritedd behaviour
consist of more or less predictable, genetically programmed responses (or sequences of responses) to different types of stimuli
Learned behavior
Behavior that is acquired as a result of the experience of an individual
Orientation Behavior
Processes that an insect uses to organize its behavior with respect to spatial features of the environment
Primary (positional) orientation: Body position, posture control, e.g. dorsal light reaction
Secondary orientation: translational processes: kinesis, taxis (movement)
Primary Orientation
The dorsal light reaction
Dragonflies maintain their vertical orientation by turning their bodies until the immatidia of the two eyes are equally illuminated
Important in flight
Backswimmers (notonecta) have a ventral light reaction
Secondary Orientation
Kinesis: random or undirected locomotor reaction in which the speed of movement or the frequency of turning depends on the intensity of stimulation
Taxis: non-random movements directed toward or away from a source of stimulation
How can Kineses be classified?
By type of Stimulus
Hygrokinesis: to humidity or moisture
Photokinesis: to light
Stereokinsesis: to contact with surfaces
Chemokinesis: to a chemical gradient
By type of movement
Orthokinesis: speed of movement depends on stimulus intensity
Klinokinesis: frequency of turning depends on stimulus intensity
Kinesis allow th einsect to randomly search the environment but to slow down or stop moving when it encounters desirable conditions
Taxis
A movement of orientation in response to a source of stimulation
positive: if orientation is toward the stimulus source
negative: if orientation is away from the stimulus source
Phototaxis
Negative phototaxis - movement away from a light source
Positive Phototaxis - movement toward a light source
Why do moths move towards light sources?
Moths use the moon as positional indicator in order to maintain bee-line flight at night
Lamps are mistaken by moths to be no more than small moons
moths fly round and round a lamp, at each turn getting a bit closer to it
Menotaxis
Astrotaxis
Menotaxis: Constant angle to stimulus
Astrotaxis: Sun or moon (can take into account movement of light source - navigation)
Phonotaxis
oriented movement of an organism with respect to a sound
Female cicadas orient to the sounds made by male cicadas who have special vibrationg structures, tymbals on their abdomen
Rheotaxis
Aquatic insects often orient themselves with respect to a water current; this is rheotaxis
For instance, a black fly larva will situate itself where the current is fastest, so that it can capture the maximal of floating detritus in its labral fans
Chemotaxis
Odors also provide a cue for insect movement
In a typical scenario, insects reorient their direction of movement toward something that smells attractive
Overview over different taxes
Phototaxis: light
Chemotaxis: chemical oor
Phonotaxis: sound
Rheotaxis: water current
Thermotaxis: temperature
Skototaxis: darkness
What factors can influence a basis taxis?
Below 16°C honey bees are negatively phototactic, above 16°C their response is positive
Ips (Coleoptera) are positively phototactic when flying. When feeding their response is negative
Taxes can be influenced by the physiological state of the insect (hunger, mating condition)
Types of learning behavior
Avoidance behavior - avoid negative stimulus
Habituation - prolonged exposure to stimulus lead to an eventual loss of response
Conditioning - capacity to associate a stimulus with a reward or punishment
Locality learning - learning the position of food or nest; “homing” behavior (e.g. Ammophila, honeybees)
Preimaginal conditioning
Carry over of learned information from an immature to the adult stage. Most common with feeding behaviors, involving inducible preferences
Chemical ecology
Chemical ecology explores the role of chemistry in mediating interactions among organisms and between organisms and their environments
What do organisms use chemicals for?
Lure their mates
Associate with symbionts
deter enemies
fend off pathogens
Semiochemicals: Infochemicals
Pheromones: within species
Allelochemicals: between species
Types of Allelochemicals
Synomones: Sender + Receiver +
e.g. Floral scents attracting pollinatiors
Kairomones: Sender- Receiver +
e.g. Plant feeding stimulants
Allomones: Sender+ Receiver-
e.g. Plant & insect defensive chemicals (repellents, plant toxins)
What is a Pheromone?
defined chemical signal between members of the same species, eliciting a particular behavior or physiological change
broader definition:
any chemical signal conveying information between members of the same species
When are Pheromones used?
Mate choice
Sexual maturation
successful fertilization (aquatic animals)
Kin Recognition
Caste and reproductive status (social animals)
maternal-infant bonding
dominance hierarchy
aggression
territory and trail marking
deception (plant -> animal)
Deception (animal -> animal)
Aggregation
intruder alarm
Sex pheromones
Readiness to mate
attraction pheromones: long distance to attract mates
Previous to mating
emitted by males and/or females at a short distance/high concentration persuade females/males to mate
After mating: defence of reproductive investment
dissuades rival males from mating with the same female
e.g. Benzyl cyanide in P. brassicae transferred during copulation
Alarm pheromones
released in response to predator attack
e.g. Aphid alarm pheromone (E)-beta-farnesene
causes aphid dispersion: walking away or dropping from the plant
Plants also produce (E)-beta-Farnesene, it disappears within about 10 min
Pheromones in social insects
nestmate recognition
trail-following & recruitment: foraging for food
Caste determination
territorial
Primer pheromones
physiologically active
change in insect development
slow onsetg
long persistence
Releaser pheromones
Behaviorally active
Rapid response
Quick degradation
Aggregation pehromones
mate finding & mass attack
aggregation pheromones used to control stored product insects
mimicry
pheromines subverted for deception
What are the problems?
Making chemical signals that convey information and broadcast/distribute them
Detecting & discriminating signals among the noise
Responding to signals quickly and learly and making the right decisions
Sex pheromones in crop protection
Pheromone traps
wide-area mating disruption
Sex pheromone become ubiquitous, thus males are confused & not able to find female
Allelochemicals
Chemcials that trigger a response in members of a different species
Mediate vital insect behaviors
- host habitat discrimination
- host detection
- host recognition & acceptance
- Feeding behavior: stimulants or deterrents
- social interactions
Allelochemicals - Host detection, finding, recognition & acceptance
olfaction: smell (detections of odors-long & short range
taste: contact chemoreception (detection of chemicals in solid or liquid form - short range)
Allelochemicals - Insect chemical defence
Sequestration = acquisition of toxic chemicals from foods consumed by an insect
More than 43 spp. of insects are known to sequester chemicals: grasshoppers, aphids, beetles, wasps, butterflies & moths
True ssequestration requires the toxic to be systematically translocated from the gut to other body tissues
See example on page 57, monarch butterfly
