Movement of individuals from one place to another

Dispersal

benefits of dispersal

Escape from predation and unfavorable conditions.

Enables access to resources over a greater geographic range to reduce competition

Types of Dispersal

Passive Dispersal: Assistance from external sources or human-made structures

Active: Move from one location to another without assistance

Passive Dispersal leads to

Limitation where they have what? and a balance of

Little control over the destination and survivability

balance with high reproductive rate

Adapatations to capture wind currents such as long hair or silken thread

Ballooning behavior

Ballooning behavior characteristics

- Leave egg mass

- Climb to end of branch or shoot & drop down on silk strand

- Wait to be blown by wind to find suitable host

Active Dispersal Characterisitics

Increase the probability of finding suitable habitat

Normal mode for most insects

Adaptation for Locomotion is what?

Efficient locomotory appendages and energy, using specialized sensory and neuromuscular systems

Migration is considered what

specialized behavior

Migration types:

Uninterrupted flight patch

persistent movement

Migration Types:

Specific destination

Straight movement

Migration Types

separate from foraging behavior

unresponsive to most stimuli

Migration Type

physiological changes resulting in reallocation of resources

Observable pre- and post-migratory behaviors

Migration can occur across

multiple generations

This insect is considered a multigenerational migration?

green darner; migrated dragonfly in North America

Green Darner Adapative Strategy

Spreads reproductive effort across multiple, widely separated water bodies
• Lowers the risk of predation, competition and
drought

Multigenerational Migration

3 types of generations

First generation is migratory, emerges
between February and May and dies in North

Second generation emerges in North,
migrates South and dies

Third generation: offspring of migratory
individuals in fall, is non-migratory and
emerges in South in November

Migration

A suite of pre-migratory behaviors that predispose to long movement

Migratory syndrome

Migration Cost/Benefits

• Migration begins before resource depletion, showing it’s anticipatory.
• There’s a trade-off between migration and reproduction.
• Energy is shifted from reproduction to fuel and muscle, reducing future reproductive ability.

Monarch Butterfly Migration

Characteristics

• Triggered by photoperiod and temperature, not population density
• Helps avoid harsh winters and follow milkweed availability
• Caterpillars eat only milkweed; adults feed on various nectar sources during migration

Monarch Buttefly

Adaptations

• Cluster for warmer microclimates, stay mostly inactive until spring
• Females enter reproductive diapause (no egg production before migration)
• Reproductive activity resumes before return trip; eggs laid on milkweed along the way

Monarch Butterfly Navigation

• Monarchs use genetic memory to find ancestral sites
• Navigate with a sun-based compass and circadian rhythms to adjust orientation

Monarch Butterfly Navigation Mechanisms

• Use geographical features and landmarks for navigation
• Follow chemical markers on plants left by past generations

Symbol of conservation in America:

Keystone species

Major threat:

Habitat destruction

Environmental
Constraints Issues

• Habitat loss from overwintering site destruction and fewer host plants
• Limited relocation ability due to reduced habitat
• Insecticides/herbicides harm survival
• Large-scale movement can lead to environmental damage

Migratory Locust

• Orthoptera species example of migratory pest insect
• Generalist herbivores (polyphagous), prefer cereals and grasses
• Major agricultural pests
• Show phenotypic plasticity—change behavior based on environment

Locust

• Increased population density triggers locust phase change via leg stimulation
• Serotonin release from seeing other locusts promotes aggregation

Swarm Formation of Locust

• End of dry season and rapid plant growth boost grasshopper numbers
• Overcrowding triggers shift to gregarious phase
• Swarms lead to mass egg deposition

Locust Swarms

• Locust swarms can cover hundreds of miles
• Climate change alters rainfall, triggering outbreaks in dry regions
• Rapid response needed—management is challenging