VL 1 Flashcards
Why are insects important?
Pollination
Food source
Large biomass
Disease vector
Biocontrol
Decomposition
Pests
Culture
Honey
Protein
Wax
Silk
What is insect ecology
Study of how insects, individually or as a community, interact with the surrounding biotic (plants, animals, fungi etc.) and abiotic (light, temperature, atmosphere) environment
How many of all described species are insects?
50%
What is an insect?
Body consists of Head, Thorax and Abdomen
1 pair of antennae
3 pairs of legs
Chitinous exoskeleton
Usually has wings
Advantageous morphology / life history
Flight:
- spread within and between environments - exploit new niches
- escape from predators
Reproductive rate:
- fast generation time
- large numbers of offspring
- more likely to get new mutations
Small size:
- muscles require less energy/oxygen
- access to more environments / niches
Chitinous exoskeleton:
- Defence and shock absorption
- waterproof
Wide diet breadth
Herbivoure
Carnivore
Parasite
Detrivore
Necrophage
Cophrophage
Complex adaptations
Farming
Building
Mimicry
Toxic defenses
Spraying acid
Complex sensory systems
Varying life cycles
Complete metamorphosis
Holometabolous
Egg -> Larvae -> Pupa -> Adult
Insect transforms into a different morphology
- 85% of insects
- can specialize in different stages
- can go dormant in unfavourable conditions
Incomplete metamorphosis
Hemimetabolous
Egg -> Young nymph -> Later nymph -> Adult
Insect molts when too large for exoskeleton but looks the same
- go through sevral ‘nymph’ stages
- can eat constantly
- vulnerable and soft after molting
Diapause
complete pause in development / reproduction, at any growth stage
Diapause is triggered by hormones, usually in response to change in day length and is broken by: more light, change in temperature or wetting due to rainfall
It can allow insects to survive environmental conditions, or travel, that they otherwise would not - ie. Aedes mosquitoes and Monarch butterflies
Ecosystem
biological community of interacting organisms and their physical environment
Ecosystem services
key interactions that have a major impact on the ecosystem or without which ecosystem function would break down
3 broad categories of ecosystem services
Nutrient cycling
Damage and Disease
Support
Ecosystem service: Nutrient cycling
Food chain:
Insect herbivores convert plant and algal biomass -> animal biomass
Insects are the an important food source for animals, birds, reptiles, humans etc. moving energy up the food chain
Decomposition:
Insects feed on decaying plant and tree matter (detritovore) or animal corpses or feces (necrophage/coprophage) and play a strong role in recycling energy and nutrients
Detrivores
Chew up leaves or bore into dying trees -> speed up bacterial / fungal colonisation
Decomposers
Accelerate corpse decomposition through colonization with flies, beetles etc. carry off or invade animal feces
Ecosystem services: Support
Maintenance of plant communities:
Insects regulate plant and tree populations through herbivory, preventing overpopulation and allowing new growth, and are involved in both pollination and seed dispersal
Pollination:
pollination by insects is essential for 35% of global fruit and seed production. The economic value of pollination worldwide is estimated to be over 153 billion Euros
Insects aerate soil by moving through it, allowing for water movement and replenish the nutrients in it
Ecosystem services: Damage and disease
Extreme herbivory / predation: insects can have devastating effects on diversity and numbers of other organisms, especially in the case of extreme or invasive species. They can cause local extinctions, or a shift in what species are numerous in an ecosystem
Disease vectors of plants, animals and humans: insects are critical carriers of many pathogens which affect health and numbers of important species
Keystone species
Keystone species have an effect on other species / environment disproportionate to their numbers
Bsp.
Bees: Responsible for pollinating 250’000 plant species, most of which would not be pollinated enough if they were absent
Ants: Have symbiotic relationships with multiple other organisms, and are predators suppressing other species of harmful arthropod
Why do insects contribute so heavily to ecosystem services?
Insects are critical to all stages of ecological functions partially due to:
Diversity - many different traits / habitats / ecological niches
High abundance (impact due to sheer numbers)
