The Importance of Insects in Ecosystems

What roles do insects play in ecosystems?

They function at multiple trophic levels as herbivores, predators, parasites, parasitoids, detritivores, prey, and pollinators.

How do insects regulate each other's populations?

Through predation and competition, with insect-on-insect regulation being highly efficient.

Why is food rarely a limiting factor for insects?

Many are polyphagous and can switch food sources, and different life stages or sexes often have different diets.

How does total metamorphosis reduce competition in insects?

Immature and adult stages often have completely different diets.

What environmental factors regulate insect populations?

Weather, predators, parasites, and pathogens.

How is climate change disrupting insect population control?

Warmer temperatures can allow plants to develop faster than insects can adapt, leading to desynchronisation.

What is phenological mismatch in insects?

A growing disconnect between insect life cycles and plant development, e.g. leaf-out timing not aligning with herbivore emergence.

What evidence shows phenological mismatches?

A European study showed vegetation phenology advancing four times faster than insect phenology.

What makes some aphids potential primary producers?

They contain carotenoids obtained via horizontal gene transfer from fungi, allowing them to harvest light energy.

What is special about green aphids?

They contain more carotenoids and produce more energy in sunlight than other color morphs.

How might aphids benefit from sunlight-harvesting abilities?

As a backup energy source during host-switching or environmental stress.

What is the significance of xanthopterin in hornets?

It can convert sunlight into electrical energy, acting like a natural solar panel.

What proportion of plant material is typically consumed before dying?

Only about 10%; most carbon remains locked in dead material.

What do insect decomposers do?

They break down dead organisms and waste, releasing nutrients and carbon back into the ecosystem.

Why is decomposition important for energy flow?

Without it, energy and nutrients remain locked in organic matter, reducing biodiversity.

Which insects are key decomposers?

Beetles (scarabs, silphids), flies (muscids, calliphorids), springtails, mites, and others.

What is ecological succession in decomposition?

The predictable sequence of insect colonisation on dead material.

How is decomposition used in forensic science?

Insect development stages and temperatures are used to estimate time of death.

What is notable about insects degrading plastics?

Some beetles and moths can break down synthetic polymers like polystyrene and polyethylene.

What happens during decomposition?

Organic material is physically destroyed, dispersed, and chemically degraded into CO₂, water, and mineral salts.

How do dung beetles interact with dung?

They consume it, bury it, tunnel under it, or roll it away for food and shelter.

How did dung beetles evolve?

They pre-date large mammals but diversified with them as dung availability increased.

What ecosystem services do dung beetles provide?

Decomposition, nutrient cycling, pathogen control, seed dispersal, and reduction in fly populations.

How do dung beetles help reduce use of fossil fuels?

They reduce the need for artificial fertilisers, which are made and transported using fossil fuels.

Why is marsupial dung important in Australia?

It's smaller and drier, and native beetles are specially adapted to process it.

How many dung beetle species were introduced in Australia?

53 species were introduced between 1969 and 1990; 23 established.

Why were some introduced dung beetles ineffective?

Geographical and seasonal gaps meant some didn't match cattle dung production times.

What is the role of phoretic mites on dung beetles?

They feed on fly larvae and nematodes, helping control pests.

How do dung beetles improve soil?

By digging, they increase water infiltration, reduce runoff, and enhance fertility.

How do dung beetles aid carbon sequestration?

By burying carbon-rich dung, reducing CO₂ emissions and improving plant growth.

What nutrients are recycled by dung beetles?

Carbon, nitrogen, and phosphorus - all important for soil health and crop productivity.

How do termites digest wood?

With the help of gut symbionts (bacteria and protozoa) that produce cellulolytic enzymes.

What greenhouse gas is produced by termite digestion?

Methane (CH₄), which is 30x more potent than CO₂.

How much methane do termites produce globally?

Previously estimated at 30%, now believed to be 1-3%.

What mitigates termite methane emissions?

Melanotrophic bacteria in nests absorb some of the methane.

How do termite mounds help in drought conditions?

They create "islands of fertility" with better soil, more water retention, and improved vegetation growth.

What roles do termites play in ecosystems?

Decomposers, soil engineers, nutrient cyclers, and drought buffers.

What is pedogenesis and how are termites involved?

Soil formation, by breaking down organic matter and mixing it into soil.

What is a termitophile?

An organism that lives symbiotically with termites, including microbes and some vertebrates.

How do termites buffer savannahs from desertification?

They enhance soil fertility and moisture, allowing vegetation to persist and reseed barren areas.

Why is termite biomass significant?

They make up 75% of insect biomass and 10% of animal biomass in tropical ecosystems.

What major role do insects play in carbon cycling?

Decomposing dead organic matter and recycling carbon into the atmosphere or soil.

What's "Insectageddon"?

A term describing the dramatic global decline in insect populations and diversity.

What did the Rothamsted Insect Survey show?

A 28% decline in larger moths across 40 years in the UK.

How much did insect biomass decline in German reserves?

76% over 27 years.

What are the possible causes of insect decline?

Climate change, habitat loss, pollution, pesticides, invasive species, and desynchronised phenology.

What was found in Puerto Rico's Luquillo rainforest?

98% of ground insects and 80% of canopy insects disappeared over 35 years.

Why is long-term insect population data hard to gather?

Lack of standardised sampling and decline in trained entomologists.

Why is population decline in common species concerning?

These species often play major ecological roles and their loss has widespread impacts.