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The good

• Nutrient recycling – Leaf-litter and wood degradation – Dispersal of fungi – Disposal of carrion and dung – Soil turnover

The good

• Plant propagations – Pollination (!) – Seed dispersal

The good

• Maintenance of community composition structure – Phytophagy – Food for insectivorous vertebrates

1 1/24/17

The good

• -derived products – Silk – Cochineal red dye – Shellac

The good

• Food – Very common in non-western diets. – Very rich in proteins, fats, and dietary roughage. – Any other foods we get from ?

The bad

• Disease vectors – Human health – health

2 1/24/17

The bad

• Agricultural pests • Timber pests – E.g. mountain bark beetle outbreaks • Invasive pests – E.g. gypsy moth • Grain and stored product pests

The bad

• Destruction of construction products – Termites – Book lice – Carpenter bees

The ugly…

• OK, this is a somewhat subjective category…

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And others…

• Cloning – A LOT of insects do this as a matter of course.

And others…

• Microrobotics – The smallest insect known, the Dicopomorpha echmepterygis is smaller than a Paramecium. – Also models for unmanned surveillance: only non-vertebrates to evolve flight.

And more…

• Genetics – Our entire understanding of functional genetics, population genetics, and developmental genetics was built on the back of Drosophila.

4 1/24/17

Even more…

• Genomic imprinting – Was first suggested by S.W. Brown 50 years ago when working on scale insects. – Was theoretically proposed in the 1980s by David Haig – Was shown to happen through methylation in the late 1990s

This could go on and on…

• Their diversity and abundance underlies their importance. • Over 1/2 of all species described are insects. • Found on every continent in every ecosystem. • Fill every terrestrial and freshwater niche that fill.

Biodiversity and Conservation

“Scientists know far more about (and spend vastly more money studying) the systematics of stars than the systematics of earthly organisms. Consequently, they have as good a knowledge of the number of atoms in the universe — an unimaginable abstraction — as they do of the number of species of plants and animals.” Robert May, 1992

5 1/24/17

Outline

• Entomology & Insects • How many species? – – Estimates (Guesstimates?) • Why so many species? • What implications does this have for conservation?

Entomology as a Discipline

• The study of insects • Encompasses a very diverse set of biologists, all united by their study organism.

What is an insect?

• What are the defining characters?

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What is an insect?

• BODY with three distinct regions – Head – Thorax – Abdomen

What is an insect?

• HEAD – One pair of antennae – One pair of mandibles – One pair of maxillae – A labium

What is an insect?

• THORAX – Three pairs of legs – What about wings?

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What is an insect?

• ABDOMEN – No locomotor appendages

• There’s lots more, but we’ll focus on that later.

Hexapoda & Insecta

• Strictly speaking, insects are a subset of with six legs, the Hexapoda. • We will discuss the distinction later. • For now, we will treat the two synonymously.

Insect Diversity

• The diversity of insects underlies their importance. • Current evidence suggests that they make up about half of global species diversity.

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But how many species are there?

• We could base this on the number that have been described and organized into higher taxa by taxonomists.

But how many species are there? • Taxonomists have named approximately 1,000,000 species of insect. • These names follow a very specific convention.

But how many species are there? • Taxonomists have named approximately 1,000,000 species of insect. • These names follow a very specific convention. • Their classification also follows a very specific convention.

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But how many species are there?

• Most described insect diversity is concentrated in four insect orders. • Is 1,000,000 likely to be an accurate estimate?

How many species?

• Unfortunately, most insect taxonomists are a lot like Charles Darwin: – Live in north temperates – Lower in species richness

How many species? • Therefore, we know the least about the most diverse areas: The Tropics. • Temperates still impressive, though: • In 1920, Frank Lutz found 1,250 species of insect in a one-acre yard in the suburbs of northern New Jersey…

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How many species, already!?

• Estimates range from 2 million to 80 million or more. • 30 million based on a classic study by Terry Erwin.

Erwin’s estimate

• Based on canopy fogging in tropical forests and a lot of extrapolation: – Fogged trees in tropical rainforest in Panama. – Focused in on beetles. – Found 163 beetle species restricted to one particular tree species. – There are 50,000 species of tropical trees.

Erwin’s estimate

• Based on canopy fogging in tropical forests and a lot of extrapolation: – 163 beetle species X 50,000 species of tropical trees = 8,150,000 species of tropical canopy beetles. – Beetles make up ~40% of all insects, putting the estimate at 20,000,000 species. – There are approximately twice as many canopy species as ground, therefore the total estimate comes in at 30,000,000!

11 1/24/17

Erwin’s estimate

• Lots of assumptions. • What are some of them?

We really haven’t a clue…

• Recent fogging in Peru has yielded 10,000 species on a single tree. • Before he started, there were 6 known species in the ground beetle Agra, there are now >1500.

We really haven’t a clue… • Some groups yield unexpected diversity: – 13 species known of genus Cladochaeta; a review of museum collections yielded 105 more. – One described rove beetle species turned out to be a complex of at least 45 species.

12 1/24/17

More complications

• Complicating this, many species of insect are exceedingly rare. • In an intensive canopy fogging survey in Borneo, 58% of beetle species were singletons. • Similar findings for New World nymphalid butterflies!

What is it that makes insects so diverse?

• Small size = small niches. • Experience fine- grained habitat = selection for specialization.

What is it that makes insects so diverse? • Small size • Short generation time • Sensory and neuro-motor sophistication – Habitat specialization – Mate recognition • Evolutionary interactions with other organisms • Metamorphosis • Mobile winged adults

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What is it that makes insects so diverse? • These all entail persistence in small areas, high dispersal capabilities, and intense selective pressures. • These are all features that can drive rapid speciation.

What does this mean for conservation?

• Some of the very same features that lead to insect diversification also make them vulnerable to extinction.

What does this mean for conservation?

• The diversity of insects also means that we know very little about the vast majority of them. • What roles do they play? What would be the impact of their disappearance?

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What does this mean for conservation?

• There are currently 687 insect species listed by the International Union for Conservation of Nature and Natural Resources (IUCN) as vulnerable to extinct (0.013% to 0.0009% of total). • Compare to 1,219 species of mammals (23%).

What does this mean for conservation?

• What does this mean for insect conservation? • Is there motivation for protection? • How might they be protected?

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