W11: Invertebrate Physiology (The Insect Apocalypse) [Dr. Blair]

Question 1

Insect apocalypse attributes? (5)

Answer 1

• Insect abundance (~75%) has declined in the last 50 years.
• Several reasons/global threats have contributed to this as a whole.
• Important orders (butterflies, beetles & bees) are disappearing as they provide us with ecosystem services.
• The physiology of insects has been negatively impacted.
• No single over-arching cause.

Question 2

What are the primary drivers towards the insect apocalypse? (5)

Answer 2

• Habitat loss/Fragmentation.
• Pollution.
• Pesticide usage.
• Invasive species.
• Climate change.

Question 3

Habitat loss/Fragmentation attributes? (7)

Answer 3

• PAs host most insect species.
• PAs have higher levels of abundance & diversity.
• Affected most species.
• Reduced access to habitat/resources.
• Biggest physiological stressors.
• Physiological stress = nutrient stress.
• No real physiological stress.

Question 4

Urbanisation effects/attributes? (5)

Answer 4

• Affected most species.
• Urban heat islands: ~1-7 degrees celcius hotter than surrounding areas.
• Major physiological stressor.
• Physiological stress = Thermal stress.
• Physiological responses of insects = heat shock proteins & acclimation.

Question 5

Habitat alteration effects/attributes? (4)

Answer 5

• Johannesburg is largest man-made urban forest.
• Afforestation.
• Alters resources & microclimates.
• Changes the guilds of insects (i.e., changes the composition & functionality of insect communities).

Question 6

Pollution effects/attributes? (6)

Answer 6

• Pollution of air & water resources, and light pollution.
• Physiological stressor.
• Physiological stress = Toxicity.
• Physiological response of insects = resistance.
• Emerging pollutants such as microplastics contribute to toxicity.
• No physiological responses to microplastics.

Question 7

Air pollution effect/attributes? (3)

Answer 7

• Affects most terrestrial species.
• Pollutants & particulate matter cause mediocre air quality in Joburg.
• Toxicity & Respiratory stress.

Question 8

Water pollution effects/attributes? (5)

Answer 8

• Affects most aquatic species.
• Lethal to sensitive species.
• Physiological stress = Toxicity.
• Use species as bio-indicators.
• Use SASS5 to assess river health.

Question 9

Light pollution effects/attributes? (3)

Answer 9

• Affects most nocturnal species.
• Affects the navigation of nocturnal species.
• Makes nocturnal species more susceptible to predation (phototaxis).

Question 10

Egs of nocturnal species that prey upon insects due to light pollution (phototaxis)? (3)

Answer 10

• Bats.
• Spiders.
• Mantids.

Question 11

Climate change effects/attributes? (4)

Answer 11

• Elevated CO2 causes dilution effect, structural effect & metabolite effect (explain when writing).
• Cause slowed growth, prolonged development, slow digestion & reduced reproduction.
• Physiological responses of insects = compensatory feeding, increase midgut length & foregut changes.
• High temperatures affect insect distributions & ranges (winners, movers & losers).

Question 12

Invasive species effects/attributes? (3)

Answer 12

• Made possible through globalisation.
• No more geographic barriers via globalization.
• Enables the introduction of invasive species.

Question 13

Egs of invasive predators/species? (2)

Answer 13

• Polyphagous Shot Hole Borer (PSHB).
• Harmonious ladybird.

Question 14

PSHB attributes/effects? (6)

Answer 14

• Arrived in SA from southeast Asia.
• Kills trees, which then have to be cut down.
• Affects ~200 tree species.
• Physiological stressor.
• Causes competition & displacement of native species.
• Short term physiological responses by native species are insufficient in the long term.

Question 15

Harmonious ladybird attributes? (2)

Answer 15

• Native species are not adapted to it.
• Short physiological responses of native species are ineffective.

Question 16

Pesticide usage effects/attributes? (4)

Answer 16

• Impacts native groups.
• Extensive in South Africa (globally).
• Toxicity caused through non-target effects.
• Resistance by target species but not native species as it’s not their selective pressure.

Question 17

Let’s recap on those primary drivers? (5)

Answer 17

• Habitat loss/Fragmentation.
• Pollution.
• Invasive species.
• Pesticide usage.
• Climate change.

Question 18

Ways to save insects from these drivers/mortality/extinction? (2)

Answer 18

• Conservation.
• Policy interventions.

Question 19

Kindly specify how these interventions can be implemented? (3)

Answer 19

• Protecting habitats.
• Reducing pollution.
• Limiting pesticide use.

Question 20

Super summary? (3)

Answer 20

• The “Apocalypse” (loss of insect abundance, ecosystem services).
• Losing insects (no single outright cause, accumulation of several causes, urbanisation/pollutions/climate/invasions).
• General trends (major concerns, physiology isn’t enough, intervention. conservation & policy).