The Report A think tank specialising in public policy released these findings about the global decline of insect populations. A comprehensive review of 73 l...

(a) Two causes and two consequences of insect population decline [4]

Causes (any two, 1 mark each):

• Habitat loss from intensive agriculture: As farming expands and intensifies, natural habitats such as meadows, hedgerows, and wetlands are destroyed, removing the environments insects need to breed and feed.
• Widespread pesticide use: Chemicals designed to kill crop pests also harm non-target insect species, including pollinators like bees and butterflies.
• Light pollution from urban expansion: Artificial lighting disrupts insect behaviour, particularly nocturnal species that navigate by natural light sources such as the moon.
• Climate change: Shifting temperatures and weather patterns alter the timing of flowering and insect life cycles, creating mismatches between pollinators and the plants they depend on.

Consequences (any two, 1 mark each):

• Over 40% of insect species could face extinction within three decades if the current decline continues.
• Biodiversity is threatened as insects form a critical part of most ecosystems.
• Global food security is endangered because insects pollinate roughly 75% of food crops.
• Loss of a primary food source for birds, bats, and freshwater fish, which depend on insects as a key part of their diet, triggering cascading effects through food webs.

(b) The line of reasoning connecting insect decline to global food security [4]

The report builds a causal chain with four links, each earning 1 mark:

1. Insects are essential pollinators: The report states that insects pollinate approximately 75% of the world's food crops. This establishes insects as a critical input in global food production.
2. Insect populations are collapsing: With biomass declining at 2.5% per year, the population of pollinating insects is shrinking significantly over time.
3. Fewer pollinators means reduced pollination: If there are fewer insects available to transfer pollen between plants, pollination rates fall, directly reducing the ability of crops to produce fruit, seeds, and vegetables.
4. Reduced crop yields threaten food security: Lower pollination leads to lower agricultural output. With less food produced globally, food prices rise and availability falls, particularly in regions heavily dependent on insect-pollinated crops. This is the mechanism by which insect decline translates into a food security crisis.

(c) Two policy actions to address insect decline at an international level [6]

Each policy earns up to 3 marks: 1 for identification and 2 for justification explaining why international action is appropriate.

Policy 1: An international treaty restricting the most harmful pesticides

A binding agreement to ban or phase out pesticides known to be most damaging to insect populations (such as neonicotinoids) would directly address one of the principal causes identified in the report. The justification for international rather than national action is that pesticides cross borders through trade in agricultural products. If one country bans harmful pesticides but its trading partners do not, domestic farmers face higher costs while imported food continues to be produced using those chemicals. A global agreement prevents countries from undercutting each other's environmental standards, similar to how the Montreal Protocol successfully phased out ozone-depleting substances through collective commitment.

Policy 2: A global fund to incentivise habitat restoration

An internationally financed fund, resourced through levies on intensive agricultural exports, could provide grants and technical support for restoring insect habitats (wildflower corridors, hedgerow replanting, wetland recovery). The justification for international coordination is that habitat loss is identified as the leading cause of decline, and the costs of restoration fall disproportionately on developing countries where farmers may lack resources to change practices voluntarily. A global fund redistributes the financial burden, recognising that insect populations do not respect national borders and that ecosystem services such as pollination benefit all countries. Without international financing, the countries with the greatest insect biodiversity but the least economic capacity would bear the highest restoration costs.