The life-histories of insects and vertebrates are coupled. Predator and prey cannot exist without one-another. Species richnessThe number of species within a given area. Note, this is often confused with biodiversity but is very different. Species richness is not equal in all areas. Desert species richness is lower but the scale and intensity of species function can still be significant as biodiversity is not about number of species, it's about ecosystem processes. More is higher in systems with predators [1] because they perform a function(Of an ecosystem). A subset of ecosystem processes and structures, where the ecosystem does something that provides an ecosystem service of value to people. More of free surplus energyThe energy of a system that is emitted as waste and is not part of ecosystem processes. There is always some free surplus energy as this creates the basis for evolution where new species exploit gaps in the ecosystem where free energy becomes available. Surplus energy can occur as a result of disruption or disturbance. When free surplus energy reaches More -minimisation, necessary for the integrity of the food chainA single thread in a food web illustrating the chain of animals that eat each other. At the base of the food chain are small high-energy (fast metabolism) animals and at the other end large low metabolism animals. An example would be whales eating krill that eat plankton that eat algae. Or lions that eat gazelles that eat grass. More beneath.
Healthy insect populations depend on healthy songbird populations and decline in the latter (along with other large vertebrates) could be a major contributor to ongoing destabilisation of insect populations globally.
There is increasing and overwhelming evidence for the role of higher-order vertebrates in the functioning of ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More. But our obsession with studying “impacts” often leads us to linear conclusions about cause and effect. These can be very misleading, when we separate groups of animals from the overall ecosystem and energy-structure. We might, for instance, imagine that having fewer birds means having more insects. It doesn’t. That’s a linear argument. Under a systems response, the two can’t stabilise without each other.
It’s similar to how a layperson toys with the idea atmospheric carbon causes global warming but we know the real risk is increasing unpredictability of Earth’s weather patterns. It’s climate ‘change’ and instability that is the real threat.
So, when we talk about collapse of insect populations, we aren’t talking about more or fewer insects, we are talking about the destabilisation of an entire ecosystem. In fact, it’s more closely coupled to climate than we have any idea … yet.
To frame the discussion about insect decline in any meaningful way i.e. how it matters to humans, we have to consider the whole system response. In other words, ask: what are the factors that would re-enable insects to thrive?
Clearly one of these is habitat. Grasslands are thousands of times more species-rich on a small scale, than rainforests and in the Czech Republic can have 44 species for every 25 x 25 cm – that’s 7,500 times more species-rich than a hectare of the Ecuadorian rainforest. All over the world, entire grassland habitatsWhat is habitat for animals and people? Habitat, hence the word "habitable" describes the natural surroundings in which any animal (or human) lives, that houses basic needs, such as food and shelter. Vegetation, for example, is habitat for animals. On its own, habitat is not necessarily stable or sustainable, which is why it differs from an ecosystem. Habitat in disrepair More went decades ago. Pesticides are unlikely to be responsible for the majority of insect loss as their decline would have started with the transformation of grassland to agriculture – pesticides continue to suppress recovery.
But it was vertebrates, particularly migratory animals, that enabled the ecosystems to diversify in the first place [2]. Light-footed-megafauna, perfectly adapted to savannah grasslands, stimulate growth and selectively graze, which increases plant and animal diversity, amplifying the availability of energy inside the system (removing it, so it isn’t surplus and chaos-forming).
Mosaics of grazing lines, criss-crossing the plains, the application of manure droppings and soft hoof depressions, created niches to support countless other birds and animals. These smaller residents, in turn, amplified nutrientA substance that contains the raw materials for life. At a chemical level, these are contained inside compounds that are absorbed into the body and essential energy-containing molecules are extracted, so that energy can be transformed into other chemical processes that use the energy for living. More processes at ever decreasing spatial scales, until every square millimetre had maximum energy order, right down to the tiniest microscopic lifeform. If wildebeest didn’t stride through ahead on the African plains, for instance , the scene would not be set, for other animals and insects to follow up.
One of the greatest modern threats to insect ecosystems is the collapse of migratory songbird populations, which have declined by 50% in biomassThe weight of living organisms. Biomass can be measured in relation to the amount of carbon, the dry weight (with all moisture removed) or living weight. In general it can be used to describe the volume of energy that is contained inside systems, as the size of animals relates to their metabolism and therefore, how much energy they contain and More in just a few decades. Songbirds keep free surplus energy from insects, under control and therefore allow insects to diversify and avoid extinction.
What happens to all that waste energy without songbirds? It gets pushed lower down the trophic food chain but rather than benefiting insects, it generates a form of chaos(Of energy and ecosystems). Ecosystems are thermodynamically driven. Disorder occurs when energy dissipates and becomes more chaotic. For example, the release of hot air into the atmosphere results in that energy is freer to disperse (maximum entropy). The opposite is true when energy is locked into biological processes, when it is stored inside molecules (minimum entropy). Stability in ecosystems occurs More, similar to climate change but in terms of soil integrity, water retention and various nutrientEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More cycles. When the amount of free energy reaches a certain point, you might get locust plagues, which further strip-mine free surplus energy to the detriment of all other insects. Effectively, without the larger animals, the amount of available nutrient doesn’t decline, it just gets spread out more thinly so it can’t support as much diversity.
In short, the only way to solve this, is to rebuild the food chain. If you want more insects, you’re going to need to recreate the ecosystem structures that made them in the first place. The good news is, that means better food security, more carbon-capture and a more stable climate too ; )
1. Sergio, F., et al., Ecologically justified charisma: Preservation of top predators delivers biodiversityWhat is the definition of biodiversity? When we ask, what is the definition of biodiversity? It depends on what we want to do with it. The term is widely and commonly misused, leading to significant misinterpretation of the importance of how animals function on Earth and why they matter a great deal, to human survival. Here I will try to More conservationWhy is animal conservation important? Animal conservation is important, because animals are the only mechanism to create biodiversity, which is the mechanism that creates a habitable planet for humans. Without animals, the energy from today’s plants (algae, trees, flowers etc) will eventually reach the atmosphere and ocean, much of it as carbon. The quantity of this plant-based waste is so More. Journal of Applied Ecology, 2006. 43: p. 1049-1055.
2. Holdo, R., et al., Plant productivityThe power of an ecosystem to process energy. The most productive ecosystems have reached a steady stable-state with maximum entropy production. That’s to say, the number of species has reached an optimum and the functions they fulfil, have translated free surplus energy into nutrients that is either stored inside plants and animals, or is entrained within the biological cycles that More and soil nitrogen as a function of grazing, migration and fire in an African savanna. Journal of Ecology, 2006. 95: p. 115-128.
