“When Dinosaurs Rules the World”
We hear that phrase when talking about when non-avian dinosaurs were running about. Today we think of the world as a human world. That we rule it. Both are incorrect. Earth was and will continue to be an insect world.
Who has the largest biodiversity?
Who has the largest biomass?
What animal kills the most people?
Only if you look like a yummy seal
Is it snakes?
Not even close
They kill more people than sharks, but not them.
The deadliest animal is the mosquito. With the second deadliest being the sand fly. Both transmit deadly diseases to humans.
Why are insects gangsters?
One reason why insects rule the world is because they have shorter lifecycles. With short lifecycles, they can adapt to their environment, prey and predators quickly. When humans start using an insecticide it only takes a few generations for insects to adapt and become immune or resistant to the insecticide.
Compare a termite to a tree. The termite can reproduce several times in one year. A tree may reproduce only once a year. For a termite to go from an egg to a sexually reproductive adult only takes months. For a tree going from a seed to an adult takes years to decades.
Like humans, if a tree develops an insecticide or toxin the insects will quickly adapt. Imagine the race between the insect and the tree. The insect will always win with a shorter lifecycle.
If insects rule the world then why haven’t they eaten everything?
There was a study that came out a few years ago that concluded that if all spiders on earth switched their food source to be humans it would take one year for the spiders to eat all humans on earth. A scary thought. Luckily spiders mostly eat insects.
A lot of insects eat plants. So why don’t they eat all the plants on earth?
The reason why they don’t is that their population would go down. It would follow a predator-prey model of the population. It would be hard for them to eat all the plants and many would die from lack of food.
What is the Insect Problem?
The insect problem is this: how do insects prevent themselves from eating all the plants?
How do they exist with their food?
Don’t be sad for the insects. The insects are constantly innovating. They have already created some solutions for this problem.
Insect Solution 1: Social Insects and Hives
One solution to this problem is to create classes within the species. One group that does this is bees. There is a queen that lays the eggs. There are workers which are the sisters or daughters of the queen that organize and take care of the eggs and larva. The last group in the hive/colony are drones, males that collect resources. Each has a role.
The population is both controlled bottom-up, the drones collecting resources. And the population is controlled top-down, the number of eggs the queen lays.
The only issue is when the number of queens is not equal to one. If there is no queen then a worker will start feeding a larva royal jelly and that larva will turn into a queen. If there is more than one queen then the hive/colony will split or will kill one of the queens.
This system is stable it will continue to exist for a long time. Recently we are worried about the bees, especially the honey bee. There are many factors that are causing bees to have trouble, one of them is that we have selected bees to be less aggressive and because of this they don’t fight off infections or invaders. We are worried about a problem that we created. And we created the problem because of the systems we use (agriculture). Bees will be around, but honey bees in agriculture probably won’t be.
Insect Solution 2: Hibernation, Wait for Food to Grow, and Avoid Predators
Another solution is to eat most of the food then go to a safe place and lower the body’s energy requirements (hibernate). Wait until the food grows back and you can wake up again.
Insects that do this include cicada and locusts. There are multiple benefits to waiting. First is the food supply. The other is that there are so many individuals that predators can not eat them all.
Interestingly plants also have adapted the waiting game strategy. Bamboo has different flowering times some take up to 40 years to flower and produce seeds. Bamboo does this because it will produce so many seeds that the predators will miss some and the next generation will grow from the missed seeds.
Insect Solution 3: Parasitoid, The Prey Regulates the Predator’s Reproduction
A parasite is when one agent/enity gains benefit at the cost of another. Stealing is a parasitic activity.
A predator is when an agent benefits from the destruction of another. Hunting is a predator activity.
So now let’s smash these two words together fast!
Parasite + Predator = Parasitoid
A Parasitoid acts as both a predator and parasite. There are many species of parasitoid wasps. These wasps look for caterpillars. Some plants might even signal to the wasps that a caterpillar is eating their leaves. When the wasp finds the caterpillar the wasp does not kill it, but stings it, laying its eggs inside of it.
Some wasps hijack the caterpillar’s brain. The caterpillar will start spinning a cocoon to protect the wasp eggs inside of it. The wasp eggs hatch inside of the caterpillar and feed off of it from the inside. Eventually, the new wasps burst open from the caterpillar and will start eating what’s left of the body. Ever seen the film, Alien? Yeah, it’s like that.
The reason why these solution works are that parasitoids don’t collapse a population as predators do. Parasitoids always need individuals from the prey population to reproduce.
Other insects use this solution that is not parasitoids. Some insects will integrate specific time events in the lifecycle of the prey that will start the reproductive cycle of the predator. Such as only feeding on mature adults of a species.
Insect Solution 4: Cannibalism
Spider silk is a really strong structure. And extremely flexible. Spider silk is stronger than steel and stronger than kevlar. Kevlar, you know the stuff we make bulletproof vests out of? If it’s so great then why aren’t their spider farms?
Humans have farms for all other animals we think are useful: chickens, cows, sheep, and even silk worm. Why not spiders for spider silk? They tried and failed. The reason why spider farms fail is that you can’t have a lot of spiders in the same place. There is a maximum density and that density isn’t high enough to farm spider silk. What happens if the density of spiders goes over the maximum you ask? They start to eat each other. Spiders will conduct cannibalism to keep their density low. It is strategic to do this as they are reliant on insects to catch. If there are too many spiders in one place then they will all starve because there isn’t enough food to go around. Spiders will decrease their population to make sure the food will go around.
I know spiders aren’t true insects, but they have short lifecycles and have been around for a long time.
Insects have an issue with controlling their population sizes because they’re gangsters. Insects are gangsters because they have short lifecycles, large diversity, and adapt quickly. Insects have solved their own problem by being social, forming hives, hibernating for food to regrow, incorporating their reproduction with prey (parasitoid), and conducting cannibalism. All of these solutions control the population and prevent a population collapse.