Lesson video

Welcome to this lesson from the unit, Reproduction In Plants.

The title of today's lesson is Insects and Food Security, and we're gonna be looking at insects and how they act as pollinators, and why that's important to make sure that we have enough food for our growing human population.

My name's Mrs. Barnard, and I'm going to be taking you through today's lesson.

We've got some keywords in today's lesson, and our keywords are insects, pollinators, food security, and crops.

I'm gonna put a slide with the definitions, so if you want to pause the video to write them down, you can do; otherwise, we'll be going through them as we go through today's lesson.

So, by the end of today's lesson, you should be able to explain the importance of insects for human food security and suggest how we can protect them.

Our lesson today is in three parts; the first is about pollinators, so this is animals that can transfer pollen from one flower to another, and we are going to be focusing on insects.

And then, food security, so why that's important for making sure that we have food to feed our population.

And finally, what we can do to protect these pollinators.

So, let's get started with the first part of today's lesson, which is pollinators.

So, a little bit of a recap now from previous lessons.

So, pollination is the process of transferring pollen grains from a male anther to a female stigma.

So, you can see this diagram here which part is the anther, so it's part of the stamen, the male part of the plant, and it transfers the pollen onto the stigma.

Now, that process can be self pollination; so the pollen comes from the same flower and lands on the same flower's stigma, or it can be cross pollination.

So, the pollen comes from the the flower of a different plant, and then it comes across to the stigma of a different plant.

And this enables the plant to reproduce sexually, which means that the seeds that it makes will have DNA of two different plants, and that provides variation.

So, the pollen from the flower of one plant can be transferred to the stigma of another plant of the same species by wind, water, or insects.

And the insects that transport pollen are called pollinators.

So, here's an example of bee; think that's probably the example that most people will recognise.

And it's taking the pollen from the anther of one over, and it drops it off on the stigma as it visits the flowers during its day.

So, there's the pollen stuck to its fur, and it is called a pollinator.

So, 80% of pollination is carried out by insect pollinators.

So, this isn't just bees, it also includes flies and wasps and butterflies and beetles.

So, even though bees are our most important pollinator, there's lots of other insects that pollinate.

Now, this is quite important because different flowers of different colours will attract different pollinators, and that might be important for the flower, the type of pollinator that visits.

And also, it might be the time of day.

So, different flowers will look different colours at different times of day, and that will be when different insects are active.

So, the variety is actually important.

Larger animals can also be pollinators, and that includes birds, bats, and other small mammals like lemurs.

So, example, we've got a hummingbird here, and then we've got a white and black rock lemur.

So, this lemur lives in Madagascar, and it's the only pollinator of a certain tree, because it's got really tough shell round its fruit, and it pries it open with its hands, and it sticks its nose in to get the fruit, and it gets pollen on it, and therefore it will transfer it then onto another plant.

And then, we've got the bat.

Now, the bat is one of the major pollinators in Australia of eucalyptus plants.

So, which of these animals are insect pollinators? So, you can see they're all named.

They've got particular names for which ones are insect pollinators.

So, pause the video while you make your choice.

Okay, so you might not have heard of all the names of them, but hopefully you recognise the words on the end.

So, a chafer beetle is an insect, 'cause beetles are insects.

A honey bee is an insect.

A pipistrelle bat is a bat, but so it's not an insect, even if it could act as a pollinator.

But the cabbage white butterfly is also an insect.

So, those three are names of insect pollinators.

So, if you've got all those right, then well done.

So, a little bit of a reminder about what an insect is.

So, sometimes people get the idea of insects and bugs, or mini beasts in their garden, mixed up.

Insects have very, very specific features.

Now, you might have learned about these when you were younger.

Can you recall any of them? Maybe talk to the person next to you and see if you can.

What makes an insect an insect? So, pause the video, and then we'll have a little think and see how you've got on.

Okay, did you manage to get a few features that are just for insects? So, we've got an exoskeleton; so that's like a shell around the outside.

And then, we've got three body parts; sometimes they're not that obvious that it's in threes, but they've got a head, they've got a thorax, which is sort of the middle section, and then they've got an abdomen.

Now, these can vary in size, but it always has three parts.

They've got six legs, okay? And they've got a pair of antennae.

So, if you've got all of those things, those are the things that an insect, an insect, and those are what we are focusing on today in terms of our pollinators.

So, pollinators are important, as they transfer the pollen for sexual reproduction, and that's needed in order for plants to reproduce.

And plant reproduction is essential for making crops.

So, here's an example here of a carrot crop.

And 70% of our food crops are pollinated by insects.

So, you can see why those insects are so important to our food supply.

So, crops are things that we grow on farms, such as wheat, rice, or vegetables, and they're grown on farms for human consumption or for animals to consume that we might then go on to consume.

So, we've got a carrot crop, which is a vegetable, and a wheat crop, okay, which goes on to make all sorts of carbohydrate-based food.

So, from the pictures below, can you identify which of them are crops? So, pause while you decide.

Okay, let's how we see how we got on.

So, this is a corn crop, so that is a crop.

B is trees, so that's an orchard.

And then, we've got here, we've got lettuces grown in the fields, so that one is a crop too.

So, if you've got those two right, then well done.

So, time for our practise test now.

So, Sam has drawn a labelled diagram to describe the role of a pollinator.

It looks like he's done a pretty good job.

He said the bee is an insect pollinator, which is something that we've just covered.

And he said the pollen is dropped off at the flower for reproduction.

So, his work is actually correct.

He's labelled the flower and he's labelled the pollen, but he's missing some of the keywords and detail that we've already discussed.

So, if you could copy Sam drawing please, and improve it, and add some extra keywords and extra detail to the descriptions.

So, pause the video while you do that, and then we'll come back and we'll see how you got on after.

Okay, let's see how we got on with that then.

So, here's the diagram.

Hopefully you managed to copy that or label one.

So, to make the descriptions a little bit more detailed, we could say that the pollen is deposited on the stigma of the flower.

The bee is an insect pollinator, and it carries the pollen from the anther of a flower.

The pollen is needed for a seed to be formed in reproduction.

And you should have on there labelled the pollen and the stigma, as well as the flower.

And if you've labelled other bits, as well, then that's great, okay, but this is the level of detail that we need in order to show that this process is taking place, pollination.

So, time to move on to the second part of our lesson, which is food security.

So, food security is having access to enough affordable and nutritious food.

So, what that means is that we need enough for our energy intake in order to carry out our daily activities, but that has to be at a price that we can actually afford to buy it.

And it has to include all of the different nutrient groups in order that we can thrive, particularly in children where they need lots of different groups in order to grow properly.

There is enough food in the world for everyone to have a varied diet.

However, the global population and food supply are not spread evenly.

So, you can see in this map below the population density.

So, the darker colours, the darker the red, the more the population.

So, you can see there's certain regions in the world that are very, very densely populated, and there's some that aren't populated at all.

But food doesn't necessarily grow in relation to the population size.

Different countries in the world produce, and therefore export, different food products.

So, for example, we've got bananas grown in India.

Now, bananas are grown in lots of different countries, but India is the major producer of bananas.

And we've got corn that's grown in the USA, United States, and we've got rice that's grown in China.

Now, lots of these products are eaten by people in other countries, so they have to be exported.

Some countries, however, have more money, and therefore they can buy more of these than their populations require, and therefore lots of that food is wasted.

So, if you think about, in your own lives, how much food that might be bought and end up going in the bin.

Now, that is just our modern life, but it doesn't mean to say that it is the right thing, because we have excess food in some cases.

That means that some people in some countries have less.

And often, in countries where they're producing the food, they end up not having it because lots of it is exported in order for them to be able to make an income.

Now, as 70% of our food crops rely on insect pollinators, the protection of these species is really essential to the production of food.

And as the population of the world increases, we need more and more food, and therefore we need to rely on these pollinators in order that we can allow plants to reproduce so we can grow more food.

The population of pollinators have an effect on food security, so our ability to grow enough food that is affordable and nutritious.

And here's an example of a couple of pollinators for apples.

So, we've got apple flowers there being pollinated by bees, and we've also got apple flowers being pollinated by butterflies.

And then, this is the apple crop that you get after pollination has taken place in the image in the middle.

So, let's have a quick check.

So, food security is growing enough food to feed a country's population.

Is that true or false? And once you've decided whether it's true or false, have a little look at the statements below.

Which one do you think best justifies the reason that you chose true or false? So, pause while you decide, and then we'll come back and we'll see how you got on.

Okay, food security is growing enough food to feed a country's population; that is false.

And the reason it's false is because food security is growing enough nutritious food that is accessible to the world population.

So, let's have a look at this practise test.

So, Lucas and Andeep are discussing the importance of insect pollinators for food security.

And Lucas says, "Pollinators transfer pollen from one flower to another." And Andeep says, "Pollinators help with the reproduction of crop plants." Now, Lucas and Andeep have both made correct statements, but what I would like you to do is I'd like you to write an explanation for the importance of pollinators to food security, including their ideas.

So, in your answer, it's really important that you finish with why this is important to food security.

So, pause while you do this piece of extended writing, and then we'll come back and we'll see how you got on.

Okay, let's see how you got on with this task then.

So, you needed to write an explanation for the importance of pollinators to food security, including Andeep and Lucas's ideas.

So, we could have said pollinators move pollen from one crop plant to another.

This allows crop plant reproduction to take place.

And crop reproduction is needed to provide enough varied food for the global population.

And this is called food security.

Now, you might have put some other detail or keywords in your answer, and that's great.

It's just important that you definitely know what the definition of food security is.

So, well done for that task.

And then, let's move on to the third part of today's lesson, which is protection of pollinators.

The number of pollinating insects is decreasing, and this is particularly affecting bees.

So, you can see a bee here that's pollinating a bean plant.

You can see it's right at the top of that flower there, and the beans are coming off the stem.

Bees alone pollinate 35% of human crops, and that includes fruit, vegetables, and nuts.

And that has led to a 3% to 5% decrease in the amount of these that are being produced.

So, even though the world population is going up, there's a decrease of 3% to 5% of these particular types of crops; these vegetables, fruits, and nuts.

It's another example of an image at the bottom here with a courgette flower, and you can see bees inside, pollinating that vegetable.

Now, these crops are the ones that are the most nutritious to humans.

So, things like wheat, rice and corn are wind-pollinated, but they don't contain as many vitamins as the fruit and vegetables and nuts that humans need in order to have a nutritious diet, which is one of the key things about food security.

So, the decrease in crop production is making it more difficult to improve food security across the world.

And bee populations are decreasing due to a number of things.

So, here are some of the examples.

So, the loss of habitat, so to do with building and infrastructure, the loss of wild places.

Decrease in flowering plants, so maybe people having a lot more paving in the garden or artificial grass, or grass is being cut.

Climate change; that's changing the temperatures, global temperatures.

Pesticides, so these are chemicals which kill pests.

And finally, other competitors and disease.

So, pesticides are used to kill insects that damage crops, but lots of them can also kill insects that act as pollinators.

So, climate change can also have an impact, because it affects seasonal temperatures.

And so, this means that the nesting time for bees might not match the flowering time for plants.

And one of the reasons that ecosystems work is because of the interdependence of species; they all rely on each other in order to survive.

And changes in temperatures can affect that interdependence, which means that we can't pollinate flowers that require pollination at certain times of year.

There's also species that are invasive, so species that aren't part of the natural ecosystem, so for example, carpenter bees.

Honey bees visit flowers in order to collect nectar, 'cause this is their food source, this is the sweet liquid in a flower.

And when they do so, they collect pollen.

And as they move from flower to flower, the pollen is transferred.

But invasive species from other countries can affect this fine balance, because these particular carpenter bees, what they do is that they're able to remove the nectar without pollinating the flower, and therefore they reduce the food source for the honeybees.

So, therefore, there'll be a reduction in the number of honeybees.

Now, carpenter bees can pollinate, they just don't pollinate as effectively.

So, therefore, by removing honeybees 'cause of the lack of food, we're reducing the amount of pollination that is available.

Also, there is a decrease in the number and types of flowering plants that bees rely on.

So, for example, people put down grass, and they cut their grass.

So, when their weeds come up, like dandelions et cetera, they'll cut those off before they have a chance to flower.

And because more of our public spaces are like this, this means that there's less flowers available for the bees to visit; and one, to get food sources; but two, to pollinate.

However, there are some changes that we can do to protect our pollinators.

So, it's not all bad news.

There's the things that we can do.

So, the first thing we can do is we can increase the number of pollinator plants in our gardens and public spaces.

So, you might have seen in shops, like, wild seed mix where you can put down, like, meadow flowers like in this first picture.

Also, you might have seen, like, on roadside verges and roundabouts that often they have what's called a relaxed mowing scheme, and that is so that they don't mow straight away, so they have chance for these flowering plants to come out so pollination can take place.

Reduce the use of pesticides, so not using pesticides in your own gardens, but also farmers not using as many pesticides.

And again, in public spaces like parks, not using pesticides.

Buying organic food.

Now, if consumers choose to buy organic food, and now this is quite a difficult choice because organic food is often more expensive, so therefore some people might not be able to afford to do that.

Organic food is grown without using pesticides.

So, if enough organic food is bought, the more farmers will start growing their crops organically, and therefore less pesticides would be used.

And you can provide nesting sites.

You might have done some of these bug hotels, or you might have seen them about; sometimes you see them in local parks, and you might have made them before as well.

And also, we need to let the weeds in our gardens flower before we mow the lawn.

That can be quite tricky 'cause we want to get rid of those weeds.

If we allow the flower first, it provides sites for our bees to go and get their food, but they're also pollinating at the same time.

And finally, often pollinators need water, so you can put water out in your garden.

The suggestion is to put a few rocks or steps in there so that they can sit on those while they drink the water, like this image at the bottom.

So, time for a quick check.

So, choose the factors that are contributing to the decline in bee population.

So, pause the video while you decide.

Okay, let's see what you got.

So, climate change, pesticide use, and disease.

So, if you've got all of those right, then well done.

Next, choose the images which show crop plants that are affected by bee decline.

So, the crops that are affected are peas and apples, but not wheat, because wheat is wind-pollinated.

It's our vegetables and our fruit that we are the most concerned about.

Now time for a practise task.

So, Izzy and Alex are writing an article about the declining bee population for a gardener's website, and Izzy is saying "We should include details of what is affecting bee populations," and Alex says, "I think we should also include some ways gardeners can help." So, the first part of your task is to decide what else you could include in your article.

And the next one is to write an article for a website, including Izzy and Alex's ideas, and adding your own.

Now, this is your chance to be quite creative if you've got time.

Okay, so you could do this using a computer, or you could design it to make it really visually appealing.

But when you're ready and you've done, come back and check your answers.

Okay, let's see how you got on with this task then.

So, the first part was to decide what else you could include in the article.

So, you could include what pollination is, how pollination links to reproduction, effect of reduced pollinators on crop plants, and the impact of pollinator decline on food security.

So, did you include all of those in your article? And then, these are the things that might be in your website article.

So, pollination involves the transfer of pollen grains from a male anther to a female stigma.

80% of pollination is carried out by insect pollinators like bees.

Pollen is needed to make a seed for a plant to reproduce.

Fewer bees means fewer crops; for example, fewer fruit and vegetables can reproduce.

Bee numbers are in decline due to climate change, pesticides, reduction in flowering plants, disease, and competitors.

Climate change is affecting seasonal temperatures and competitors.

And fewer flowers affect the bees' food sources.

Disease and pesticides also kill bees.

Gardeners can help by increasing flowering plants, providing nesting sites, and water.

So, if you managed to include lots of those details in your article, and any other details that you found, then well done.

So, that brings us to the end of today's lesson, and here is our summary.

Pollinators transport pollen between flowers, which enables a plant to reproduce sexually.

The majority of pollinators are insects, with bees being the largest group.

Many food crops are insect pollinated, particularly fruit, vegetables, and nuts, which are high in nutrients.

Food security means having access to enough affordable and nutritious food in an area or country.

Pollinators have an effect on the food security of vegetables, fruits, and nuts.

Pollinating insects need to be protected from pesticides, climate change, and habitat loss.

So, well done for your work on today's lesson.