Paradise Island Activity 5 Holly A teaching sequence

Paradise Island Activity 5 Holly A teaching sequence from the Species at War unit version 1. 0 Activity from the Species at War unit © upd 8 wikid 2010 This page may have been changed from the original

n Use an understanding of food webs to plan how to control a pest. 2

Hi, I’m Maddie. I grow holly trees like these in my organic nursery. Elaborate 3

But look what’s happening! People won’t buy the trees if the leaves look like this. What could be damaging them? Elaborate 4

I’ve identified the culprit. This fly lays its eggs on the leaves and its larvae eat it from the inside. It’s a holly leaf miner. Elaborate 5

I need you to figure out why there are so many on my trees, and come up with a way of getting rid of them. Here’s what I know so far. Elaborate 6 SS 1

Species at War Paradise 5 Holly SS 1 The holly leaf miner An adult holly leaf miner fly emerges. Blue tits also eat aphids, which feed on the sap of the holly, and wasps. The larva grows into an adult fly inside a pupa in the leaf. A mine forms as the larva eats the leaf from inside. This is one of their predators – a blue tit. It can use its sharp beak to tear a larva out of its leaf. The fly lays a single egg on a holly leaf The larva hatches and burrows into the leaf. The larvae have many predators. This means that not many survive to become adult flies. A parasitic wasp called C. gemma competes with the blue tits for leaf miner larvae. It lays its eggs inside them, so that its own larvae can eat them from the inside. Another wasp (P. amyntas) does this to the C. gemma larva. Sparrowhawks are the blue tits main predator.

There would be fewer flies if they had more predators. But how can we find out what their main predators are? Elaborate 8 SS 2– 5

Species at War Paradise 5 Holly SS 2 Investigation instructions At the holly tree Results Table 1 1 Choose a branch. 2 Ignore the first few young leaves as they may be too immature to have mines on them. 3 Then count 10 leaves from the end of the branch and pick any leaves with mines on them. 4 Record the number of leaves without mines in Table 1. 5 Do this for 10 branches. Table 2 What happened to the holly leaf miner? Back in class 6 Use a scalpel to cut around the mine, but do not cut into the mine itself. A Killed by blue tit 7 Use the key to find out what happened to the holly leaf miner. B Successful larva, pupa or adult holly leaf miner 8 Record your results in Table 2. C Larva or pupa killed by a wasp Reproduced with permission of the Field Studies Council D Other death Tally chart Total