A tale of life and death in the garden as aphids and lady birds battle for survival in the hot summer sun on their swan plant universe. Resources are at a premium. The swan plant starts the food chain and it all ends horribly for aphids. Aphids, ladybirds, ladybird larvae and caterpillars are unaffected by the deadly cardenolide glycosides stockpiled in swan plant leaves as a chemical deterrent to predators.
Chemical warfare in the garden,
Early summer and dark chemical processes are at work in the bright sunlight. Swan plants are producing and stockpiling deadly molecules in their sap and leaves. A chemical defence system designed to kill insects foraging for food. The main components of this molecular arsenal are cardenolide glycosides, steroids with an attached sugar structure. These toxins can induce cardiac arrest.
Monarch caterpillars and butterflies are immune to these poisons. Caterpillars voraciously devour swan plant leaves. In the process they hijack the plant’s chemical defence system for use against predators. Birds associate becoming sick with a diet of brightly coloured caterpillars or butterflies and drop them from their diet.
Attack of the killer wasps.
Asian paper wasps are very determined predators of monarch caterpillars and are unaffected by the cardenolides. Wasps need protein for nest construction and developing larvae in spring and early summer. Caterpillars are a good source of protein at this stage.
I watched wasps make their way through dense foliage in relentless pursuit of their prey. Monarch caterpillars appear to understand the danger and some seek refuge amongst the spines of the swan plant seed pods. The aerial bombardment is relentless and a plant can be completely stripped of the caterpillar population in a day. The big mature caterpillars are a favourite target and I have seen them stand up on a leaf in a forlorn attempt to beat off a merciless attacker.
The assault has a number of stages
- The wasp lands on the caterpillar and probably stings it
- The wasp starts to skin the caterpillar while it is still moving. It bites through the skin which rolls back to reveal the underlying body.
- It may move the whole carcass to a more stable location where it slices it up into manageable chunks to fly away with.
In late summer when the need for protein has diminished, wasps change their diet, feasting instead on the nectar produced by swan plant flowers.
Relationship beteeen steroids and cardenolide glycosides
Hydrocarbons are found in oil. We burn them polymerise them turn them into pharmaceuticals paints explosives and plastics. Virtually everything not made of wood, animal skins, stone or metal has oil at its source. Crude oil and gas are important to our society but what costs are we prepared to pay to maintain supplies? I watched John Key on the TV programme Campbell live this evening. He appeared to be softening us up, manufacturing consent so that we are happy to let loose our rats of war. We’ll hold back the full sized dogs because after all New Zealand is a small country. The justification used by Mr Key ( Prime Minister New Zealand) was the need to intervene and stop savage beheadings carried out by ISIS. He argued that New Zealanders would probably support a military intervention and he may be right.
We should be clear about our objectives in this endeavour. I want assurance from my Government that any future military involvement in this region has nothing to do with protecting oil pipelines and the hydrocarbons that flow through them.
- Iraq has large productive oilfields
- There are huge oil reserves, the prospective structures on the maps
- There are vulnerable oil pipelines.
Transparency and honesty around objectives for military involvement is essential for informed consent in a democratic process.
The Campbell Live programme on TV3 is a breath of fresh air on New Zealand issues. It is time to apply your undoubted investigative talents to the international scene.
Try the speed and acceleration problems and fill in feedback at end of the quiz.
Year 10, writing fully balanced chemical equations homework
A whole lot of the chemistry you have studied this year comes together in this exercise.
- ions and how they are formed.
- naming ionic compounds and writing their formula
- word equations.
…….. and finally the last piece in the jigsaw writing a fully balanced chemical equation.
If you study NCEA chemistry at level 1 next year a rough guide is
Achievement: writing word equations.
Merit: Inserting chemical formulae into an equation.
Excellence: producing a fully balanced chemical equation.
Revise what we did today by watching the video then do the short exercise. In your notebook write down the word equation and complete it (achievement) Underneath the word equation insert the chemical formula of each substance (merit). Finally balance the equation (excellence) NOTE this usually involves sticking 2 in front of something
1 sodium hydroxide + sulphuric acid ——->
2 copper oxide + hydrochloric acid ——–>