OUR INSECTS ARE DISAPPEARING
GARDENERS MUST TAKE SOME RESPONSIBILITY
BACK in November last year I penned an article espousing the benefits of increasing the organic matter levels in our garden and farming soils in order to reduce, and hopefully reverse, the increase in carbon dioxide levels in our fragile earth’s atmosphere.
A simple 1% increase in organic matter in one square metre of our soil will remove 8.8kg of CO2 from the atmosphere and will enable the soil to hold an extra 17 litres of precious and currently very scarce rainwater.
This week saw scientists announce, unsurprisingly, that some studies have found that up to 41% of the known insect species on this earth are in decline, with a third of these species rapidly heading towards extinction.
Importantly, we must understand that all insects have a critical role to play in the circle of life, whether it’s pollinating our ornamental plants, vegies and crops, acting as a food source for higher animals, or recycling organic matter in a forest.
Now, some readers may remember times when, say, a car trip to Brisbane and back left a collection of various bugs smeared across the windscreen and stuck in the front grille of the family station wagon.
Those days are long gone, with a similar trip nowadays perhaps collecting one or two unfortunate insects that happen to be crossing our path as we hurtle along.
I’d also hasten to add that the usual number of night-time moths and other nocturnal insects have been sadly missing from around our kitchen fluorescent for quite a number of years in our neck of the woods.
Whilst this example is certainly not part of any scientific research program, it serves as a stark reminder that insect numbers have definitely declined in rural areas such as the Lockyer Valley and Darling Downs, where they existed in large numbers as a result of the wide range of crops being grown at any one time, as well as the remnant bushland where many native species had bred.
In our home gardens, it’s a little more difficult to know whether insect numbers have changed or not.
Occasionally, we may notice that there might be a variation in the number of pollinators, such as bees and butterflies, but it’d be fair to say that many gardeners have, in the past, concentrated on ridding their gardens of any insect that casts even a sideways hungry glance towards their precious plants.
It seems that our preoccupation with pest control and eradication has taken its toll on our earth’s insect population, both good and bad, and this is expected to have dire ramifications for the animals that feed on these insects, which, of course, affects we humans as well.
One has only to take stock of the massive range of pest control and eradication products gracing the aisles of our nurseries and garden centres to realise that we haven’t really signed a peace deal or enacted an armistice with many insects that visit our garden for a feed, and that the “war” continues to be waged on many and varied fronts.
Now, I’m not as naive to suggest that we should all simply let hordes of ravenous caterpillars or squadrons of fruit flies have their way with our prized ornamentals and expensively-produced vegies, but I’d suggest it’s time to think a little more strategically about how we garden, so that we minimise the damage to all insects on this earth.
HOW CAN WE GARDENERS LIVE IN HARMONY WITH INSECTS?
Here’s a few strategies to help insects, and we humans, survive together on this earth.
Probably one of the most important strategies you can enact is to create and ensure diversity (and practice “planned chaos”) in your garden.
This means growing a wide range of ornamental and edible plants so that populations of pest species cannot build up to unmanageable levels, and placing them in a garden so that plants of similar attractiveness to pests are not all in the same area.
For example, in a vegie garden, don’t plant all your cabbages together, space them randomly amongst other vegies.
This tends to reduce the ability of pests such as the cabbage white butterfly to zero in on their food plants.
Research plants that may be more resistant to pests (such as cherry tomatoes = fruit fly resistant), and grow other plants that may help to deter or repel some pests (such as marigolds and mustard to repel nematodes).
Consider using exclusion methods to keep pesky insects off your plants – exclusion bags on tomatoes, and maybe a structure covered in fruit fly exclusion netting over an entire garden area.
Think about using natural predators to help control pest populations – predatory wasps, ladybeetles, hoverflies and lacewings amongst others.
Clever planting will attract them to a garden, or they can be purchased from companies that breed them for gardeners and farmers.
If you decide to use insecticides, practice thoughtful pest reduction techniques.
These can be measures such as using very target specific products, such as Bacillus thuringiensis (Dipel) to target cabbage white butterfly larvae on brassicas, or fruit fly traps hung on attractive plants.
Spray insecticides only when you can no longer tolerate the damage to your plants, not immediately you see just one or two pests.
Use the lowest toxicity product that will do the job, not something that will kill all insects within a half kilometre radius!
Spray damaging populations at night, so that non-target species won’t be affected (e.g. bronze orange bugs on citrus)
Knock aphids off with a jet of water. Above all, grow healthy plants.
It’s been proven that insect pests ignore strong, healthy plants and zero in on weak and soft growth and those plants with less than optimal nutrition.
Create a vibrant, living soil in which to grow plants, and don’t overdo the application of inorganic fertilisers.
We must resist the urge to annihilate our earth’s insects.
Please think before reaching for the insecticide bottle.