A Lesson in I.P.M.
As you probably are aware, the Antonio Garden is a brand new garden, created from a vacant lot, and bordered by a condo complex on the west, by a retirement village to the south (both complete with chemical/pesticide maintenance) and an avocado orchard on the other. Our goal is to use Integrated Pest Management to keep our organic garden free from toxins and naturally controls pests. This is difficult with this brand new garden since there are no resident predator populations in the area.
A month ago, we had an invasion of aphids which attacked our broccoli and cauliflower plus a couple of other cabbage-family plants. Without predators in the garden, they were able to take hold and become established.
Some of the gardeners were ready to pull out pesticides and/or insecticidal soaps to eliminate the pests. However, I implored the gardeners to try the most benign solution first – water jetting the offending insects from the plants.
Aphids become atrophied and immobile when they have settled in and, once washed off, cannot climb back up your plant.
The reason we used a simple water solution instead of sprays is this: water will physically remove most of the pests and, just as importantly, it does not harm the predatory insects that may be hunting the pests.
Had we let the gardeners use insecticidal soaps, they would have killed some, but not all, of the pests. Aphids have a waxy coating, and many water-based sprays or mists will simply roll off their backs. Spraying would not have destroyed the pests, but would more than likely destroyed all the predatory insects, which lack the waxy-protection, in the process.
Yesterday, I was able to show the children and their parents, the aphids that were left in the garden. What was evident at that time was predation by tiny wasps and aphids dying from both predation and fungal diseases.
I took some photos, but all I had was a video cam that doesn’t do extreme close-ups. I pulled the still (above) from one of the videos. There were large areas, thick with aphids, primarily within the curled leaf margins. We also saw dead aphids and aphid ‘mummies’, indicating that predation was happening. The big tip: we saw wasps actively working the aphids.
What is most interesting is that no one had released wasps in the garden, and they probably do not come from the over-maintained condo complexes surrounding the garden.
But the wasp still found us, and they have come to the rescue…
I went back this morning, about 16 hours later, to re-take the photos with a macro lens, and what I found this morning was very different from what I saw just a half day before.
The aphids had been reduced by 75% to 80% – literally over night. In place of the mass of aphids was a battlefield, littered with skeletal remains of aphids sucked dry (possibly by roving ladybug larva) and ‘mummies’, aphids that have been parasitized from within.
You all saw the movie, “Alien”, right? Same thing…
This picture to the left shows the same leaf that is shown in the first photo. Instead of fields of aphids, there are a few survivors, and the tiny wasps are at work, laying eggs in them for the next generation.
This picture is amazing – it shows a wasp, which has pupated in the body of an aphid, emerging from the Look for head and antennae exiting the body of the aphid. It is really had to see; click the photo for a closer view.
In this photo, an adult wasp (almost transparent) is caught in the act of laying an egg for the next generation of predators that will protect our garden.
The last photo, a close-cropped view, is enhanced to make the wasps more visible. Many aphids show the dark spot on their rear ends indicating they have been parasitized.
Our aphid problem is not at an end – we will continue to get these and other pest into the garden. However, if we refrain from whipping out toxins, we can help nature take its chosen course and have a productive, toxin and pest free garden.
The take-away here is that IPM is nature’s own way of managing pests and that it works. Like so many other things, Nature’s way of managing pests works best and it is in our own interests to learn how to work within this system.
One Final Update:
I went back again yesterday with my granddaughters to show them the wasps in action. The original leaf I photographed had 11 aphids left, and most of those showed signs of great distress – like they were being attacked from within…
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