The nematodes arrive – a nasty surprise – and guess who is coming to dinner………..

I ordered enough nematodes for 40m2 of soil, for some reason the garden center sent me enough nematodes for 1200m2 of soil. Do they know something I don’t? So I read the instructions as I go along and put the nematode carrier substance in 10 liters of water, discover to my horror that they need to be diluted in an additional 100 liters  of water (think balconies, sinks, bathtubs, no outdoor faucets………) , pre-watered the pots so they were soaked and the nematodes could disperse well, distributed the nematode solution in all my pots, re-watered the pots to ensure that the nematodes were carried safely into the darkness of the soil away from lethal UV light and watched the resultant waterfalls cascade onto my neighbour Mrs. Kindly Organised Gardeners patio.

Tracking earth through the apartment, protecting pots from sunlight and generally getting very tired, cross and nematode covered, I finished and without further ministrations, likely looking a little distraught and unkempt I went downstairs to apologize for the second flood in a week and gave Mrs. Kindly Organised gardener the left-over 2 liters of concentrated solution as a peace offering. So that she could rain death on any larvae on her patch of earth. She thanked me with a bar of chocolate, which was sweet.
On my return I studied the balcony and resultant havoc, and despite being tired at least felt I was making progress. In the past weeks I have repotted most plants, thrown away earth, condemned and pardoned Cetonia aurata larvae, who await transfer to safer soils in their Noah’s ark pot, and thought I was ahead of the game, as it has been so cold that I figured the insects haven’t emerged yet.  But what did I find on the soil of the rose plant on my last round of inspection?:  Yes, a fully-grown BlackVine Weevil (Otiorhynchus sulcatus): 

Vine Weevil

For those of you who haven’t been paying attention or haven’t developed an insect obsession like I have the Black Vine Weevil eats it’s way through your roses and rhododendrons, and if you haven’t any of those, it will happily feed on anything else you have – in my case Perilla Frutescens, Basil plants, any other herb you might have – oh and the peonies. The adults (around 1cm long) eat the plant leaves, looks like someone took a big bite out of each leaf.  This is a great diversion tactic because while you are focused on the damage to your plants from an aesthetic point of view the larvae are happily munching on the root system of your plants in the darkness, out of sight. Ultimately if you have a bad infestation, the larvae not the adults will kill the plant(s). Otiorhynchus sulcatus, was the reason I re-potted all my plants and was frantically digging through pots to find the larvae. Reader beware – it gets very “science’y” from now on, this may not appeal to some of you, but believe me it is cool stuff!!  Looking for a good way to kill the insects I discovered nematodes. On the following webpage at you can find lots of interesting information on Nematode Heterorhabditis in the publication: The biology and genome of Heterorhabditis bacteriophora* Todd Ciche of the Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824 USA.

In summary – the nematode Heterorhabditis bacteriophora is an insect pathogenic nematode associated with the bacterium, Photorhabdus luminescens. N.heterorhabditis is used as a biological insect control. According to the website more than 200 species of pest insects from 100 insect families are susceptible to these nematodes. The Nematodes locate their host either directly by identifying host cues (carbon dioxide emissions), or indirectly by identifying root damage and thus areas with high likelihood of host presence. They migrate towards these areas, enter the host, and regurgitate the bacteria Photorhabdus luminescens, which then kills the host. Subsequently the Nematodes proliferate and then leave the cadaver in search of new larvae. Here is a photo of nematodes courtesy of the website:

Conley was studying the effects of microgravity on tiny worms called "nematodes." — Photo: snickclunck (flickr)Best months to put out nematodes are April and May, and August and September, and apart from the mess, which can probably be avoided with proper planning, it’s a nice biological way to kill the Black Vine Weevil and other pests without polluting the water or harming animals, and humans etc.
Unfortunately adult Black Vine Weevils are not susceptible to nematodes. The insect is active at night, so you can put down pots with newspaper shreds in them into which the weevils will crawl during the night. In the morning you can then collect and discard the beetles.
So 10:0 for the insects – I have in the past weeks re-potted my plants, thrown away a lot of earth, buried many a dead and dying plant, and distributed nematodes everywhere, only to discover, that some of the insects are already at a stage where nematodes will no longer harm them. I hope I have at least won a small battle even if the war apparently is not over… in addition now that the soil is wet, and the humidity is high, a fungus has appeared on the wet soil…….
And there I was planning to switch from complaining about insects to writing about cooking, but I suspect this story isn’t over yet


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