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Braconid wasps, Pieris sp. caterpillars and brassicas

The caterpillars decimated the nasturtiums nine-times over. However there has been a further development. It appears that at least some of the caterpillars were parasitised by Cotesia glomerata. Some of the caterpillars are now 'zombies', guarding the pupae of the emerged grubs. Why do the pupae need guarding? Cotesia glomerata is the target host for yet another wasp and the 'programmed' behaviour of the ex-host caterpillar helps to prevent that.


It appears that Cotesia glomerata was introduced into N. America as a biological control of 'cabbage whites', but has since inflicted itself on native fauna as well. That reminds me of harlequin ladybirds...


  • waterbuttswaterbutts Posts: 1,214

    Aphalara itadori  is to be introduced to this country to control Japanese knotweed. We are assured that strict laboratory tests have been done to check that no native plants will be wiped out by this non-native species.

    Watch this space...

  • Waterbutts - Lab tests only cover what they were specified to do.


    This could rapidly diverge away from gardening. Is this being discussed elsewhere?

  • waterbuttswaterbutts Posts: 1,214

    True. And so often they reflect the views of the body that commissioned them. Dunno if there is an ecology section, but surely gardening is about ecology?  Wouldn't worry too much about divergence. Lots of posts seem to be about cake.image

  • Update on the nasturtiums. The plants were totally ravaged by the caterpillars. The wee beasts departed. Not a nasturtium leaf in sight, a few very ragged flowers and well grazed stems.

    Barely 2 weeks later and the plants are bouncing back very rapidly, feeding off the root system that they developed before the top growth was 'repurposed'. Fresh leaves, new flowers. The only thing that will stop the nasturtiums now is a frost. I may get to mix a few bright, peppery flowers with a late salad.

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