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drscottr

Pediobius wasps vs Mexican Bean Beetles

drscottr
9 years ago

Quick report - I released the wasps twice this summer - two weeks apart on the siting of Mexican Bean Beetle larva. I continue to see an occasional adult beetle but zero larva. I would call the experiment a success and the beans are doing well (except for the Japanese beetle attacks).

Comments (11)

  • pnbrown
    9 years ago

    I bought them last year and there was definitely a result, though I'm not sure they eventually parasitized every MBB. The year before there was a very severe infestation. This year there is a small presence of MBB, but it is also the coldest summer in living memory hereâ¦

  • drscottr
    Original Author
    9 years ago

    I've used the wasps for the past 5 years and they have worked well 4 of the 5. One year I just mistimed the release. The key seems to be that I buy mummies and then release the wasps in two portions a week apart once I see the first larva.

  • pnbrown
    9 years ago

    This year would have been a waste of money for me since the nights have been too cold for pediobus.

  • gwpunt2
    9 years ago

    We've released Pediobius for the past 3 years in our community garden in Georgia. First year started too late - July - to save the beans but beetles all but vanished. Achieved excellent control last year and this year with only one release each May though I can see the advantage of 2 releases (they just cost so much). Still picking beans in late August! Believe they work on the similar squash beetle too, tho squash vines have so many other issues they die out anyway.

  • mdfarmer
    9 years ago

    My gloves are stained yellow from smashing bean beetles and larvae in my pole beans. I'm a killing machine but don't make a dent in their numbers. I've been spraying insecticidal soap every week to at least kill larvae, but I'm not sure how well that's working. I've thought about spraying Pyganic, but there are just too many flowers in the beans and I don't want to harm bees.

    Where does everyone buy these wasps? I might try it next year.

  • gwpunt2
    9 years ago

    Just Google Pediobiius faveolatus, there are several suppliers. Be prepared for sticker shock, though we could justify it since we have an organic community garden with many members kicking in $.

  • pnbrown
    9 years ago

    Yeah, it's over $100. I try to grow my whole year's worth of beans, so that's how I justified the expense last year.

    Pediobilus was brought into the country to deal with MBB in FL, in the 70's, and from what I have read it was a super-successful strategy. The season is so long there and MBB was so present (including on weeds) that the wasp was able to spread vast distances and wreaked absolute destruction on MBB (yes!), before cold weather.

    So for the deep south, and maybe up to the mid-atlantic region, it should be a no-miss weapon. Where I am is a bit marginal, even last year's warm summer it did not do as well as I had hoped. I think that simple rotations and good soil condition are more effective in the long run, for me, and a lot cheaper.

  • drscottr
    Original Author
    9 years ago

    Two weeks since last report and no MBB larva. I'm declaring victory.

    I just put down milky spore for the Japanese beetles and will follow with nematodes. Let's see in the spring how well this works.

  • pnbrown
    9 years ago

    That's good news. I have seen some MBB in both of my gardens where I released wasps last summer, so clearly destruction was not total.

  • drscottr
    Original Author
    9 years ago

    It's my understanding that the Bean beetles migrate northward every year so the pediobius wasps have to be used each year. Essentially you're setting up a new ecosystem every year where enough bean beetle larvae survive to act as wasp hosts for several yearly generations.

  • pnbrown
    9 years ago

    See, that's what doesn't make sense to me, setting up a situation where you can't grow a crop without importing an expensive exotic parasite.

    There are certainly better ways to manage MBB, but they aren't quick.

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