“Insect pollinated” crops that don’t actually require insect pollination

Cucumber fruit 20160713_103558

Yesterday evening I learned that a large grant application that I’d submitted earlier this year had failed to secure funding.  Statistically there was a high likelihood of this happening but that doesn’t make it feel any better: weeks and weeks of work have come to nothing.

So in a mood of bloody-minded contrariness and general displeasure at the unfairness of the world I thought I’d provide an alternative to the Bees’ Needs week I mentioned yesterday by focusing on food crops that look as though they should be insect pollinated (and their ancestors certainly were) but which don’t actually require pollinators.

The example pictured above is an F1 hybrid cucumber (Cucumis sativus) variety called “Mini Munch”, kindly grown from seed and given to me by my friend and colleague Dr Janet Jackson.  Many cucumbers don’t need insect pollination, despite their large, colourful flowers, and the fact that related crops (melons, courgettes, squashes, etc.) generally do require pollinators.  Indeed some varieties taste bitter if they are pollinated.  I can recommend this web page on how to grow cucumbers for further advice.

As I was taking that photograph, and in another demonstration of how the world is against me at the moment, I spotted a bee feeding on one of the all-female flowers of this variety.

Megachile on cucumber 20160713_103627

It spent some time there probing the centre with its tongue, so I think these flowers still produce nectar despite them not needing pollinators, a hang-over from their ancestry.  Plants have a whole range of mechanisms that ensure reproduction without the agency of insects and other animal pollinators, and this has been exploited by crop breeders who have selected crop varieties for their ability to self pollinate or to reproduce asexually via apomixis (as in the case of this cucumber).

The same bee then flew onto a tomato (Solanum lycopersicum) flower (another group which varies in its demands for pollination) and I got a better look – seems to be a Leaf-cutter Bee of the genus Megachile.

Megachile on tomato 20160713_103712

The final example of a crop which requires little or no insect pollination are the chillies (Capsicum spp.) all of which are self-pollinating, I believe.  This variety is a scrambling purple type called Orzoco*.

Orzoco chilli 20160713_102213

So, crops vary hugely in their need for pollinators and the presence of certain traits of animal pollination, such as large, brightly coloured flowers and nectar, is no guarantee that the crop really does have to be serviced by pollinators.  The only way to be certain is to experimentally test the plants, a topic I hope to come back to later in the summer.

Don’t worry, this grumpiness won’t last long, in no time at all I’ll be back to banging on about the importance of pollinators.  At least Monty, one of our two cats, still loves me.


*At least, that’s what it said on the seed packet; I’ve also seen it referred to as Orozco – does anyone know which name is correct?

19 thoughts on ““Insect pollinated” crops that don’t actually require insect pollination

    1. jeffollerton Post author

      Yep, good example, though not sure if it’s all varieties – has anyone done any work on grape pollination by insects? The Megachile didn’t buzz when it was on the tomato, but that’s not to say it can’t. Some Anthophora species certainly can.

  1. Helen

    Sorry about the grant application. Interesting post, though. Does chard need pollinators? Or lettuce? Rocket?

    I mention these are they self-seed so readily in my garden. I have seen insects round the rocket but not sure about the others.

    1. jeffollerton Post author

      Thanks Helen. Yes, I’ve seen pollinators on flowering rocket. Not sure about lettuce – again, it may vary with the variety. Chard is wind pollinated.

  2. spamletblog

    Looks like you’ve crossed it with the aubergine below. :)I thought most Solanums had the anthers held in a cone over the stigmas, so was surprised that so many people were saying they needed pollinators. Mine never have, but I used to tap the stems just to make sure.Only the aubergines seemed odd, with the ‘two up, one down’ male to female flower arrangement.Sorry about the grant. Seems you have to have some whacky but trendy psychological beliefs about curing the World by the mere power of thought, to be sure of getting‎ funding these days…RegardsSteve Hawkins From: Jeff Ollertons Biodiversity BlogSent: Wednesday, 13 July 2016 11:56To: steve.a.hawkins@ntlworld.comReply To: Jeff Ollerton’s Biodiversity BlogSubject: [New post] “Insect pollinated” crops that don’t actually require insect pollination

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    jeffollerton posted: ”

    Yesterday evening I learned that a large grant application that I’d submitted earlier this year had failed to secure funding.  Statistically there was a high likelihood of this happening but that doesn’t make it feel any better: weeks and weeks of work “

    1. jeffollerton Post author

      My latest hybridisation experiment…. 🙂 Yes, Solanums have the anthers in a cone and are “buzz pollinated” by bees that vibrate their thoracic muscles to a frequency that results in the pollen being dispensed. As the pollen is quite dry and loose it can trickle out under gravity, but yes, tapping the plants can encourage this.

      Not really sure what’s needed to get funding these days, seems good ideas backed up by publications in top journals isn’t enough….

  3. sleather2012

    sorry about the grant Jeff – my last ever is in at the moment – it is really liberating to know that I won’t have to go through the process ever again but it would be nice if I am able to go out on a high.

    Interesting post as well

    1. jeffollerton Post author

      Thanks Simon, best of luck with the application. Just out of interest, do you recall what the success rates were for Research Council grants back in the 80s and 90s? Presumably not as low as they are now?

  4. Pingback: Third International Conference on Pollinator Biology, Health and Policy – Pennsylvania – 18-20 July, 2016 | Jeff Ollerton's Biodiversity Blog

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