Cockroaches as pollinators: a new example just published

When you think of the word “pollinator” what comes to mind? For most people it will be bees, particularly the western honeybee (Apis mellifera). Some might also think of hoverflies, butterflies, moths, bats, hummingbirds…..but cockroaches?! The first published example that I know of which demonstrated that the flowers of a plant are specialised for cockroach pollination is from the mid-1990s. Since then only a handful of well documented cases have come to light, but there are undoubtedly more out there waiting to be discovered, particularly in the wet tropics. Most of the c. 4,600 species of cockroaches are nocturnal, and cockroach-pollinated flowers tend to open at night, which is one reason why they are under documented.

In a new study, published this week in the American Journal of Botany, a team of Chinese, German and British biologists has shown that a species of Apocynaceae from China is the first known example of cockroach pollination in that large family. Here’s the reference with a link to the study; if anyone wants a copy please email me:

Xiong, W., Ollerton, J., Liede-Schumann, S., Zhao, W., Jiang, Q., Sun, H. Liao, W. & You, W. (2020) Specialized cockroach pollination in the rare and endangered plant Vincetoxicum hainanense (Apocynaceae, Asclepiadoideae) in China. American Journal of Botany (in press)

The abstract for the paper follows:

Premise

Species of Apocynaceae are pollinated by a diverse assemblage of animals. Here we report the first record of specialized cockroach pollination in the family, involving an endangered climbing vine species, Vincetoxicum hainanense in China. Experiments were designed to provide direct proof of cockroach pollination and compare the effectiveness of other flower visitors.

Methods

We investigated the reproductive biology, pollination ecology, pollinaria removal, pollinia insertion, and fruit set following single visits by the most common insects. In addition, we reviewed reports of cockroaches as pollinators of other plants and analyzed the known pollination systems in Vincetoxicum in a phylogenetic context.

Results

The small, pale green flowers of V. hainanense opened during the night. The flowers were not autogamous, but were self‐compatible. Flower visitors included beetles, flies, ants and bush crickets, but the most effective pollinator was the cockroach Blattella bisignata, the only visitor that carried pollen between plants. Less frequent and effective pollinators are ants and Carabidae. Plants in this genus are predominantly pollinated by flies, moths and wasps.

Conclusions

Globally, only 11 plant species are known to be cockroach‐pollinated. Because their range of floral features encompass similarities and differences, defining a “cockroach pollination syndrome” is difficult. One commonality is that flowers are often visited by insects other than cockroaches, such as beetles, that vary in their significance as pollinators. Cockroach pollination is undoubtedly more widespread than previously thought and requires further attention.

5 Comments

Filed under Apocynaceae, Biodiversity, China, Pollination

5 responses to “Cockroaches as pollinators: a new example just published

  1. Peter Bernhardt

    Cockroaches may be important pollinators in regions other than the wet tropics. Here is an intriguing 2017 report from someone funded by National Geogrqphic to work on pollination in dry Chilean scrublands.

    https://www.nationalgeographic.com/news/2017/05/cockroaches-pollination-insects-chile-animals/ [https://www.bing.com/th?id=OVP.l_Ya20fhFT5n-G3eCUcqrgEsCo&pid=Api] This Cockroach May Pollinate Flowers-Extremely Rare Find In the scrublands of central Chile,wild roaches are feeding on pollen and may even be helping plants to propagate. http://www.nationalgeographic.com

    ________________________________

    Liked by 1 person

    • Hi Peter – yes, we cited the study that is mentioned. I wasn’t suggesting that cockroach pollination is restricted to the wet tropics, just that this is a biome where (a) cockroaches are very diverse and abundant; and (b) the pollination systems of most of the plants have never been studied.

      Like

  2. P A Azeez

    Can you please provide me a PDF of the paper?
    Regards

    Like

  3. Pingback: Why are bees like Bactrian camels? Because they both have two humps! | Jeff Ollerton's Biodiversity Blog

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