 |
| Figure 1. Watsonia densiflora Photo by: H. Booysen |
This is the Watsonia densiflora (Figure 1). This flowering plant can be found in open grasslands of KwaZulu-Natal and the Pondoland region, in South Africa. The flowers of this plant attract pollinators with its nectar, rewarding with food any insects that will land on it (Johnson & Morita, 2006).
Particularly,
this plant attracts a certain species of fly, the Philoliche
aethiopica (Figure 2), as a pollinator (Johnson & Morita, 2006). Because of its long proboscis tabanid (a long, tubular mouth
part), this fly is well adapted to feed on floral nectar and reach the bottom
of their tube, and will be able to spread its pollen from a plant to another (Karolyi, Colville, Handschuh, Metscher & Krenn, 2014)
 |
| Figure 2. Philoliche aethiopica foraging on a Watsonia densiflora Photo by: M. Whitehead. |
But this insect as also been observed pollinating and favouring another similar plant: the flowering plant Disa nervosa (Johnson & Morita, 2006)
 |
| Figure 3. Disa nervosa Photo by: R. Boon |
And this is not a coincidence. In fact, the Disa nervosa (Figure 3) is a liar. This plant has a similar distribution to Watsonia densiflora, and its flowers look very alike to Watsonia's flowers in both dimensions and colours. The only difference is that the Disa nervosa doesn't produce any reward for its pollinators. But due to this high ressemblance and common distribution they share the same pollinators, as the Philoliche aethiopica cannot differ between those two plants. While this fly thinks it will land on a Watsonia densiflora and will beneficiate of its nectar as nutrients, it might actually land on a Disa nervosa by visual mistake and won't be able to collect any nectar, but will still be covered by its pollen and will spread it on another flower (Johnson & Morita, 2006)
According to Johnson and Morita's research (2006), this technic of pollination by mimicry is quite effective in some sites, as it has been found that 50% of Disa nervosa's flowers has received or exported pollen.
Reference list
Boon, R. (2015). Disa nervosa [Image]. Retrieved from http://www.ispotnature.org/node/644187
Booysen, H. (n.d.) Watsonia densiflora [Image]. Retrieved from https://midlandsconservanciesforum.wordpress.com/2015/02/11/dargle-wildlife-sightings-january-2015/
Johnson, S. D. &
Morita, S. (2006). Lying to Pinocchio: floral deception in an orchid
pollinated by long-proboscid flies. Botanical Journal, 152(3), 271-278.
Karolyi, F. Colville,
J. F. Handschuh, S. Metscher, B. D. Krenn, H. W. (2014). One proboscis,
two tasks: Adaptations to blood-feeding and nectar-extracting in long-proboscid
horse flies (Tabanidae, Philoliche). Arthropod Structure and
Development, 43(5), 403-413.
Whitehead, M. (2013) Philoliche aethiopa foraging on a Watsonia densiflora [Image]. Retrieved from https://michaelrwhitehead.wordpress.com/2013/01/
