Consequences of high abundance of Bombus terrestris on the pollination of Vicia faba

 by Smith-Ramírez C, Rendón-Funes A, Barahona-Segovia RM, Moya W

Photo: A. Rendón-Funes: B. terrestris on top of closed V. faba flower
after robbing nectar, the hole can be seen in the base of the flower

Bombus terrestris is an invasive species in Chile, and is a frequent visitor of Vicia faba. During two seasons, we recorded frontal and robbery visits of all pollinators and its behaviour along the flower lifespan in a V. faba´s field in southern Chile. We found seven species of floral visitors. The only species that did flower robbery were B. terrestris and A. mellifera.  On average the flower lives 3.1 days. Most of the visits were done by Apis mellifera, followed by B. terrestris. 87.2% of visits of B. terrestris were robbery and visited on average 23 times one flower perforation in the flower’s life. Frequency of frontal visits and robbery varied with pollinator identity and year. The seconds spend in robbery visits decreased more acutely than the time spend in frontal visits regarding flower´s age. We conclude that B. terrestris contributes relatively little to pollination and may induce interspecific competition for nectar.

 

Read the scientific publication in JPE.

An updated insect exclosure design for pollination ecology

 by Troy Tetreault, Ken Ah

Exclosures on an alpine meadow, Beartooth Plateau,
Montana/Wyoming Border, USA

Floral exclosures, or structures that act to inhibit animals from visiting flowers, are commonly used to determine various effects that insects or other animals have on plants.

With climate change having significant impacts on ecosystems, information obtained from this type of study can be valuable for informing conservation practices.

These types of studies are important for monitoring plant-pollinator relationships over time and are especially important considering climate change has drastic impacts on these systems. However, past studies have used a variety of terms to refer to exclosures, and/or do not give clear descriptions of exclosures. This practice decreases replicability of pollination studies and could inhibit scientific progress in the field.

We summarized previous descriptions of pollinator exclosures in the literature, and field tested an updated design on the Beartooth Plateau, located north of Yellowstone National Park, USA. These exclosures were left on the plateau for the duration of the alpine growing season and monitored daily. Over 95% of our exclosures remained in place, despite being subjected to extreme weather conditions. Exclosures meant to inhibit pollination worked, with flowers in these exclosures producing fewer fruit. The design was also lightweight, cost-effective, easy to produce, and could be used in many ecosystems. The combination of these findings makes our exclosure design useful for future pollination ecology studies. We also bring to light the issue of repeatable methods, and hope that future studies using exclosures will include the information necessary for replication.

Read the scientific publication in JPE.