Selective flower visitation behavior by pollinators in a radish F1 seed production field

Abstract

For F 1 seed production in Brassicaceae crops, cross-pollination between the two parental lines is vital and is dependent on the visitation behavior of insect pollinators. In a radish F 1 seed production field using cytoplasmic male sterility system, visitation behaviors of different pollinator species and seed productivity of the recipient line were investigated in three stages during the flowering. As a result, honey bees (Apis mellifera and A. cerana) selectively visited either of two lines, while syrphid flies (various flies belonging to Syrphidae) tended to visit both lines. Despite the few observations of pollinator movements between the two lines, all flowers had received cross-pollen grains a few days after flowering. But in the late stage of flowering, increased cross-pollination by syrphid flies appeared to lead to an increase in the amount of crosspollen grains deposited on the stigmas. The percentage of pod set and the number of seeds per pod varied among the three stages of the flowering. These variations might be caused by shifts in the amount of crosspollen grains deposited on the stigmas due to the pollinators' selective visitation behaviors. The selective visitation behavior of insect pollinators could potentially result in unstable F 1 seed production through the insufficient cross-pollination.

Grain Legumes

“…In most food legumes, the absence or low natural cross-fertilization is the major bottleneck in exploiting hybrid vigour at a commercial scale. Kobayashi et al (2010) argued that cultivars are generally bred by the artificial selection of agronomic traits that are of commercial interest but with little regard to pollinator-related traits and preferences. Consequently, insect-pollinated cultivars may not be attractive to pollinators, resulting in low seed production.…”

An analysis of the energetic reward offered by field bean (Vicia faba) flowers: Nectar, pollen, and operative force

“…Flowers are the interface at which a plant and pollinator interact, and their structure, color, scent, and reward, among other traits, will influence how likely an animal is to visit the flower. However, despite the reliance of crop yield on pollinators, breeding programmes do not generally select directly for floral traits, instead focusing on agronomic traits such as harvest index, drought resistance, and disease resistance (Kobayashi, Tsukamoto, Tanaka, Niikura, & Ohsawa, ; Richards, ; Tester & Langridge, ). Therefore, optimal floral trait combinations to attract pollinators and maintain high pollination rates may have been lost by genetic drift or selective sweeps.…”

“…traits such as harvest index, drought resistance, and disease resistance (Kobayashi, Tsukamoto, Tanaka, Niikura, & Ohsawa, 2010;Richards, 2000;Tester & Langridge, 2010). Therefore, optimal floral trait combinations to attract pollinators and maintain high pollination rates may have been lost by genetic drift or selective sweeps.…”

How can an understanding of plant–pollinator interactions contribute to global food security?

“…In light of these two statements it is clear that pollination biology has a large, and increasingly urgent, role to play in protecting and maintaining global food supply. Crop breeding programmes select for agronomic traits such as yield or disease resistance [3]. Therefore, it is highly likely that insect-pollinated crops grown today, bred in an environment where pollinators were more abundant and pollination was less likely to limit fruit set, are suboptimal in terms of their floral traits with respect to attracting and sustaining their pollinator populations.…”