Willows (Salix spp.) as pollen and nectar sources for sustaining fruit and berry pollinating insects

Abstract

. 2015. Willows (Salix spp.) as pollen and nectar sources for sustaining fruit and berry pollinating insects. Can. J. Plant Sci. 95: 505Á516. Willows (Salix spp.) are ubiquitous in the northern hemisphere, serving as an important pollen and nectar resource for insect pollinators and for the enhancement of insect-pollinated agricultural crops such as fruits and berries. We used a common-garden field test containing seven native North American willow species to assess attractiveness of male and female flower catkins by documenting visits of Andrena spp. (Apoidea: Anthophila), other wild bees (all native), and flower flies (Syrphidae). Most willows in Canada's Maritimes begin flowering very early in spring, as the first wild pollinators become active following winter, and stop flowering by mid-May. A later-flowering group normally begins flowering in mid-May and stops flowering by mid-June. Pollinator species were largely opportunistic, visiting whatever species of willow flowers were available during foraging, but Andrena dunningi appeared to prefer flowers of S. nigra and S. interior. There was a general preference for male flower catkins, with 72% of Andrena spp. and 82% of all flower flies collecting pollen and/or nectar from male flowers, because pollen is the major component of nest provisioning for most solitary bees and the major source of protein used to develop reproductive tissues in most flower flies. Most andrenids and flower flies were collected within the AprilÁJune flowering period of six of the seven willow species studied, indicating that these willows could be used to support the pollinator community before the flowering period of commercially valuable flower-pollinated crops such as lowbush blueberry, cranberry, and apple.Key words: Andrena, crop pollination, flower flies, Salix spp., wild insect pollinators, willow flowering phenology Ostaff, D. P., Mosseler, A., Johns, R. C., Javorek, S., Klymko, J. et Ascher, J. S. 2015. Le saule (Salix spp.), source de pollen et de nectar pour les insectes qui fe´condent les espe`ces fruitie`res. Can. J. Plant Sci. 95: 505Á516. Le saule (Salix spp.) pousse partout dans l'he´misphe`re nord. Il constitue donc une importante source de pollen et de nectar pour les insectes pollinisateurs et concourt a`l'ame´lioration des cultures fe´conde´es par les insectes, notamment celles qui produisent des fruits. Les auteurs ont recouru a`une parcelle expe´rimentale ame´nage´e en jardin re´unissant sept espe`ces de saule indige`nes al 'Ame´rique du Nord pour e´valuer l'attrait des chatons de fleurs maˆles et femelles pour Andrena spp. (Apoidea : Anthophila), d'autres abeilles sauvages (toutes indige`nes) et des mouches a`fleurs (Syrphidae) en fonction du nombre de visites recense´es. Dans les provinces maritimes du Canada, la plupart des saules fleurissent tre`s toˆt au printemps, lorsque les insectes sauvages pollinisateurs commencent a`s'activer au sortir de l'hiver. Leur floraison prend fin a`la mi-mai. Un groupe plus tardif commence habituellement a`fleurir a`la mi-mai...

Biomass and root stem production of a colony-forming willow (Salix interior) on highly disturbed, low fertility sites

“…Although we haven't yet quantified flower production, anecdotal observations from ongoing pollination studies [48] show that some clones have more prolific flower production than others. Therefore, flower production for promotion of insect pollinators in various agricultural applications, such as berry or fruit production, may also be a trait for genetic selection and clonal development.…”

“…Under natural conditions, INT usually occurs in direct association with stream channels, floodplains, and narrow riparian corridors. In other restoration plantings across this coal mine site, INT appeared to survive and thrive best when associated with active erosion stream channels that provided a source of water throughout most of the growing season [48].…”

“…The ramet with the largest aboveground biomass per clonal plot was harvested at ground level, and the fresh weight (including stems, branches, and any remaining leaves that had not yet fallen away) was measured to the nearest 0.01 kg using an electronic infant weigh scale (Electronic Infant Scale, model ACS-20A-YE). Measurements of fresh and dry weight taken from field tests at the Montreal Botanical Garden demonstrated that percentage moisture content was approximately 50 ± 2% [48] both among and within species.…”

Assessment of Salix spp. pollen availability to insects based on aerobiological investigations

“…A high value of pollen and nectar from various Salix species in terms of reward for insects was emphasized by Ostaff et al [54] in Canada. The authors have found that Salix pollen and nectar may be highly important in early spring as a source of nutrition for pollinating insects.…”

Characterization ofSalix nigrafloral insect community and activity of three nativeAndrenabees

“…Early spring emergence of flowers is extremely important in supplying nutritive rewards, such as pollen and nectar, for many native arthropods, while the host plant benefits with an increased chance of successful sexual reproduction. The most common cross-pollinators in agricultural systems are often made up of arthropods that collect pollen from many unrelated hosts such as flies belonging to the family Syrphidae, eusocial bee species such as honey bees ( Apis mellifera L.), and polylectic solitary bees (Ostaff et al 2015). Lack of discrimination among hosts allows these arthropod groups to more flexibly collect resources for survival and population growth.…”