Determining pollinator activity/visitation during the spring in camelina and field pennycress
Pollinator summary for 2018:
Pennycress and camelina flowering and insect visitation were monitored at Ames, IA, Rosemount and Morris, MN in 2018. In 2018, flowering of field pennycress commenced two to three weeks later than in 2017 (Figure 13, Table 4). Flower cover of field pennycress reached 2 to 3.5% at all sites. Winter camelina flowered successfully at all sites in 2018, reaching about 2% cover in Morris and Rosemount, but less than 1% cover in Ames. Anthesis of winter camelina typically commenced one to two weeks later than that of field pennycress both years.
Insect visitation to flowers of field pennycress and winter camelina in 2018 was similar to that in 2017, with highest rates for field pennycress between 5 and 9 insects min-1 and that for winter camelina between 3 and 7 min-1 (Figure 13). Flies, solitary bees, and insects in Apidae family represented 45, 15, and 0% (Morris); 65, 11, and 3% (Rosemount); and 54, 26, <1% (Ames) of total insect visitors in field pennycress, respectively. Analogous values for winter camelina were 29, 11, and 7% (Morris); 37, 0, and 4% (Rosemount); and 40, 41, and 4% (Ames), respectively. As in 2017, flies (especially syrphids) were a common pollinator for both crops; solitary bees usually had significant representation; and Apidae were scarce, especially in field pennycress. Rarity of Apidae likely reflected the migratory status of commercial honey bees (Apis mellifera L.) (i.e., in transit from West Coast and Gulf Coast apiaries at the time of field pennycress flowering) and temperature-regulated phenology for bumble bees. The slightly greater numbers of Apidae in 2018 than in 2017 probably was associated with later flowering, which provided more time for transient honey bees to return to the Midwest as well as higher air temperatures, which would have facilitated activity of bumble bee queens. Identification of all Diptera to family has been completed for 2016, 2017, and 2018 samples from Minnesota and for 2017 samples from Iowa by Sue Boldgett, Iowa State University. We anticipate completing identification of 2018 Diptera samples to family within one more month.
Hymenoptera specimens were pinned and labeled with appropriate information from all Minnesota samples and the 2017 samples from Iowa. Once the 2018, Hymenoptera samples are pinned and labeled, all individuals will be shipped to the USDA ARS Bee Laboratory in Logan, UT for further identification.
A manuscript describing results from 2017 and 2018 is in preparation. The results from Iowa and Minnesota will be compared with analogous results from previous studies on camelina and/or pennycress from Connecticut, South Dakota, and Germany. Comparisons will include analyses of landscape diversity at each of these locations.
At Ames, field pennycress (PC) and winter camelina (WC) flower cover and pollinator data was collected in the spring 2018 by manually recording the insects visiting the cover crop flowers. Insects were also collected by setting up a pan traps in PC and WC plots. In 2018, the flowering in PC started about 10 days later compared with 2017. Similar to 2017, PC in 2018 started flowering earlier then WC. In both, PC and WC small bees and flies contributed to about 80% of total insect visitation. Field pennycress, however, had higher number of insects visiting its flower per unit time compare to WC. Flower cover in PC was at least four times higher than the WC.
2017
Heather Matthees along with an entomologist collaborator, Matt Thom, provided a webinar based training on March 28, 2017 to introduce participants at Ames, Rosemount, and Prosper site to provide background information on pollinators and aims and scope of collecting pollinator visitation data. Also included in the webinar was an overview of the protocol and software developed to collect data. Onsite training for participants was then provided to ensure proper pollinator identification and protocol in Ames on 25 April with collaborators from both Ames and Rosemount present. Onsite training in Prosper was provided on 8 May. Pollinator visitation data were collected at each site throughout flowering periods.
Pollinators were grouped into broad categories of insects and included honey bees, Bumble bees, small bees, flies, butterflies, beetles, and other. The estimated average percent flower cover during the period of flowering was 0.5% for field pennycress and 0.4% for camelina. The sparse nature of field pennycress and camelina flowers made collection of data difficult. Overall, field pennycress tended to attract more flies while camelina attracted more small (native) bees (Fig. 12). Few honey bees and bumble bees were observed visiting the flowers of either species, as transient honey bees likely had not yet returned from the West Coast and queen bumble bees probably had not yet emerged from hibernation.
