scholarly journals Honey bee (Apis mellifera) colony strength and its effects on pollination and yield in highbush blueberries (Vaccinium corymbosum)

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11634
Author(s):  
Kennedy Judith Grant ◽  
Lisa DeVetter ◽  
Andony Melathopoulos

Many pollination studies with honey bees have examined the effect of colony density on crop yield and yet overlook the effect of variation in the population size of these colonies. High colony density in northern highbush blueberry has been met with concerns from beekeepers who feel higher densities will intensify outbreaks of European foulbrood (EFB, Melissococcus plutonius, Truper and dé Clari), a honey bee brood disease. The purpose of this study was to confirm the prevalence of EFB in colonies pollinating blueberries and to determine whether field-level variation in the population of adult workers in colonies explained variation in blueberry fruit set and/or yield. We addressed these objectives over the course of two production seasons at 13 commercial blueberry fields in Oregon, USA, stocked with identical densities of 10 colonies/ha. We confirmed that all colonies had negligible symptoms of EFB at the start of blueberry pollination, but 53% of colonies in 2019 and 41% in 2020 had symptoms immediately following the pollination season. We also validated a method for rapidly assessing adult honey bee colony populations, namely by counting the rate of foragers returning to colonies, and it was found to be strongly correlated to true internal adult bee population independent of year and ambient temperature at the time of evaluation. Using returning forager counts, we determined there was considerable variation in the average population of colonies at each field, ranging from an estimated 10,300 to 30,700 adult worker bees per colony. While average colony strength did not predict variation in fruit set, it was related to variation in yield, independent of year. Our linear model of flight count (as a proxy for colony strength) predicts estimated yield increases of up to 25,000 kg/ha of blueberries could be achieved by colonies stronger than the recommended six frame minimum, suggesting that higher pollination benefits could be achieved without increasing hive density if stronger colonies are promoted.

HortScience ◽  
2016 ◽  
Vol 51 (10) ◽  
pp. 1228-1232
Author(s):  
Lisa W. DeVetter ◽  
Sean Watkinson ◽  
Ramesh Sagili ◽  
Timothy Lawrence

Commercial production of northern highbush blueberry (Vaccinium corymbosum) is dependent upon rented colonies of honey bees (Apis mellifera) for meeting pollination requirements. Despite the prevalent use of honey bees, growers in Washington State and the greater Pacific Northwest (PNW), particularly those located in the western regions, claim pollination is limited and yield potential is subsequently reduced due to pollination deficits. However, there have been no studies or surveys that document this occurrence for this economically important region of blueberry production. The objective of this study was to survey honey bee activity in commercial plantings of ‘Duke’ highbush blueberry in western and eastern Washington and to assess the relationship between honey bee activity, growing region, and select yield components. Honey bee colony strength was also assessed to evaluate this variable’s relationship to honey bee activity and measured yield components. Sixteen and 18 commercial ‘Duke’ blueberry fields across Washington State were surveyed in 2014 and 2015, respectively. Average number of honey bee visitations per plant and honey bee colony strength were determined to evaluate overall honey bee activity. Estimated yield, berry number per plant, berry size (mass), and seed number per berry were also determined and analyzed to determine their relationship to honey bee activity through regression analysis. Honey bee visitation rates differed between western and eastern Washington, with western Washington sites consistently below recommended honey bee densities. Colony strength was also below recommended levels, but was lower for western Washington relative to eastern Washington. Estimated yield and berry number differed across sites and years, but were not related to honey bee visitation rates. Regression analysis revealed few significant relationships, although honey bee visitation rates were positively related to seed number per berry and seed number was positively related to berry size (R2 = 0.25 and 0.16, respectively). Berry size was also positively related to colony strength (R2 = 0.63). This study demonstrates that honey bee activity is limited in Washington blueberry production, particularly in western Washington, when compared with recommendations for optimal honey bee activity in blueberry. However, yields were unaffected between the compared regions. The lack of a relationship between honey bee visitation rates and yields suggests that pollination is sufficient for ‘Duke’ blueberry in Washington State and pollination deficits do not limit yield for this cultivar under the conditions of the study.


HortScience ◽  
2007 ◽  
Vol 42 (7) ◽  
pp. 1612-1615 ◽  
Author(s):  
Jeffrey G. Williamson ◽  
D. Scott NeSmith

Greenhouse and field experiments were conducted to determine the effects of the growth regulator N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) on fruit set, berry size, and yield of southern highbush blueberry (Vaccinium corymbosum hybrids). The experiments were conducted over a period of several years in Georgia and Florida. CPPU sprays were capable of increasing fruit set and berry weight of southern highbush blueberry, although the responses to CPPU treatment were variable and appeared to be influenced by factors such as rate, spray timing, and cultivar. In Florida, high natural fruit set may have prevented increased fruit set from CPPU. A slight delay in berry maturity was noted in several experiments. Spray burn occurred on several occasions and may be related to factors such as cultivar, rate, spray volume, and use of surfactant.


1988 ◽  
Vol 28 (2) ◽  
pp. 287 ◽  
Author(s):  
RD Goodman ◽  
KA Clayton-Greene

The role of honeybees (Apis mellifera) in the pollination of highbush blueberries was studied in an experimental planting at Knoxfield, Victoria. Honeybees comprised 95.4% of all insect visitors to this crop, and their foraging activity made them efficient pollinators. Plants visited by bees had a greater percentage fruit set (61 v. 18%), increased fruit numbers (1156 v. 144) and more fruit by weight (1.6 v. 0.2 kg), than did plants caged to prevent access by bees and larger insects. Bird netting did not impede pollination. Flowers inside a bird-proof cage had a greater frequency of bee visitations (8.25 v. 1.5 bees/14 plants) than did plants outside the enclosure.


HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 613f-614
Author(s):  
Robert G. Danka ◽  
Gregory A. Lang

`Gulfcoast' southern highbush blueberry (Vaccinium corymbosum × V. darrowi) plants were placed in 3 × 6 × 2.5 m net cages with one colony of honey bees per cage and one of three pollinizer treatments: “self (other `Gulfcoast' plants), “cross/highbush” (other southern highbush cultivars), or “cross/rabbiteye” (various rabbiteye blueberry cultivars). In addition to unlimited pollination, bee foraging was controlled on individual flowers by placing small bags over corollas after 0, 1, 5, or 10 visits. Fruit set, fruit weight, fruit development period, and seed number data were taken, as well as data to relate floral morphology to duration of bee foraging. All measures of fruiting increased significantly with increased bee visitation; the threshold for significant gains in production occurred between 1 and 5 visits. Ten visits generally provided a good approximation of unlimited pollination. Set, weight, and earliness of ripening was as good, or better, for fruit derived from rabbiteye pollen compared to fruit from self- or cross/highbush-pollination.


HortScience ◽  
2017 ◽  
Vol 52 (9) ◽  
pp. 1259-1264 ◽  
Author(s):  
Matthew Arrington ◽  
Lisa Wasko DeVetter

Fruit set in northern highbush blueberry (Vaccinium corymbosum L.) can be low under certain climatic conditions, contributing to reduced yields in northwestern Washington. The mechanisms influencing fruit set are complex, but reduced fruit set may be associated with inadequate nutrient availability during critical stages of flowering, ovule fertilization, and initial fruit development. Calcium (Ca) and boron (B) are of particular interest for reproductive developmental processes and are frequently applied annually by growers in the Pacific Northwest region because of the perception that these nutrients enhance fruit set and corresponding yields. Evaluation of commonly applied products containing these nutrients and their effects on fruit set and yield are of specific importance to justify the application of these nutrients. To address this, commercially available fertilizers containing Ca and B were applied to ‘Draper’ and ‘Bluecrop’ blueberry as foliar sprays, either alone or in combination, during the 2015 and 2016 growing seasons in northwestern Washington. Treatments included calcium chloride (750 and 1500 ppm Ca), calcium sulfate (150 ppm Ca), and tetra borate (125 and 250 ppm B) foliar sprays, repeated six times per season every 7–10 days from early pink bud through petal fall. No significant increases were observed for fruit set, estimated yield, and fruit quality (firmness and berry weight) across the treatments. Increased concentrations of B were observed in leaf tissues in 2015 and 2016, and to a lesser extent fruit tissues. Calcium remained unchanged regardless of treatment and tissue type. Under the conditions of this study, foliar applications of Ca and B did not lead to increased fruit set or yield. This research suggests that other approaches should be explored to increase fruit set and corresponding yields of highbush blueberry grown in northwest Washington.


1991 ◽  
Vol 116 (5) ◽  
pp. 770-773 ◽  
Author(s):  
Gregory A. Lang ◽  
Robert G. Danka

To study self- and cross-pollination effects on fruit development in southern highbush (mainly Vaccinium corymbosum L.) blueberries, `Sharpblue' plants were caged with honey bees (Apis mellifera L.) and other `Sharpblue' or `Gulfcoast' plants at anthesis. Ratios of pollinizer: fruiting flowers ranged from 2.1 to 4.5. Cross-pollination increased fruit size by ≈14% and seed count by 27% but did not influence fruit set. Overall, seed count decreased by 58% during the 30 days of harvest, but this did not directly affect fruit size. Seed count appeared to influence earliness of ripening as much as it influenced fruit size. Cross-pollination increased the harvest percentage of early-ripening fruits by ≈140% and of premium market fruits (those ≥ 0.75 g) by 13% and decreased the percentage of small fruits by 66%. Consequently, a 43% increase in premium early market crop value (nearly $5000/ha) resulted from optimizing `Sharpblue' cross-pollination.


HortScience ◽  
2017 ◽  
Vol 52 (6) ◽  
pp. 844-851 ◽  
Author(s):  
Bernadine C. Strik ◽  
Amanda J. Vance ◽  
Chad E. Finn

Northern highbush blueberry (Vaccinium corymbosum L.) cultivars were evaluated from planting (Oct. 2006) through 2014 in a certified organic research site in Aurora, OR. The treatments included cultivar (Duke, Bluecrop, Reka, Bluejay, Bluegold, Draper, Legacy, Liberty, Ozarkblue, and Aurora), amendment-mulch [“compost + sawdust” (included preplant amendment and a surface mulch of either an agricultural on-farm crop waste compost or yard-debris compost and sawdust), and “weed mat” (no preplant amendments but with a sawdust mulch topped with weed mat)]. Adding on-farm compost as a preplant amendment and as part of the mulching program increased soil pH from 4.9 to 6.9, organic matter content (OM), and calcium (Ca), magnesium (Mg), and potassium (K) levels compared with the weed mat treatment. The reduced plant growth and yield in some cultivars grown in the compost + sawdust treatment was likely due to the higher soil pH. ‘Bluegold’ and ‘Draper’ were among the cultivars with consistently high flower bud set (40% to 57%), whereas others had consistently low values (e.g., 22% to 45% in ‘Bluecrop’). The number of flowers per bud was affected only by cultivar. There was no effect of year or amendment-mulch treatment on percent fruit set which averaged 93% during the study; however, ‘Ozarkblue’ had a significantly lower fruit set (88%) than only ‘Aurora’ (96%). Berry weight was affected by year (plant age), cultivar, and amendment-mulch treatment. ‘Ozarkblue’ produced the largest berries. Type of amendment-mulch had little effect on berry weight, except in ‘Ozarkblue’, ‘Aurora’, and ‘Reka’ where plants grown with weed mat produced larger fruit than those grown with compost + sawdust. On average, ‘Bluejay’, ‘Draper’, and ‘Liberty’ fruit had the highest percent soluble solids (TSS) and ‘Ozarkblue’ the lowest. Fruit harvested from plants grown with weed mat were firmer than when compost + sawdust was used. ‘Draper’ fruit were much firmer than those of the other cultivars in all years of the study. The number of flower buds per plant multiplied by the number of flowers/bud and berry weight (cultivar specific) and average fruit set was a good predictor of yield in young plants. Yield per plant increased from the second through seventh growing seasons as plants matured in all cultivars except for ‘Duke’ which had the greatest yield in 2014. Cumulative yield was highest in ‘Legacy’ and lowest in ‘Bluejay’ and in ‘Draper’, which had relatively low yield when plants were young. Most cultivars had greater yield when grown with weed mat, whereas ‘Bluegold’ and ‘Liberty’ were unaffected by amendment-mulch treatment. Because weeds were managed in all plots, the cultivar response to amendment-mulch was likely a reflection of sensitivity to preplant amendment with on-farm compost and the resulting higher soil pH. It is possible that the cultivars differed in their adaptability to the various fertility regimes caused by the amendment-mulch treatments and fertilizers used in our study.


HortScience ◽  
2018 ◽  
Vol 53 (2) ◽  
pp. 191-194
Author(s):  
Matthew Arrington ◽  
Lisa Wasko DeVetter

Yield components including fruit set and berry size in northern highbush blueberry (Vaccinium corymbosum) can be limited in key production regions like western Washington. Climactic conditions influence the activity levels of blueberry’s primary commercial pollinator, honey bee (Apis mellifera). Cool springs with frequent rainfall, which are common during the spring bloom period in western Washington, can reduce honey bee activity, pollination efficiency, and subsequent fruit set and yields. Increasing honey bee hive density may be a simple technique that growers can employ to increase the number of honey bees foraging during periods of good weather, interspersed with the poor weather, and therefore, increase fruit set and related yield components. The objective of this study was to evaluate if increased honey bee hive densities improve pollination and subsequent yield components in western Washington blueberry. Three field sites with mature ‘Duke’ plants were stocked with 10 hives/ha of honey bees (control), and three other field sites (also ‘Duke’) were stocked with 20 hives/ha (high hive density). Honey bee visitation and yield components, including fruit set and berry weight, were measured. Estimated yield, seed number/berry, and fruit firmness were also monitored. There were no significant differences in fruit set regardless of honey bee hive density. However, honey bee visitation and estimated yield increased with increased honey bee hive density. Berry weight and seed number per berry were also increased with increased honey bee hive density, although firmness was unaffected. Results indicate that increasing honey bee hive densities can help blueberry growers improve berry size and overall yields, suggesting this is a practice growers can implement if their production is constrained by insufficient pollination.


HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 866A-866
Author(s):  
S. Alan Walters* ◽  
Bradley H. Taylor

Most small pumpkin growers in Illinois have traditionally relied upon natural insect pollinators to achieve fruit set and development. Many growers fail to understand the importance of pollination and are not aware of the potential benefits of using honey bee colonies to improve pollination and subsequent fruit set of pumpkin. Therefore, a study was conducted over the 2000 and 2001 growing seasons to measure the effectiveness of honey bee colonies on jack-o-lantern pumpkin production. Yields (kg·ha-1) of several cultivars (e.g., `Appalachian' and `Howden') almost doubled when honey bee colonies were present during flowering. Pumpkin weights with the inclusion of honey bees averaged 31,547 kg·ha-1 compared to 22,353 kg·ha-1 for those without honey bees. However, the number of pumpkins per ha was not as drastically influenced by the addition of honey bees; total pumpkin fruits per ha averaged 1,896 with honey bees as compared to 1,704 without honey bees. These results indicate that there were sufficient natural pollinators to induce pumpkin fruit set under field conditions during the study, but fruit size can be significantly increased with the addition of a strong honey bee colony during flowering. Since pumpkins are generally sold on a weight basis, growers should realize greater revenues with the inclusion of honey bee colonies in pumpkin fields.


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