Vaccinium Angustifolium Research Articles

Predation of lowbush blueberry insect pests by ground beetles (Coleoptera: Carabidae) in the laboratory

Agriculture relies on ecosystem services, such as biological control of pests, for economic success and sustainability. Commercially managed lowbush blueberries are an important crop in eastern North America, but pest control by natural enemies has not been well studied. In this paper we address questions about consumption of two blueberry pests by ground beetles (Carabidae) that are common in blueberry fields. In the first experiment, a Poecilus l. lucublandus, Carabus nemoralis, or Pterostichus mutus beetle was placed with two blueberry spanworm larvae, Itame argillacearia, in a simple (cup only or cup + soil) or more complex (cup + soil + blueberry sprigs) treatment arena. In most cases, probability of spanworm consumption reached 100 % in simple arenas by the end of the experiment (48 h) but was 25–50 % lower in more complex arenas. In a second experiment, a male or female Pterostichus melanarius or Harpalus rufipes beetle was placed in a plastic container with saturated or dry soil into which mature blueberry maggots, Rhagoletis mendax, dropped from blueberries to pupate. Approximately 40–80 and 35 % fewer pupae were recovered when a P. melanarius and H. rufipes beetle was present, respectively, but soil moisture and beetle sex were not significant factors. Our results demonstrate that ground beetles can prey upon important blueberry pests, but suggest that consumption may be influenced by microhabitat structure.

Factors affecting head capsule development in field populations ofAltica sylvia(Coleoptera: Chrysomelidae)

AbstractTraits such as larval growth rate and head capsule width are often measured in economically important insects to determine their developmental stage. However, these traits have the potential to vary between genotypes or in response to several ecological factors. To determine whether geographic or ecological factors cause variability in the head capsule width ofAltica sylviaMalloch (Coleoptera: Chrysomelidae), and to verify whether measures of head capsule width are adequate to identify larval instars in this species,A. sylvialarvae were recovered from 35 fields ofVaccinium angustifoliumAiton (lowbush blueberry; Ericaceae) of eastern New Brunswick, Canada. The distribution of head capsule widths varied in response to accumulated degree-days,A. sylvialarval density, and latitude. An overlap between measures of head capsule width of first-instar and second-instar larvae in fields supporting a high density ofA. sylvialarvae suggested that intraspecific competition caused a reduction in larval growth rate that affected head capsule development and may have induced developmental polymorphism. Based on these results, we stress that the sampling protocol of studies conducted to determine head capsule width intervals in a species should include diverse ecological settings as well as several locations within the range of the species.

Effect of liquid nitrogen pretreatments on osmotic dehydration of blueberries

Fresh blueberries are highly perishable and must be preserved by either freezing or drying technologies. However, moisture impermeability of their skin is a barrier against the moisture diffusion slowing down the drying process. The aim of this study was to investigate the impact of liquid nitrogen pretreatments on osmotic dehydration kinetics of two blueberry species, Vaccinium corymbosum L. and Vaccinium angustifolium Ait, and on the physicochemical quality of dehydrated fruits.The number of immersions in liquid nitrogen was a determinant factor that accelerated water loss. Depending on the blueberry species, a reduction of dehydration time from 45% to 65% was obtained for liquid nitrogen treated samples when compared to control blueberries. Microscopic observations of the blueberry skin before and after the liquid nitrogen pretreatment revealed a decrease of the cuticle thickness, dewaxing of the skin surface and the presence of micro-fissures facilitating moisture and sugar transfer during the osmotic process. The dewaxing of the blueberry skin due to liquid nitrogen immersions was confirmed by wax quantification before and after the cryogenic pretreatments. Osmotic dehydration and liquid nitrogen pretreatments showed a slight decrease in the levels of phenolic compounds and anthocyanins compared to the fresh blueberries.

Molecular markers and antioxidant activity in berry crops: Genetic diversity analysis

Debnath, S. C., Siow, Y. L., Petkau, J., An, D. and Bykova, N. V. 2012. Molecular markers and antioxidant activity in berry crops: Genetic diversity analysis. Can. J. Plant Sci. 92: 1121–1133. An improved understanding of important roles of dietary fruits in maintaining human health has led to a dramatic increase of global berry crop production. Berry fruits contain relatively high levels of vitamin C, cellulose and pectin, and produce anthocyanins, which have important therapeutic values, including antitumor, antiulcer, antioxidant and anti-inflammatory activities. There is a need to develop reliable methods to identify berry germplasm and assess genetic diversity/relatedness for dietary properties in berry genotypes for practical breeding purposes through genotype selection in a breeding program for cultivar development, and proprietary-rights protection. The introduction of molecular biology techniques, such as DNA-based markers, allows direct comparison of different genetic materials independent of environmental influences. Significant progress has been made in diversity analysis of wild cranberry, lowbush blueberry, lingonberry and cloudberry germplasm, and in strawberry and raspberry cultivars and advanced breeding lines developed in Canada. Inter simple sequence repeat (ISSR) markers detected an adequate degree of polymorphism to differentiate among berry genotypes, making this technology valuable for cultivar identification and for the more efficient choice of parents in the current berry improvement programs. Although multiple factors affect antioxidant activity, a wide range of genetic diversity has been reported in wild and cultivated berry crops. Diversity analysis based on molecular markers did not agree with those from antioxidant activity. The paper also discusses the issues that still need to be addressed to utilize the full potential of molecular techniques including expressed sequence tag-polymerase chain reaction (EST-PCR) analysis to develop improved environment-friendly berry cultivars suited to the changing needs of growers and consumers.

Seasonal changes in photochemistry, light use efficiency and net photosynthetic rates of wild blueberry (Vaccinium angustifoliumAit.)

Percival, D., Kaur, J., Hainstock, L. J. and Privé, J.-P. 2012. Seasonal changes in photochemistry, light use efficiency and net photosynthetic rates of wild blueberry (Vaccinium angustifolium Ait.). Can. J. Plant Sci. 92: 1135–1143. The seasonal variation of carotenoid concentration, chlorophyll a and b levels, dark- (Fv/Fm) and light-adapted (Fv′/Fm′) variable to maximal chlorophyll fluorescence (an indication of the quantum efficiency of PSII photochemistry) and net photosynthesis of the wild blueberry (Vaccinium angustifolium Ait.) was examined in the vegetative and cropping phases of production. Chlorophyll levels ranged from 2.0 to 12 µg cm−2and from 0.042 to 1.4 µg cm−2for chlorophyll a and b, respectively, were significantly lower in the cropping phase of production, and were also lower in the latter stages of the growing season. Similarly, carotenoid concentrations ranged from 0.67 to 4.1 µg cm−2and were lower in the cropping phase of production. However, carotenoid concentration and dark- and light-adapted variable to maximal chlorophyll fluorescence (Fv/Fm and Fv′/Fm′) decreased marketably at the mid-point of the growing season, presumably as a result of photoinhibition. Net photosynthetic values of upright stems ranged from 2.1 to 7.6 µmol m−2s−1, were substantially higher in the vegetative phase of production and also decreased significantly in the latter part of the growing season. Results from this investigation indicate that the wild blueberry has a relatively low photosynthetic rate, which may be prone to photoinhibition and limited carbohydrate supply (i.e., source) when compared with other temperate fruit crops.

Seasonal growth dynamics and carbon allocation of the wild blueberry plant (Vaccinium angustifoliumAit.)

Kaur, J., Percival, D., Hainstock, L. J. and Privé, J.-P. 2012. Seasonal growth dynamics and carbon allocation of the wild blueberry plant ( Vaccinium angustifolium Ait.). Can. J. Plant Sci. 92: 1145–1154. Field studies were conducted at the Wild Blueberry Research Station, Debert, NS, to examine the carbon allocation dynamics within the wild blueberry (Vaccinium angustifolium Ait.). This was achieved with biweekly measurements of dry weight, soluble sugar and starch levels of the rhizomes, roots, stems/leaves and berries of plants in the vegetative (i.e., sprout phase) and cropping phases of production. Non-structural carbohydrate levels were determined using high-performance liquid chromatography (HPLC). Growth parameters included phenology, stem height, dry weights of the above-ground vegetation (stems and leaves), berries, rhizomes and roots. Interestingly, root growth was observed prior to upright shoot emergence and dry weight for rhizome remained higher compared with stems and leaves. The rhizomes acted as a carbohydrate source during stem and root growth. The developing berry crop appeared to be a strong sink for photo-assimilates, as berries were found to import sucrose and convert it to fructose and glucose during maturation, and HPLC studies further confirmed the increasing levels of fructose and glucose. Given the phenology of the wild blueberry, the results exemplify the importance of the rhizomes as a strong carbohydrate source, especially in the early stages of a growing season when the carbohydrate production is limited.

Honey bee stocking numbers and wild blueberry production in Nova Scotia

Eaton, L. J. and Nams, V. O. 2012. Honey bee stocking numbers and wild blueberry production in Nova Scotia. Can. J. Plant Sci. 92: 1305–1310. Wild blueberries (Vaccinium angustifolium Ait.) require cross pollination by insects. Introduction of managed species such as honey bees (Apis mellifera L.) and alfalfa leafcutting bees (Megachile rotundata Fabr.) is costly. We assessed the effects of stocking rates of honey bee hives and the interacting effects of the numbers of honey bees and other bees on yield of blueberries in commercial fields. Blueberry fields were sampled from 101 fields in years 1991 to 2010 in Nova Scotia. We recorded field size, numbers of beehives, yield, densities of bees, numbers of buds, blossoms and set fruit. Yields increased linearly with numbers of beehives, up to∼4 hives/hectare, but at higher stocking rates there was too much variation to adequately determine the effects. Yields also increased linearly with numbers of honey bees, but there was an interaction with other bees that decreased the effects of honey bees, such that at maximum densities of other bees, there was no effect of honey bees on yield. These results suggest that other bees and honey bees compete for pollination. If producers have limited numbers of beehives, we suggest that more should be placed in areas where densities of other bees are lower, up to approximately 4 hives/hectare.

Quantification of Chlorogenic Acid and Hyperoside Directly from Crude Blueberry (Vaccinium angustifolium) Leaf Extract by NMR Spectroscopy Analysis: Single-Laboratory Validation

A single-laboratory-validated NMR spectroscopy method was established for determining the quantity of chlorogenic acid and hyperoside from crude extract material of blueberry leaves of the species Vaccinium angustifolium var. laevifolium House. The calibration curve of chlorogenic acid showed a highly linear regression, R = 0.99998. NMR spectroscopy identification and quantification of the constituents directly from the mixture, within the error of HPLC-diode array detector analysis, were determined as 7.53 mM chlorogenic acid (64.0 mg chlorogenic acid/g powdered leaf) and 0.77 mM hyperoside (8.58 mg hyperoside/g powdered leaf). The LOD was calculated to be 0.01 mM and the LOQ 0.01 mM by the 9 min and 13 s NMR spectroscopy experiment utilized. The assay showed no significant interference from different field strengths, extraction mesh size, gravimetric scale precision, NMR spectroscopy tube type, pulse program, amount of starting dry material, or day-to-day operation. The robustness of NMR spectroscopy as a means of definitively monitoring chlorogenic acid and hyperoside content directly from crude extracts was demonstrated by Youden statistical analysis.

Post-Disturbance Plant Community Dynamics following a Rare Natural-Origin Fire in a Tsuga canadensis Forest

Opportunities to directly study infrequent forest disturbance events often lead to valuable information about vegetation dynamics. In mesic temperate forests of North America, stand-replacing crown fire occurs infrequently, with a return interval of 2000–3000 years. Rare chance events, however, may have profound impacts on the developmental trajectories of forest ecosystems. For example, it has been postulated that stand-replacing fire may have been an important factor in the establishment of eastern hemlock (Tsuga canadensis) stands in the northern Great Lakes region. Nevertheless, experimental evidence linking hemlock regeneration to non-anthropogenic fire is limited. To clarify this potential relationship, we monitored vegetation dynamics following a rare lightning-origin crown fire in a Wisconsin hemlock-hardwood forest. We also studied vegetation in bulldozer-created fire breaks and adjacent undisturbed forest. Our results indicate that hemlock establishment was rare in the burned area but moderately common in the scarified bulldozer lines compared to the reference area. Early-successional, non-arboreal species including Rubus spp., Vaccinium angustifolium, sedges (Carex spp.), grasses, Epilobium ciliatum, and Pteridium aquilinium were the most abundant post-fire species. Collectively, our results suggest that competing vegetation and moisture stress resulting from drought may reduce the efficacy of scarification treatments as well as the usefulness of fire for preparing a suitable seedbed for hemlock. The increasing prevalence of growing-season drought suggests that silvicultural strategies based on historic disturbance regimes may need to be reevaluated for mesic species.

Growing Degree-day Models for Predicting Lowbush Blueberry (Vaccinium angustifolium Ait.) Ramet Emergence, Tip Dieback, and Flowering in Nova Scotia, Canada

Experiments were established to evaluate the suitability of growing degree-day (GDD, Tbase = 0 °C) models for predicting emergence, tip dieback, and flowering of lowbush blueberry ramets in Nova Scotia, Canada. Data for model development were collected from quadrats established in several non-bearing and bearing blueberry fields throughout the dominant blueberry production areas in northern and central Nova Scotia. Blueberry ramets emerged between 222 and 265 GDD (6 May to 14 May) and reached 90% emergence between 619 and 917 GDD (7 June to 5 July). Emergence continued to slowly increase until late summer or early fall. Tip dieback began between 598 and 792 GDD (14 June to 21 June) and duration of this phase depended on whether late-emerging ramets developed to tip dieback. A four-parameter Weibull and a three-parameter Gompertz equation adequately explained cumulative blueberry ramet emergence and cumulative ramets at tip dieback as functions of GDD in the non-bearing year, respectively. The four-parameter Weibull function also explained the relationship between cumulative flowering ramets and GDD in the bearing year. Flowering ramets were first observed between 376 and 409 GDD (19 May to 30 May) in the bearing year. Model predictions for initiation of emergence, tip dieback, and flowering were 243, 692, and 389 GDD, respectively. Models were validated with independent data sets collected throughout northern and central Nova Scotia. The relationship between the percentage of open flowers on individual ramets and GDD in the bearing year was well described by a Gaussian model at two sites with a predicted peak number of open flowers between 552 and 565 GDD.

Berry unexpected: Nocturnal pollination of lowbush blueberry

Cutler, C. G., Reeh, K. W., Sproule, J. M. and Ramanaidu, K. 2012. Berry unexpected: Nocturnal pollination of lowbush blueberry. Can. J. Plant Sci. 92: 707–711. Lowbush blueberry, Vaccinium angustifolium, is an economically important crop of eastern North America that is critically dependent on insect-mediated cross-pollination for successful fruit set and high yields. It is generally assumed that bees are responsible for the vast majority of lowbush blueberry pollination, and producers usually augment the natural pollination force with managed bees. Little is known, however, of the potential role of nocturnal pollinators in lowbush blueberry production. We conducted a field experiment where patches of blooming blueberry were exposed to flying insects 24 h a day, only during the day (sunrise to sunset), only at night (sunset to sunrise), or 0 h a day. We found that significant fruit set occurred on blueberry stems that were exposed only at night, although it was higher on stems exposed during the day or 24 h a day. However, ripe fruit produced on stems exposed only at night weighed just as much as those exposed 24 h. Captures with Malaise traps activated only at night consisted mainly of several families of Lepidoptera and Diptera, although we do not know if these taxa pollinated blueberries. We conclude that nocturnal pollination may contribute significantly to lowbush blueberry fruit set.

Pollen diversity collected by honey bees in the vicinity of Vaccinium spp. crops and its importance for colony development1This article is part of a Special Issue entitled “Pollination biology research in Canada: Perspectives on a mutualism at different scales”.

Access to a rich diversity of flowering plants is very important for the development of honey bee colonies introduced in crops for pollination. The aim of this observational study was to determine the impact of surrounding pollen diversity on the health of honey bee colonies introduced in lowbush blueberries ( Vaccinium angustifolium Ait.) in June and cranberries ( Vaccinium macrocarpon Ait.) in July. The results suggest that monocultures of lowbush blueberries are not suitable for optimal brood rearing. In the blueberry environments we studied, the dominant pollen collected by honey bees were Alnus Mill. spp. and Taraxacum officinale F.H. Wigg., which are deficient in some essential amino acids. Significant reduction of brood rearing during honey bees’ stay in blueberry monocultures in June may, therefore, be explained by nutritional deficiencies. In July, the polliniferous flora in the vicinity of cranberry monocultures was poorer but of better nutritional quality. Pollen analysis allowed the identification of Brassicaceae, Trifolium L. spp., and V. macrocarpon as the three dominant taxa collected by honey bees during this period. The complete lists of plant taxa foraged by honey bees for pollen during the pollination of lowbush blueberries and cranberries are provided.

Design and experiment of hand-push lowbush blueberry picking machine

Design and experiment of hand-push lowbush blueberry picking machine

The Biology of Canadian weeds. 150 Erechtites hieraciifolius (L.) Raf. ex DC.

Darbyshire, S. J., Francis, A., DiTommaso, A. and Clements, D. R. 2012. The Biology of Canadian weeds. 150 Erechtites hieraciifolius (L.) Raf. ex DC. Can. J. Plant Sci. 92: 729–746. Erechtites hieraciifolius, American burnweed, is a herbaceous annual in the Asteraceae native to forest zones of eastern North America, but introduced to parts of Europe and the Pacific region. Confusion sometimes arises in distinguishing it from other weedy rayless composites in Canada, such as Senecio vulgaris (common groundsel) and Conyza canadensis (Canada fleabane). A pioneer therophyte species of forest zones, it occurs in large numbers when associated with major disturbances such as forest fires, but is also common in areas of smaller scale disturbance such as shores, forest edges and wind-throws. Soil conditions may vary greatly in nutrient content, moisture content, pH and salinity. In Canada, it is generally considered a minor garden and agricultural weed. It is most common in crops such as lowbush blueberry (Vaccinium spp.), cranberry (Vaccinium macrocarpon), strawberry (Fragaria×ananassa) and vegetable crops; however, it occasionally occurs in other field and forage crops. Impacts include a variety of problems contributing to increased production costs or crop yield losses, including herbicide resistance, resource competition, and as a reservoir harbouring crop pathogens. It has been valued as a medicinal herb for treating a variety of ailments. Populations may grow rapidly in response to disturbances typical of managed landscapes, but E. hieraciifolius can usually be effectively controlled by chemical, cultural or manual weed control tactics.

Effect of a wild blueberry (Vaccinium angustifolium) drink intervention on markers of oxidative stress, inflammation and endothelial function in humans with cardiovascular risk factors

Wild blueberries (WB) (Vaccinium angustifolium) are rich sources of polyphenols, such as flavonols, phenolic acids and anthocyanins (ACNs), reported to decrease the risk of cardiovascular and degenerative diseases. This study investigated the effect of regular consumption of a WB or a placebo (PL) drink on markers of oxidative stress, inflammation and endothelial function in subjects with risk factors for cardiovascular disease. Eighteen male volunteers (ages 47.8 ± 9.7 years; body mass index 24.8 ± 2.6 kg/m²) received according to a cross-over design, a WB (25 g freeze-dried powder, providing 375 mg of ACNs) or a PL drink for 6 weeks, spaced by a 6-week wash-out. Endogenous and oxidatively induced DNA damage in blood mononuclear cells, serum interleukin levels, reactive hyperemia index, nitric oxide, soluble vascular adhesion molecule concentration and other variables were analyzed. Wild blueberry drink intake significantly reduced the levels of endogenously oxidized DNA bases (from 12.5 ± 5.6 % to 9.6 ± 3.5 %, p ≤ 0.01) and the levels of H₂O₂-induced DNA damage (from 45.8 ± 7.9 % to 37.2 ± 9.1 %, p ≤ 0.01), while no effect was found after the PL drink. No significant differences were detected for markers of endothelial function and the other variables under study. In conclusion, the consumption of the WB drink for 6 weeks significantly reduced the levels of oxidized DNA bases and increased the resistance to oxidatively induced DNA damage. Future studies should address in greater detail the role of WB in endothelial function.

Lowbush blueberries, Vaccinium angustifolium, modulate the functional potential of nutrient utilization and DNA maintenance mechanisms in the rat proximal colon microbiota

Background: The core gut microbiota encodes for a metabolic capacity that often surpasses the metabolic potential of its host. Lowbush wild blueberries (LWB) are a rich source of bioactive compounds, and the gut microbiota is an important modulator of their activity. The objective of this research is to study the effect of a diet enriched with LWB on the gastrointestinal microbiota’s metabolic potential. Methods: Nine three-week-old male Sprague Dawley rats were randomly assigned to two groups. The control group (N=4) was placed on the AIN93 diet, and the treatment group (N=5) was fed the same diet with 8% (w/w) LWB powder substituting for dextrose. The animals consumed the diets for six weeks, after which they were sacrificed. Functional profiles and metabolic potential of the colon microbiota in response to diet were analyzed using deep whole genome sequencing (WGS). Results: Proteins predicted from WGS DNA sequences were assigned to 3,746 COG, 5,577 KEGG, and 4,474 Pfam families. Statistical comparisons of the protein-coding genes revealed significant changes in 25 Gene Ontology (GO), 186 KEGG, and 20 Pfam protein families representing 2.1%, 3.3%, and 0.02% of all hits identified, respectively. Overall, the combined inquires into these databases represented an emphasis on membrane trafficking, DNA regulation, modification and repair, and nutrient metabolism. Protein families that significantly increased by the enrichment of LWBs were involved with amino acid metabolism, 2,4-dienoyl-CoA reductase, metal ion binding, glutamate synthase, REDOX homeostasis, and aryl transferases. In contrast, protein families involved with integrase/recombinase, reverse transcriptase, and transposon/transposase were at a lower abundance. Conclusions: The results from this study reflect the potential impact that LWBs have on the functional repertoire of bacterial communities in the proximal colon. The results demonstrate a higher potential for the metabolism of amino acids and a lower potential for horizontal integration of plasmids and lower phage/transposon activity in the LWB diet, suggesting that the genome at the time of sampling was more stable. This study helps unravel diverse mechanisms of microbial adaptation to LWBs in the diet of mammals and can provide guidance in optimizing functional diets.

High-Throughput Screening for Anti–Influenza A Virus Drugs and Study of the Mechanism of Procyanidin on Influenza A Virus–Induced Autophagy

In this research, we have established a high-throughput screening (HTS) platform based on the influenza A virus (IAV) vRNA promoter. Using this HTS platform, we selected 35 medicinal plants out of 83 examples of traditional Chinese medicine and found that 7 examples had not been reported. After examining many previous reports, we found that Vaccinium angustifolium Ait., Vitis vinifera L, and Cinnamomum cassia Presl had a common active compound, procyanidin, and then determined the anti-IAV effect of procyanidin and explored its mechanism of action. With a plaque inhibition assay and a time-of-addition experiment, we found that procyanidin could inhibit the IAV replication at several stages of the life cycle. In the Western blot and EGFP-LC3 localization assays, we found that procyanidin could inhibit the accumulation of LC3II and the dot-like aggregation of EGFP-LC3. In the RT-PCR and Western blot assays, we found procyanidin could inhibit the expression of Atg7, Atg5, and Atg12. Finally, by the bimolecular fluorescence complementation–fluorescence resonance energy transfer and co-immunoprecipitation assays, we found that procyanidin could inhibit the formation of the Atg5-Atg12/Atg16 heterotrimer and the dissociation of the beclin1/bcl2 heterodimer. In conclusion, we have established an HTS platform and identified procyanidin as a novel and promising anti-IAV agent.

Ant Diversity and Distribution (Hymenoptera: Formicidae) Throughout Maine Lowbush Blueberry Fields in Hancock and Washington Counties

Ant Diversity and Distribution (Hymenoptera: Formicidae) Throughout Maine Lowbush Blueberry Fields in Hancock and Washington Counties

Lethal and sublethal effects of some insecticides recommended for wild blueberry on the pollinator Bombus impatiens

AbstractManaged and wild colonies of common eastern bumble bee (Bombus impatiens Cresson) (Hymenoptera: Apidae) are effective pollinators of wild blueberry (Vaccinium angustifolium Aiton) (Ericaceae) in Atlantic Canada. Because insecticides are used during bloom to manage insect pests, bumble bees may be at risk of exposure. We therefore assessed the susceptibility of B. impatiens to some insecticides used or projected for use in blueberry pest management. Workers were killed by topical applications of spinosad, spinetoram, deltamethrin, and phosmet, but not flubendiamide. Similarly, when ingested in honey solution, spinetoram and deltamethrin were toxic, whereas flubendiamide did not cause mortality up to double its recommended label rate. In another experiment, workers were fed one sublethal dose of contaminated honey solution and placed in microcolonies to assess impacts on feeding, life span, and reproduction. The highest concentration of deltamethrin (17 mg a.i./L) reduced feeding. Workers treated with deltamethrin had shortened life spans and produced fewer males. Flubendiamide (2000 mg a.i./L) and spinetoram (0.8 mg a.i./L) caused no sublethal effects. These results indicate that flubendiamide should be safe to apply to blueberries where B. impatiens is foraging, while some other insecticides we tested may be hazardous under different exposure scenarios.

Evidence of functional gender polymorphisms in a population of the hermaphroditic lowbush blueberry (Vaccinium angustifolium)1This article is part of a Special Issue entitled “A tribute to Sam Vander Kloet FLS: Pure and applied research from blueberries to heathland ecology”.

Lowbush blueberry ( Vaccinium angustifolium Aiton) is a wild, but cultivated for profit, agricultural system grown primarily in the northeastern regions of North America. It has been suggested that a functional gender specialization may be occurring in this hermaphroditic species in which some individuals (termed clones) effectively function as bearers (high ovule production but little or nonviable pollen) or as pollen donors (low ovule number with high quantities of viable pollen). The purpose of this study was to investigate if functional gender specialization was occurring in a randomly chosen population of 56 clones from the Blueberry Hill Research Farm in Jonesboro, Maine. For each clone, the mean number of ovules and the mean number of viable microspores per flower were determined. From this, functional gender was calculated. Five out of 56 clones, or approximately 10% of clones, were found to be functioning primarily as females, owing to their low levels of viable pollen. Thus, some evidence was found of a functional gender specialization occurring—the presence of a few plants that were nearly male-sterile. Since the most common evolutionary pathway to gynodioecy involves the invasion of male steriles, it is interesting to speculate that a trend towards gender dimorphism could be occurring in lowbush blueberry.