Crop production in the USA is frequently limited by a lack of pollinators.

Most of the world's crops depend on pollinators, so declines in both managed and wild bees raise concerns about food security. However, the degree to which insect pollination is actually limiting current crop production is poorly understood, as is the role of wild species (as opposed to managed honeybees) in pollinating crops, particularly in intensive production areas. We established a nationwide study to assess the extent of pollinator limitation in seven crops at 131 locations situated across major crop-producing areas of the USA. We found that five out of seven crops showed evidence of pollinator limitation. Wild bees and honeybees provided comparable amounts of pollination for most crops, even in agriculturally intensive regions. We estimated the nationwide annual production value of wild pollinators to the seven crops we studied at over $1.5 billion; the value of wild bee pollination of all pollinator-dependent crops would be much greater. Our findings show that pollinator declines could translate directly into decreased yields or production for most of the crops studied, and that wild species contribute substantially to pollination of most study crops in major crop-producing regions.

Managed and Wild Bee Flower Visitors and Their Potential Contribution to Pollination Services of Low-Chill Highbush Blueberry (Vaccinium corymbosum L.; Ericales: Ericaceae).

Highbush blueberry (Vaccinium corymbosum L.; Ericales: Ericaceae) is an important crop grown throughout the eastern United States and Canada. Cross-pollination by insects greatly enhances pollination and fruit set in highbush blueberry. In Florida, low-chill cultivars that flower during the winter when most bees are dormant are used, thus, making it difficult to utilize and depend on unmanaged bees. We investigated flower visitation rates by managed and wild bees and the subsequent berry formation, berry weight, and number of seeds/berry in highbush blueberry fields in north-central Florida. Additionally, we tested three pollinator treatments: 1) pollinator-excluded flowers, 2) open-pollinated treatments that were available to managed and wild bees, and 3) flowers that were hand pollinated. Overall, we found seven native bee species that contribute to highbush blueberry pollination in Florida, but managed honey bees and bumble bees were the main flower visitors. Additionally, 14.5 times more blueberries formed in the open treatments than in the pollinator exclusion treatments, thus illustrating the economic impact bees have on blueberry pollination. Most of the wild bees observed visiting blueberry flowers were ground-nesting species that need uncultivated areas for nesting sites. Therefore, leaving field edges uncultivated and some undisturbed habitat may increase native bee numbers within blueberry farms over time.

Managed Bumble Bees (Bombus impatiens) (Hymenoptera: Apidae) Caged With Blueberry Bushes at High Density Did Not Increase Fruit Set or Fruit Weight Compared to Open Pollination.

Highbush blueberry (Vaccinium corymbosum L.) is an important crop grown throughout Florida. Currently, most blueberry growers use honey bees (Apis mellifera L.) to provide pollination services for highbush blueberries even though bumble bees (Bombus spp.) have been shown to be more efficient at pollinating blueberries on a per bee basis. In general, contribution of bumble bees to the pollination of commercial highbush blueberries in Florida is unknown. Herein, we determined if managed bumble bees could contribute to highbush blueberry pollination. There were four treatments in this study: two treatments of caged commercial bumble bee (Bombus impatiens Cresson) colonies (low and high weight hives), a treatment excluding all pollinators, and a final treatment which allowed all pollinators (managed and wild pollinators) in the area have access to the plot. All treatments were located within a highbush blueberry field containing two cultivars of blooming plants, 'Emerald' and 'Millennia', with each cage containing 16 mature blueberry plants. We gathered data on fruit set, berry weight, and number of seeds produced per berry. When pollinators were excluded, fruit set was significantly lower in both cultivars (<8%) compared to that in all of the other treatments (>58%). Berry weight was not significantly different among the treatments, and the number of seeds per berry did not show a clear response. This study emphasizes the importance of bumble bees as an effective pollinator of blueberries and the potential beneficial implications of the addition of bumble bees in commercial blueberry greenhouses or high tunnels.

Precision large field scanning system for high numerical aperture lenses and application to femtosecond micromachining of ophthalmic materials.

A precision, large stroke (nearly 1 cm) scanning system was designed, built, and calibrated for micromachining of ophthalmic materials including hydrogels and cornea (excised and in vivo). This system comprises a flexure stage with an attached objective on stacked vertical and horizontal translation stages. This paper outlines the design process leading to our most current version including the specifications that were used in the design and the drawbacks of other methods that were previously used. Initial measurements of the current version are also given. The current flexure was measured to have a 27 Hz natural frequency with no load.

Protein levels and colony development of Africanized and European honey bees fed natural and artificial diets.

Pollen substitute diets are a valuable resource for maintaining strong and health honey bee colonies. Specific diets may be useful in one region or country and inadequate or economically unviable in others. We compared two artificial protein diets that had been formulated from locally-available ingredients in Brazil with bee bread and a non-protein sucrose diet. Groups of 100 newly-emerged, adult workers of Africanized honey bees in Brazil and European honey bees in the USA were confined in small cages and fed on one of four diets for seven days. The artificial diets included a high protein diet made of soy milk powder and albumin, and a lower protein level diet consisting of soy milk powder, brewer's yeast and rice bran. The initial protein levels in newly emerged bees were approximately 18-21 µg/µL hemolymph. After feeding on the diets for seven days, the protein levels in the hemolymph were similar among the protein diet groups (~37-49 µg/µL after seven days), although Africanized bees acquired higher protein levels, increasing 145 and 100% on diets D1 and D2, respectively, versus 83 and 60% in the European bees. All the protein diets resulted in significantly higher levels of protein than sucrose solution alone. In the field, the two pollen substitute diets were tested during periods of low pollen availability in the field in two regions of Brazil. Food consumption, population development, colony weight, and honey production were evaluated to determine the impact of the diets on colony strength parameters. The colonies fed artificial diets had a significant improvement in all parameters, while control colonies dwindled during the dearth period. We conclude that these two artificial protein diets have good potential as pollen substitutes during dearth periods and that Africanized bees more efficiently utilize artificial protein diets than do European honey bees.

Susceptibility of Aethina tumida (Coleoptera: Nitidulidae) larvae and pupae to entomopathogenic nematodes.

In this study, we evaluated the potential use of entomopathogenic nematodes as a control for the beetle Aethina tumida Murray (Coleoptera: Nitidulidae). In particular, we conducted 1) four screening bioassays to determine nematode (seven species, 10 total strains tested) and application level effects on A. tumida larvae and pupae, 2) a generational persistence bioassay to determine whether single inoculations with nematodes would control multiple generations of A. tumida larvae in treated soil, and 3) a field bioassay to determine whether the nematodes would remain efficacious in the field. In the screening bioassays, nematode efficacy varied significantly by tested nematode and the infective juvenile (IJ) level at which they were applied. Although nematode virulence was moderate in screening bioassays 1-3 (0-68% A. tumida mortality), A. tumida mortality approached higher levels in screening bioassay 4 (nearly 100% after 39 d) that suggest suitable applicability of some of the test nematodes as field controls for A. tumida. In the generational persistence bioassay, Steinernema riobrave Cabanillas, Poinar & Raulston 7-12 strain and Heterorhabditis indica Poinar, Karunaka & David provided adequate A. tumida control for 19 wk after a single soil inoculation (76-94% mortality in A. tumida pupae). In the field bioassay, the same two nematode species also showed high virulence toward pupating A. tumida (88-100%) mortality. Our data suggest that nematode use may be an integral component of an integrated pest management scheme aimed at reducing A. tumida populations in bee colonies to tolerable levels.

Screening for diabetic retinopathy: a comparative trial of photography and scanning laser ophthalmoscopy.

AIMS: To evaluate the sensitivity and specificity of wide-field scanning laser ophthalmoscopy (WSLO) in the detection of referable diabetic eye disease, and to compare its performance with digital retinal photography. METHODS: Patients enrolled into the study underwent non-mydriatic WSLO imaging, then single- and dual-field mydriatic digital retinal photography, and examination with slit lamp biomicroscopy, the reference standard. Grading of retinopathy was performed in a masked fashion. RESULTS: A total of 380 patients (759 eyes) were recruited to the study. Technical failure rates for dilated single-field retinal photography, dual-field retinal photography and undilated WSLO were 6.3, 5.8 and 10.8%, respectively (0.005 < p < 0.02 for photography vs. WSLO). The respective indices for screening sensitivity were 82.9, 82.9 and 83.6% (p > 0.2). Specificity was 92.1, 91.1 and 89.5%, respectively (p > 0.2). CONCLUSIONS: Sensitivity and specificity for WSLO were similar to retinal photography. The technical failure rate was greater for the WSLO used in this study.

The efficacy of small cell foundation as a varroa mite (Varroa destructor) control.

Due to a continuing shift toward reducing/minimizing the use of chemicals in honey bee colonies, we explored the possibility of using small cell foundation as a varroa control. Based on the number of anecdotal reports supporting small cell as an efficacious varroa control tool, we hypothesized that bee colonies housed on combs constructed on small cell foundation would have lower varroa populations and higher adult bee populations and more cm(2) brood. To summarize our results, we found that the use of small cell foundation did not significantly affect cm(2) total brood, total mites per colony, mites per brood cell, or mites per adult bee, but did affect adult bee population for two sampling months. Varroa levels were similar in all colonies throughout the study. We found no evidence that small cell foundation was beneficial with regard to varroa control under the tested conditions in Florida.

Macular oedema is not predicted by perifoveal single blot haemorrhages.

AIMS: To ascertain which perifoveal changes on digital retinal screening in diabetes predict the need for subsequent macular grid or focal laser therapy. METHODS: Between 1 January 2004 and 31 December 2005, all consecutive retinal images where any lesion was within one disc diameter of the fovea were reviewed. Patients were categorized by lesion at screening as having microaneurysm, single blot haemorrhage, multiple blot haemorrhages and exudates or circinate exudates within one disc diameter of the fovea. We compared these retinal images with the findings on slit lamp examination and the related decision for laser photocoagulation. RESULTS: Four hundred and twenty-four retinal images were identified. Of these, 52 were excluded, principally because of an interval between photography and clinic attendance of greater than 120 days, leaving 372 retinal images in the study group (313 patients). No patients with a single blot haemorrhage required immediate laser therapy at ophthalmology review compared with 13 (23%) of those with multiple blot haemorrhages and 36 (16%) of those with exudates or circinate lesions (P < 0.001). Thirty-nine patients with a single blot haemorrhage who did not require laser therapy underwent ongoing follow-up. None of these underwent laser therapy for maculopathy within the study time frame (9 months from initial screening event). CONCLUSIONS: In this study, no patients with a single blot haemorrhage within one disc diameter of the fovea on digital retinal screening required laser treatment.

Can we predict which patients are at risk of having an ungradeable digital image for screening for diabetic retinopathy?

PURPOSE: We aimed to determine the reasons for, and variables which predicted, ungradeable retinal photographs during screening patients for diabetic retinopathy. MATERIALS AND METHODS: Age, duration of diabetes, visual acuity, and HbA1c were recorded. Following dark adaptation, a single 45 degrees nonmydriatic photograph was taken of each fundus. The pupils were then dilated and the photograph repeated. Using slit lamp biomicroscopy, lenticular changes (LOCS III), and fundus appearance were recorded. RESULTS: In ungradeable photographs the fovea could not be visualised in 98% of cases of images from nonmydriatic photography, and in 88% if mydriasis was used. Poor definition in the nonmydriatic image was associated with a subsequent ungradeable mydriatic photograph (P=0.001), however, the positive predictive value was poor (34%). Age, posterior subcapsular cataract, and near vision predicted ungradeable status of nonmydriatic photographs (P<0.001, P=0.004, P=0.006, respectively; regression analysis). Nuclear colour and poor definition of the nonmydriatic photograph predicted ungradeable status of mydriatic photographs (P=0.006 & P=0.001, respectively). CONCLUSION: Inability to visualise the fovea is the commonest cause of an ungradeable image from digital retinal photography. Age and posterior subcapsular cataract were best predictors of ungradeable status of nonmydriatic fundus photographs. Nuclear colour was the strongest predictor for ungradeable mydriatic photography.

Fear of visual loss in patients with diabetes: results of the prevalence of diabetic eye disease in Tayside, Scotland (P-DETS) study.

AIMS: To describe the relationship between fear of visual loss and dependent variables (visual acuity, retinopathy treatment, severity of retinopathy) in community-based diabetic patients. METHODS: Subjects were identified from the Diabetes Audit and Research in Tayside, Scotland (DARTS) diabetes register. From a total of 4825 individuals known to have diabetes and who were resident in Dundee and Perth (population 216 204; diabetes prevalence 2.23%), 586 persons with diabetes were randomly selected. Participants completed a self-administered questionnaire in Likert grade format which incorporated two items addressing presence and intensity of fear of visual loss. RESULTS: Questionnaires were returned by 61.4% of the cohort. Fear of visual loss was 'often in mind' for 37% of respondents, and that fear was intense for 47.4%. Analysis by diabetes type revealed differences in reported fear of Type 1 and Type 2 patients in relation to disease and treatment variables. Linear regression highlighted the complexity of the issue with retinal status, acuity and treatment only partly explaining reported patient concern (r(2) range: 0.051-0.125 for presence of fear; 0.026-0.04 for intensity of fear, depending on diabetes type). CONCLUSIONS: Fear of visual loss is preoccupying and intense for a substantial proportion of the diabetic population. Reasons for this are multiple and complex. Objective measures of visual impairment and retinal status are inadequate predictors of fear. Carers and researchers need to be mindful of this when approaching patients with diabetes.

Implementation of national diabetes retinal screening programme is associated with a lower proportion of patients referred to ophthalmology.

AIMS: To examine the impact of a new national retinal screening programme on screening attendance, technical quality of images, and referrals to the ophthalmology clinic. METHODS: Results from the previous ad hoc retinal screening service were compared with data from the first year of the new Scottish Diabetes Retinal Screening Programme in Dundee, which was administered according to criteria recommended by the Health Technology Board Scotland. RESULTS: Of 5150 patients invited for screening, 10.3% of patients did not attend. Overall, 4574 patients underwent single-field digital retinal photography and 25.4% required mydriasis for an adequate image. After screening, 1.9 and 90.5% were recalled for repeat photography at 6 months and 1 year, respectively, whilst 4.6% were ungradable and 3.0% were referred to the ophthalmology clinic. Compared with the last 18 months of the previous scheme, with the new programme a smaller proportion of patients were referred to ophthalmology (3.0 vs. 5.9%; P < 0.001, difference 2.9%: 95% confidence interval 2.1-3.7%). Moreover, the attendance was higher (89 vs. 82%; P < 0.01) and there were fewer ungradable images (4.6 vs. 7.1%; P < 0.001). CONCLUSIONS: Introduction of a systematic retinal screening programme can reduce the proportion of patients referred to the ophthalmology clinic, and use ophthalmology services more efficiently.

Frequency and predictors of hypoglycaemia in Type 1 and insulin-treated Type 2 diabetes: a population-based study.

AIMS: To ascertain the frequency and identify predictors of self-reported hypoglycaemia in Type 1 and insulin-treated Type 2 diabetes. METHODS: A random sample of 267 people with insulin-treated diabetes were recruited from a population-based diabetes register in Tayside, Scotland. Each subject prospectively recorded the number of mild and severe hypoglycaemic episodes experienced over a 1-month period. Ordinal logistic regression was performed to identify potential predictors of hypoglycaemia. RESULTS: Five hundred and seventy-two hypoglycaemic events were reported by 155 patients. The participants with Type 1 diabetes had a total of 336 hypoglycaemic events with a rate of 42.89 events per patient per year. Of these, nine were severe hypoglycaemic events, with a rate of 1.15 events per patient per year. Participants with insulin-treated Type 2 diabetes experienced a total of 236 hypoglycaemic events with a rate of 16.37 events per patient per year. Of these, five were severe hypoglycaemic events, which would be equivalent to 0.35 events per patient per year. Predictors of hypoglycaemia in Type 1 diabetes were a history of previous hypoglycaemia (P = 0.006) and co-prescribing of any oral drug (P = 0.048). In patients with insulin-treated Type 2 diabetes, a history of previous hypoglycaemia (P < 0.0001) and duration of insulin treatment (P = 0.014) were significant predictors. CONCLUSION: The incidence of self-reported severe hypoglycaemia in insulin-treated Type 2 diabetes is lower than in Type 1 diabetes but does occur more often than previously reported and with sufficient frequency to cause significant morbidity. Duration of insulin treatment is a key predictor of hypoglycaemia in insulin-treated Type 2 diabetes.

Prevalence of diabetic eye disease in Tayside, Scotland (P-DETS) study: methodology.

AIMS: To describe the use of a validated diabetes register for sampling frame generation and assessment of the representative nature of participants in a fieldwork study of diabetic eye disease. METHODS: We performed an observational, cross-sectional fieldwork study of diabetic retinal disease using reference standard eye examination. We sampled the entire diabetic population using the Diabetes Audit and Research in Tayside Study (DARTS) diabetes register. RESULTS: The study population comprised 4825 diabetic patients aged over 16 years registered with one of 166 general practitioners (GPs) in 41 practices in Tayside in October 1999. This represented 61.1% of the Tayside diabetic population (7903). A total of 586 (66%; 95% confidence interval 63, 70) patients were examined from a sampling frame of 882 living patients registered with a Tayside GP. Demographic and disease parameters recorded on the DARTS patient register allowed comparison between participants and non-participants. CONCLUSIONS: This study shows the clear benefit of using a complete diabetic population as a sampling frame. This allows potential selection bias and external validity to be evaluated using routine data sources. Studies performed and reported in this way will aid the critical appraisal process.

Effect of mydriasis and different field strategies on digital image screening of diabetic eye disease.

AIMS: To assess the effects of (1) mydriasis and (2) single versus three field photography on screening for diabetic eye disease using digital photography METHOD: Slit lamp examination findings were compared to digital fundal photographs for the detection of any retinopathy and for referable retinopathy in 398 patients (794 eyes). A Topcon TRC-NW6S digital non-mydriatic fundus camera was used. Three photographic strategies were used: undilated single field, dilated single field, and dilated multiple fields. The photographs were presented in random order to one of two retinal screeners. For the single field photographs the screeners were masked to the use of mydriatics. In 13% of fundal photographs, grading was performed by both, rather than just one grader. RESULTS: Mydriasis reduced the proportion of ungradable photographs from 26% to 5% (p<0.001). Neither mydriasis nor three field photography improved the sensitivity or specificity for the detection of any retinopathy or of referable retinopathy when compared with undilated single field photography. The sensitivity and specificity for detecting referable retinopathy using undilated single field photography was 77% (95% CI 71 to 84) and 95 % (95% CI 93 to 97) respectively. Using dilated single field photography the figures were 81% (95% CI 76 to 87) and 92% (95% CI 90 to 94) respectively. Using dilated three field photography the figures were 83% (95% CI 78 to 88) and 93% (95% CI 91 to 96) respectively. Intergrader reliability for the detection of referable retinopathy in gradable photographs was excellent (Kappa values 0.86-1.00). CONCLUSIONS: Mydriasis reduces the technical failure rate. Mydriasis and the three field photography as used in this study do not increase the sensitivity or specificity of detecting diabetic retinopathy.

Oviposition by small hive beetles elicits hygienic responses from Cape honeybees.

Two novel behaviours, both adaptations of small hive beetles ( Aethina tumida Murray) and Cape honeybees ( Apis mellifera capensis Esch.), are described. Beetles puncture the sides of empty cells and oviposit under the pupae in adjoining cells. However, bees detect this ruse and remove infested brood (hygienic behaviour), even under such well-disguised conditions. Indeed, bees removed 91% of treatment brood (brood cells with punctured walls caused by beetles) but only 2% of control brood (brood not exposed to beetles). Only 91% of treatment brood actually contained beetle eggs; the data therefore suggest that bees remove only that brood containing beetle eggs and leave uninfected brood alone, even if beetles have accessed (but not oviposited on) the brood. Although this unique oviposition strategy by beetles appears both elusive and adaptive, Cape honeybees are able to detect and remove virtually all of the infested brood.

Prison construction and guarding behaviour by European honeybees is dependent on inmate small hive beetle density.

Increasing small hive beetle (Aethina tumida Murray) density changes prison construction and guarding behaviour in European honeybees (Apis mellifera L.). These changes include more guard bees per imprisoned beetle and the construction of more beetle prisons at the higher beetle density. Despite this, the number of beetles per prison (inmate density) did not change. Beetles solicited food more actively at the higher density and at night. In response, guard bees increased their aggressive behaviour towards beetle prisoners but did not feed beetles more at the higher density. Only 5% of all beetles were found among the combs at the low density but this percentage increased five-fold at the higher one. Successful comb infiltration (and thus reproduction) by beetles is a possible explanation for the significant damage beetles cause to European honeybee colonies in the USA.

Does direct ophthalmoscopy improve retinal screening for diabetic eye disease by retinal photography?

AIMS: To identify whether after performing retinal photography, direct ophthalmoscopy can improve the yield of screening for the detection of sight-threatening diabetic eye disease (STDED). METHODS: Patients (n = 408) who had previously received both dilated direct ophthalmoscopy by a diabetologist and retinal photography graded by a diabetologist within 3 months of each other were included. The results of the other screening modality were not available to the grader/screener. The first 308 patients were consecutive attendees at the clinic who fulfilled the study criteria and 100 were selected because they were identified as having potential STDED by either one of these modalities. An ophthalmologist using slit lamp biomicroscopy then examined patients identified with potential STDED. RESULTS: In 357 (88%) patients there was agreement between the two modalities about whether referral to an ophthalmologist was required (kappa 0.62). Retinal photography identified 38 patients for referral to ophthalmology which ophthalmoscopy missed. Of these, the ophthalmologist agreed that STDED was present in 32 (84%) and four patients required early laser. Ophthalmoscopy identified 13 patients for referral who were not identified by photography. Of these, the ophthalmologist agreed with the diabetologist that STDED was present in seven (54%) and one patient required early laser. CONCLUSION: Ophthalmoscopy may identify the occasional patient with diabetes who has STDED which is missed by retinal photography. For a systematic retinal screening programme, adding ophthalmoscopy to retinal photography will increase false-positive referrals and is likely to detect only a few extra patients requiring laser.