Self-limiting fall armyworm: a new approach in development for sustainable crop protection and resistance management.

BACKGROUND: The fall armyworm, Spodoptera frugiperda, is a significant and widespread pest of maize, sorghum, rice, and other economically important crops. Successful management of this caterpillar pest has historically relied upon application of synthetic insecticides and through cultivation of genetically engineered crops expressing insecticidal proteins (Bt crops). Fall armyworm has, however, developed resistance to both synthetic insecticides and Bt crops, which risks undermining the benefits delivered by these important crop protection tools. Previous modelling and empirical studies have demonstrated that releases of insecticide- or Bt-susceptible insects genetically modified to express conditional female mortality can both dilute insecticide resistance and suppress pest populations. RESULTS: Here, we describe the first germline transformation of the fall armyworm and the development of a genetically engineered male-selecting self-limiting strain, OX5382G, which exhibits complete female mortality in the absence of an additive in the larval diet. Laboratory experiments showed that males of this strain are competitive against wild-type males for copulations with wild-type females, and that the OX5382G self-limiting transgene declines rapidly to extinction in closed populations following the cessation of OX5382G male releases. Population models simulating the release of OX5382G males in tandem with Bt crops and non-Bt 'refuge' crops show that OX5382G releases can suppress fall armyworm populations and delay the spread of resistance to insecticidal proteins. CONCLUSIONS: This article describes the development of self-limiting fall armyworm designed to control this pest by suppressing pest populations, and population models that demonstrate its potential as a highly effective method of managing resistance to Bt crops in pest fall armyworm populations. Our results provide early promise for a potentially valuable future addition to integrated pest management strategies for fall armyworm and other pests for which resistance to existing crop protection measures results in damage to crops and impedes sustainable agriculture.

Pest control and resistance management through release of insects carrying a male-selecting transgene.

BACKGROUND: Development and evaluation of new insect pest management tools is critical for overcoming over-reliance upon, and growing resistance to, synthetic, biological and plant-expressed insecticides. For transgenic crops expressing insecticidal proteins from the bacterium Bacillus thuringiensis ('Bt crops') emergence of resistance is slowed by maintaining a proportion of the crop as non-Bt varieties, which produce pest insects unselected for resistance. While this strategy has been largely successful, multiple cases of Bt resistance have now been reported. One new approach to pest management is the use of genetically engineered insects to suppress populations of their own species. Models suggest that released insects carrying male-selecting (MS) transgenes would be effective agents of direct, species-specific pest management by preventing survival of female progeny, and simultaneously provide an alternative insecticide resistance management strategy by introgression of susceptibility alleles into target populations. We developed a MS strain of the diamondback moth, Plutella xylostella, a serious global pest of crucifers. MS-strain larvae are reared as normal with dietary tetracycline, but, when reared without tetracycline or on host plants, only males will survive to adulthood. We used this strain in glasshouse-cages to study the effect of MS male P. xylostella releases on target pest population size and spread of Bt resistance in these populations. RESULTS: Introductions of MS-engineered P. xylostella males into wild-type populations led to rapid pest population decline, and then elimination. In separate experiments on broccoli plants, relatively low-level releases of MS males in combination with broccoli expressing Cry1Ac (Bt broccoli) suppressed population growth and delayed the spread of Bt resistance. Higher rates of MS male releases in the absence of Bt broccoli were also able to suppress P. xylostella populations, whereas either low-level MS male releases or Bt broccoli alone did not. CONCLUSIONS: These results support theoretical modeling, indicating that MS-engineered insects can provide a powerful pest population suppressing effect, and could effectively augment current Bt resistance management strategies. We conclude that, subject to field confirmation, MS insects offer an effective and versatile control option against P. xylostella and potentially other pests, and may reduce reliance on and protect insecticide-based approaches, including Bt crops.

New self-sexing Aedes aegypti strain eliminates barriers to scalable and sustainable vector control for governments and communities in dengue-prone environments.

For more than 60 years, efforts to develop mating-based mosquito control technologies have largely failed to produce solutions that are both effective and scalable, keeping them out of reach of most governments and communities in disease-impacted regions globally. High pest suppression levels in trials have yet to fully translate into broad and effective Aedes aegypti control solutions. Two primary challenges to date-the need for complex sex-sorting to prevent female releases, and cumbersome processes for rearing and releasing male adult mosquitoes-present significant barriers for existing methods. As the host range of Aedes aegypti continues to advance into new geographies due to increasing globalisation and climate change, traditional chemical-based approaches are under mounting pressure from both more stringent regulatory processes and the ongoing development of insecticide resistance. It is no exaggeration to state that new tools, which are equal parts effective and scalable, are needed now more than ever. This paper describes the development and field evaluation of a new self-sexing strain of Aedes aegypti that has been designed to combine targeted vector suppression, operational simplicity, and cost-effectiveness for use in disease-prone regions. This conditional, self-limiting trait uses the sex-determination gene doublesex linked to the tetracycline-off genetic switch to cause complete female lethality in early larval development. With no female progeny survival, sex sorting is no longer required, eliminating the need for large-scale mosquito production facilities or physical sex-separation. In deployment operations, this translates to the ability to generate multiple generations of suppression for each mosquito released, while being entirely self-limiting. To evaluate these potential benefits, a field trial was carried out in densely-populated urban, dengue-prone neighbourhoods in Brazil, wherein the strain was able to suppress wild mosquito populations by up to 96%, demonstrating the utility of this self-sexing approach for biological vector control. In doing so, it has shown that such strains offer the critical components necessary to make these tools highly accessible, and thus they harbour the potential to transition mating-based approaches to effective and sustainable vector control tools that are within reach of governments and at-risk communities who may have only limited resources.

Investigation of the Peripapillary Choriocapillaris in Normal Tension Glaucoma, Primary Open-angle Glaucoma, and Control Eyes.

PRECIS: The peripapillary choriocapillaris (CC) was observed to be significantly impaired in normal tension glaucoma (NTG) subjects compared with normal controls using optical coherence tomography angiography (OCTA). PURPOSE: The aim was to quantitatively evaluate the peripapillary CC in NTG, primary open-angle glaucoma (POAG), and control eyes using OCTA. MATERIALS AND METHODS: Ninety eyes (30 controls, 30 NTG, and 30 POAG) from 73 patients were imaged using the Zeiss Plex Elite 9000. Five repeat 3×3 mm OCTA scans were acquired both nasally and temporally to the optic disc and subsequently averaged. Four CC flow deficit (FD) measures were calculated using the fuzzy C-means approach: FD density (FDD), mean FD size (MFDS), FD number (FDN), and FD area (FDA). RESULTS: Temporal NTG CC parameters were associated with visual field index and mean deviation (P<0.05). The control group showed a significantly lower nasal FDD (nasal: 3.79±1.26%, temporal: 4.48±1.73%, P=0.03), FDN (nasal: 156.43±38.44, temporal: 178.40±45.68, P=0.02), and FDA (nasal: 0.22±0.08, temporal: 0.26±0.10, P=0.03) when compared with temporal optic disc. The NTG group showed a significantly higher FDD (NTG: 5.04±2.38%, control: 3.79±1.26%, P=0.03), FDN (NTG: 185.90±56.66, control: 156.43±38.44, P=0.04), and FDA (NTG: 0.30±0.14 mm2, control: 0.22±0.08 mm2, P=0.03) nasal to the optic disc compared with controls. CONCLUSIONS: Association between CC parameters and glaucoma severity in NTG, but not POAG subjects, suggests vascular abnormalities may be a potential factor in the multifactorial process of glaucoma damage in NTG patients.

Resurgence of ocular syphilis in British Columbia between 2013-2016: a retrospective chart review.

OBJECTIVE: To characterize the trends and explore the demographics, ophthalmic manifestations, and outcomes of ocular syphilis cases in British Columbia. DESIGN: Retrospective chart review. PARTICIPANTS: Ocular syphilis cases reported to the British Columbia Centre for Disease Control (BCCDC) between January 2013 and December 2016. METHODS: The demographic and clinical data were extracted from the BCCDC's centralized sexually transmitted infection database and the ophthalmologists' clinical charts. RESULTS: There was a steady increase in the rate of syphilis infection per 100 000 population, from 3.4 in 2010 to 18.4 in 2018. There were 39 ocular syphilis cases identified from January 2013 to December 2016. The median age was 50 years (interquartile range: 40-59.5 years); 82.1% were male and 51.3% were HIV positive. The clinical charts belonging to 32 patients were available for review, 14 of which (43.8%) presented with bilateral ocular complaints (46 affected eyes). The most commonly noted ocular presentations were uveitis (93.5%), including retinal vasculitis in 54.3%, and optic nerve involvement in 65.2% (which included papillitis, optic nerve swelling, or pallor). Panuveitis was the most frequent type of uveitis (52.2% of all eyes); 77.8% of affected eyes with best-corrected visual acuity (BCVA) ≤20/50 on presentation had an improvement of 2 or more Snellen lines of visual acuity at their final assessment. At presentation, 37.0% of eyes had BCVA ≤20/200, which decreased to 17.1% at final assessment. CONCLUSION: Ocular syphilis, although rare, is on the rise globally and can result in serious ocular sequelae. A high index of suspicion is required for proper diagnosis and treatment.

Ensemble Deep Learning for Diabetic Retinopathy Detection Using Optical Coherence Tomography Angiography.

Purpose: To evaluate the role of ensemble learning techniques with deep learning in classifying diabetic retinopathy (DR) in optical coherence tomography angiography (OCTA) images and their corresponding co-registered structural images. Methods: A total of 463 volumes from 380 eyes were acquired using the 3 × 3-mm OCTA protocol on the Zeiss Plex Elite system. Enface images of the superficial and deep capillary plexus were exported from both the optical coherence tomography and OCTA data. Component neural networks were constructed using single data-types and fine-tuned using VGG19, ResNet50, and DenseNet architectures pretrained on ImageNet weights. These networks were then ensembled using majority soft voting and stacking techniques. Results were compared with a classifier using manually engineered features. Class activation maps (CAMs) were created using the original CAM algorithm and Grad-CAM. Results: The networks trained with the VGG19 architecture outperformed the networks trained on deeper architectures. Ensemble networks constructed using the four fine-tuned VGG19 architectures achieved accuracies of 0.92 and 0.90 for the majority soft voting and stacking methods respectively. Both ensemble methods outperformed the highest single data-type network and the network trained on hand-crafted features. Grad-CAM was shown to more accurately highlight areas of disease. Conclusions: Ensemble learning increases the predictive accuracy of CNNs for classifying referable DR on OCTA datasets. Translational Relevance: Because the diagnostic accuracy of OCTA images is shown to be greater than the manually extracted features currently used in the literature, the proposed methods may be beneficial toward developing clinically valuable solutions for DR diagnoses.

Retrospective analysis of ophthalmology consults to a tertiary academic teaching centre.

OBJECTIVE: This study was conducted to analyse data from emergency ophthalmology referrals after-hours from different hospitals to identify the most common pathologies and compare accuracy of diagnoses. The primary objective was to identify common presenting entities and common causes of misdiagnosis in the emergency department to help guide education initiatives. DESIGN: This was a retrospective chart review that looked at consults occurring between September 1, 2015, and October 21, 2016. METHODS: Emergency ophthalmology consults were reviewed and the date, time, age, sex, and provisional diagnosis were recorded. Ophthalmic diagnosis was compared with provisional diagnosis to compare agreement rate. Diagnoses were categorized to determine most frequent etiologies presenting on an emergent basis. RESULTS: A total of 697 consults were reviewed. The most common consults by diagnostic category were anterior segment (36.4%) and posterior segment (27.4%) pathologies. Together, these categories accounted for over 60% of all consults. Agreement between provisional diagnosis and final ophthalmology diagnosis was 65.8%. CONCLUSIONS: There was a reasonable agreement rate between referring services diagnosis and ophthalmology diagnosis. The retrospective nature of this study and use of categories to determine agreement are potential biases and the agreement rate may not reflect clinical practice. Most common diagnoses were similar to previous studies. The authors noted several diagnostic categories that could be targeted as areas for medical education to help increase recognition in the primary care setting and facilitate appropriate ophthalmic referral.

Prospective analysis of emergency ophthalmic referrals in a Canadian tertiary teaching hospital.

OBJECTIVE: This study was conducted to analyze data from emergency ophthalmology referrals after hours from different hospitals to identify the most common pathologies and compare accuracy of diagnoses. Additionally, examination findings, including visual acuity (VA), intraocular pressure (IOP), and pupils from referring service and ophthalmic examination, were compared to assess agreement. DESIGN: This was a prospective study that reviewed information collected from referring services to the emergency on-call ophthalmology service and compared it with ophthalmic examination between February 2017 and July 2017. METHODS: The number of referrals from each hospital was reviewed. Referring physician provisional diagnosis, VA, IOP, and pupil assessment were collected to analyze the agreement between ophthalmic examination and diagnosis. RESULTS: The observed agreement rate was 67.0% between referring source and ophthalmic diagnosis. Posterior vitreous detachment (12.2%) was the most common diagnosis, followed by corneal abrasion (7.4%) and retinal detachment (5.3%). Referring services measured VA to be worse than on-call ophthalmology service (right eye Z = -5.47, p < 0.001; left eye Z = -5.44, p < 0.001), and IOP measurement by referring services was significantly higher (p < 0.05). The observed agreement rate of pupillary assessment was 91% between referring services and ophthalmology services. CONCLUSION: Data suggest that there is moderate agreement for diagnostic category between referring service and ophthalmology examination in regard to provisional diagnosis and pupillary assessment. Both VA and IOP were measured to be higher by referring services. This study highlights common emergency ophthalmic referrals and suggests potential areas for teaching initiatives for primary care physicians assessing ophthalmic emergency patients.

Exposure to genetically engineered olive fly (Bactrocera oleae) has no negative impact on three non-target organisms.

Bactrocera oleae (Diptera: Tephritidae) remains a major pest of olive fruit production worldwide. Current pest management programs largely depend on chemical insecticides, resulting in high economic and environmental costs. Alternative pest control approaches are therefore highly desirable. We have created a conditional female-specific self-limiting strain of B. oleae (OX3097D-Bol) that could be applied for sustainable pest control. OX3097D-Bol olive fly carries a fluorescent marker (DsRed2) for identification and a self-limiting genetic trait that is repressed by tetracycline. In the absence of tetracycline, the tetracycline transactivator (tTAV) accumulates, resulting in female death at larvae and early pupal stages. The aim of this study was to evaluate the impact of genetically engineered OX3097D-Bol olive fly on three non-target organisms that either predate or parasitize olive flies, one from the guild of parasitoids (Psyttalia concolor) and two from the guild of predators (Pardosa spider species and the rove beetle Aleochara bilineata). No significant negative effect was observed on life history parameters, mortality and reproductive capacity of the non-target organisms studied. These results suggest that potential exposure to DsRed2 and tTAV gene products (e.g. mRNA and encoded proteins) would have a negligible impact on on-target organisms in the guilds or predators and parasitoids.

Correlation of novel PAX6 gene abnormalities in aniridia and clinical presentation.

OBJECTIVE: To describe the clinical presentation and genotype of subjects with aniridia with a particular focus on foveal hypoplasia. DESIGN: Prospective cohort study. PARTICIPANTS: Thirty-three Canadian participants with aniridia and of various ethnic backgrounds residing in British Columbia. METHODS: Full ophthalmic examinations and posterior segment spectral domain-optical coherence tomography (SD-OCT) imaging were performed. Foveal hypoplasia was graded independently by 2 staff ophthalmologists. PAX6 sequencing was performed and chromosomal 11p anomalies investigated. Candidate gene and single-nucleotide polymorphism sequencing in genes functionally related to PAX6 were also studied. RESULTS: Best corrected visual acuities in the cohort ranged from 0.0 logMAR to no light perception. Total absence of iris tissue was seen in the majority (42 of 66 eyes). In those in whom SD-OCT was possible, foveal hypoplasia was seen in the majority (45 of 56 eyes, 80%). Molecular genetic defects involving PAX6 were identified in 30 participants (91%), including 4 novel PAX6 mutations (Gly18Val; Ser65ProfsX14; Met337ArgfsX18; Ser321CysfsX34) and 4 novel chromosome 11p deletions inclusive of PAX6 or a known PAX6 regulatory region. CONCLUSIONS: The number of PAX6 mutations associated with aniridia continues to increase. Variable foveal architecture despite nearly identical anterior segment disease in 4 participants with an Ex9 ELP4-Ex4 DCDC1 deletion suggested that molecular cues causing variation in disease in the posterior segment differ from those at play in the anterior segment. Results in 3 patients without identifiable PAX6 mutations and a review of the literature suggest that such cases be described as phenocopies rather than actual cases of the syndrome of aniridia.

Acute Macular Neuroretinopathy Associated With Chikungunya Fever.

A 47-year-old man with recent travel to the Caribbean was admitted with acute febrileillness associated with arthralgia and skin rash followed by sudden onset of bilateral visual field defects. Funduscopy revealed subtle bilateral paracentral dark lesions nasal to the fovea best seen on near infrared imaging as hyporeflective, wedge-shaped, paracentral macular lesions. Spectral-domain optical coherence tomography (SD-OCT) through the lesions revealed hyperreflective bands at the level of the outer plexiform layer and outer nuclear layer (ONL), with concomitant attenuation of the underlying external limiting membrane (ELM), ellipsoid zone (EZ), and interdigitation zone (IZ). Neither fluorescein angiography nor speckle variance OCT angiography (sv-OCTA) showed any defects in retinal circulation. Work up revealed positive Immunoglobulin M for Chikungunya virus (CHIKV). Six months later, the patient had persistent scotomas, although reduced in size. SD-OCT showed subtle ONL thinning and restoration of the ELM, although EZ and IZ remained disrupted. Chikungunya fever may manifest as bilateral acute macular neuroretinopathy (AMN). Clinicians should be aware of possible systemic associations of AMN. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:596-599.].

Correlation in Severity Between Glaucoma and Erectile Dysfunction.

PURPOSE: To examine the association between open-angle glaucoma and erectile dysfunction (ED), and investigate the correlation in severity between these 2 conditions. METHODS: Cross-sectional study with patient questionnaire and retrospective chart review. A total of 167 male patients over 40 years of age who attended ophthalmology clinic visits in Vancouver, British Columbia, Canada, participated in the study by providing written consent and responding to the survey. Patients with previous radiation or surgical prostate treatment were excluded, leaving final sample sizes of 61 glaucoma patients and 67 control patients. Presence and severity of ED was determined using a validated patient questionnaire (the International Index of Erectile Function questionnaire). Presence of glaucoma was based on previous clinical diagnosis, and severity was graded based on visual field index using a 30-2 visual field test with the SITA Standard protocol. Bivariate analysis examined the presence of ED in glaucoma patients versus controls. Risk factors including dyslipidemia, diabetes, hypertension, and smoking were adjusted for using multiple logistic regression. The association between glaucoma and ED severity was assessed with correlation and scatterplot analysis. RESULTS: Glaucoma was found to be a significant risk factor for ED in our population, with an odds ratio of 2.58 (95% confidence interval, 1.15-5.83). Severity of glaucoma and ED were significantly correlated (r=0.365, P=0.007). CONCLUSIONS: Our results demonstrate that there is a positive association between the presence of ED and the diagnosis of glaucoma and a positive association between the severity of ED and the severity of glaucoma.

Assessment of the Impact of Potential Tetracycline Exposure on the Phenotype of Aedes aegypti OX513A: Implications for Field Use.

BACKGROUND: Aedes aegypti is the primary vector of dengue fever, a viral disease which has an estimated incidence of 390 million infections annually. Conventional vector control methods have been unable to curb the transmission of the disease. We have previously reported a novel method of vector control using a tetracycline repressible self-limiting strain of Ae. aegypti OX513A which has achieved >90% suppression of wild populations. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the impact of tetracycline and its analogues on the phenotype of OX513A from the perspective of possible routes and levels of environmental exposure. We determined the minimum concentration of tetracycline and its analogues that will allow an increased survivorship and found these to be greater than the maximum concentration of tetracyclines found in known Ae. aegypti breeding sites and their surrounding areas. Furthermore, we determined that OX513A parents fed tetracycline are unable to pre-load their progeny with sufficient antidote to increase their survivorship. Finally, we studied the changes in concentration of tetracycline in the mass production rearing water of OX513A and the developing insect. CONCLUSION/SIGNIFICANCE: Together, these studies demonstrate that potential routes of exposure of OX513A individuals to tetracycline and its analogues in the environment are not expected to increase the survivorship of OX513A.

Does an association exist between pseudoexfoliation syndrome and chronic kidney disease?

PURPOSE: To determine whether pseudoexfoliation (PEX) syndrome is associated with an increased risk of chronic kidney disease (CKD). PATIENTS AND METHODS: In this cross-sectional study, 271 consecutive patients were recruited into 3 study groups---PEX syndrome (n=86), primary open-angle glaucoma (POAG) (n=91), and nonglaucoma controls (n=94)---and underwent serum creatinine testing to determine their glomerular filtration rates (eGFR). Repeat eGFR and testing for urine albumin:creatinine ratio were performed a minimum of 3 months later if the initial eGFR was less than 60 mL/min/1.73 m. CKD was diagnosed if both eGFR levels were less than 45 mL/min/1.73 m or both eGFR levels were less than 60 mL/min/1.73 m and the urine albumin:creatinine ratio was greater than 2.0. The main outcome measure was the rate of CKD for each group. RESULTS: The CKD rate for the control group (11.7%, 11 of 94) was statistically higher than the PEX (3.5%, 3 of 86, P=0.050) and the POAG (3.3%, 3 of 91, P=0.049) groups. However, there was a significantly higher rate of diabetes mellitus, a known risk factor for CKD, in the control group than the PEX and POAG groups. After adjusting for the differences in the rate of diabetes mellitus and mean age (another risk factor for CKD) between groups, a multivariate logistic regression analysis showed that none of the study groups was a predictor of an increased rate of CKD. A post-hoc analysis performed with all patients with diabetes mellitus removed also showed no statistical difference between groups for CKD rates and mean eGFR levels. CONCLUSIONS: Compared with age-matched patients with POAG and nonglaucoma controls, PEX syndrome was not found to be associated with an increased prevalence of CKD.

Helicobacter pylori infection and the risk for open-angle glaucoma.

PURPOSE: To determine the frequency of exposure to Helicobacter pylori infection in glaucoma patients. DESIGN: Prospective case-control study. PARTICIPANTS: Ninety-seven consecutive patients attending a glaucoma clinic. These included 38 patients with primary open-angle glaucoma (POAG), 19 with normal pressure glaucoma (NPG), 16 with pseudoexfoliation glaucoma (PXE), and 24 with ocular hypertension (OHT). Ninety-four age-matched participants without glaucoma served as a control population. METHODS: Serum was analyzed for the presence of H. pylori-specific immunoglobulin G antibodies by enzyme-linked immunosorbent assay. MAIN OUTCOME MEASURES: Serologic analysis for H. pylori. RESULTS: Seropositivity for H. pylori was higher in patients with glaucoma (26.0%) than in controls (20.2%), but this did not achieve statistical significance (P = 0.46). A total of 26.3% of POAG patients, 26.3% of NPG patients, 25.0% of PXE patients, and 25.0% of OHT patients were seropositive. CONCLUSIONS: This study suggests that exposure to H. pylori infection is not associated with open-angle glaucoma.