Potential exposure of honey bees to neonicotinoid seed treatments in US rice.

Neonicotinoid insecticide seed treatments are commonly used in rice (Oryza sativa) production to control rice water weevil (Lisorhoptrus oryzophilus). With the use of neonicotinoid seed treatments, there is potential that honey bees (Apis mellifera) could be exposed to neonicotinoids through translocation to the pollen. Studies were conducted in 2015 and 2016 to determine the level of neonicotinoids present in flag leaves, pollen, and grain of rice. Thiamethoxam was applied as a seed treatment and foliar prior to flooding. Clothianidin was applied as a seed treatment and as a foliar at a preflood and postflood timing. Subsamples of flag leaves, pollen, and grain were analyzed for positive neonicotinoid detections and abundance. Thiamethoxam was detected in 8.9% of samples and clothianidin was detected in 1.4% of samples. For both thiamethoxam and clothianidin, more positive samples were observed in flag leaf samples than in pollen or grain. An average of 4.30 ng/g of thiamethoxam was detected in flag leaves from seed-applied thiamethoxam. An average of 1.25 ng/g of clothianidin was found in flag leaves from a preflood application of clothianidin. A survey of honey bees present in rice fields was conducted in Mississippi and Arkansas to determine the abundance of honey bees present in rice fields based on the time of day. Honey bee densities were low in rice, with less than 5% and 3% positive detections observed in Mississippi and Arkansas, respectively. More positive detections and higher densities of honey bees were observed for mid-day sampling than for morning or evening sampling.

Herbicide spray drift from ground and aerial applications: Implications for potential pollinator foraging sources.

A field spray drift experiment using florpyrauxifen-benzyl was conducted to measure drift from commercial ground and aerial applications, evaluate soybean [Glycine max (L.) Merr.] impacts, and compare to United States Environmental Protection Agency (US EPA) drift models. Collected field data were consistent with US EPA model predictions. Generally, with both systems applying a Coarse spray in a 13-kph average wind speed, the aerial application had a 5.0- to 8.6-fold increase in drift compared to the ground application, and subsequently, a 1.7- to 3.6-fold increase in downwind soybean injury. Soybean reproductive structures were severely reduced following herbicide exposure, potentially negatively impacting pollinator foraging sources. Approximately a 25% reduction of reproductive structures up to 30.5-m downwind and nearly a 100% reduction at 61-m downwind were observed for ground and aerial applications, respectively. Aerial applications would require three to five swath width adjustments upwind to reduce drift potential similar to ground applications.

Standardized Field Trials in Cotton and Bioassays to Evaluate Resistance of Tobacco Thrips (Thysanoptera: Thripidae) to Insecticides in the Southern United States.

Foliar-applied insecticide treatments may be necessary to manage thrips in cotton (Gossypium hirsutum L.) under severe infestations or when at-planting insecticide seed treatments do not provide satisfactory protection. The most common foliar-applied insecticide is acephate. Field observations in Tennessee suggest that the performance of acephate has declined. Thus, the first objective was to perform leaf-dip bioassays to assess if tobacco thrips, Frankliniella fusca (Hinds) (Thysanoptera: Thripidae), in cotton production regions have evolved resistance to foliar-applied insecticides. A second objective was to assess the performance of commonly applied foliar insecticides for managing thrips in standardized field trials in Arkansas, Tennessee, Mississippi, and Texas. For both objectives, several insecticides were evaluated including acephate, dicrotophos, dimethoate, lambda-cyhalothrin, imidacloprid, and spinetoram. Field trials and bioassays were completed from 2018 to 2021. Dose-response bioassays with acephate were performed on tobacco thrips field populations and a susceptible laboratory population. Bioassay results suggest that tobacco thrips have developed resistance to acephate and other organophosphate insecticides; however, this resistance seems to be most severe in Arkansas, Tennessee, and the Delta region of Mississippi. Resistance to other classes of insecticides were perhaps even more evident in these bioassays. The performance of these insecticides in field trials was variable, with tobacco thrips only showing consistent signs of resistance to lambda-cyhalothrin. However, it is evident that many populations of tobacco thrips are resistant to multiple classes of insecticides. Further research is needed to determine heritability and resistance mechanism(s).

Efficacy of Helicoverpa Armigera Nucleopolyhedrovirus on Soybean for Control of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in Arkansas Agriculture.

Helicoverpa armigera nucleopolyhedrovirus (HearNPV) is a naturally occurring virus commercially produced for control of Heliothines, including Helicoverpa zea. One drawback with using this virus for control has been the slower time to mortality compared with synthetic insecticides. However, a new formulation (Heligen®) has anecdotally been thought to result in quicker mortality than previously observed. The objective of this study was to evaluate percent defoliation, the efficacy of HearNPV on mortality for each H. zea larval instar, and the potential for control of a second infestation. Fourteen days after the first infestation, all plants were re-infested with a second instar larva to simulate a second infestation. Helicoverpa armigera nucleopolyhedrovirus was effective at killing 1st-3rd instars, resulting in 99% mortality over 4-6 days. However, 4th and 5th instar mortality only reached 35%. Second infestation larvae died between 3.4 and 3.8 days, significantly faster than the 1st infestation of 2nd instars, which had a mean time to mortality of 4.9 days. An increase in mortality rate is probably due to increasing viral concentrations after viral replication within the first hosts. Final defoliation percentages were significantly smaller in the treated plants versus the untreated plants. Only 3rd and 4th instar larvae caused percent defoliation to exceed the current Arkansas action threshold of 40%. Helicoverpa armigera nucleopolyhedrovirus in the Heligen formulation can control 1st-3rd instars within 4-6 days, while keeping defoliation below the action threshold of 40%.

Effects of Soybean Planting Date on Yield Loss From Defoliation.

Soybean, Glycine max (L.) Merr., is planted during 3.5-4 mo across the Mid-South United States. Currently, no information exists regarding the effects of planting date on soybean yield loss from early season defoliation. In 2015 and 2016, to evaluate the effects of planting date on yield loss from defoliation, soybean were planted in field plots 2 wk apart from early April to mid-June, for a total of six planting dates. Each planting date included a nondefoliated control and a 100% defoliation treatment where leaves were manually excised at the V4 growth stage. Mean yield loss from defoliation varied across planting dates, with mid-April plantings having the least amount yield reduction, 573 kg/ha, and early-June plantings having the greatest yield reduction, 904 kg/ha. Percent yield reduction from defoliation increased as planting was delayed, suggesting that defoliation thresholds might need adjustment based on planting date and yield potential. However, more research is needed at lower levels of defoliation to accurately delineate such thresholds.

Clerkships in Emergency Medicine.

Planning for clerkships in emergency medicine (EM) can be stressful, prolonged, and challenging. Therefore, medical students should start planning for them early. In this article, we offer guidance regarding several issues pertinent to the EM clerkship, such as the best time to schedule one (or more) during medical school, the most appropriate institution or program to schedule it, the process of selecting and applying for the clerkship, and the number of EM clerkships to consider. We will explain why an EM clerkship should be scheduled between June and October and the reason that 2 EM clerkships at different sites are sufficient for the majority of students. Additionally, we emphasize that clerkships in emergency departments associated with EM residency programs or with reputations for outstanding student teaching tend to be most beneficial. Above all, students interested in EM should attempt to leave a great impression after completing their clerkships by providing stellar patient care, demonstrating enthusiasm at all times, and maintaining professionalism. In turn, they will gain knowledge and clinical experiences that should prove valuable in their future.

Impact of Planting Date on Melanaphis sacchari (Hemiptera: Aphididae) Population Dynamics and Grain Sorghum Yield.

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), has become a major pest of grain sorghum, Sorghum bicolor (L.) Moench, in the United States in recent years. Feeding by large densities of sugarcane aphids causes severe damage, which can lead to a total loss of yield in extreme cases. Our objective was to determine the effect of grain sorghum planting date on sugarcane aphid population dynamics and their potential to reduce yields. We conducted field experiments from 2015 to 2017 in which an aphid-susceptible grain sorghum hybrid was planted at four different dates, which encompassed the typical range of planting dates used in Arkansas production systems. Plots were either protected from sugarcane aphid feeding using foliar insecticide sprays, or left untreated to allow natural populations of sugarcane aphids to colonize and reproduce freely. Planting date impacted both the magnitude and severity of sugarcane aphid infestations, with the highest population densities (and subsequent reductions in sorghum yield) generally occurring on plots that were planted in May or June. Sugarcane aphid feeding reduced yields in the untreated plots in two of the four planting date categories we tested. Earlier planting generally resulted in less sugarcane aphid damage and improved yields compared with later planting dates. While the effect of planting date on sugarcane aphid populations is likely to vary by region, sorghum producers should consider grain sorghum planting date as a potential cultural tactic to reduce the impact of sugarcane aphid.

Letters of Recommendation.

Letters of recommendation (LORs) are a central element of an applicant's portfolio for the National Resident Matching Program (known as the "Match"). This is especially true when applying to competitive specialties like emergency medicine (EM). LORs convey an applicant's potential for success, and also highlight an applicant's qualities that cannot always be recognized from a curriculum vitae, test scores, or grades. Traditional LORs, also called narrative LORs, are written in prose and are therefore highly subjective. This led to the establishment of a task force by the Council of Emergency Medicine Residency Directors in 1995 to develop a standardized LOR. Revisions of this form are now referred to as a standardized letter of evaluation. These evaluations in this format have proven to increase inter-rater reliability, decrease interpretation time, and standardize the process used by EM faculty to prepare evaluations for EM applicants. In this article, we will discuss LORs; address applicants' concerns, including from whom to request LORs (EM faculty vs. non-EM faculty vs. non-clinical faculty), number of LORs an applicant should include in his or her application materials, the preferred manner of requesting and the timing in which to ask for an LOR, as well as the philosophy behind waiving the right to see the letter.

Influence of Sweep Length on Rice Stink Bug (Hemiptera: Pentatomidae) Capture and Reliability of Population Density Estimates.

The rice stink bug, Oebalus pugnax (F.), is a key pest of heading rice, Oryza sativa L. (Poales: Poaceae), in the southern United States. Sweep net sampling is the recommended method for sampling rice stink bug in rice, but there currently exists no specific recommendation for sweep length, and a large amount of variation likely exists amongst samplers. The objectives of this study were to determine the role that sweep length plays in sampling accuracy and determine the feasibility of using sweep lengths smaller than 180°. When monitoring sweep lengths by consultants, producers, and researchers, a large amount of variation in sweep length and a significant linear relationship between sweep length and rice stink bug catch per 10 sweeps was observed. Sweep length was then controlled at three levels (0.8, 1.8, and 3.5 m) and a change from 0.8 to 1.8 m in sweep length led to an increase on average of 2.28 rice stink bugs per 10 sweeps. These data suggest knowledge of sweep length is vital, and paired with large amounts of observed variation in sweep length, recommending a specific sweep length is ideal. Using Taylor's values, it was determined that 1.8 m sweeps resulted in density estimates that were as reliable as 3.5 m (180°) sweeps, suggesting a longer sweep length was not necessary. A 1.8 m sweep length recommendation would create an easier sampling regimen that is still reliable, which could lead to more accurate action threshold decisions being made for rice stink bug if it increases adoption in consultants and producers.

Field Studies on the Horizontal Transmission Potential by Voluntary and Involuntary Carriers of Helicoverpa armigera nucleopolyhedrovirus (Baculoviridae).

Horizontal transmission of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) has been found to occur through several pathways involving abiotic factors such as soil, wind, and rain, and biotic factors such as predators, parasitoids, and infected hosts. Previous studies examining horizontal transmission through certain biological carriers speculated they were likely not significant in increasing infection rates, however; these studies only focused on a relatively small number of arthropods present within a field setting. This study was conducted to evaluate the horizontal transmission potential of HearNPV by all potential biological carriers when applied as a foliar bioinsecticide or as virus-infected, nonmotile Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) larvae in a soybean field. Soybean plots were either sprayed with HearNPV or infested with late-stage HearNPV-infected larvae, and sample zones were sampled 3, 7, 10, 14, 17, and 21 days after the infestation, and analyzed for viral presence using PCR. We then identified HearNPV carriers through contamination from the application (involuntary) or through contact with a HearNPV-infected larva (voluntary). Both were confirmed through PCR analysis. Regardless of application technique, on average, HearNPV was capable of disseminating up to 61.0 m in 3 d after inoculation and was found within the sampled canopy 13-21 d after inoculation. Several arthropods were identified as novel carriers of HearNPV. Results from this study indicate that many novel HearNPV carriers are likely important in disseminating HearNPV.

Sublethal Effects of Imidacloprid on Honey Bee Colony Growth and Activity at Three Sites in the U.S.

Imidacloprid is a neonicotinoid pesticide heavily used by the agricultural industry and shown to have negative impacts on honey bees above certain concentrations. We evaluated the effects of different imidacloprid concentrations in sugar syrup using cage and field studies, and across different environments. Honey bee colonies fed sublethal concentrations of imidicloprid (0, 5, 20 and 100 ppb) over 6 weeks in field trials at a desert site (Arizona), a site near intensive agriculture (Arkansas) and a site with little nearby agriculture but abundant natural forage (Mississippi) were monitored with respect to colony metrics, such as adult bee and brood population sizes, as well as pesticide residues. Hive weight and internal hive temperature were monitored continuously over two trials in Arizona. Colonies fed 100 ppb imidacloprid in Arizona had significantly lower adult bee populations, brood surface areas and average frame weights, and reduced temperature control, compared to colonies in one or more of the other treatment groups, and consumption rates of those colonies were lower compared to other colonies in Arizona and Arkansas, although no differences in capped brood or average frame weight were observed among treatments in Arkansas. At the Mississippi site, also rich in alternative forage, colonies fed 5 ppb imidacloprid had less capped brood than control colonies, but contamination of control colonies was detected. In contrast, significantly higher daily hive weight variability among colonies fed 5 ppb imidacloprid in Arizona suggested greater foraging activity during a nectar flow post treatment, than any other treatment group. Imidacloprid concentrations in stored honey corresponded well with the respective syrup concentrations fed to the colonies and remained stable within the hive for at least 7 months after the end of treatment.

Blood pressure variability in controlled and uncontrolled blood pressure and its association with left ventricular hypertrophy and diastolic function.

High systolic blood pressure (SBP) variability has been associated with higher risk for target-organ damage. In a cross-sectional study done in a tertiary outpatient hypertension clinic, we compared short-term SBP variability among controlled and uncontrolled hypertensive patients and evaluated the association between higher levels of SBP variability and diastolic function and left ventricular hypertrophy (LVH). Patients were evaluated by 24-h ambulatory blood pressure monitoring and transthoracic Doppler echocardiogram. Blood pressure (BP) variability was evaluated by the time-rate index and high variability corresponded to index values in the top quartile of distribution. Echocardiographic parameters were compared in patients with and without higher BP variability within controlled and uncontrolled office BP (⩽140/90 mm Hg). The analyses included 447 patients with 58±12 years of age, 67% were women, 68% white, 43% current or previous smokers and 32% with diabetes mellitus. Among the whole sample, 137 patients had controlled and 310 uncontrolled BP. The 75th percentile cutoff points for the time-rate index were 0.502 mm Hg min(-1) and 0.576 mm Hg min(-1) for participants with controlled and uncontrolled BP, respectively. After adjustment for confounders, the time-rate index did not differ between controlled and uncontrolled patients. BP variability was not associated with LVH or diastolic function in controlled and uncontrolled BP after adjustment for 24-h SBP and age. Patients with controlled and uncontrolled BP had similar SBP variability assessed by time-rate index, which was not associated with LVH or diastolic function. These findings should be confirmed in studies with larger sample size.

Potential exposure of pollinators to neonicotinoid insecticides from the use of insecticide seed treatments in the mid-southern United States.

Research was done during 2012 to evaluate the potential exposure of pollinators to neonicotinoid insecticides used as seed treatments on corn, cotton, and soybean. Samples were collected from small plot evaluations of seed treatments and from commercial fields in agricultural production areas in Arkansas, Mississippi, and Tennessee. In total, 560 samples were analyzed for concentrations of clothianidin, imidacloprid, thiamethoxam, and their metabolites. These included pollen from corn and cotton, nectar from cotton, flowers from soybean, honey bees, Apis mellifera L., and pollen carried by foragers returning to hives, preplanting and in-season soil samples, and wild flowers adjacent to recently planted fields. Neonicotinoid insecticides were detected at a level of 1 ng/g or above in 23% of wild flower samples around recently planted fields, with an average detection level of about 10 ng/g. We detected neonicotinoid insecticides in the soil of production fields prior to planting at an average concentration of about 10 ng/g, and over 80% of the samples having some insecticide present. Only 5% of foraging honey bees tested positive for the presence of neonicotinoid insecticides, and there was only one trace detection (< 1 ng/g) in pollen being carried by those bees. Soybean flowers, cotton pollen, and cotton nectar contained little or no neonicotinoids resulting from insecticide seed treatments. Average levels of neonicotinoid insecticides in corn pollen ranged from less than 1 to 6 ng/g. The highest neonicotinoid concentrations were found in soil collected during early flowering from insecticide seed treatment trials. However, these levels were generally not well correlated with neonicotinoid concentrations in flowers, pollen, or nectar. Concentrations in flowering structures were well below defined levels of concern thought to cause acute mortality in honey bees. The potential implications of our findings are discussed.

Blood pressure-lowering effect of simvastatin: a placebo-controlled randomized clinical trial with 24-h ambulatory blood pressure monitoring.

Part of the efficacy of statins in the prevention of cardiovascular events can be attributed to their blood pressure-lowering effect, but clinical trials primarily designed to investigate this effect are scarce. In a double-blind parallel placebo-controlled clinical trial with ambulatory blood pressure (ABP) monitoring, 79 hypertensive patients were randomly assigned to 40 mg of simvastatin (n=40) or placebo (n=39) taken in the morning for 2 months. Between-group deltas of ABP change, adjusted for the corresponding baseline BP, were 2.8 mm Hg (95% CI: 0.4-5.1; P=0.02) for 24-h diastolic blood pressure (DBP), 4.2 mm Hg (95% CI: 0.1-8.4; P=0.04) for daytime systolic BP and 3.1 mm Hg (95% CI: 0.4-5.9; P=0.02) for daytime DBP. There was no effect on nighttime BP. There was an interaction between baseline cholesterol levels and treatment effect, which was restricted to patients with cholesterol above the median of the whole sample. There was no significant change in office BP. In conclusion, simvastatin lowers ABP in patients with hypertension, particularly in the presence of higher levels of cholesterol. This effect may contribute to the beneficial effects of statins in the prevention of cardiovascular disease.

Perception of uncontrolled blood pressure and non-adherence to anti-hypertensive agents in diabetic hypertensive patients.

We assessed the association between adherence to antihypertensive drug treatment and patient's perception of uncontrolled blood pressure (BP) in diabetic hypertensive subjects. This was a cross-sectional study that evaluated adherence to antihypertensives (Morisky questionnaire), patients' perception of abnormal BP, office BP, and ambulatory BP monitoring in diabetic hypertensive subjects. We evaluated 323 patients, 65.2% women, aged 56.5 ± 7 years, glycosylated hemoglobin (HbA1c) 8.0% (range, 6.9%-9.6%), diabetes duration of 10 years (range, 5-17 years). Adherence to drug treatment was 51.4%. Patients who reported hypertension-related symptoms (60.4%) had a lower level of adherence (P < .001). Non-adherence occurred four times more frequently in patients who reported hypertension-related symptoms (P < .001, adjusted for use of three or more anti-hypertensives, age, and duration of diabetes). Non-adherents had higher office diastolic BP (83.6 ± 11.9 vs. 79.8 ± 9.9; P = .003), but no difference between groups was observed considering systolic, diastolic, and mean BP evaluated by ambulatory BP monitoring. Low rates of adherence to antihypertensive drug treatment were observed in outpatient hypertensive diabetic subjects. Perception of uncontrolled BP levels was strongly and independently associated with non-adherence. Non-adherence determined repercussion on office BP that may have clinical implications in cardiovascular risk.