Rice physical defenses and their role against insect herbivores.

MAIN CONCLUSION: Understanding surface defenses, a relatively unexplored area in rice can provide valuable insight into constitutive and induced defenses against herbivores. Plants have evolved a multi-layered defense system against the wide range of pests that constantly attack them. Physical defenses comprised of trichomes, wax, silica, callose, and lignin, and are considered as the first line of defense against herbivory that can directly affect herbivores by restricting or deterring them. Most studies on physical defenses against insect herbivores have been focused on dicots compared to monocots, although monocots include one of the most important crops, rice, which half of the global population is dependent on as their staple food. In rice, Silica is an important element stimulating plant growth, although Silica has also been found to impart resistance against herbivores. However, other physical defenses in rice including wax, trichomes, callose, and lignin are less explored. A detailed exploration of the morphological structures and functional consequences of physical defense structures in rice can assist in incorporating these resistance traits in plant breeding and genetic improvement programs, and thereby potentially reduce the use of chemicals in the field. This mini review addresses these points with a closer look at current literature and prospects on rice physical defenses.

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%.

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.

National audit of antidote stocking in acute hospitals in the UK.

BACKGROUND: Inadequate stocking of essential antidotes in hospitals for the treatment of poisoned patients has been reported worldwide. Joint National Poisons Information Service (NPIS)/College of Emergency Medicine (CEM) guidelines for antidote stocking in UK emergency departments and acute hospitals were published in 2008. AIM: To determine the impact of these guidelines by surveying the availability of antidotes in acute hospitals in the UK. METHODS: A two-page questionnaire consisting of antidote stocking information was distributed in 2010 to the Chief Pharmacist in all acute hospitals in the UK. The availability of 28 antidotes in the NPIS/CEM antidote guidelines as well as that of Intralipid was surveyed. RESULTS: Surveys were completed for 196 of the 224 (87.5%) hospitals. Over 90% of hospitals had acetylcysteine, activated charcoal, dantrolene, desferrioxamine, naloxone, flumazenil and vitamin K available within the recommended time period. Pralidoxime was reported to be held in only 33% of hospitals, though pralidoxime is supplied by the Department of Health to 95 hospitals in the UK that act as holding centres. Cyproheptadine and viper venom antiserum were held in around 50% of acute hospitals. For the treatment of cyanide and toxic alcohol poisoning, more than one antidote is available. For cyanide poisoning, most hospitals held at least one antidote (usually dicobalt edetate) but 9 (5%) held none of the four antidotes. For toxic alcohol and glycol poisoning, most hospitals held ethanol for intravenous use but not fomepizole and 30 (15%) did not stock any antidote for toxic alcohol poisoning. CONCLUSION: Stocking of less commonly used antidotes is inconsistent. This is likely to result in delayed access to treatment and worse patient outcomes.

A pilot study to evaluate a community pharmacy-based monitoring system to identify adverse drug reactions associated with paediatric medicines use.

INTRODUCTION: Current pharmacovigilance systems are limited by spontaneous reporting of adverse drug reactions (ADRs), lack of a denominator, and lower than expected reporting rates. The aim of our study was to undertake a formal pilot evaluation of a community pharmacy-led ADR monitoring system. METHODS: The setting was community pharmacies in five Health Boards areas of Scotland. Subjects were parents, guardians, or children presenting prescriptions for children 16 years and under prescribed serotonin specific reuptake inhibitors (SSRI), anticonvulsants, or medicines for the treatment of attention deficit hyperactivity disorder (ADHD). All pharmacies (n = 827) were invited to participate. Over a 3-month period they were asked to identify prescriptions for targeted medicines and give out an ADR questionnaire. Questionnaire content included child demography, duration of medicine use, indication, perceived ADRs, and their description and severity. The study was approved by the North of Scotland Research Ethics Committee. RESULTS: Seventy-two community pharmacists (8.7%) agreed to take part. Two hundred and twenty-nine questionnaires were distributed and 55 (24%) completed and returned by parents. Forty-one questionnaires related to ADHD medications, 13 to anticonvulsants, and 1 to an SSRI. Thirty questionnaires reported 44 possible ADRs, 19 of which were related to methylphenidate. CONCLUSIONS: The proposed ADR monitoring system identified expected ADRs thus demonstrating face and content validity for our approach. However the process was limited by low community pharmacist participation rates and low questionnaire return rates.