A standardised bioassay method using a bench‐top spray tower to evaluate entomopathogenic fungi for control of the greenhouse whitefly, Trialeurodes vaporariorum

BACKGROUND: Bioassays evaluating entomopathogenic fungi (EPF) isolates for effective microbial control of whitefly are a fundamental part of the screening process for bioprotectants, but development of repeatable, robust bioassays is not straightforward. Currently, there is no readily available standardised method to test the efficacy of EPF on whitefly. Here, we describe the calibration and use of a spray tower to deliver a standardised protocol to assess EPF activity; the method was validated using 18 EPF from four genera in tests against greenhouse whitefly, Trialeurodes vaporariorum (Westwood). RESULTS: At 138 kPa, the sprayer delivered 0.062 mL mm−2 (620 L ha−1) and an even deposition of spray across the central 1590 mm2 of the spray area. Average conidial deposition for all EPF was 252 conidia mm−2 and equivalent to 2.5 × 1012 conidia ha−1 at an application concentration of 1 × 107 conidia mL−1. Conidial deposition of a test Beauveria bassiana suspension increased with increasing application concentration. Egg laying by T. vaporariorum adults was restricted to 177 mm2 using clip cages specifically designed to ensure that third‐instar T. vaporariorum received a uniform spray coverage. Nymphs occupied 373 ± 5 mm2 of the leaf after migrating during the first instar. Average T. vaporariorum mortality totaled 8–89% 14 days after application of 1 × 107 conidia mL−1 of each EPF isolate. CONCLUSION: Combining the calibrated sprayer and bioassay method provides a reliable, standardised approach to test the virulence of EPF against whitefly nymphs. This laboratory‐based assay is affordable, replicable and allows the user to alter the dose of conidia applied to the target

TLR7-mediated skin inflammation remotely triggers chemokine expression and leukocyte accumulation in the brain

Background: The relationship between the brain and the immune system has become increasingly topical as, although it is immune-specialised, the CNS is not free from the influences of the immune system. Recent data indicate that peripheral immune stimulation can significantly affect the CNS. But the mechanisms underpinning this relationship remain unclear. The standard approach to understanding this relationship has relied on systemic immune activation using bacterial components, finding that immune mediators, such as cytokines, can have a significant effect on brain function and behaviour. More rarely have studies used disease models that are representative of human disorders. Methods: Here we use a well-characterised animal model of psoriasis-like skin inflammation—imiquimod—to investigate the effects of tissue-specific peripheral inflammation on the brain. We used full genome array, flow cytometry analysis of immune cell infiltration, doublecortin staining for neural precursor cells and a behavioural read-out exploiting natural burrowing behaviour. Results: We found that a number of genes are upregulated in the brain following treatment, amongst which is a subset of inflammatory chemokines (CCL3, CCL5, CCL9, CXCL10, CXCL13, CXCL16 and CCR5). Strikingly, this model induced the infiltration of a number of immune cell subsets into the brain parenchyma, including T cells, NK cells and myeloid cells, along with a reduction in neurogenesis and a suppression of burrowing activity. Conclusions: These findings demonstrate that cutaneous, peripheral immune stimulation is associated with significant leukocyte infiltration into the brain and suggest that chemokines may be amongst the key mediators driving this response

Efficacy of reduced rates of chlorantraniliprole seed treatment on insect pests of irrigated drill‐seeded rice

© 2019 Society of Chemical Industry Background: For the past decade, insecticidal seed treatment has been the most widely used control tactic against insect pests of rice (Oryza sativa L.) in the USA. Seed treatments are used primarily to control the most economically important early-season pest of rice, the rice water weevil (Lissorhoptrus oryzophilus Kuschel). This study was conducted to evaluate the efficacy of reduced rates of chlorantraniliprole seed treatment against the rice water weevil, fall armyworm (Spodoptera frugiperda J.E. Smith), and sugarcane borer (Diatraea saccharalis F.) under field and laboratory conditions. Concentrations of chlorantraniliprole in plant tissues were determined at vegetative and reproductive developmental stages of rice plants. Results: Chlorantraniliprole seed treatment reduced the densities of rice water weevil larvae relative to non-treated controls even at rates 75% lower than the label rate. Increased mortality of fall armyworm larvae was observed at reduced seed treatment rates relative to a non-treated control. Chlorantraniliprole seed treatment increased the mortality of sugarcane borer larvae at all rates relative to controls and the mortality was consistently higher in larvae that were fed stems from treated plants at the vegetative developmental stage than larvae that were fed stems from plants at the reproductive stage. Concentrations of chlorantraniliprole in plant tissues increased with seed treatment rate and decreased with plant age. Conclusion: This study has shown that reduced chlorantraniliprole seed treatment rates can provide adequate control against the rice water weevil, fall armyworm, and sugarcane borer, particularly at early developmental stages of rice plants. © 2019 Society of Chemical Industry