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

Spence, Eleanor L. ORCID: https://orcid.org/0000-0002-5268-9554; Chandler, David; Edgington, Steve; Berry, Shaun D.; Martin, Gareth; O'Sullivan, Christine; Svendsen, Claus ORCID: https://orcid.org/0000-0001-7281-647X; Hesketh, Helen ORCID: https://orcid.org/0000-0003-1794-7658. 2020 A standardised bioassay method using a bench‐top spray tower to evaluate entomopathogenic fungi for control of the greenhouse whitefly, Trialeurodes vaporariorum. Pest Management Science, 76 (7). 2513-2524. 10.1002/ps.5794

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Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1002/ps.5794
UKCEH and CEH Sections/Science Areas:	Biodiversity (Science Area 2017-) Pollution (Science Area 2017-)
ISSN:	1526-498X
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	entomopathogenic fungus, spray tower, bioassay, biopesticide, whitefly
NORA Subject Terms:	Biology and Microbiology
Date made live:	09 May 2020 16:11 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/527657

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