Validation of morphological keys for identification of Bursaphelenchus xylophilus (Nematoda, Parasitaphelenchidae) to group and species level

Abstract

Official analyses undertaken in the framework of an official survey, or import controls need reliable results. This can be achieved by using validated methods. For morphological tests, this validation process is rarely illustrated despite guidance provided in EPPO PM 7/98 (1) Specific requirements for laboratories preparing accreditation for a plant pest diagnostic activity. This paper presents validation for the morphological identification of Bursaphelenchus xylophilus, with the evaluation results of published identification keys and of internally designed identification keys at B. xylophilus group and species levels. For published identification keys some criteria were shown not to be reliable for routine use: excretory pore position and number of caudal papillae. The key designed in the laboratory for xylophilus group identification was shown to be sensitive and specific when one male and one female were observed. The key designed for B. xylophilus species identification is sensitive, specific and reproducible if only one female of B. xylophilus is observed. The tools designed were validated as simple and reliable for routine analysis. The advantages and limitations of the validation process for morphological tools are discussed for process improvement.