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Completing the development of a detection kit for a range of grain storage mite species


HGCA PROJECT REPORT 377

Completing the development of a detection kit for a range of grain storage mite species


by

J A Dunn, C Danks, B B Thind and J Chambers

Central Science Laboratory, Sand Hutton, York YO41 1NZ

October 2005

Abstract

The aim of this study was to complete the development of a user-friendly field diagnostic kit to detect storage mite pests. This was achieved by a) adapting the immunoassay method for the detection of the flour mite, Acarus siro (L.), developed in a previous HGCA project, into a fully tested and validated field kit, b) extending application of the kit to detect other storage mite pests, and c) developing a decision tree to guide use of the kit and interpretation of results.

The results demonstrate that:

  • The A. siro antibodies can detect mites in a wide variety of samples including wheat, barley, oats and oilseed rape (OSR); different cultivars of wheat and OSR; different qualities of wheat including admixture and screenings.
  • A prototype simple field kit, in the form of a lateral flow device (LFD), was developed successfully from the immunoassay (ELISA) method for detecting A. siro in wheat. Results compared well with those from the ELISA (linear regression r2= 0.891) but the LFD is superior for ease of use in the field.
  • The A. siro kit was successfully validated in the field by end-users. Mill staff LFD results compared well with scientists' LFD, ELISA and flotation results (r2 = 0.959, 0.883, 0.847 from mill 1 and 0.876, 0.813, 0.807 from mill 2). An empirical decision tree for interpreting the results was developed.
  • New antibodies were raised which offer the prospect of kits to detect the cosmopolitan food mite (Lepidoglyphus destructor), the grocers' itch mite (Glycyphagus domesticus), the grainstack mite (Tyrophagus longior) and the mould mite (Tyrophagus putrescentiae); mites of the Tyrophagus genus, mites of the Glycyphagus genus; all storage mites.
  • From the new panel of antibodies, another prototype LFD was developed and validated to detect different species in the genus Tyrophagus. Results using mite-infested wheat samples also compared well with the ELISA (r2= 0.990).

This work demonstrated the feasibility of LFDs being used in grain stores to target mite control effort in problem areas. LFDs are easy to use, rapid and cheap (approximately £3-5) and enable more samples to be analysed than previous methods.

The LFD could be used throughout the food supply chain to establish the degree of contamination and point of entry by mites. Validation work is required to confirm the commercial capability of the LFDs and to develop kits from the other species/genera specific antibodies; however, A. siro and mite species of the genus Tyrophagus are the most prevalent in UK grain stores. Further work is required to construct a model to simulate mite distributions in grain bulks.



 

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