Differential levels of mite infestation of wheat and barley in Czech grain stores

Abstract

While mites are able to utilize numerous food sources, the suitability of the food strongly influences population growth. The different suitabilities of various stored agricultural products will thus affect the level of infestation. In this study, we compared field mite infestation rates in two stored cereals: wheat and barley. We analyzed mite abundance, frequency and species composition in samples of grain obtained from 79 selected Czech grain stores. Stored barley seemed to be more vulnerable to mite attack than wheat, as we consistently found more infested samples, more species and higher mean and median mite abundance per sample in barley as compared to wheat. The mean mite abundance per sample were 55 and 506 individuals for wheat and barley, respectively. In barley, 10% of samples exceeded allergen risk threshold (i.e., 1 000 individuals per kg of grain). Altogether, 25 species were identified from approximately 35 000 individuals. The most frequently identified species were the same in wheat and barley, that is, Tydeus interruptus Sig Thor, Acarus siro L., Tarsonemus granarius Lindquist, Lepidoglyphus destructor (Schrank) and Tyrophagus putrescentiae (Schrank). Based on principal components analysis, we found a closer association of T. interruptus, T. putrescentiae, L. destructor and Cheyletus eruditus (Schrank) with barley samples, corresponding to the high frequency and abundance values of these mites. The probable reasons for the higher infestation, especially mite abundance in barley, are discussed in relation to the higher proportion of crushed parts, which may release favorable nutrient sources and amplify the abundance values.

A review on the factors affecting mite growth in stored grain commodities

“…Barley has been found to be more vulnerable to mite attack than wheat, which may be due to barley grains being more suitable sources of nutrients or having greater amounts of crushed parts to allow greater accessibility to nutrients (Hubert et al 2009;White et al 1999). The rough surface of barley grains may also provide a more suitable surface for the adhesion of mite eggs and provide greater protection from disturbance than the smooth surface of wheat grains (Hubert et al 2009).…”

“…Cheyletus spp. are more successful at reducing prey numbers in coarse large-sized particles than in fine small-sized materials where extra refuge is afforded to the prey species (Cusack and Brennan 1976;Hubert et al 2009;Thind and Ford 2006).…”

“…The rough surface of barley grains may also provide a more suitable surface for the adhesion of mite eggs and provide greater protection from disturbance than the smooth surface of wheat grains (Hubert et al 2009). …”

“…Mites utilise many food sources, however, the suitability of the food strongly influences population growth (Hubert et al 2009;White et al 2003). Grain condition affects the initial rate of establishment in the early stages of an infestation, with mites unable to penetrate grains if the seed coat is intact, although usually less than 10% are so intact (Solomon 1946b(Solomon , 1969a.…”

Pest control strategies and damage potential of seed-infesting pests in the Czech stores - a review

“…Plant resistance belongs among the important preventive methods of stored seed protection (Throne et al 2000). Hubert et al (2009a) found that stored barley seed is more seriously infested by mites than wheat in the Czech stores. Kucerova and Stejskal (1994) compared the varietal resistance of Czech winter wheat seeds against the infestation of stored grain.…”