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Digitized by Kansas Correctional Industries

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Environmental factors exert a great effect on the occurrence of aphids and thrips, their abundance and damage done in cereal crops, as well as the time of appearance of these pests in the crops, timing of their control and means used. Species diversity of aphids and thrips in winter rye, triticale, wheat, and spring barley was identified. Variation of the abundance of the main species of aphids and thrips in the mentioned crops was determined in relation to crop growth stages and environmental factors. For the first time in Lithuania we estimated migration activity of R. padi and S. avenae using a suction trap and compared with the abundance of these aphid species in cereal crops. The experimental data obtained in this study enables assessment of damage done by aphids and thrips in winter rye, triticale and wheat crops and estimation of expedience of the application of aphids and thrips control measures. Thrips threshold of harmfulness at which it is expedient to apply control measures was identified in winter rye.

Analyses were made of concentrations of six elements (the micronutrients copper, iron, manganese and zinc, and the macronutrients calcium and magnesium) in samples of Triticum spetta and the soil they were grown on to investigate relationships between the two, and the possibility of sourcing material found in the archaeological record. Charred and fresh grains of geographically and geologically diverse locations were broken down in nitric acid using a microwave digestion technique. The resultant solutions were analysed by atomic absorption spectroscopy. Soil extractions using nitric acid and diethylene triamine penta-acetic acid allowed analyses of total and available elements. The results of soil / grain digests were investigated but no consistently significant relationships could be discerned. Growth experiments were performed by growing grain samples from various locations on one soil type to assess which factors were primarily important in elemental uptake. Calcium and magnesium uptake appears strongly influenced by the growing environment, but that of the micronutrients is additionally affected by genetic factors. In order to assess changes in elemental concentration due to burial, diagenetic experiments were carried out using grain from various locations and a series of differing burial periods. It was found that there was a trend for concentrations of the micronutrients and magnesium to decrease, whilst calcium concentrations increased substantially. On completion of work with modem grain, samples from the archaeological record were analysed. Elemental concentrations were found to be very different in ancient material and more significantly related to the burial environment. It appears possible to differentiate between leached, rural and waterlogged/urban sites.