In the years I 999-2000 the studies on the population of true bugs colonizing the inflorescences of quinoa (Chenopodiwn quinoa Willd.) were conducted in Chrząstowo near Bydgoszcz. The dominating species was Lygus rugulipennis Popp. The species was recorded in 81.44% in 1999 and 83.64% in 2000 of all collected true bugs.

Soil, the main element of natural environment is constantly contaminated and degraded by various man's activities. Big industrial factories, which emit to the atmosphere excessive quantities of harmful solid, liquid and gaseous substances, are the main cause of this phenomenon. Lm proper usage of fertilisers and chemical plant protection agents effects the soil in a lesser degree, but it is still unfavourable. The aim of this research was to use potato beetle larva in stage L4 as a soil bioindicator fi-om the plantations of spring wheat, potatoes, and corn which were treated with herbicides. The obtained results did not show any negative effect of herbicides used on potato beetle larva growing in the soil.

The aim of the field experiments was to evaluate the effect of herbicide Proponit 720 EC used commercially (which content in I I - 720 g of propisochlor) for grass- and dicotyledonous weed control in winter wheat, winter barley, sugar beet, pea, potato and maize. The field trials were conducted over period 1995-1998 in experimental stations, which belong to the institute of Plant Protection. Proponit 720 EC effectively controls Apera spica-venti and Echinochloa crus-gal/i. In winter cereals dicotyledonous weed control was satisfactory but at other tested crops better weed control was obtained while Proponit 720 EC application with other herbicide. The yield of crops was increased after Proponit 720 application. Proponit 720 EC was not enough safe for sugar beet but was selective for other tested crops.

Occurrence of aphid species was studied in four types of midfield thickets in the Lower Vistula Landscape Park in Poland. This paper presents and discusses the relationships between aphid communities, their species diversity and dominance structure in these thickets.

In the Institute of Plant Protection Branch in Sośnicowice an investigation was performed on establishing novel methods for testing biological activity of seed dressings against snow mould (Microdochiwn nivale). Seeds of winter wheat used for the experiments in artificial conditions were disinfected in sodium hypochlorite, subsequently infected with the pathogen, and treated with seed dressing fungicides (Baytan Universal 19.5 WS, Zaprawa Funaben T, Maxim 025 FS, Raxil Extra 515 FS and Vitavax 200 FS). In laboratory tests inoculation with conidial suspension was applied, and in climatic chamber experiments either conidial suspension or inoculum grown on sand-cornmeal medium was used. The field experiment with the same seed dressings was carried out on naturally infested plots, and the disease developed under snow cover lasting for 58 days. Two novel climatic chamber methods (Z and PK) proved to be suitable for testing biological activity of seed dressing fungicides against snow mould (M nivale) as correlation coefficients with field results at P=0.05 were 0.9760 and 0.9453. Method Z was recognised as more suitable. Differences between seed dressings were statistically insignificant. The laboratory method was recognised as useful for controlling the pathogen (M. niva!e), but its usefulness for controlling the disease (snow mould) may not be sufficient under a range of different winter conditions.

The purpose of applying an additional air flux in field sprayers is limiting liquid drift. The flux also influences the quality of plant spraying. Air Plus Spridotrain sprayer, produced by RAU company, was applied in the research on the influence of air flux on the quality of coverage ofwinter wheat (Roma variety). The plant coverage was determined using water sensitive papers.

The influence of powdered fruits of Foeniculum capillaceum Gilib. on the fecundity ofSitophilus oryzae was examined. The powder was added in paper bags to the rearing of the insects to prevent a direct contact. The sign i fi cant reduction of the fecundity of females was recorded. The sequent effect of activity of the powder was also observed. It resulted in the decrease of the fecundity of offspring generation - F2 reared on wheat grains without the powder.

The process of plant selection by insects is mediated by repellents and attractants. Several compounds may be involved in this interaction. Thus intraspecific variation of the compounds concentration play an important role in the herbivory. The best tool for the characteristic of this variation is chemometrics. The strategy of the analysis with the use of literature data on terpen es and sesquiterpenes variations in Pin us caribaea needles in relation to Atta laevigata herbivory is exemplified herein. Simple cluster analysis and principal components analysis were used for the data study. Two factors were found lo be sufficient to describe total variation in more than 90%. Factor I is responsible for repellent properties. From factor loading, the relevant chemical compounds were identified.

In the years 1977-1979 and 2000 the bugs (Heteroptera) were collected from yarrow, well-known herbaceous plant. It turned out that the bugs made up to 30% on average of all arthropods collected from yarrow, The most numerous were phytophagous bugs (79-96%), among them the known pest of genera Lygus and Plagiognathus. Among zoophagous bugs the most numerous were genera Nab is and Orius. Both of phytophagous and zoophagous bugs of these genera had their life cycle on yarrow. For comparison Heteroptera from yarrow growing in the wild were also collected.

In 1997-1999 observations of health status of spring barley grown in two-component mixtures with cereals or pea were performed in two experiments, differing in the agricultural utility of soil. A much better health status of the studied species was found in the mixed crop than in their pure stand. Two-component mixtures were differentiated in the occurrence of leaf diseases caused by Drechslera teres, Drechslera graminea, Puccinia graminis and P. hordei, Rhynchosporium secalis and Erysiphe graminis. The healthiness of lower parts of stem and roots depended on the quality of soil and mixtures factor. A higher infection due to foot root rot complex was noted on barley cultivated on the poorer soil in homogenous stand.