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.

Azadirachtin is the most active substance separated from Azadirachta indica. It acts destructively on numerous species of insects and mites. The aim of the presented investigations was to determine the effect of azadirachtin on one of the most dangerous pests of cabbage plants, Pieris brassicae, and on its natural enemy, Apanteles glomerarus. The results of the field observations did not show any repellent effect of azadirachtin relating to laying their eggs cabbage butterflies. However, a significant effect of the azadiraehtin solution on reduction the number of cabbage butterfly caterpillars (it was more distinctly marked in respect to young larva stages) as well as on limited feeding by caterpillars. No negative influence of azadirachtin on a parasite of Pieris brassicae caterpillars, Apanteles glomeratus was distinctly shown.

The research into the occurrence of herbivorous heteroptera of Orthops genus on Sosnowski’s hogweed (Heracleum sosnowskyi Manden.) was carried out over 1999–2002 in the vicinity of Bydgoszcz. The analysis of the faunistic material collected of Heteroptera order showed the occurrence of 3 species where dominant heteroptera were represented by: Orthops campestris L. (48.57%) and Orthops kalmi L.(44.91%), while Orthops basalis Costa was scarce. The maximum abundance of these species coincided with full flowering and the beginning of hogweed fruit formation.

Water extractsfrom selected Geraniaceae plants, to which paraffin oil was added as adjuvant, were tested. It was observed that the plant extracts researched limited Colorado potato beetle feeding and development and adding adjuvant increased the effects. The highest antifeedant activity towards Colorado potato beetlesand their larvae wasobs erved in extractsobtained from Pelargonium × hortorum Bailey and Geranium pusillum L. The extract from Pelargonium × hortorum Bailey added to food showed a negative effect on the development of female reproductive organs and embryo development and showed the highest effectiveness in field conditions.

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.

In 1997 and 1998, insects settling cultures of goats rue (Galega orientalis Lam.) at Mochelek were caught. Amongst ground beetles the dominating species were: Pterostichus melanarius lll., Carabus auratus L., Harpalus rufipes De Geer, Harpalus aeneus F., and Bembidion lampros Hbst. and Harp alus frolichi Sturm. were subdominants.