Apple cultivars investigated as new hosts for two-spotted spider mite, Tetranychus urticae Koch appeared to provide good environment for its development and reproduction. The best conditions for two-spotted spider mite development were on leaves of cultivars Novamac and Freedom with a net reproduction (R_o) 22.6 and 20.3 respectively, while the worst on cultivars Pioner and Primula with R_o 8.9 and 10.2 ,respectively.

Number of hairs on abaxial leaf surface of 13 apple cultivars differed significantly. The most hairs per 1 cm² on abaxial surface were on cvs. Lodel (2,578.3) and Jonafree (2,462.2). Leaves of cultivars Antonówka and Novamac had the least number of hairs (1,054.4; 1,285.7; respectively). Correlation between number of hairs on abaxial leaf surface of investigated apple cultivars and Tetranychus urticae (Koch) female fecundity decreased during 10 first days of their lives. Along with increased number of hairs, the fecundity of this species declined.

Characterisation of two-spotted spider mite ( Tetranychus urticae Koch , Acari: Tetranychidae) response to aqueous extracts from selected plant species. Aqueous extracts from four plant species of known insecticidal activity on arthropods were tested against two-spotted spider mite females to describe their mode of action on the spider mite. The extracts effects on: (a) the mite establishment on host plant; (b) initiation of feeding (probing behaviour); (c) initiation of permanent feeding and (d) the mite mortality (a toxic effect) was measured using various experimental techniques. The highest toxic action was shown by NeemAzal-T/S (an extract from Azadirachta indica; production of Trifolio-M GmbH company) and repellent by water extract from Allium sativum and Urtica dioica. NeemAzal T/S also shown a strong activity as a feeding suppresant for T. urticae.