The antifeedant activity of lactones with di- and trimethylcyclohexane system was assessed in choice and no-choice bioassays against Leptinotarsa decemlineata and Alphitobius diaperinus larvae and beetles. The results showed that feeding deterrent activity depends on the structure of the tested compounds. Additional methyl group in the molecule of some compounds influences their activity increase or changes their properties from attractant to deterrent ones. The present results also demonstrate the species and developmental stage dependence of antifeedant activity.

The deterrent effect of limonene enentiomers and limonene derivative: ( + )-(1S,4S,6S)-4-(1-methylethenyl)-9-oxabicyclo[ 4.3.0]nonan-8-one, on Myzus persicae was investigated. Only S-enantiomers of limonene and its derivative showed feeding deterrent properties. S-limonene inhibited phloem sap ingestion and reduced the number of phloem sap ingestion phases during aphid stylet penetration of plant tissues. Aphids spent twice less time on leaves painted with ( + )-1S,4S,6S-4-(1-methylethenyl)-9-oxabicyclo[ 4.3.0]nonan-8-one than on control and S-limonene-treated leaves and the probes were shorter than 2 minutes on these leaves. Our studies confirmed that the chiral centre configuration of the lactones was important in expression of feeding deterrent activity.

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.

The aim of the work was to study the feeding deterrent activity ofprecocenes, their synthetic analogues, and some related compunds to storage pests: Sitophi/us granarius L., Tribolium con/usum Duv., Trogoderma granarium Ev., and aphids: Myzuspersicae (Sulz.). Among all tested compounds precocenes I and 11 exhibited the best feeding deterrent activity against all tested insects. 4-Chromanols ( 16, 17 and I 8), alcohols 19, 20 and 3-chromanone (15) showed high deterrence towards the larvae of T con/usum. The best antifeedant activity towards the adults of both T confusum and S granarius was observed for substituted phenols with methoxy group at benzene ring. The biological tests carried out on aphids showed that the presence ofmethoxy group in the molecule was a crucial structural factor for the appearance of antifeedant activity against these insects.