Modern methods of raspberry protection aim at a substantial reduction of chemicals use. The investigation on potential biological control of phytophagous mites on this crop has been begun. Field studies on the occurrence, species composition, and density of populations of tetranychid mites (Tetranychidae) and phytoseiid mites (Phytoseiidae) in different areas of raspberry growing in Poland was carried out in 2000-2001. Leaf samples were collected from 71 plantations located in five of the main regions of Polish raspberry production. There were clear differences in the densities of tetranychid mite populations between regions, with raspberry spider mite Neotetranychus rubi (Trag.) being more numerous than two-spotted spider mite Tetranychus urticae (Koch.) in most except the Skierniewice region. Among the phytoseiid mites collected from raspberry leaves, eleven species were identified. Although their occurrence and species composition varied with region, Amblyseius bryophilus Karg, Euseius finlandicus (Oudemans) and Amblyseius andersoni (Chant) were the most common; each species occurred at least in three regions. Results obtained showed good prospects for the deployment of the phytoseiids in biological control of spider mites on raspberry.

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.

The population dynamics of Tetranychus urticae (two-spotted spider mite – TSSM) are influenced by environmental factors, which were investigated to identify methods limiting the development and harmfulness of this pest. This paper presents findings from a laboratory study on the effect of spraying with water-based extracts of Mentha piperita and Tagetes patula plants on the growth rate of TSSM larvae and nymphs. The time required for the transformation of the larvae into protonymphs was longer for T. patula water- based extracts than extracts from M. piperita. Differences in the time of transformation from the nymphal stage to adult TSSM were also observed depending on the plant waterbased extracts, their concentration, and the host plant on which nymphs were developing. The use of 100 g ∙ l-1 French marigold extract was associated with longer transformation time of nymphs on discs of pea leaves than all tested concentrations of French marigold extract applied to sugar beet leaves. Ten percent of the extracts from peppermint plants had a stronger limiting effect on TSSM nymphs on pea leaves than on bean or sugar beet leaves.

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.

This study investigates the acaricidal, ovicidal, and repellent effects of the Tagetes patula Linn. (Asteraceae) leaf extract against both the adult female and egg stages of Tetranychus urticae Koch (Trombidiformes: Tetranychidae) under laboratory conditions. The Tagetes patula ethanolic leaf extract [TpEtOH70%] was screened for adulticide and ovicide bioassays in order to consider its acute toxicity. One sublethal concentration was used to assess egg-laying capacity (fecundity), repellent, and oviposition deterrent activities. The chemical characterization was conducted by gas chromatography-mass spectrometry (GC-MS) analysis to identify the TpEtOH70% bioactive components. Results showed that the LC50 value of TpEtOH70% leaf extract predicted by Probit analysis against T. urticae adult females at 24 h was 0.99%. The TpEtOH70% leaf extract showed a significant toxic effect as the highest mean mortality rates (± SE) of the treated adult females was 88.9 ± 3.7%. However, the TpEtOH70% leaf extract was insignificant in affecting the egg-laying capacity of the adult females treated with a sublethal dose of 0.5% even after 72 h. The TpEtOH70% leaf extract was classified repellent since the repellent index (RI) value was lower than 1 – SD. In addition, it had a high oviposition deterring effect based on a 100% reduction of the total number of eggs. The TpEtOH70% leaf extract had a significant ovicidal effect on T. urticae eggs, with 56.04% reduction in hatching. Five bioactive compounds from various classes of phytochemicals were identified in the TpEtOH70% leaf extract and the major compound was phytol (62.72%). This pioneering investigation reveals the adulticidal, ovicidal, and repellent activities of the TpEtOH70% leaf extract against T. urticae. A combination of multiple modes of action of different plant components may act alone or in synergism to delay the development of mite resistance.

Tetranychus urticae (Acari: Tetranychidae) infesting many plants but Mentha viridis L., and Mentha piperita L., were low in number of infestation. Therefore the objective of this study was to identify the resistance of M. viridis and M. piperita plants against T. urticae by studying the external shape and internal contents of those plants. For morphological studies, dried leaves were covered with gold utilizing an Edwards Scan coat six sputter-coater. For histological studies, arrangements of Soft Tissue technique were used. For phytochemical studies, the plants were cut, dried and then high performance liquid chromatography (HPLC) was used. While feeding the mites were collected from the area between oily glands, trichomes and respiratory stomata in both mint species. The most important leaf structures in aromatic plants are the oily glands found on the external part of the leaves (both upper and lower epidermis). The number of oil glands in M. viridis leaves was greater than in M. piperita; the trichomes on the epidermis of M. viridis were greater in number than in M. piperita; the spongy mesophyll in M. viridis was much thicker than in M. piperita. The essential oils in the leaves of both mint species contained 71 compounds representing 99.61% of the total oil constituents identified from M. viridis before infestation, and 90.95% after infestation, and about 99.65% from M. piperita before infestation, and 99.98% after infestation.

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.