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There are various modern pest-control management systems used in the current apple production, such as integrated pest management (IPM) or organic systems. All aims to support occurrence of natural enemies that should help to reduce populations of pests. Here we investigated the effect of fungicide-treated and fungicide-free (resistant tree varieties) treatment combined with biological, IPM, and conventional systems on spiders, as the major group of natural enemies occurring on foliage of apple trees. The biological treatment was based on the use of biopesticides; IPM system was based on the use of selective insecticides, conventional included the use of broad-spectrum insecticides. Abandoned plot served as a control. The study was done for three consecutive years. Spiders were sampled from canopies by beating at weekly intervals during season. We found that fungicide-treated plots had lower abundance of spiders for two years but not species richness than fungicide-free plots. Among the three pest-control management systems, IPM and conventional supported greater spider abundance but not species richness than the biological treatment. Comparison of spider abundance before and after insecticide applications revealed that only very few pesticides, particularly the broad-spectrum ones, reduced spider numbers. In addition, we focused on the comparison of three traits (body size, maturity, fecundity) among treatments. Of six species, only Philodromus cespitum showed a smaller body size on biological than the other treatments. There were three species in which adults occurred earlier on conventional treatment than on the other treatments. Neither clutch size of Phylloneta impressa nor egg size was different among treatments. The small though significant differences in abundance, richness, and selected traits, found among IPM, conventional, and biological treatments and the control show that these pest-control management systems had similar effect on spiders. Use of IPM system combined with scab resistant apple varieties is recommended. [ABSTRACT FROM AUTHOR]

Within‐species variation in body size of males and females of an ant‐eating spider Zodarion rubidum was studied by analysing 15 populations across Europe. The relationship between the body size of both sexes was allometric with female‐biased sexual size dimorphism. Body size of males did not change with latitude or temperature, while that of females changed significantly with temperature. Larger females were found in regions with higher temperature which is presumably a result of an optimal climate: higher temperature and longer season provide higher prey availability which accelerates the growth rate of females, leading to a larger body size. As female size varied more than male size, a sexual size dimorphism cline was observed in Z. rubidum. Larger sexual size dimorphism was found in warmer regions. These results thus suggest that environmental conditions (temperature) influence intraspecific variation in sexual size dimorphism in Z. rubidum. [ABSTRACT FROM AUTHOR]

Based on morphological characters, two species of the genus Zodarion, Z. hamatum and Z. italicum, were placed into the italicum group. The aim of this study was to evaluate similarity of these two species in respect of various aspects of their natural history and karyotypes. Both species had similar phenological patterns, being univoltine, but some specimens reached adulthood the same year before winter. Both representatives had nocturnal activity and were able to capture various ant species. Zodarion hamatum seems to be specialized on Myrmicinae ants, and Z. italicum on Formicinae ants. Zodarion hamatum showed more agile predatory behaviour than Z. italicum presumably due to specialization on Myrmicinae ants, which have lower population density. Both species are generalized mimics of bicoloured (orange-dark brown) ants, such as Lasius emarginatus; they performed similar courtship and mating. The two study species exhibited contrasting reproductive strategies. Zodarion hamatum spiders had higher fecundity than Z. italicum as a result of larger body size but Z. italicum had larger eggs than Z. hamatum. This is presumably an adaptation to different availability of prey ants. Both species had the same diploid chromosome number, sex chromosome system and pattern of X chromosome heteropycnosis in testes. Results support a very close relationship between these two Zodarion species. [ABSTRACT FROM AUTHOR]