The predation on insects on leaves was measured by direct observation using live larvae of Calliphora vicina (Diptera: Calliphoridae) as bait placed on 15 common species of woody plants in a floodplain forest in the temperate region. The predation rate was measured in terms of the proportion of the larvae that were missing or had been attacked after 30 min of exposure on leaves. Despite the fact that the important predators differed during the course of a season, the most frequently recorded predators were birds and ants and less frequently recorded wasps and spiders. Analysis of the pattern in the distribution of the attacks confirmed that it is best described by a negative binomial distribution, which corresponds to a clumped dispersal of predation. Based on the results of the best-fitted generalized additive model, we could not reject an equal probability of attacks on the different species of woody plants. Further, predation at the forest edge was notably higher than in the forest interior. The model also predicted marked variations in the incidence of attacks during the course of a day and a season, with the attacks occurring mainly in three periods during the year and two during the day. In general, the sampling method used could become the standard measure of the risk of insects living on trees being attacked by predators in future studies., Michaela Drozdová, Jan Šipoš, Pavel Drozd., and Obsahuje seznam literatury
Enemy-free space. A distribution of particular individuals in nature is not governed by stochastic events. Proper taxon for studies of distribution iof organisms is herbivorous insects. Many ecologists try to explain: i) spatial distribution; ii) temporal distribution; iii) specialization of herbivorous insects in an environment. A distribution of herbivores can be affected by vegetation which negatively influences fitness of herbivores thanks to low ration on nitrogen to carbon and because of a content of toxic chemical substances. Predators can influence abundance of herbivores directly (killing the prey) or indirectly (stress factors). Interactions between herbivores, vegetation and predators can be changed by abiotic environmental factors. Environmental conditions can mitigate effect of predators and vegetation on herbivorous insect or can increase importance of one of these factors. From the perspective of the Enemy-free space theory the most important factor controlling distribution and abundance of insects is a predation. Herbivores can avoid predators by choosing a safe microhabitat or time period which is free from predators. Other possibility for herbivores is to specialize on particular plant and use its chemical defence against predators. Interaction between predators and its prey is not invariant but is very variable in time and space and we can describe it more like a mosaic. Therefore it is very difficult to proof if the enemy-free space exist.