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
In diapause-destined larval cultures of the blow fly, Cailiphora vicina, competition through severe overcrowding forces down body size and causes the smaller individuals to escape from the diapause \"programme\" to form miniature puparia. Among the diapausing cohort, smaller larvae contain a similar proportion of fat to larger larvae, and a similar rate of fat metabolism over the first 7 weeks in diapause. However, these smaller diapausing larvae are much less cold tolerant than larger individuals. Of the miniature larvae that side-step the diapause programme to form puparia, even the smallest of them are capable of development to the adult, and these small-sized adults are capable of depositing \"full-sized\" eggs (although fewer of them) which hatch to produce \"full-sized\" and viable larvae. These data suggest that the smallest individuals, by avoiding the diapause programme, may gain a selective advantage by completing another autumnal generation instead of entering diapause and failing to survive because of a reduced cold tolerance.