Abstract. 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.
1 Experimental tests of whether predation pressure on insects is sometimes restricted to particular forest microhabitats have been carried out only in one or two vegetation periods and described for only a few predators. In the present study, we describe the seasonal dynamics of a wide spectrum of insect predators among forest microhabitats. 2 We also examine the impact of weather conditions on insect predation, and predict that forest openness would influence the predation trends among forest microhabitats. 3 The design of our experiments enabled direct measurement of relative predation pressure on bait (larvae of the blowfly Calliphora vicina) pinned onto selected microhabitats (the base, trunk and leaves of trees) within a temperate floodplain forest (Czech Republic). 4 The most parsimonious generalized additive model showed significant trends in the predation rate among the forest microhabitats. The highest predation rate for bait was at the base of trees and the lowest predation rate was on leaves. 5 We also observed significant differences in the species structure of predators in various microhabitats. The most common source of predation on trunks was from birds, whereas wasps were the most common predator on leaves and ants were the most common at the base of trees.in biomass partitioning among forest layers can influence the abundance of predators, with higher densities tending to be found in layers with the greatest amount of biomass (De Dijn, 2003;Vance et al ., 2007). This information can be useful when examining whether certain safe refuges for prey exist. For insects, spatial refuges can be located on different scales: (i) various habitats within a plant; (ii) different layers within the forest; and (iii) different types of forest habitat.Studies from tropical and temperate forests imply that predation activity differs across forest layers (Jeanne, 1979;Olson, 1992;Loiselle & Farji-Brener, 2002). The main disadvantages of recent predation studies are that they: (i) focus only on a few predators (mostly ants and birds); (ii) are carried out only in one or two growing seasons; (iii) do not examine diurnal or seasonal variability in the predation rate in different forest layers; and (iv) do not examine the effect of
As canopy structure produces spatial heterogeneity of litter microclimatic conditions and thus is a crucial factor affecting ground insects, we hypothesized that low canopy openness has a positive effect on the activity of ground insect predators in forest and non-forest habitats. Blowfly larvae were used as bait along the canopy openness gradient (forest interior, forest edge, base of a solitary tree and meadow) and the attack rate was assessed after 30 min of exposure. Although the predation rate has a varying pattern throughout the year in different habitats, in contrast to previous studies, we observed a significant positive trend in predation rates toward the forest interior. A significant trend in predation rate was not observed in non-forest areas. We found that the trend was strongly influenced by ants as the most active taxon of predators (65%) attacking our baits, whereas ground beetles, the second-most active predators (21%), showed the opposite trend along the canopy openness gradient.
The Shannon-Wiener index is a popular nonparametric metric widely used in ecological research as a measure of species diversity. We used the Web of Science database to examine cases where papers published from 1990 to 2015 mislabelled this index. We provide detailed insights into causes potentially affecting use of the wrong name 'Weaver' instead of the correct 'Wiener'. Basic science serves as a fundamental information source for applied research, so we emphasize the effect of the type of research (applied or basic) on the incidence of the error. Biological research, especially applied studies, increasingly uses indices, even though some researchers have strongly criticized their use. Applied research papers had a higher frequency of the wrong index name than did basic research papers. The mislabeling frequency decreased in both categories over the 25-year period, although the decrease lagged in applied research. Moreover, the index use and mistake proportion differed by region and authors' countries of origin. Our study also provides insight into citation culture, and results suggest that almost 50% of authors have not actually read their cited sources. Applied research scientists in particular should be more cautious during manuscript preparation, carefully select sources from basic research, and read theoretical background articles before they apply the theories to their research. Moreover, theoretical ecologists should liaise with applied researchers and present their research for the broader scientific community. Researchers should point out known, often-repeated errors and phenomena not only in specialized books and journals but also in widely used and fundamental literature.
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