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Trophic interactions may strongly depend on body size and environmental variation, but this prediction has been seldom tested in nature. Many spiders are generalist predators that use webs to intercept flying prey. The size and mesh of orb webs increases with spider size, allowing a more efficient predation on larger prey. We studied to this extent the orb‐weaving spider Araneus diadematus inhabiting forest fragments differing in edge distance, tree diversity, and tree species. These environmental variables are known to correlate with insect composition, richness, and abundance. We anticipated these forest characteristics to be a principle driver of prey consumption. We additionally hypothesized them to impact spider size at maturity and expect shifts toward larger prey size distributions in larger individuals independently from the environmental context. We quantified spider diet by means of metabarcoding of nearly 1,000 A. diadematus from a total of 53 forest plots. This approach allowed a massive screening of consumption dynamics in nature, though at the cost of identifying the exact prey identity, as well as their abundance and putative intraspecific variation. Our study confirmed A. diadematus as a generalist predator, with more than 300 prey ZOTUs detected in total. At the individual level, we found large spiders to consume fewer different species, but adding larger species to their diet. Tree species composition affected both prey species richness and size in the spider's diet, although tree diversity per se had no influence on the consumed prey. Edges had an indirect effect on the spider diet as spiders closer to the forest edge were larger and therefore consumed larger prey. We conclude that both intraspecific size variation and tree species composition shape the consumed prey of this generalist predator. [ABSTRACT FROM AUTHOR]

In forests, besides tree diversity, tree identity can determine herbivore species diversity. Herbivore species diversity can also depend on spatial factors, such as edge effects; however, empirical evidence for this remains scarce. Furthermore, patterns in herbivore diversity may differ between forest stand level and responses at individual tree species. It is therefore important to disentangle stand‐level patterns from associational responses specific to certain host species.We studied the effects of edge distance, tree diversity and tree species composition on leaf miner abundance, richness and diversity in temperate forests. We disentangled leaf miners' responses at stand level from those of miners associated with each of three individual tree species: Quercus robur L., Quercus rubra L. and Fagus sylvatica L.We found that tree diversity increased stand‐level leaf miner richness and diversity. Fagus sylvatica and stand‐level leaf miner abundance increased closer to edges. This was suppressed at stand level in more diverse mixtures. Underlying tree diversity effects, stand‐level leaf miner metrics are strongly associated with tree species composition, due to many unique species found on F. sylvatica and Q. robur. Additionally, F. sylvatica experienced associational susceptibility to abundance in mixtures with Q. robur. Quercus robur experienced association susceptibility to miner richness in the mixture with Q. rubra.Studying the herbivore community at different spatial scales is a first step towards better understanding tree identity effects underlying tree diversity effects. Our findings emphasise context dependency of positive diversity effects on herbivores in terms of edge effects and tree species composition. [ABSTRACT FROM AUTHOR]

In France, during the summer, cattle in mountainous pastures can be highly exposed to tabanid bites. The persistent biting behaviour of tabanids not only causes disturbance, but is also responsible for transmitting diseases, such as bovine besnoitiosis. The purpose of this study was to better identify the level of tabanid annoyance on cattle by means of insect trapping and direct observation of cows. Tabanids were active during the entire daily observation period (10:00-16:00), except for Haematopota sp., which were less active in the morning. The tabanids collected in Nzi traps were generally representative of those that landed on cattle, except for Haematopota sp., as Nzi traps were not very effective for these species. The preferred feeding sites for most species appeared to be cow's legs or udder. Leg stamping was the defensive reaction most related to a tabanid alighting on a host. Generalized linear mixed models showed that the parameters associated with tabanid landings on hosts were related to weather and altitude, but not to landscape structure. Increased landings were mostly associated with the higher temperatures and lower wind speeds at midday, but some differences were observed between species. The results indicate that cattle-protection measures should be taken during the peak of tabanid abundance when climatic conditions favour intense biting activity. Nzi traps set close to livestock were very effective to catch tabanids and could help in reducing the annoyance caused by horse flies.