Caucasian hogweeds are plants introduced to Europe from the Caucasus area. This review concerns the two most common ones—the giant hogweed Heracleum mantegazzianum and the Sosnowsky’s hogweed Heracleum sosnowskyi. The first of them was imported as garden decorations from the 19th century, mainly to Western Europe, while the second one was introduced from the mid–20th century to agricultural areas in Eastern Europe. Nowadays, these two species create one of the most problematic invasions in the world. This review aimed to synthesize research on those invaders based on 277 articles selected from the “Scopus” database. Most of the articles concerned their extensive distribution, at least on a continental scale and the rapid dispersal. The reviewed research showed that the complex physicochemical properties of hogweeds tissues and secretions significantly affected insects, aphids, ants, nematodes, fungi, soil microorganisms, plant communities, birds, and many other components of the ecosystems. This knowledge turned out to be disproportionately small to the scale of the problem. The review also showed what ecological traits of hogweeds were responsible for their wide and various role in the environment. Thus far, no effective method to eradicate Caucasian hogweeds has been found. This could be a growing mistake, given that they are probably during the rapid evolutionary changes within the range of their invasion.

The trade-off between animal’s parental reproductive effort and survival is still poorly understood. Parental allocation between the workload during breeding attempts and the parents’ own body conditions can be assessed through the offspring quality. Here, I questioned whether the immune responsiveness of female great tits may be considered as a mediator of this trade-off. Specifically, I tested whether (1) the parental reproductive effort decreases, (2) the food composition provided to chicks changes, and (3) whether the nestling immunocompetence and body mass decrease after experimental immunisation. Two populations of great tit Parus major occupying nest boxes were studied in Niepołomice Forest and Krzyszkowice Forest (Southern Poland) in 2011 and 2012, respectively. Three days after hatching, half of the females were challenged with sheep red blood cells (SRBC), while other females were injected with phosphate-buffered saline PBS (control). Six days later, food provided by the parents was collected from nestlings. After another 2 days, the offspring’s body mass was measured and wing web swelling in response to an additional phytohaemagglutinin (PHA) injection. In both years, immunocompetence and in 2012 also body mass in the offspring of SRBC-immunised mothers were lower than in control nestlings, indicating a cost of mounting the immune response in the female. Six days after the start of the female treatment, the number of caterpillars and the volume of food items provided by parents to chicks were higher, whereas the number of spiders was lower in nests with SRBC treatment than in control ones. This might be explained by compensational parental feeding after recovery from the inflammation of a female. Thus, the trade-off between parental effort and survival of parents is mediated by the costs incurred for their immunity and can be assessed by the amount and quality of food provided to the nestlings and the offspring condition.

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