Seeds of many species of plants may survive for a long time in the soil and germinate when brought to the surface, but
whether they are subsequently eaten by seed predators is unknown. We examined the preferences of three species of carabids
(Coleoptera: Carabidae) for 25 species of seeds and determined the difference in palatability between freshly dispersed and those
buried for six years. The stability of their preferences was tested using a collection of seeds of different species, each of which was
offered fresh or after being buried. Carabid beetles readily accepted previously buried seeds as food. In total, Pseudoophonus
rufi pes and Amara littorea ate more fresh seeds than previously buried seeds, while the opposite was true for Harpalus affi nis. The
seeds of some species were even more attractive to carabids after burial than in the fresh state. For all the species of carabids
tested, the diet breadth was similar when the beetles were fed fresh or buried seeds, but the preferences for fresh and buried seed
of particular species were correlated only in P. rufi pes and A. littorea. We measured the seed characteristics (mass and viability)
likely to be associated with the loss of attractiveness to carabids during burial. The change in carabid consumption was not related
to changes in any of these characteristics. This fi nding indicates that factors responsible for variation in seed acceptability are
complex. This study provides the fi rst conclusive evidence that invertebrate seed predators will feed on seeds from seed banks,
although they prefer fresh seeds.
Ground beetles (Carabidae: Coleoptera) are predators of the seed of herbaceous plants scattered on the ground, but prefer that of certain species. Foraging beetles encounter both freshly dispersed and seed exhumed from the soil bank. The predation on seed from the soil bank has never been studied and the effect of burial on seed acceptability is unknown. The preferences of two generalist granivorous carabids, Harpalus affinis and Pseudoophonus rufipes, were investigated by offering them fresh (stored frozen after dispersal) and buried (for 6 months in the soil under field conditions) seed of six common weed species. Significantly more of the buried seed of Tripleurospermum inodorum and significantly less of that of Taraxacum officinale was eaten than fresh seed. For four other weed species the consumption of both kinds of seed did not differ. The preferences were similar in both species of carabid. The change in preference probably occurred because the seed of T. officinale was partially decayed and the repellent surface of T. inodorum seed abraded. Provided the seed in the soil bank does not decay it may have a similar or better food value for carabids than fresh seed.
Development rates of the eggs of 9 species, larvae of 6 species and pupae of 6 species of the genus Amara (Coleoptera: Carabidae) were recorded at five constant temperatures between 17 and 28°C, and thermal constants for each development stage calculated. The lower development threshold varied between 9.2-13.5°C for different stages and species. Rate isomorphy, which implies the existence of a common temperature threshold for all development stages, was demonstrated in 5 species. The sum of effective temperatures differed between stages. On average the egg stage took 18%, the first larval instar 13%, second instar 13%, third instar 35% and pupa 21% of the total development time. A poor diet increased the SET of the larvae. The results are compared with published data on Carabidae.
Lady beetles (Coleoptera: Coccinellidae) are a classical group for studying the mechanisms that determine local and temporal trends in colour polymorphism. Here we report long term trends in variation in the percentage of different morphs in a population of Hippodamia variegata (Goeze) at Štúrovo, Slovakia (47°48´N, 18°43´E). The morphs differ in the number and location of the spots on their elytra. Beetles were sampled from stands of herbaceous plants using a standard method each year in August over a period of 74 years from 1937 to 2011. Twenty two morphs (out of 74 possible) were recorded in a total sample of 6,984 individuals. Four dominant morphs made up 90% of the total sample and varied in their annual frequency independently of one another. Frequency of "pale" morphs (0–3 spots per elytra), supposedly favoured by a warm climate, increased from 1981 to 2000s’ during a period of climate warming, but only after a decrease that took place between 1937 and 1981, which did not parallel a change in climate. Moreover, the differences in the extent of the melanization of the elytral surface are too small to significantly affect thermoregulation in the different morphs. Therefore, the results presented do not provide unequivocal support for climate change determining the long term trends in the variation in the proportions of the different morphs., Alois Honek ... [et al.]., and Obsahuje seznam literatury