Piotr Ceryngier

Agricultural intensification and biodiversity partitioning in European landscapes comparing plants, carabids, and birds

Effects of agricultural intensification (AI) on biodiversity are often assessed on the plot scale, although processes determining diversity also operate on larger spatial scales. Here, we analyzed the diversity of vascular plants, carabid beetles, and birds in agricultural landscapes in cereal crop fields at the field (n = 1350), farm (n = 270), and European-region (n = 9) scale. We partitioned diversity into its additive components alpha, beta, and gamma, and assessed the relative contribution of beta diversity to total species richness at each spatial scale. AI was determined using pesticide and fertilizer inputs, as well as tillage operations and categorized into low, medium, and high levels. As AI was not significantly related to landscape complexity, we could disentangle potential AI effects on local vs. landscape community homogenization. AI negatively affected the species richness of plants and birds, but not carabid beetles, at all spatial scales. Hence, local AI was closely correlated to beta diversity on larger scales up to the farm and region level, and thereby was an indicator of farm- and region-wide biodiversity losses. At the scale of farms (12.83-20.52%) and regions (68.34-80.18%), beta diversity accounted for the major part of the total species richness for all three taxa, indicating great dissimilarity in environmental conditions on larger spatial scales. For plants, relative importance of alpha diversity decreased with AI, while relative importance of beta diversity on the farm scale increased with AI for carabids and birds. Hence, and in contrast to our expectations, AI does not necessarily homogenize local communities, presumably due to the heterogeneity of farming practices. In conclusion, a more detailed understanding of AI effects on diversity patterns of various taxa and at multiple spatial scales would contribute to more efficient agri-environmental schemes in agroecosystems.

The relationship between agricultural intensification and biological control: experimental tests across Europe

Agricultural intensification can affect biodiversity and related ecosystem services such as biological control, but large-scale experimental evidence is missing. We examined aphid pest populations in cereal fields under experimentally reduced densities of (1) ground-dwelling predators (-G), (2) vegetation-dwelling predators and parasitoids (-V), (3) a combination of (1) and (2) (-G-V), compared with open-fields (control), in contrasting landscapes with low vs. high levels of agricultural intensification (AI), and in five European regions. Aphid populations were 28%, 97%, and 199% higher in -G, -V, and -G-V treatments, respectively, compared to the open fields, indicating synergistic effects of both natural-enemy groups. Enhanced parasitoid: host and predator: prey ratios were related to reduced aphid population density and population growth. The relative importance of parasitoids and vegetation-dwelling predators greatly differed among European regions, and agricultural intensification affected biological control and aphid density only in some regions. This shows a changing role of species group identity in diverse enemy communities and a need to consider region-specific landscape management.

Mating and activity of gonads in pre-dormant and dormant ladybirds (Coleoptera: Coccinellidae)

Summary We checked voltinism tendencies in four ladybird species considered to be univoltine in Central Europe. The developmental state of male and female gonads and the incidence of mating females were investigated between September 1998 and April 1999 in ladybirds sampled from two localities in the Czech Republic: (1) in the vicinity of the town of Ceske Budejovice (S Bohemia) and (2) at the top of the hill Raná (N Bohemia). Interspecific differences in those aspects of reproductive activity were checked in the pre-dormancy/early dormancy period (September) in Ceratomegilla undecimnotata (Schneid.), Coccinella septempunctata L., C. quinquepunctata L. and C. magnified Redtb. Changes in the course of dormancy were monitored in C. undecimnotata and C. septempunctata. Since C. septempunctata from S Bohemia was relatively heavily parasitized by a braconid, Dinocampus coccinellae (Schrank), the effect of parasitization by this parasitoid on ladybird sexual activity was also analysed. In September, all C. undecimnotata females had completely inactive ovaries, and none of them had mated, while some females of Coccinella spp. displayed a certain degree of ovarian activity and many females had mated. The activity of testes varied greatly in all species, but the least active, on average, was C. undecimnotata. In both C. undecimnotata and C. septempunctata males, the mean activity of the testes considerably decreased between September and January and then increased in April. However, at each date it was significantly lower in C. undecimnotata than in C. septempunctata. The ovaries of some C. septempunctata females started to mature already in April, while all C. undecimnotata females still had inactive ovaries. C. septempunctata females parasitized by D. coccinellae were more often mated and more often snowed certain activity of ovaries than unparasitized ones. In males, however, parasitization caused reduction in the activity of gonads. It can be concluded that the entire central European population of C. undecimnotata is probably obligatorily univoltine, while in populations of the three Coccinella species some individuals are potentially multivoltine. Diapause and post-diapause development is modified, at least in C. septempunctata, due to parasitization by D. coccinellae.

Flight potential and oxygen uptake during early dormancy in Coccinella septempunctata

Two flight parameters (take‐off and duration) and respiration level were measured, in two years in summer and early autumn, in dormant Coccinella septempunctata L. (Coleoptera: Coccinellidae) collected while hidden in grass tussocks in hibernation sites (HID) and in beetles collected on plants (PLA). The duration of tethered flight of HID beetles measured in the laboratory in late August and September 1995 (range of geometric means 190–440 s) was slightly longer than the flight of PLA beetles (80–310 s), both being much longer than trivial flight recorded in beetles foraging for prey during the breeding season (35 s). In general, the flight performance had a tendency to increase in September and to decrease in October.

Landscape complexity is not a major trigger of species richness and food web structure of European cereal aphid parasitoids

In fragmented farmland landscapes structural complexity and low agricultural intensification should decrease the abundance of crop aphids due to increased abundances and species diversity of aphid enemies, including hymenopteran parasitoids. Here we study the effects of landscape structure and agricultural intensification on parasitism rates, abundances, and species richness of aphids and their parasitoids in five different regions in Europe. While total aphid numbers did not differ significantly among regions, we observed marked differences between Scandinavian and central European sites with respect to the species composition of aphids and their parasitoids and parasitism rates. In the cross country comparison landscape complexity and agricultural intensification did not significantly affect total aphid densities, although we observed species-specific reactions to land use. We also observed a tendency towards increased parasitoid species richness at low agricultural intensification but not at high landscape structure.

The first record of Orthostigma cratospilum (Thomson, 1895) (Hymenoptera: Braconidae, Alysiinae) in Poland, with a note on its host and a description of the female

The alysiine wasp, Orthostigma cratospilum, is reported for the first time from Poland (Dziekanow Leśny near Warsaw). It was found to parasitize the larvae of the phorid fly, Megaselia minor, which developed in dead pentatomid bugs, in the litter under pine trees. The hitherto unknown female of O. cratospilumis described.