Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 15

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  true bug
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Numerous environmental factors are confirmed to have significant influence on the habitat choice of invertebrates and thus on the assemblage structure. In dry, sandy grasslands the vegetation cover and height are assumed to be the most important factors in shaping the distribution of spiders and true bugs. The present study was carried out at a natural sand dune area in the Kiskunság region of the Hungarian Great Plain. Two adjacent sand dunes and the dune valley between them were sampled using a transect consisting of pitfall traps. The traps were arranged in 4 parallel transects, running from the sand dune top through the dune valley to the adjacent sand dune. Each row consisted of 40 traps, three meters apart. The effect of microhabitat parameters on the species richness and abundance of invertebrate assemblages were tested with linear regressions with forward selection procedure. A total number of 1447 spider and 1580 true-bug individuals of 58 and 55 species were collected, respectively. The mean number of spider species along the transects was 10.5 ± 3.7 and 9.8 ± 3.0 for true bugs. Although our data did not show a significant effect of the plant species number on species richness and abundance of the two studied taxa along this gradient, the results of the canonical correspondence analysis and the Mantel test emphasized the importance of the total coverage and vegetation composition on the distribution of invertebrate species. The correspondence analysis and the multivariate ANOVA revealed different spider and true-bug assemblages on the two slopes (multivariate ANOVA: Araneae: F = 3.609, P <0.001, Heteroptera: F = 5.248, P <0.001), possibly due to the more dense and diverse vegetation on the north facing slope, which is presumably brought about by the different insolation and moisture conditions of the slopes.
Sinopachymeridium popovi, a new genus and species of fossil true bugs is described. The new species is reported from the Jiulongshan Formation (Middle Jurassic), in Daohugou Village, Shantou Town, Ningcheng County, Inner Mongolia, China. It clearly belongs to Pachymeridiidae by Sc, R and M diverging at a single point and presence costal fracture. The new genus is most similar to Pachycoridium Popov, 1986, but can be distinguished from the latter by the larger body, rostrum extending to second abdominal sternite, first vein of membrane situated remote from anterior margin of fore wing and fourth and fifth veins forming a merged vein.
The localités of 15 species new for the fauna of "Góra Św. Anny" Landscape Park in the Opole voivodeship are presented. The surveys were conducted mostly in the kserothermic grassland, in the season 1998-2000. Some of the mentioned species are very rare in Upper Silesia.
The cowpea aphid (Aphis craccivora Koch) is considered a serious insect pest attacking several crops. We carried out biochemical studies to elucidate the role of the metabolising enzymes in conferring resistance to thiamethoxam, in two strains (resistant and susceptible) of the cowpea aphid. Bioassay experiments showed that the thiamethoxam selected strain developed a 48 fold resistance after consecutive selection with thiamethoxam for 12 generations. This resistant strain also exhibited cross-resistance to the tested carbamates; pirimicarb and carbosulfan, organophosphorus (malathion, fenitrothion, and chlorpyrifos-methyl), and the neonicotinoid (acetamiprid). Synergism studies have indicated that S,S,S-tributyl phosphorotrithioate (DEF), a known inhibitor for esterases, increased thiamethoxam toxicity 5.58 times in the resistant strain compared with the susceptible strain. Moreover, the biochemical determination revealed that carboxylestersae activity was 30 times greater in the resistant strain than in the susceptible strain. In addition, the enzyme activity of glutathione S-transferase (GST) and mixed function oxidases (mfo) increased only in the resistant strain 3.7 and 2.7 times, respectively, in relation to the susceptible (the control). Generally, our results suggest that the higher activity of the detoxifying enzymes, particularly carboxylesterase, in the resistant strain of the cowpea aphid, apparently have a significant role in endowing resistance to thiamethoxam, although additional mechanisms may contribute.
The green plant bug (Apolygus lucorum Meyer-Dür) is a key pest of Bt cotton in China. Along with biological control, chemical control is one of the most important strategies in A. lucorum Integrated Pest Management (IPM). The goal of this study was to evaluate the toxicity of eight conventional insecticides to A. lucorum and to assess the susceptibility of two generalist predators Chrysopa sinica (Jieder) and Propylaea japonica (Thunbery) to insecticides that are commonly used in A. lucorum management. Via glass-vial and leaf-dip bioassay, toxicity tests with selected insecticides at two different life-stages of A. lucorum indicated significant differences between the LD50 or LC50 values for these compounds within different insecticidal classes. Phenylpyrazole fipronil had the highest toxicity to 4th-instar nymphs and adults of A. lucorum, whereas neonicotinoid imidacloprid had the lowest toxicity among the insecticides. Females were more tolerant to insecticides than were males, as shown by the higher LD50 values for females. Furthermore, laboratory tests showed that endosulfan had the highest selectivity to C. sinica and P. japonica: the selective toxicity ratios (STRs) were superior to other tested insecticides, particularly imidacloprid, and were 5.396 and 4.749-fold higher than baseline STRs, respectively. From this study, we conclude that fipronil can potentially be used to efficiently control A. lucorum. An alternative control agent worth consideration is endosulfan, owing to its relative safety to non-targeted natural enemies.
Phytohormones function as signal molecules that regulate physiological processes to protect plants from environmental stresses, including aphids’ attack. We studied the pattern within the defense mechanisms of soybean [Glycine max (L.) Merr. cv. “Nam Dan”] regarding the signaling pathways of salicylic acid (SA), and jasmonic acid (JA) in response to cowpea aphid (Aphis craccivora Koch). With infestation by cowpea aphid, SA was the first to accumulate and reached high levels 24 hours post-infestation (hpi). An accumulation of SA in the early response of soybean probably triggers inducible specific defense reactions. Following SA, JA was later induced and continuously increased to high levels 96 hpi. An accumulation of JA in the later response may be a critical step in the signaling of the downstream defense cascade. In addition, phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) and benzoic acid 2-hydroylase (BA2H), enzymes involved in the biosynthesis of SA, and lipoxygenase (LOX, EC 1.13.11.12), an important enzyme in the JA biosynthesis pathway, were also induced by cowpea aphid. The changes in the enzymatic activity of PAL, BA2H and LOX, and expression of gene encoding PAL were closely associated with the accumulation of endogenous SA and JA, respectively. The variations in the levels of these defense-related compounds were strongly connected with density and the duration of cowpea aphid infestation. Different accumulations of SA- and JA-signaling pathways may contribute to a coordinated regulation leading to the formation of resistant lines in the defense mechanisms of G. max cv. “Nam Dan” against A. craccivora.
The papers provides information about the third locality of Utecha lugens (Germ.) in Poland. This rare, European species was found in the xerothermic, antropogenic ecosystems of the city of Częstochowa. The key to the identification of Ulopidae occuring in Poland and distributional map of U. lugens are also given.
In the years 1999-2000 the studies on the population of true bugs colonizing the inflorescences of quinoa (Chenopodium quinoa Willd.) were conducted in Chrząstowo near Bydgoszcz. The dominating species was Lygus rugulipennis Popp. The species was recorded in 81.44% in 1999 and 83.64% in 2000 of all collected true bugs.
Auchenorrhyncha represents a group of sucking herbivores belonging to the hemipterans. They are an important component of terrestrial ecosystems, many species feed on a certain plant genus or even on one single plant species. In Poland, 514 species of Auchenorrhyncha have been recorded so far. From this number 135 species are recognized as rare, found only in a few places. Four species: Cicadetta montana (scop.), Cicadetta podolica (elchw.), Aphrophora major uhler and Aphrophora similis Leth. are endangered and should be protected. We suggest preserving xerothermic swards for Cicadetta montana and C. podolica, peatbogs and marshes for Aphrophora major and A. similis. A short morphological, ecological and chorological characteristics of these species are also given.
A list of 127 species of terrestrial true-bugs (Heteroptera) recorded from the Babia Góra Mountain is presented. 43 species are noted for the first time from the study area, among them 6 species rarely collected in Poland: Calocoris alpestris (MEYER-DÜR), Psallus piceae (REUTER), Orthops montanus (SCHILLING), Acompocoris alpinus REUTER, Myrmedobia exilis (FALLÉN), and Scolopostethus puberulus (HORVÁTH).
New faunistic data on the occurrence of terrestrial true-bugs in Ujście Warty National Park are presented. Field studies were carried out in four localities. In total, the paper presents the data concerning 39 species of Heteroptera.
Information on the occurrence of the species belonging to genus Tritomegas Amyot et Serville, 1843 (Heteroptera: Cydnidae) in north-western Poland is presented. Due to the reporting of Tritomegas sexmaculatus (Ramb.) from Pomerania Lake District, its northern border of range has been moved above 52°N. Photos facilitating the identification of both species are presented.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.