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22. Host spatial pattern influences induction of parasitization by Trichogramma (Hymenoptera: Trichogrammatidae)

Creator:
Voinovich, Nataliya D., Umarova, Taisiya Ya., and Sergey Ya.
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Type:
article, bibliography, model:article, and TEXT
Subject:
zoologie, entomologie, hmyz, blanokřídlí, Trichogrammatidae, Trichogramma principium, samičky, parasitizmus, Sitotroga cerealella (hostitel), vajíčka hostitele, uspořádání vajíček, vztahy, 591.5, 576, and 595.2/.7
Language:
English
Description:
The influence of host intrapatch spatial distribution on parasitoid host acceptance behavior was investigated with Trichogramma principium parasitizing eggs of grain moth, Sitotroga cerealella. Single females were placed in Petri dishes, each containing 60 host eggs arranged either as a compact patch or partitioned into 60 or 12 clusters each consisting of 1 or 5 eggs, respectively. Partitioned patches provoked parasitization more often than compact patches. The percentage of ovipositing females (i.e., females parasitizing at least one of 60 host eggs) increased with the number of clusters, while it was independent of the intercluster distance over intervals of 2.5-15 mm. The mean number of eggs parasitized by ovipositing females during 48 h was almost independent of the host egg spatial pattern. As a result, the rate of parasitization was higher when the hosts were sparsely distributed within a patch than when they were aggregated., Nataliya D. Voinovich, Taisiya Ya. Umarova, Sergey Ya. Reznik, and Lit
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23. Host-plant mediated influences on population development of Sitobion avenae (Sternorrhyncha: Aphididae)

Creator:
Alois Honěk and Martinková, Zdenka
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Type:
article, bibliography, conference publication, model:article, and TEXT
Subject:
Third European Workshop of Invertebrate Ecophysiology (1998 : Birmingham, Česko), zoologie, fyziologie živočichů, ekofyziologie, hmyz, Aphididae, Sitobion avenae, vývoj populace, hostitelské rostliny, obilniny, ozimá pšenice, vliv kultivaru, vliv hustoty porostu, 591.5, 061.3, and 595.2/.7
Language:
English
Description:
We investigated the effects of genetic differences and host plant density on population development of the rose-grain aphid Sitobion avenae (F.) (Sternorrhyncha: Aphididae) in winter wheat stands. Aphid numbers on ears were recorded on 11 cultivars (6 years) and on plots where crop density was varied by thinning (12 years). Crop density significantly affected whole plant, tiller and ear mass, number of tillers, and leaf area and chlorophyll content. The duration and rate of aphid population growth, and the maximum numbers of aphids were ascertained by weekly counts. Maximum abundances increased with the length of time available for the growth of aphid populations while the rate of population growth was less important. Variation of maximum numbers of S. avenae on different cultivars was not significant, probably due to the small variation in the period available for the development of aphid populations. By contrast, there was a significant Variation of aphid performance associated with host plant density. Aphid populations on solitary plants persisted longer and became more abundant than in dense stands. The prolonged survival of aphid populations was probably caused by an extended period of tillering and lower average age of tillers of solitary plants. There was large annual variation in aphid abundance. It is likely that modifications of host plant development caused by differences in winter weather may contribute to this variation., Alois Honěk, Zdenka Martinková, and Lit
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24. Hybridisation between Aphis grossulariae and Aphis schneideri (Sternorrhyncha: Aphididae): An experimental approach

Creator:
Rakauskas, Rimantas
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Type:
article, bibliography, model:article, and TEXT
Subject:
zoologie, entomologie, hmyz, Sternorrhyncha, Aphididae, Aphis grossulariae, Aphis schneideri, hybridizace, laboratorní pokusy, 595.2/.7, and 591.1
Language:
English
Description:
A. schneideri and A. grossulariae clones from southern Poland produced fertile hybrid eggs under experimental conditions. Established hybrid clones expressed normal parthenogenetic reproduction but bisexual generations were not obtained, though a few sexuales developed in some cases. Morphological features of A. schneideri and host-specificity of A. grossulariae tended to dominate in the majority of hybrid clones. Independent inheritance of the studied morphological characters and host specificity can therefore be presumed. Present results do not exclude the possibility of natural hybridisation of studied aphid species. Natural crosses might cause taxonomic and currant pest management problems., Rimantas Rakauskas, and Lit
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25. Immunocytochemical distribution of angiotensin-I converting enzyme in the central nervous system of insects and speculations about its possible function

Creator:
De Loof, Arnold, Isaac, , Elwyn, Salzet, Michel, Huybrechts, Roger, Veelaert, Dirk, Schoofs, Liliane, Macours, Nathalie, and Vandingenen, Anick
Format:
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Type:
article, bibliography, model:article, and TEXT
Subject:
zoologie, entomologie, hmyz, Locusta migratoria, corpus cardiacum, pars intercerebralis, neuropeptidy, angiotensin-I převodní enzym, funkce, rozšíření, imunocytochemické stanovení, 595.2/.7, and 591.1
Language:
English
Description:
Insect peptidyl-dipeptidase A [angiotensin I - converting enzyme (ACE)] is a soluble single-domain peptidyl-dipeptidase that has many properties in common with the C-domain of mammalian somatic ACE and with the single-domain mammalian ACE. In agreement with a variety of insects, immunocytochemical studies reveal the presence of an ACE-like protein in Locusta migratoria. ACE-like immunoreactivity is present in neurosecretory cells of the pars intercerebralis. These cells have axons projecting into the nervus corporis cardiaci I and into the storage part of the corpus cardiacum, a neuroendocrine organ directly releasing into the aorta. The localisation of ACE in neurosecretory cells is consistent with its proposed role as a processing enzyme that is involved in the generation of active peptide hormones., Dirk Veelaert, Liliane Scoofs, Nathalie Macours, Anick Vandingenen, Arnold De Loof, Elwyn Isaac, Michel Salzet, Roger Huybrechts, and Lit
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26. Immunolocalization of two types of allatostatins in the central nervous system of the cricket Gryllus bimaculatus (Ensifera: Gryllidae)

Creator:
Witek, Günther, Verhaert, Peter, Lorenz, Matthias W., and Hoffmann, Klaus H.
Format:
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Type:
article, bibliography, model:article, and TEXT
Subject:
zoologie, fyziologie živočichů, hmyz, Gryllidae, Gryllus bimaculatus, centrální nervový systém, neuropeptidy, allatostatiny, lokalizace, stanovení, imunocytochemické metody, 595.2/.7, and 591.1
Language:
English
Description:
Two anti-peptide antisera (anti-A and anti-B) raised against Gryllus bimaculatus allatostatin A1 (Grb-AST A1) and B1 (Grb-AST B1), respectively, were applied in the peroxidase-antiperoxidase (PAP) immunohistochemical technique on complete series of sections from the brain, suboesophageal ganglion, corpora cardiaca (CC), and corpora allata (CA) of G. bimaculatus. Both antisera yielded intense staining of numerous cells and nerve fibres. Serial sections, alternately stained with anti-A and anti-B confirmed that the anti-B generally stained more cells and nerves. Extensive immunoreactivity in the retrocerebral complex suggests that the CC and CA may represent a storage and/or release site for both allatostatin types or allatostatin-like molecules produced in the brain., Günther Witek, Peter Verhaert, Matthias W. Lorenz, Klaus H. Hoffmann, and Lit
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27. Impacts and responses at population level of herbivorous insects to elevated CO2

Creator:
Whittaker, John B.
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Type:
article, bibliography, conference publication, model:article, and TEXT
Subject:
Third European Workshop of Invertebrate Ecophysiology (1998 : Birmingham, Česko), zoologie, fyziologie živočichů, ekofyziologie, hmyz, herbivorní hmyz, populace, životní cyklus, klimatické změny, oxid uhličitý, vliv CO2, 591.5, 061.3, and 595.2/.7
Language:
English
Description:
Most studies of responses of insects to elevated carbon dioxide have been made using short-term exposures to treated food plants and have involved measurements of responses in growth, reproduction, food consumption and efficiencies of conversion at specific stages in the life cycle. These will be reviewed in the light of longer-term studies recently published where whole generations have been reared in chambers with simultaneous treatment of plants and where insects have been free to select their food and microenvironment. Factors such as seasonal change in plants, choice of food plant, mode of feeding, timing of exposure, temperature, the role of natural enemies are considered and the whole placed in the context of other aspects of climate change. It is concluded that in studies to date, the only feeding guild in which some species have shown increases in population density in elevated carbon dioxide are the phloem feeders. Chewing insects (both free-living,and mining) generally have shown no change or reduction in abundance, though relative abundance may be greatly affected. Compensatory feeding is common in these groups., John B. Whittaker, and Lit
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28. Insect cold tolerance: How many kinds of frozen?

Creator:
Sinclair, Brent J.
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Type:
article, bibliography, conference publication, model:article, and TEXT
Subject:
Third European Workshop of Invertebrate Ecophysiology (1998 : Birmingham, Česko), zoologie, fyziologie živočichů, ekofyziologie, hmyz, tolerance k chladu, tolerance k mrazu, netolerance k mrazu, teplotní strategie, 591.5, 061.3, and 595.2/.7
Language:
English
Description:
Insect cold tolerance mechanisms are often divided into freezing tolerance and freeze intolerance. This division has been criticised in recent years; Bale (1996) established five categories of cold tolerance. In Bale's view, freezing tolerance is at the extreme end of the spectrum of cold tolerance, and represents insects which are most able to survive low temperatures. Data in the literature from 53 species of freezing tolerant insects suggest that the freezing tolerance strategies of these species are divisible into four groups according to supercooling point (SCP) and lower lethal temperature (LLT): (1) Partially Freezing Tolerant-species that survive a small proportion of their body water converted into ice, (2) Moderately Freezing Tolerant-species die less than ten degrees below their SCP, (3) Strongly Freezing Tolerant-insects with LLTs 20 degrees or more below their SCP, and (4) Freezing Tolerant Species with Low Supercooling Points which freeze at very low temperatures, and can survive a few degrees below their SCP. The last 3 groups can survive the conversion of body water into ice to an equilibrium at sub-lethal environmental temperatures. Statistical analyses of these groups are presented in this paper. However, the data set is small and biased, and there are many other aspects of freezing tolerance, for example proportion of body water frozen, and site of ice nucleation, so these categories may have to be revised in the future. It is concluded that freezing tolerance is not part of Bale's (1996) continuum, but rather a parallel, alternative strategy of cold tolerance., Brent J. Sinclair, and Lit
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29. Intertidal respiration of Anurida maritima (Collembola: Neanuridae)

Creator:
Rüssbeck, Raimund, Biefang, Marc, Baumgärtl, Horst, and Zinkler, Dietmar
Format:
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Type:
article, bibliography, conference publication, model:article, and TEXT
Subject:
zoologie, fyziologie živočichů, ekofyziologie, Collembola, Anurida maritima, dýchání, hypoxie, adaptace na stres, regulace dýchání, 591.5, 061.3, and 595.2/.7
Language:
English
Description:
The intertidal collembolan Anurida maritima can endure periods of twice-daily submergence by seawater. The air-breathing terrestrial apterygote insect has developed specific adaptations to prevent respiratory failure during hypoxic stress. When submerged, the animal is initially enclosed by an air-bubble. This bubble lasts three times longer than the small amount of stored oxygen would allow. The air bubble acts not only as an oxygen store but also as a compressible gas gill. This was demonstrated by an O2-needle electrode technique which allowed recordings of pO2 changes in the watery medium close to the animal. Oxygen uptake in A. maritima follows an aerial mode of respiration during the first three hours of submergence. Oxygen consumption rate at decreasing ambient O2 partial pressures showed oxyregulating behaviour during severe hypoxia., Dietmar Zinkler, Raimund Rüssbeck, Marc Biefang, Horst Baumgärtl, and Lit
Rights:
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30. Intracellular calcium in PTTH-stimulated prothoracic glands of Manduca sexta (Lepidoptera: Sphingidae)

Creator:
Birkenbeil, Heiner
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Type:
article, bibliography, model:article, and TEXT
Subject:
zoologie, fyziologie živočichů, hmyz, motýli, Sphingidae, Manduca sexta, prothorakální žlázy, ekdysteroidy, syntéza, stimulace, vápník, 595.2/.7, and 591.1
Language:
English
Description:
Larval Manduca prothoracic gland cells in vitro responded to prothoracicotropic hormone (PTTH) from neurosecretory cells of the brain with an increase of intracellular free calcium. This effect is reversible and dose-dependent. Preincubation of the glands with TMB-8 and dantrolene, which inhibit the release of calcium from intracellular stores, did not decrease the PTTH-stimulated increase in calcium, indicating that intracellular calcium stores are not involved in the control of ecdysteroidogenesis. Pharmacological studies of the PTTH effect with calcium channel blockers revealed that the increase in calcium was totally blocked by cadmium, partially inhibited by nickel and lanthanum and by amiloride, an antagonist of T-type calcium channels. All other inhibitors tested were ineffective, suggesting that the increase in cytosolic calcium is induced by opening of calcium channels, presumably of the T-type, in response to PTTH. The action of PTTH on these channels may be mediated by a G-protein as shown by the effect of mastoparan, a G-protein activator, which increased the concentration of cytosolic calcium comparable to that evoked by PTTH., Heiner Birkenbeil, and Lit
Rights:
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