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Cage Experiments (cage + experiment)

Distribution by Scientific Domains

Life Sciences	100%

Distribution within Life Sciences

Entomology	44%
Ecology & Organismal Biology	33%

Selected Abstracts

The importance of scent and nectar filters in a specialized wasp-pollination system

FUNCTIONAL ECOLOGY, Issue 5 2009
Adam Shuttleworth
Summary 1.,Plants with open flowers and exposed nectar should attract a wide diversity of flower visitors, yet, for reasons that are not yet well understood, some plants with these ,generalist' floral traits have highly specialized pollination systems. 2.,We investigated this problem in the African milkweed Pachycarpus grandiflorus which has open flowers that produce copious amounts of exposed and concentrated nectar, yet is visited almost exclusively by spider-hunting wasps in the genus Hemipepsis. 3.,These wasps were the only visitors found to consistently carry pollinaria and a cage experiment showed that they are capable of successfully pollinating this plant. Furthermore, experimental hand-pollinations showed that P. grandiflorus is genetically self-incompatible and thus reliant on pollinators for seed set. 4.,We investigated the roles of chemical (nectar and floral scent) and spectral properties in the selective attraction of wasps and the filtering out of other potential flower visitors. Nectar palatability experiments showed that the nectar is unpalatable to honeybees but palatable to the wasps. Choice experiments conducted in the field and using a Y-maze in the laboratory showed that wasps are attracted primarily by scent rather than visual cues. Analysis of scent using Gas Chromatography-Mass Spectrometry showed that these inflorescences produce 36 different compounds, mostly monoterpenes and aliphatics. Analysis of spectral reflectance showed that flowers have similar colouring to the background vegetation. 5.,We conclude that P. grandiflorus is specialized for pollination by Hemipepsis wasps, and in the absence of morphological filters, achieves specialization through unpalatable nectar, cryptic colouring and scent as a selective pollinator attractant. 6.,This study demonstrates that plants whose flowers are not morphologically adapted to exclude particular floral visitors can achieve specialization through non-morphological filters. [source]

Fragrances, male display and mating behaviour of Euglossa hemichlora: a flight cage experiment

PHYSIOLOGICAL ENTOMOLOGY, Issue 4 2003
Thomas Eltz
Abstract., Male euglossine bees (Apidae: Euglossini) collect volatile substances (fragrances) from floral and nonfloral sources and store them in hair-filled cavities in their hind tibiae. Over time, males accumulate large quantities of complex and species-specific blends of fragrances. Various hypotheses have been put forward to explain this behaviour, including the idea that fragrance stores reflect the genetic quality of individual males and have evolved through sexual selection and female choice. Clear support of this hypothesis is lacking, largely because male,female interactions are both rare and difficult to observe in nature. Here, we report a flight cage experiment performed in Panama that permitted mating between virgin females (raised from brood cells) and males captured in the forest at fragrance baits. In the cage, eight individually marked males defended small territories around vertical perch sites and showed a characteristic display, which included a previously unreported ,leg-crossing' movement, possibly related to fragrance release. A total of six copulations and three copulatory attempts by Euglossa hemichlora were observed and partly recorded on video. The copulations, all of which were initiated by the female landing on a male perch, were short (4,10 s) and showed no signs of the transfer of chemical substances from male to female. In some cases, the male hovered directly over the female before descending to mount her, possibly facilitating fragrance evaluation by the female. After the experiment, the contents of the males' hind legs were analysed by gas chromatography-mass spectroscopy, which detected complex mixtures of terpenoids and aromatics (totalling 70 different compounds) dominated by hexahydrofarnesyl acetone, farnesene epoxide, ocimene and p -dimethoxy benzene. Individual total amounts of fragrances were neither related to display activity or perch occupancy by given males, nor to the frequency of matings achieved. Display activity was the only positive correlate of mating frequency. Generally, individuals had uniformly large amounts of stored fragrances in comparison to a previous study of three other species of Panamanian Euglossa. [source]

Biological performance of Myzus persicae and Macrosiphum euphorbiae (Homoptera: Aphididae) on seven wild Solanum species

ANNALS OF APPLIED BIOLOGY, Issue 3 2010
Y. Pelletier
Resistance level of seven accessions of wild Solanum species (Solanaceae) to Myzus persicae and Macrosiphum euphorbiae (Homoptera: Aphididae) was evaluated by measuring survival and fecundity during sleeve cage experiments and population growth on whole plants in a controlled environment. The survival was lowest on the Solanum circaeifolium spp. capsicibaccatum, Solanum pinnatisectum and Solanum trifidum accessions for M. persicae and on the S. circaeifolium spp. capsicibaccatum, Solanum okadae and S. trifidum, accessions with M. euphorbiae. Plant species significantly influenced the fecundity of both aphid species. Aphid population growth on whole plants was negatively affected by the age of the plant, but generally followed the levels of net reproductive rate on different plant species observed during the sleeve cage experiment. The population of M. persicae varied among the seven wild potato accessions with the lowest growth rates on S. circaeifolium spp. capsicibaccatum, Solanum polyadenium, Solanum tarijense and S. trifidum. The number of M. euphorbiae also varied among accessions but the smallest population was collected from S. polyadenium. The results can be used to identify sources of resistance to aphids within those accessions already known to be resistant to the Colorado potato beetle. This study highlights the difficulties involved in developing a high-throughput screening test for aphid resistance compatible with a potato breeding programme. [source]

Community effects of praying mantids: a meta-analysis of the influences of species identity and experimental design

ECOLOGICAL ENTOMOLOGY, Issue 4 2002
William F. Fagan
Abstract ,1. Generalist arthropod predators are ubiquitous in terrestrial ecosystems but experimental studies have yielded little agreement as to their effects on prey assemblages. Drawing on results from a suite of experimental field studies, a meta-analysis was conducted of the impact of praying mantids (Mantodea: Mantidae) on arthropod assemblages in order to identify predictable and unpredictable effects of these extremely generalised predators. 2. Results across different experiments were synthesised using the log response ratio framework, with a focus on quantifying net mantid impacts on arthropod density across taxonomic orders and trophic levels of arthropods, paying special attention to the contribution of mantid species identity and experimental design variables, such as the use of cages, length of experiment, and manipulated mantid density. 3. Calculated on a per mantid-day basis, the net impacts of Tenodera sinensis on arthropod density were generally weaker but more predictable than the effects of Mantis religiosa. Mantids in general had weak negative effects on density for most taxa but exhibited strong negative and positive effects on some taxa. Tenodera sinensis tended to have negative effects on Homoptera, Diptera, and Hemiptera and herbivores as a group, however M. religiosa exhibited greater variation in response of different taxa that appeared to be affected more strongly by experimental design. The effects of Stagmomantis carolina tended to be negative or non-significant. 4. Experimental cages had little influence on either the sign or magnitude of net community impacts for T. sinensis, however cage experiments reversed the sign of the mean effect for two of six taxonomic orders when the experimental predator was M. religiosa. Cages also increased the variability of effect size greatly for M. religiosa but not for T. sinensis. 5. It was concluded that it is possible to use log response ratios to determine general, predictable trends in a well-studied system. Similar meta-analyses of generalist predator effects in other systems should produce predictions of how these predators influence food webs, an important step towards defining more clearly the influences of generalist predators on community structure and dynamics. [source]

Factors influencing the effectiveness of an attracticide formulation against the Oriental fruit moth, Grapholita molesta

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2004
Maya L. Evenden
Abstract An attracticide formulation, LastCallÔOFM, was tested against the Oriental fruit moth Grapholita molesta (Busck) (Lepidoptera: Tortricidae) in replicated small plot field trials in apple, Malus domestica (Borkhausen), orchards in South-eastern Pennsylvania, USA. Attracticide treatments were applied using a calibrated hand pump, and treated plots were compared to similar untreated plots. Male moth activity was monitored using virgin female-baited traps, and the potential for reduction in mating activity was assessed using sentinel virgin females. A comparison of application rates showed that 1500 droplets per ha of the attracticide formulation was as effective as 3000 droplets per ha, and both application rates reduced captures in synthetic pheromone-baited traps for prolonged periods. Droplets placed either at high or low positions within the canopy significantly reduced trap capture and mating with sentinel females. In addition, the only sentinel females that mated in the treated plots were located in the untreated portion of the tree canopy. Mate finding behaviour was equally disrupted by formulations with and without insecticide. Therefore, under the test conditions, the mechanism by which the attracticide formulation worked was by disruption of male orientation, and not by the removal of males due to insecticide poisoning. Two field cage experiments tested the impact of population density on the competitiveness of the attracticide formulation compared to virgin females. A significant proportion of males were captured in female-baited traps at the highest female-to-droplet ratio tested. Equal proportions of males were captured in attracticide-baited traps at male moth densities of 10, 20, 40, and 80 males per cage. These results clarify some of the factors influencing the effectiveness and possible mechanisms of an attracticide management tactic against the Oriental fruit moth. [source]

Coupling long-term studies with meta-analysis to investigate impacts of non-native crayfish on zoobenthic communities

FRESHWATER BIOLOGY, Issue 2 2006
JULIA M. MCCARTHY
Summary 1. Biological invasions are widely recognised as a significant component of human-caused environmental change and a primary threat to native biodiversity. The negative impacts of species invasions are particularly evident for freshwater crayfish faunas. 2. This study provides novel insight into the ecological effects of native and non-native crayfish on zoobenthic communities (with emphasis on the non-native rusty crayfish, Orconectes rusticus) across broad scales by combining a meta-analysis of small-scale experimental studies with a long-term observational study conducted over a 24 year period in Sparkling Lake, Wisconsin, U.S.A. (46°00,N, 89°42,W). 3. The meta-analysis summarised quantitatively the results of cage experiments for seven species of crayfish spanning four continents. We found that total zoobenthos densities (primarily Gastropoda and Diptera) were significantly lower in treatments containing crayfish relative to controls; a result that was significant for non-native crayfish but not for crayfish in their native range, perhaps owing to a small sample size. In contrast to other species, rusty crayfish were also negatively associated with Ephemeroptera. 4. Results from the time series analysis comparing temporal trends in rusty crayfish and invertebrate abundances from Sparkling Lake were consistent with the findings from the meta-analysis. Rusty crayfish were negatively correlated with the abundance of total zoobenthos, Diptera, Ephemeroptera and Odonata, as well as families of Trichoptera. 5. By coupling the results from short and long-term research, our study offers greater insight into the nature of crayfish-invertebrate interactions in aquatic systems, revealing consistent effects of invasive crayfish on native fauna. The control and management of invasive species is facilitated by the knowledge that well executed small-scale studies may be extrapolated to understand larger-scale ecological interactions. [source]

The interaction between bird predation and plant cover in determining habitat occupancy of darkling beetles

OIKOS, Issue 1 2001
Elli Groner
Tenebrionid beetles in the Negev Desert exhibit size-related habitat segregation, with larger species found in denser cover. Size-dependent predation by birds has been suggested as the mechanism behind this habitat segregation. Two predictions of this hypothesis were tested: (1) plant cover reduces the predation efficiency of birds upon large tenebrionids, and (2) birds prefer larger species. Both predictions were supported: plant cover reduced predation rate by the most common spring and summer predatory birds: white storks (Ciconia ciconia) and stone curlews (Burhinus oedicnemus), in cage experiments. Results from preference experiments suggest that tenebrionid species can be divided according to their profitability as prey. Large species are the most profitable, medium-sized species are less profitable but still acceptable and small species are unprofitable and therefore ignored. Field observations demonstrated that the well-vegetated wadi habitats are dominated by large and small species whereas acceptable, medium-sized species are under-represented in this habitat. The results of the cage experiments indicate possible apparent competition between the large profitable and the medium acceptable tenebrionid species in the wadis. Aggregative response of predators in the profitable habitat is suggested as the mechanism leading to truncated distribution of prey species. Large profitable species are refuge-dependent, medium-sized acceptable species use enemy free space and small species are predator independent. [source]