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981.
Laaksonen T Adamczyk F Ahola M Möstl E Lessells CK 《Behavioral ecology and sociobiology》2011,65(2):257-264
Female birds might be able to manipulate the parental effort of their male partner through elevated transfer of hormones to
the eggs, since these hormones affect many chick traits that males might use as cues for adjusting the level of their investment.
We experimentally studied whether female pied flycatchers Ficedula hypoleuca could manipulate male investment via yolk androgens. There is much more variation in yolk androgen levels between females
than within clutches, and in order to change the androgen levels of the eggs, we swapped whole clutches between nests. To
estimate the androgen levels of the clutch, we measured the androgen content of a single egg per clutch. Females did not succeed
in manipulating male effort using yolk androgens, since there was no relationship between the division of parental care within
a pair and either original or foster egg androgen levels. One of these relationships should have occurred if females were
manipulating males. The proportion of feeding visits by the male was higher when the male was old (55%) than when he was young
(45%) and females laid eggs with higher androgen levels when mated with a young male. Young males did not exhibit any responses
to yolk androgen levels either, which indicates that females cannot exploit their effort more than that of old males. We suggest
that females may allocate yolk androgens to adjust the growth trajectories of the chicks to poor growing conditions when mated
with young males that are poor providers or occupying a poor territory. 相似文献
982.
The social spider Anelosimus studiosus exhibits a behavioral polymorphism where colony members express either a passive, tolerant behavioral tendency (social) or
an aggressive, intolerant behavioral tendency (asocial). Here we test whether asocial individuals act as colony defenders
by deflecting the suite of foreign (i.e., heterospecific) spider species that commonly exploit multi-female colonies. We (1)
determined whether the phenotypic composition of colonies is associated with foreign spider abundance, (2) tested whether
heterospecific spider abundance and diversity affect colony survival in the field, and (3) performed staged encounters between
groups of A. studiosus and their colony-level predator Agelenopsis emertoni (A. emertoni)to determine whether asocial females exhibit more defensive behavior. We found that larger colonies harbor more foreign spiders,
and the number of asocial colony members was negatively associated with foreign spider abundance. Additionally, colony persistence
was negatively associated with the abundance and diversity of foreign spiders within colonies. In encounters with a colony-level
predator, asocial females were more likely to exhibit escalatory behavior, and this might explain the negative association
between the frequency of asocial females and the presence of foreign spider associates. Together, our results indicate that
foreign spiders are detrimental to colony survival, and that asocial females play a defensive role in multi-female colonies. 相似文献
983.
James?C.?MakinsonEmail author Benjamin?P.?Oldroyd Timothy?M.?Schaerf Wandee?Wattanachaiyingcharoen Madeleine?Beekman 《Behavioral ecology and sociobiology》2011,65(5):945-958
The Red Dwarf honeybee (Apis florea) is one of two basal species in the genus Apis. A. florea differs from the well-studied Western Hive bee (Apis mellifera) in that it nests in the open rather than in cavities. This fundamental difference in nesting biology is likely to have implications
for nest-site selection, the process by which a reproductive swarm selects a new site to live in. In A. mellifera, workers show a series of characteristic behaviors that allow the swarm to select the best nest site possible. Here, we describe
the behavior of individual A. florea workers during the process of nest-site selection and show that it differs from that seen in A. mellifera. We analyzed a total of 1,459 waggle dances performed by 197 scouts in five separate swarms. Our results suggest that two
fundamental aspects of the behavior of A. mellifera scouts—the process of dance decay and the process of repeated nest site evaluation—do not occur in A. florea. We also found that the piping signal used by A. mellifera scouts to signal that a quorum has been reached at the chosen site, is performed by both dancing and non-dancing bees in
A. florea. Thus, the piping signal appears to serve a different purpose in A. florea. Our results illustrate how differences in nesting biology affect the behavior of individual bees during the nest-site selection
process. 相似文献
984.
Robin?F.?A.?MoritzEmail author H.?Michael?G.?Lattorff Kendall?L.?Crous Randall?H.?Hepburn 《Behavioral ecology and sociobiology》2011,65(4):735-740
Workers of a queenless honeybee colony can requeen the colony by raising a new queen from a young worker brood laid by the
old queen. If this process fails, the colony becomes hopelessly queenless and workers activate their ovaries to lay eggs themselves.
Laying Cape honeybee workers (Apis mellifera capensis) produce female offspring as an additional pathway for requeening. We tested the frequency of successful requeening in ten
hopelessly queenless colonies. DNA genotyping revealed that only 8% of all queens reared in hopelessly queenless colonies
were the offspring of native laying worker offspring. The vast majority of queens resulted from parasitic takeovers by foreign
queens (27%) and invading parasitic workers (19%). This shows that hopelessly queenless colonies typically die due to parasitic
takeovers and that the parasitic laying workers are an important life history strategy more frequently used than in providing
a native queen to rescue the colony. Parasitism by foreign queens, which might enter colonies alone or accompanied by only
a small worker force is much more frequent than previously considered and constitutes an additional life history strategy
in Cape honeybees. 相似文献
985.
In the absence of predators, pollinators can often maximize their foraging success by visiting the most rewarding flowers.
However, if predators use those highly rewarding flowers to locate their prey, pollinators may benefit from changing their
foraging preferences to accept less rewarding flowers. Previous studies have shown that some predators, such as crab spiders,
indeed hunt preferentially on the most pollinator-attractive flowers. In order to determine whether predation risk can alter
pollinator preferences, we conducted laboratory experiments on the foraging behavior of bumble bees (Bombus impatiens) when predation risk was associated with a particular reward level (measured here as sugar concentration). Bees foraged in
arenas containing a choice of a high-reward and a low-reward artificial flower. On a bee’s first foraging trip, it was either
lightly squeezed with forceps, to simulate a crab spider attack, or was allowed to forage safely. The foragers’ subsequent
visits were recorded for between 1 and 4 h without any further simulated attacks. Compared to bees that foraged safely, bees
that experienced a simulated attack on a low-reward artificial flower had reduced foraging activity. However, bees attacked
on a high-reward artificial flower were more likely to visit low-reward artificial flowers on subsequent foraging trips. Forager
body size, which is thought to affect vulnerability to capture by predators, did not have an effect on response to an attack.
Predation risk can thus alter pollinator foraging behavior in ways that influence the number and reward level of flowers that
are visited. 相似文献
986.
Sexually deceptive orchids of the genus Ophrys attract male insects for pollination. Pollinator attraction is achieved by mimicking sex pheromones of virgin females of
their pollinators, mostly bee species. In earlier investigations, we showed that the phylogenetically distinct Ophrys species O.
chestermanii and O. normanii on Sardinia attract their pollinator, males of the cuckoo bumblebee B. vestalis, with the same bouquets of relatively polar volatile compounds. In this investigation, we studied the sex pheromone of virgin
females of B. vestalis with the aim of identifying male-attracting compounds and of comparing them with labellum extracts of the two orchids, which
were found to release male-attracting compounds in earlier investigations (G?gler et al. 2009). In bioassays, shock-frozen females, cuticle extracts and polar fractions of cuticle extracts of virgin females stimulated
mating behaviour in the males. Using gas chromatography coupled with electroantennography (GC-EAD) and gas chromatography
coupled with mass spectrometry (GC-MS), we detected in polar fractions of cuticle extracts of B. vestalis females the same electrophysiologically active compounds as in labellum extracts of both orchid species, including aldehydes,
esters, fatty acids and alcohols. Since statistical comparisons of the relative proportions of esters showed strong similarities
between virgin females and orchids, our results support the hypotheses that this highly specialized Ophrys–pollinator relationship represents another case of chemical mimicry and that esters play a key role in male attraction. 相似文献
987.
Zohra Belala Mejdi Jeguirim Meriem Belhachemi Fatima Addoun Gwena?lle Trouv�� 《Environmental Chemistry Letters》2011,9(1):65-69
The removal of toxic metals from wastewaters by biosorption, based on the metal-binding capacities of various biological materials,
has received much interest. However, the success of this approach depends on economic feasibility, which can be obtained by
optimization of the environmental conditions. This paper evaluates, for the first time, the use of low-cost biosorbent (date
stones (DS) and palm-tree waste (PTW)) to eliminate Cu(II) from aqueous solutions. The effect of some parameters on copper
biosorption has been studied using date stones and palm-tree waste as solid sorbents. Results show that the highest percentage
of copper adsorption was obtained for the smallest size of the sorbent particles. The biosorption process was found to occur
rapidly, i.e. the maximum sorption capacity was reached within 20 min. The process involved pseudo-second-order kinetics with
an activation energy value within the normal range considered for processes, where a physical interaction between the sorbate
and the sorbent solid predominated. The thermodynamic parameters of the copper ions uptake onto the solid sorbents indicated
that, the process was endothermic and proceeds spontaneously from the date stones. However, the thermodynamic studies of the
adsorption of copper on palm-tree waste indicated that the process was exothermic and proceeds spontaneously. 相似文献
988.
Rapid incorporation and short-term distribution of a nonylphenol isomer and the herbicide MCPA in soil-derived organo-clay complexes 总被引:1,自引:0,他引:1
Patrick Riefer Timm Klausmeyer Jan Schwarzbauer Andreas Sch?ffer Burkhard Schmidt Phillipe F. X. Corvini 《Environmental Chemistry Letters》2011,9(3):411-415
Organo-clay complexes in soil are a major sink for xenobiotics and, thus, often enhance their persistence dramatically. However,
the knowledge on environmental processes of non-extractable residue formation on a short time scale is very restricted. Therefore,
this study examined the distribution of 4-(3,5-dimethylhept-3-yl)phenol (NP) and 4-chloro-2-methylphenoxyacetic acid (MCPA)
in soil over a short time period of 48 h and in different soil sub-fractions. The overall proportion of organo-clay-associated
bound residues was not only abundant but also in the same range for both substances (MCPA: 8%; NP: 11% of applied 14C-radioactivity). However, a more detailed view revealed two different distribution patterns: a higher proportion of clay-associated
NP was accompanied by a lower content of bound residues, whereas a smaller fraction of clay-associated MCPA was characterized
by a higher proportion of non-extractable residues. Further on, a selective accumulation of bound residues among clay-associated
humic fractions was observed. NP residues were linked predominantly to humic acids, whereas MCPA residues tended to be incorporated
more into fulvic acids. It was evident that the overall distribution was influenced primarily by the physico-chemical properties
of the contaminants. This study demonstrates in detail a rapid initial incorporation accompanied by a specific distribution
into soil sub-fractions for selected xenobiotics in soil and points to a complex interaction of clay-associated organic matter
with low molecular weight compounds. 相似文献
989.
Pedro Gon?alves Rodrigues Lu��s Moreira Gon?alves Paulo Jorge Magalh?es Jo?o Grosso Pacheco Jos�� Ant��nio Rodrigues Aquiles Ara��jo Barros 《Environmental Chemistry Letters》2011,9(3):405-410
An major research area in environmental chemistry is the development of methods for the analysis of biomarkers. Metallothioneins
are used as biomarkers in studies of heavy metals exposure in water, because metallothioneins are synthesized and accumulated
when organisms are exposed to toxic concentrations of pollutants. In this work, simple and sensitive voltammetric methods
were developed for metallothionein and copper (II) determinations in fish liver Lepomis gibbosus. Both analytical methodologies were optimized and applied to samples extracted from individuals previously submitted to sub-lethal
toxicological trials with copper sulphate (CuSO4) and cadmium chloride (CdCl2). The obtained results showed that both methods are very precise, sensitive, and involve simple sample preparation processes.
Moreover, metallothioneins showed better correlation with the toxic exposure than Cu2+. To the best of our knowledge, this is the first time that hepatic metallothioneins and Cu2+ contents are voltammetrically determined in order to be compared in their function as heavy metal biological indicators. 相似文献
990.
Modified ��-cyclodextrins as prospective agents for improving water solubility of organic pesticides
The drawback of some organic pesticides is their low water solubility. Cyclodextrins are used as agents for improving pesticides
water solubility. However, the stabilization of the crystalline lattice can reduces to a large extent the solubility of cyclodextrins,
especially β-cyclodextrin. Here, searching for the water soluble β-cyclodextrin derivatives, a set of new “host” compounds
were prepared by the reaction of β-cyclodextrin with methyl epoxycinnamate. The reactants ratio was varied in to study the
substitution degree of the obtained derivatives. The structure was determined by the 1H-NMR and FT IR spectra. The average degree of substitution was determined by integration of the corresponding NMR signals
and by elemental analysis. The solubility of four selected pesticides: dimethoate, simazine, linuron and thiram, in water
with and without addition of the new modified β-cyclodextrin was measured by ultraviolet spectrophotometry. Our results showed
that the modified β-cyclodextrins significantly improve solubility of pesticides. 相似文献