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Darryl T. Gwynne Winston J. Bailey Amanda Annells 《Behavioral ecology and sociobiology》1998,42(3):157-162
In katydids such as Kawanaphilanartee, a female bias in the operational sex ratio (OSR) results in female competition for mates and male choice of mates. Previous
work showed that the excess of sexually active females occurs when food availability is low, in part because less food increases
the propensity of females to mate as they forage for the large edible spermatophores produced by males. In this study with
K.nartee, a pollen-feeding species, we estimate natural variation in numbers of sexually active males and females by assessing male
calling activity and the propensity of females to respond to experimental calling males. We found an excess of sexually active
males at a site with many flowers and an excess of sexually active females at a site with few flowers about 900 m away. Between-site
differences in gut masses of calling males were consistent with the hypothesis that pollen availability controls OSR. Finally,
at a third site where flowers were at first scarce, we found that the initial excess in sexually active females changed to
an excess of sexually active males after a clump of grass-trees flowered. The mean gut mass of all sampled males from this
site increased after flowering. The large variation in OSR that we document for K. nartee highlights the importance of identifying the appropriate spatial and temporal scales over which OSRs are measured in studies
of factors controlling sexual selection.
Received: 13 May 1997 / Accepted after revision: 27 October 1997 相似文献
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Bushcricket song structure and predation by the acoustically orienting parasitoid fly Therobia leonidei (Diptera: Tachinidae: Ormiini) 总被引:2,自引:0,他引:2
Gerlind U. C. Lehmann Klaus-Gerhard Heller 《Behavioral ecology and sociobiology》1998,43(4-5):239-245
Males of most bushcricket species produce acoustic advertisement signals to attract females for mating. These signals can
also increase conspicuousness to predators. In the genus Poecilimon (Orthoptera: Phaneropterinae) males are attacked by the parasitoid fly Therobia leonidei (Diptera: Tachinidae: Ormiini) which locates males by their calls. In Greece T.leonidei parasitizes several Poecilimon species with different song structures: we examined whether host choice is related to song structure by comparing parasitism
rates in two closely related Poecilimon species. One of these species produces monosyllabic songs, the songs of the other species being polysyllabic. The tachinid
fly parasitized the polysyllabic species to a greater extent. We demonstrate in a field-experiment that this preference for
the polysyllabic species does not depend on local adaptations of the fly. The most probable explanation for the preference
of the fly for the polysyllabic singing species seems to be better detection of longer songs. This result is discussed in
the context of male song evolution.
Received: 4 November 1997 / Accepted after revision: 22 March 1998 相似文献
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Summary We tested the role of a grasshopper defensive secretion in deterring lizard predation. Adults, but not young larvae, of the chemically defended lubber grasshopperRomalea guttata (=microptera) froth a volatile secretion when attacked by predators. The lizardAnolis carolinensis failed to strike juvenile lubbers (which lack secretion) in laboratory trials. Survivorship of palatable crickets loaded with secretion offered toA. carolinensis was not significantly different from survivorship of control crickets. In experiments designed to investigate if lizards learn an aversion to the secretion, striking times forSceloporus undulatus fed wax worms coated with secretion were not significantly different over three days of trials. Three primary conclusions are drawn from these data. First, the secretion may not be necessary for lubber protection from lizards. Second, lubber secretion does not appear to deter lizards from attacking or eating prey items. Third, lizards do not appear to develop an aversion to the secretion. 相似文献
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Donald E. Champagne Murray B. Isman Kelsey R. Downum G. H. Neil Towers 《Chemoecology》1993,4(3-4):165-173
Summary Thirty-one species in twenty genera of the plant family Meliaceae were assayed for the production of growth-inhibiting phytochemicals, using the generalist herbivorePeridroma saucia. Most species were inhibitory when methanolic extracts were incorporated into artificial diets at concentrations at or below those occurring naturally. In general members of the subfamily Melioideae were more inhibitory than members of the Swietenioideae. Extracts of deciduous species with short leaf lifetimes were significantly more inhibitory than those of evergreen species with longer leaf lifetimes. In a smaller sample of species, evergreen species showed a trend towards having tougher leaves than deciduous species. These results support the resource availability hypothesis of Coleyet al. (1985), and suggest that life history attributes may be of some value in selecting plants for phytochemical prospecting. 相似文献
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Spermatophore characteristics in bushcrickets vary with parasitism and remating interval 总被引:4,自引:0,他引:4
Male bushcrickets provide females with a nuptial gift, a spermatophore, which is transferred to females at mating. The spermatophore
consists of a gelatinous mass, the spermatophylax, and the sperm-containing ampulla. Male spermatophore size is positively
correlated with insemination rate and female refractory period and therefore with male reproductive success. In this study,
we examined spermatophylax weight, ampulla weight and sperm number in males of Poecilimon mariannae parasitized by the acoustically orienting fly Therobia leonidei. We show that in parasitized males, spermatophylax weight decreases with the level of parasitism. In line with the hypothesis
that parasitism is a cost to reproduction, we found that spermatophylax weight was reduced at remating. In contrast, the replenishment
of the spermatophylax in unparasitized males was complete after 2 days and was increased no further after 3 days. Both sperm
number and ampulla weight showed an increase over time since last mating and sperm production was estimated at a constant
rate of 500,000 per day in all individuals, regardless of parasitism. The allocation of investment in components of the spermatophore
varies greatly with parasitism and remating. Both factors had rather independent effects on spermatophore constitution, revealing
functional constraints acting on spermatophore characteristics in bushcrickets, which are important for understanding the
selection pressures working on its components.
Received: 13 September 1999 / Received in revised form: 4 February 2000 / Accepted: 13 March 2000 相似文献
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Long-winged (macropterous) individuals that are capable of flight in predominantly short-winged (flightless) species can considerably affect population dynamics and range expansion. Understanding the triggers that determine macropterism is crucial for understanding whether the dispersal ability of species allows them to shift their distributions through fragmented landscapes or in response to climate change. From 2002 to 2009, we studied population densities and wing dimorphism (macroptery) of Metrioptera roeselii, on 62 plots in central Germany. In the first step, we used a generalized linear mixed-effects model to assess the variables that influence macroptery. Macroptery rates are strongly positively correlated with bush-cricket abundance and not with vegetation structure and habitat moisture. Populations with macropters had significantly higher densities than those without. In the second step, we analysed the relationship between population densities and several mesoclimate/weather parameters. Densities were positively correlated with warm and dry weather conditions during hatching time in April, and previous year weather is less important than present year weather. In the light of the ongoing range expansion of M. roeselii in large parts of Europe, our results support the hypothesis that at high latitudes macropterism and range expansion are indirectly caused by weather-driven changes in population densities. 相似文献
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Summary. The behavioural response of desert locust individuals to adult male volatiles had been investigated in a dynamic Y-T-olfactometer. Synthetic blends of a postulated adult male-produced aggregation pheromone with or without phenylacetonitrile were not attractive to fifth-instar nymphs, young or mature adults of both sexes. Instead phenylacetonitrile had a repellent effect, which was strongest in sexually mature males. The repellent effect of phenylacetonitrile was not modified by the other components of the adult male pheromone bouquet. Even at low concentrations tested the source of the pheromone was avoided. These results are in agreement with recent studies showing that this male specific pheromone is employed by mature gregarious males in sexual behaviour and acts as a courtship inhibiting pheromone. Low concentrations of phenylacetonitrile or the postulated adult male aggregation pheromone blend without phenylacetonitrile may signal the presence of swarm fellows and eventually initiate visually guided congregation behaviour in gregarious locusts. Whether this effect does significantly contribute to swarm cohesion needs further studies. 相似文献
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K. Reinhold 《Behavioral ecology and sociobiology》1996,39(3):189-194
Offspring sex ratio at hatching was examined in the bushcricket Poecilimon veluchianus. Offspring sex ratios varied significantly between females (Fig. 1). Low mortality prior to sex determination established
that this heterogeneity was already present in the primary offspring sex ratio. Sperm age and female age had no influence
on offspring sex ratio (Fig. 2). Male age at copulation, however, correlated significantly with offspring sex ratio (Fig. 3).
There were two types of males: one type produced predominantly daughters when young and an increasing proportion of sons with
age. The other type produced, independent of age, 1:1 offspring sex ratios (Fig. 4). The two types of males seem to occur
in approximately equal numbers. Sex ratio variation (1) may adaptively compensate for local sex ratio biases caused by sex-specific
motility, or (2) it may be adaptive if there is a sex-differential effect of laying date on offspring fitness.
Received: 14 March 1996/Accepted after revision: 24 June 1996 相似文献