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Omkar G. Mishra S. Srivastava A. K. Gupta S. K. Singh 《Journal of Applied Entomology》2005,129(4):217-220
Abstract: This study investigated prey consumption, egg production, percent progeny loss, reproductive, pre- and post-reproductive periods, reproductive time ratio, reproductive rate and bioconversion efficiency of four aphidophagous ladybirds, viz. Cheilomenes sexmaculata (Fabricius), Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius and Propylea dissecta (Mulsant) on Dolichos lablab Linnaeus infested with cowpea aphid, Aphis craccivora Koch. C. sexmaculata had the highest bioconversion efficiency, reproductive rate and reproductive time ratio followed in rank order by P. dissecta , C. transversalis and C. septempunctata . This study indicates that C. sexmaculata has a narrow ecological relationship with A. craccivora . The increased allocation of resources to reproduction as indicated through a high reproductive time ratio and high bioconversion efficiency of C. sexmaculata and P. dissecta suggest that they may be better adapted to compete for this prey with larger species like C. transversalis and C. septempunctata . 相似文献
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Wilkinson 《Ecology letters》1999,2(4):207-209
The evolution of antibiotic resistance in bacteria is well known. Here I describe possible mechanisms by which an increased rate of re-colonization of vertebrate guts by microbes caused by antibiotic use could lead to selection for increased virulence in currently mutualistic or benign microbes. The importance of understanding both the source and the frequency of colonization in such mutualisms is stressed and the possible importance of pseudo-vertical transmission in the evolution of these systems is discussed. A number of areas requiring experimental investigation are identified. 相似文献
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Habitat quality,population dynamics,and group composition in Colobus Monkeys (Colobus guereza) 总被引:3,自引:0,他引:3
R. I. M. Dunbar 《International journal of primatology》1987,8(4):299-329
Data from an Ethiopian population of Colobus guerezashow that territory size is fixed by the high density of the population. Groups undergo fission when their size results in
fewer than 10 trees per individual within the group’s territory. The daughter groups produced by fission emigrate into suboptimal
habitat, which acts as a demographic sink. Comparative analyses using data from other East African populations demonstrate
that mean territory size is inversely related to population density and that density, in turn, is a function of the size of
the forest block. Since both group size and reproductive rates can be shown to be positively correlated with type of forest,
it is concluded that this relationship reflects the fact that local population densities reach their ceiling more rapidly
in small forest blocks because the animals’ access to alternative territories is limited. The number of males in a colobus
group is shown to be a function of the number of females in it. Multimale groups have lower reproductive rates than one-male
groups, probably because the stress generated by competition among the males causes temporary infertility among the females. 相似文献
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Two secretary birds and three Kori bustards were studied to determine differences between their body size and gastrointestinal morphology. Body measurements were made on captive, live birds and gastrointestinal measurements on fresh postmortem specimens. For predator species, such as the Kori bustard and secretary bird, body size is a function of their ability to capture and destroy prey. While the secretary bird was clearly the taller of the two species, superior body weight, wing length, and therefore body size was noted for the Kori bustard. The size and length of the gastrointestinal tract varied between species. The secretary bird had the shorter, less complex digestive tract, with a foregut well adapted for consumption of large quantities of flesh. The large intestine was devoid of ceca. The gastrointestinal tract of the Kori bustard was markedly different from that of the secretary bird. The foregut was less complex and the large intestine possessed large, voluminous ceca. 相似文献
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G. C. Wright 《Plant and Soil》1989,116(1):111-114
Very little research has been done to investigate the effect of a dry podding zone on reproductive development in peanut plants
that are otherwise well hydrated via subsoil moisture extraction. The influence of podding zone moisture content on reproductive
development and growth of three peanut cultivars (McCubbin, Gajah and Robut 33-1) was investigated in pots grown in the glasshouse.
In two cultivars (McCubbin and Gajah) seed yield was reduced in a dry (air-dry) compared to a wet (field capacity) podding
zone. Seed yield of Robut 33-1 was unaffected by podding zone moisture content, indicating that cultivar variation in reproductive
performance in response to podding zone moisture may exist. 相似文献