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151.
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The worldwide increase in the use of antibiotics as an integral part of poultry and livestock production industry has recently received increasing attention as a contributory factor in the international emergence of antibiotic-resistant bacteria in human beings. To gauge the presence of the aforementioned scenario in the Indian context, a preliminary survey was conducted to assess the use of chlortetracycline (CTC) in 12 commercial layer farms and to quantify and confirm its residue in the egg. Samples of feed and eggs were collected at day 0 (prior to CTC addition), 3rd, 5th and 7th day during treatment and on the 9th and 14th day (2nd and 7th day after withdrawal of CTC) from each of the 12 commercial poultry farms studied. Concentration of CTC in feed was significantly (P<0.01) high on the 3rd, 5th and 7th day. On the 9th day and 14th day CTC concentration in feed was significantly (P<0.01) lower compared to the earlier 3 days studied. A highly significant difference (P<0.01) of the antibiotic residue in egg was observed in all the 5 days with high residual levels of CTC in egg. CTC in feed and its residue in egg were detected even on the 9th and 14th day respectively. 相似文献
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SCOTT A. SCHNEIDER JAN H. GILIOMEE JOHN W. DOOLEY BENJAMIN B. NORMARK 《Systematic Entomology》2013,38(4):805-817
The association between African armoured scale insects (Hemiptera: Coccoidea: Diaspididae) and ants belonging to Melissotarsus Emery (Hymenoptera: Formicidae: Myrmicinae) is the only trophobiosis known in which ants do not receive honeydew or nectar in exchange for protection and other services. Food reward for the ants in this mutualism remains unknown, despite repeated suggestions that diaspidids are consumed by the associated ants, thus serving as ‘domestic cattle’. We describe new observations on interactions between Melissotarsus emeryi Santschi and the diaspidid Morganella conspicua (Brain) from South Africa. Worker ants exhibited previously undescribed tending behaviours, most notably a ‘squeezing and licking’ performed on an adult female diaspidid and ‘culling’, in which a worker removed an adult female armoured scale from the host plant. These could represent the gathering of secretory products and the cultivation of an individual for consumption, respectively. An ant exclusion study over 12 days of isolation showed that adult female diaspidids and second‐instar nymphs secreted no wax or exudates that attending ants would ordinarily collect. Workers of M. emeryi did not defend their nest against invading colonies of Crematogaster and other unidentified ants: we hypothesize that the primary mode of defence is maintenance of isolation within galleries. We describe three new ant‐associated diaspidid species: Affirmaspis cederbergensis Schneider sp.n. from South Africa, Diaspis doumtsopi Schneider sp.n. from Cameroon, and Melissoaspis incola Schneider sp.n. from Madagascar. Melissoaspis formicaria (Ben‐Dov) comb.n. is transferred from Morganella (Brain). Diagnostic characteristics for Melissoaspis Ben‐Dov are revised, and additional taxonomic information defining this genus allows ease of identification. An updated identification key to the species of ant‐associated diaspidids is provided. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:632C1122-954A-4DE6-B946-8E6AB6A4D27F . 相似文献
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KLARA BJÖRG JAKOBSDÓTTIR þÓRA DÖGG JÖRUNDSDÓTTIR SIGURLAUG SKÍRNISDÓTTIR SIGRÍÐUR HJÖRLEIFSDÓTTIR GUÐMUNDUR Ó. HREGGVIÐSSON ANNA KRISTÍN DANÍELSDÓTTIR CHRISTOPHE PAMPOULIE 《Molecular ecology resources》2006,6(2):337-339
Nine out of 22 microsatellite primers tested were successfully amplified on three samples of cod Gadus morhua L. (two contemporary and one archived otolith samples). All loci were polymorphic (5–23 alleles/locus). The average observed heterozygosity across loci and samples was 0.625, ranging from 0.294 to 0.895 at each locus. All loci were under Hardy–Weinberg equilibrium, except PGmo56 that showed significant excess of heterozygotes in all studied samples. The isolated loci were suitable for degraded DNA and therefore useful for conducting a long‐term temporal study with DNA obtained from archived otoliths of cod. 相似文献
158.
Abstract 1. Body size in parasitic insects can be subjected to contrasting selective pressures, especially if they complete their development within a single host. On the one hand, a larger body size is associated with a higher fitness. On the other hand, the host offers a discrete amount of resources, thus constraining the evolution of a disproportionate body size. 2. The present study used the weevil Curculio elephas as a study model. Larvae develop within a single acorn, feeding on its cotyledons, and larval body size is strongly related to individual fitness. 3. The relationship between larval and acorn size was negatively exponential. Larval growth was constrained in small acorns, which did not provide enough food for the weevils to attain their potential size. Larval size increased and levelled off in acorns over a certain size (inflexion point), in which cotyledons were rarely depleted. When there were more than one larva per acorn, a larger acorn was necessary to avoid food depletion. 4. The results show that C. elephas larvae are sometimes endoparasitic, living on the edge of host holding capacity. If they were smaller they could avoid food depletion more easily, but the fitness benefits linked to a larger size have probably promoted body size increase. The strong negative effects of conspecific competition may have possibly influenced female strategy of laying a single egg per seed. 5. Being larger and fitter, but always within the limits of the available host sizes, may be one main evolutionary dilemma in endoparasites. 相似文献
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MARGUERITE A. XENOPOULOS CHRISTOF SCHNEIDER DAELYN A. WOOLNOUGH 《Global Change Biology》2011,17(4):1720-1732
The role of climate‐related disturbances on complex host–affiliate relationships remains understudied, largely because affiliate species vary in host use and are often differentially susceptible to disturbance relative to their hosts. Here we report the first set of host–affiliate species–discharge relationships (SDR) in freshwater and examine how anticipated shifts in water availability (flow) will impact coextirpations. We used SDR for freshwater mussels and fish across 11 regions (over 350 rivers) in the continental United States that we coupled to future water availability (2070) to model mussel and fish coextirpations. We also used river‐specific host–affiliate matrices (presence–absence) to evaluate how host‐specificity (mean number of hosts used by an affiliate) and host‐overlap (extent to which affiliates share hosts) relate to extirpation vulnerability. We found that the strength and predictability of SDR models vary geographically and that mussels were more susceptible to flow alterations than fish. These patterns of extirpations were strongest in the southeast where: (1) flow reductions are expected to be greatest; (2) more species are lost per unit flow; (3) and more mussels are expected to be lost per unit of fish. We also found that overall mussel losses associated with reduction in habitat (water availability) were greater than those associated with loss of fish hosts which we assumed to be a function of host redundancy. These findings highlight the utility of SDR as a tool for conservation efforts but they also demonstrate the potential severity of reductions in mussel and fish richness as consequence of climate change and water use. Mussels provide key ecosystem services but face multiple pronged attacks from reductions in flow, habitat, and fish hosts. These losses in biodiversity and ecosystem functions can translate into major effects on food webs and nutrient recycling. 相似文献
160.
Natália H Mendes Fernando AF Melo Adolfo CB Santos José RC Pandolfi Elisabete A Almeida Rosilene F Cardoso Henri Berghs Suzana David Faber K Johansen Lívia G Espanha Sergio RA Leite Clarice QF Leite 《BMC research notes》2011,4(1):269