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JOHN C. BEIER FRED K. ONYANGO JOSEPH K. KOROS MUTALIB RAMADHAN ROSE OGWANG ROBERT A. WIRTZ DAVY K. KOECH CLIFFORD R. ROBERTS 《Medical and veterinary entomology》1991,5(1):71-79
Abstract. The malaria transmission potential of wild, infective Anopheles from western Kenya was evaluated by determining the number of sporozoites transmitted in vitro by salivation when their mouthparts were inserted into capillary tubes containing either sucrose or blood. With sucrose, 86.6% of 102 infective Anopheles transmitted a geometric mean (GM) of 3.84 sporozoites (range 1–34). With blood, 23.1% of 104 infective Anopheles , tested on the day of collection, transmitted a GM of 2.30 sporozoites (range 1–117). For Anopheles held 5 days postcapture before testing with blood, 53.6% of 56 transmitted a GM of 6.04 sporozoites (range 1–420). Transmitting Anopheles contained significantly more salivary gland sporozoites than non-transmitters. No significant differences were detected between Anopheles gambiae Giles sensu lato and Anopheles funestus Giles in sporozoite transmission by individuals with sporozoites in their salivary glands.
Sporozoites were detected microscopically in the salivary duct from heads in 80.3% of 117 infective Anopheles (GM=11.2, range 1–71). Sporozoite detection in mosquito heads by ELISA was 25% less efficient than microscopic detection.
Over 98% of the infective Anopheles transmitted less than twenty-five sporozoites. Transmitted sporozoites represented only about 3% of the total sporozoites in the salivary glands suggesting that sporozoite transmission may be restricted to sporozoites in the salivary duct at the time of feeding. Results are discussed in relation to anti-sporozoite vaccine development. 相似文献
Sporozoites were detected microscopically in the salivary duct from heads in 80.3% of 117 infective Anopheles (GM=11.2, range 1–71). Sporozoite detection in mosquito heads by ELISA was 25% less efficient than microscopic detection.
Over 98% of the infective Anopheles transmitted less than twenty-five sporozoites. Transmitted sporozoites represented only about 3% of the total sporozoites in the salivary glands suggesting that sporozoite transmission may be restricted to sporozoites in the salivary duct at the time of feeding. Results are discussed in relation to anti-sporozoite vaccine development. 相似文献
5.
Effect of pea bacterial blight (Pseudomonas syringae pv. pisi) on the yield of spring sown combining peas (Pisum sativum) 总被引:1,自引:0,他引:1
S J ROBERTS K PHELPS B M McKEOWN M C HEATH V COCKERELL 《The Annals of applied biology》1995,126(1):61-73
Field trials to examine the effect of pea bacterial blight (Pseudomonas syringae pv. pisi) (Psp) on the yield of combining peas were carried out at five sites (HRI Wellesbourne, ADAS Rosemaund, ADAS Terrington, PGRO, SASA East Craigs) in the UK in 1990, 1991 and 1992. Healthy seed, cv. Solara, and seed naturally infected with Psp Race 2 was sown in large plots (c. 200 m2) in the open or under nets to prevent bird damage by pigeons. Despite relatively low disease severity levels (< 15% leaf area) and separation by at least 12 m of cv. Consort (resistant to Race 2) between plots there was considerable spread of disease into plots sown with healthy seed. Regression analysis demonstrated a significant relationship between yield and disease. Of the disease measurements examined, disease severity on the leaves (stipules) at growth stage 208 was found to be the best predictor of yield. A model containing environmental and bird damage terms, in addition to disease, suggested that a yield loss of 0.98 t/ha would be expected for a disease severity score of 1, equivalent to 5% leaf area affected, at growth stage 208. 相似文献
6.
A Low-Moisture-Content Limit to Logarithmic Relations Between Seed Moisture Content and Longevity 总被引:16,自引:1,他引:15
Seeds of quinoa (Chenopodium quinoa Willd.), sunflower (Helianthusannuus L.) and linseed (Linum usitatissimum L.) showed negativelogarithmic relations between longevity and moisture contentsbetween 4.4 and 15.4, 3.2 and 13.0, and 3.2 and 15.5%, respectively,in hermetic storage at 65 °C. However, between 1.8 and 3.1,1.1 and 1.9, and 1.1 and 2.1%, respectively, longevity did notvary. The critical moisture content, below which further reductionin moisture content no longer increased longevity in hermeticstorage at 65 °C, for each species was 4.1, 2.04 and 2.7%,respectively. Quinoa, Chenopodium quinoa Willd., sunflower, Helianthus annuus L., linseed, Linum usitatissimum L., seed storage, improved viability equation, seed longevity, seed moisture content 相似文献
7.
The durations of the photoperiod-sensitive and photoperiod-insensitivephases of development to panicle emergence were estimated infour contrasting indica cultivars of rice (Oryza sativa L.)in a reciprocal-transfer experiment. Plants were grown in potsin glasshouses maintained at warmer (32/26 C) or cooler (28/20C) day/night temperatures, and the durations from sowing topanicle emergence were determined for plants moved from relativelyshort (11 h) to relatively long (13.5 h) days and vice versaat various times after sowing. Panicle emergence was delayedby long days in all cultivars, but the traditional cvs Carreonand Peta were much more sensitive to photoperiod than the moderncvs IR8 and IR36 The durations of the photoperiod-insensitivepre-inductive phase (equivalent to some definitions of the basicvegetative phase) varied from 14.4 d in cv. Carreon at 32/26C to 42.0 d in cv. IR8 at 28/20 C. In all cultivars this initialphase was of a longer duration in the cool than in the warmregime. The duration of the photoperiod-insensitive post-inductivephase was also consistently greater, but usually only slightso, at cool than relatively warm temperatures; it varied from6.8 d in cv. IR8 at 32/26 C to 272 d in cv. Carreon at 28/20C. As expected, the length of the intervening photoperiod-sensitiveinductive phase was greater in long days, but the effect oftemperature on these durations was not consistent; for example,these durations were longer in warm than in cool temperaturesin cv. 1R8 but, if anything, they were slightly longer in coolthan in warm temperatures in cv. IR36. This difference is compatiblewith previous findings that cv. IR36 has a warmer optimum temperaturefor rate of progress towards panicle emergence than cv. IR8.A subsequent reciprocal-transfer experiment with cv. Peta providedestimates of the durations of the photoperiod-insensitive andphotoperiod-sensitive phases of pre-flowering development whichwere compatible with our earlier estimates. Furthermore, panicleinitiation was found to occur after about 80% of the photoperiod-sensitiveinductive phase had elapsed. We conclude that although the durationof the photoperiod-insensitive pre-inductive phase in rice isgreater than in many other annual crops, genotypic variationin this duration may well be less than was previously deduced.We also conclude that, despite common assumptions to the contrary,photoperiod-sensitivity during rice plant development does notend at panicle initiation. Oryza sativa L., rice, panicle initiation, panicle emergence, photoperiodism, temperature 相似文献
8.
The effects of rainfall and temperature on the behavioural ecology of Chanler's mountain reedbuck (Redunca fulvorufula fulvorufula Rothschild) were examined on ranchland near Gilgil, Kenya. Ambient temperature was shown to be the proximate determinant of diurnal activity and rumination patterns. Mountain reedbuck were active during early morning and late afternoon, but rested and abandoned rumination when temperatures peaked at midday. There was close synchrony in levels of activity, rumination and use of cover and shade between males and females. Seasonal variations in time budgets were strongly influenced by rainfall patterns. Analyses revealed a one-month lag between rainfall and both peak grass growth and a decrease in rumination frequency. The proportion of time allocated to feeding decreased one month later, and was coincident with an increase in the proportion of grass in the diet. Reedbuck may therefore be prevented from exploiting high-quality new grass, possibly by gut-fill or induced imbalances in rumen pH. It is suggested that the unexpectedly high levels of browse in the diet is an adaptive response to low rainfall during the preceding two months. 相似文献
9.
ELLIS R. H.; COVELL S.; ROBERTS E. H.; SUMMERFIELD R. J. 《Journal of experimental botany》1986,37(10):1503-1515
Positive linear relationships were shown between constant temperaturesand the rates of progress of germination to different percentiles,G, for single populations of each of five genotypes of chickpea(Cicer anetinum L.). The base temperature, Tb, at which therate of germination is zero, was 0·0°C for all germinationpercentiles of all genotypes. The optimum temperature, To(G),at which rate of germination is most rapid, varied between thefive genotypes and also between percentiles within at leastone population. Over the sub-optimal temperature range, i.e.from Tb to To(G), the distribution of thermal times within eachpopulation was normal. Consequently a single equation was appliedto describe the influence of sub-optimal temperatures on rateof germination of all seeds within each population of each genotype.The precision with which optimum temperature, Tb(G), could bedefined varied between populations. In each of three genotypesthere was a negative linear relationship between temperatureabove Tb(G) and rate of germination. For all seeds within anyof these three populations thermal time at supra-optimal temperatureswas constant. Variation in the time taken to germinate at supra-optimaltemperatures was a consequence of normal variation in the ceilingtemperature, To(G)the temperature at or above which rateof progress to germination percentile G is zero. A new approachto defining the response of seed germination rate to temperatureis proposed for use in germplasm screening programmes. In two populations final percentage germination was influencedby temperature. The optimum constant temperature for maximumfinal germination was between 10°C and 15°C in thesepopulations; approximately 15°C cooler than the optimumtemperature for rate of germination. It is suggested that laboratorytests of chickpea germination should be carried out at temperaturesbetween 10°C and 15°C. Key words: Chickpea, seed germination rate, temperature 相似文献
10.
Various daily photon doses (daily net number of photons perunit area), provided by varying both photon flux density andphotoperiod, were applied to dormant seed populations of fourgraminaceous species tested for germination in alternating-temperatureregimes on filter papers moistened with either water or a solutionof potassium nitrate. In all four species germination was dependentupon daily photon dose, the product of photon flux density andduration, and quantified by linear relations between the probitof percentage germination and the logarithm of the daily photondose determined by probit analysis. Photon flux density andphotoperiod only influenced germination indirectly as factorsof daily photon dose, except in Echinochloa turnerana (Domin)J.M. Black at high daily photon doses where lower germinationwas observed in continuous light than in 8 h d1 photoperiod.The low energy reaction, in which increasing dose promotes seedgermination, was observed in Echlnochloa turnerana and Eragrostistef(Zucc.) Trotter but not in the populations of Brachiariahumidicola (Rendle) Schwcickerdt and Panicum maximum Jacq. usedin this study. The high irradiance reaction, in which increasingthe photon dose reduces germination, was, however, observedin all four species. In Eragrostis tef potassium nitrate influencedthe response of seed germination to light, but in the remainingspecies its influence on this relationship was either additive(Panicum maximum) or nil (Brachiaria humidicola and Echinochloaturnerana) in the alternating-temperature regimes used in thisstudy. The implications of the quantal response to photon dosefor devising optimal light regimes to be applied in laboratorytests intended to maximize seed germination are discussed. Key words: Light, seed germination, seed dormancy, grasses 相似文献