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1.
Fumonisins have been reported to have diverse effects on animals, including immunosuppression in chickens and feeder calves; therefore, the effects of fumonisin B1 (FB1) on immune function in BALB/c mice was investigated. When administered i.p. with sheep red blood cells (SRBC), 5 to 100 µg of FB1 reduced the number of plaque-forming cells (PFC) produced against SRBC; however, when administered daily, 1 to 50 µg of FB1 caused a 4 to 12-fold increase in the number of PFC after SRBC injection. Therefore, FB1 is not only immunosuppressive; but also, immunostimulatory. To test the possibility that there may have been an immune response to FB1 as an antigen, FB1 was injected into mice and the number of splenic cells forming rosettes on FB1-treated SRBC was determined. There were dose-dependent increases in the antigen-binding cells, with up to 4.9- and 4.6-fold increases, respectively, upon primary and secondary immunization. FB1-binding immunoglobulins could be detected in sera from some treated mice, but this response was not obtained in every experiment. In summary, these results show that FB1 has diverse effects on the immune system, causing both stimulation and suppression of the response to foreign antigens, and apparently inducing an antigenic response to FB1.Abbreviations DMEM Dulbecco's Modified Eagle's Medium - FB1 fumonisin B1 - FCS fetal calf serum - PBS phosphate buffered saline - PFC plaque forming cells - RFC rosette forming cells - SRBC sheep red blood cells  相似文献   

2.
One hundred eight fertile eggs (Columbia × New Hampshire) were assigned to 10 groups of 10 eggs each (2 control groups had 14 eggs each). Five groups of eggs were inoculated on day 1 of incubation, while the other 5 groups were inoculated on day 10. The inoculum of the 4 treatment groups on both day 1 and 10 consisted of 1,10, or 100 µM purified fumonisin B1 (FB1) or a culture material extract (CME) ofFusarium proliferatum, having known amounts of FB1, FB2 and moniliformin (FB1 20 µM; FB2 4 µM and moniliformin 7 µM). Inoculum consisted of the respective toxin(s) dissolved in 100 µl double distilled, autoclaved water (diluent). Control eggs were inoculated with diluent only. Mortality was both dose- and time-responsive in all treatments. Eggs inoculated on day 1 with 1 µM FB1 had 50% mortality; 10 µM FB1 had 70% mortality; 100 µM FB1 had 100% mortality; and CME had 100% mortality. Eggs inoculated on day 10 with 1,10 or 100 µM FB1 or CME had 30, 60, 90 and 80% mortality, respectively. Normal chicks were hatched from all control eggs. The median death times (MDT50) were inversely dose-responsive in all treatments, ranging from 3.0 to 7.4 days in embryos exposed on day 1 and from 3.2 to 9.0 days in those exposed on day 10. Early embryonic changes in exposed embryos included hydrocephalus, enlarged beaks and elongated necks. Pathologic changes were noted in liver, kidneys, heart, lungs, musculoskeletal system, intestines, testes and brain toxin-exposed embryos.  相似文献   

3.
Several adsorbent materials were tested at 1 mg/ml for their in vitrocapacity to adsorb fumonisin B1 (FB1) from aqueous solutions. Cholestyramine showed the best adsorption capacity (85% from a solution containing 200 g/ml FB1) followed by activated carbon (62% FB1). Bentonite adsorbed only 12% of the toxin from a solution containing 13 g/ml FB1, while celite was not effective even at the lowest tested FB1 concentration (3.2 g/ml). Cholestyramine was tested in vivoto evaluate its capacity to reduce the bioavailability of fumonisins (FBs) in rats fed diet contaminated with toxigenic Fusarium verticillioidesculture material. Rats were exposed for one week to FBs-free diet, FBs-contaminated diet containing 6 or 20 g/g FB1 + FB2 and the same FBs-contaminated diet added of 20 mg/g cholestyramine. The increase of sphinganine/sphingosine (SA/SO) ratio in urine and kidney of treated rats was used as specific and sensitive biomarker of fumonisin exposure.The addition of cholestyramine to the FBs-contaminated diets consistently reduced the effect of FBs by reducing significantly (P < 0.05) both urinary and renal SA/SO ratios.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

4.
Two water-solubleFusarium metabolites, fumonisin B1 (FB1) and moniliformin (MN) were compared for their cytotoxicity in a variety of chicken primary cell cultures. Cardiac and skeletal myocytes and hepatocytes derived from embryos, and splenocytes, macrophages, and chondrocytes derived from 3-to 4-week old chickens were cultured in media containing either FB1 or MN (0 to 1 mM) for 48 hr. The colorimetric tetrazolium cleavage assay was then used for measuring cell survival. FB1 was not toxic to macrophages, hepatocytes, cardiac and skeletal myocytes but toxic to splenocytes and chondrocytes. MN was not toxic to chondrocytes and macrophages, but toxic to splenocytes, cardiac and skeletal myocytes. Median effective concentration (EC50) of MN in skeletal myocytes was 42 µM (fiducial limits: 33 to 50 µM) and in cardiac myocytes was 95 µM (fiducial limits: 84 to 122 µM). Estimated EC50 of FB1 in chondrocytes and splenocytes and EC50 of MN in splenocytes were all greater than 200 µM.  相似文献   

5.
Corn pellets, containing 30 mg/kg bw/day fumonisin B1 (FB1) or containing no FB1 were fed in two series of experiments to rats. Spontaneous and evoked potentials were measured in the neocortex both in vivo and in vitro in “corn fed control” rats and in rats after a five day dietary exposure to FB1. The FB1 content of corn was quantitated by HPLC. Auditory evoked potentials recorded in vivo on freely moving animals after feeding a corn diet containing FB1 for 5 days revealed a highly significant 20–60% decrease in the primary and mid-latency components; cortex slices in vitro showed a reduced excitability both in standard artificial cerebrospinal fluid (ACSF) solution and in a 4-aminopyridine induced epilepsy model. Spontaneous epileptic discharges after FB1 exposure had an increased latency, decreased frequency, longer duration and modified signal forms. Altered excitability and seizure susceptibility of the neocortex after fumonisin exposure are suspected to be associated with modified signal transmission. These changes may be due to concurrent effects of possible liver and renal toxicity or partly of nutritional deficiencies. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

6.
Fusarium species and fumonisin production by toxigenic strains were investigated. During 1996–1998, 158 samples of poultry feeds were collected from a factory located in the department of Río Cuarto Córdoba province, Argentina. The most common species of Fusarium were F. moniliforme (60.7%) and F. nygamai (35.4%) followed by F. semitectum, F. subglutinans, F. proliferatum, F. dlamini, F. solani, F. oxysporum and F. napiforme. Fungal counts ranged from 1 × 103 to 8 × 105 CFU/g with mean values from 1.5 × 103 to 2.3 × 105 CFU/g. The highest counts were for F. dlamini, F. subglutinans, F. moniliforme and F. nygamai. Strains of F. moniliforme, F. nygamai, and F. proliferatum were screened for their potential to produce fumonisin B1 (FB1), fumonisin B2 (FB2) and fumonisin B3 (FB3) in corn grain. The samples were analysed using a modified high performance liquid chromatography method. The strains assayed, 43 strains, produced three fumonisins. There was a high degree of variability in the quantities of FB1, FB2, and FB3 produced. The toxin produced in highest levels by the majority of the strains was FB1. The range of concentration varied from 5.4 to 3,991, 1.01 to 189 and 0.4 to 765 ppm per gram of corn for FB1, FB2 and FB3 respectively. The toxigenic pattern of strains was normal, although two strains of F. moniliforme produced exceptionally high concentrations of FB3 and minor concentrations of FB2 and FB1. This is the first report from Argentina on Fusarium species in poultry feeds and fumonisin production by these strains.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

7.
Field experiments in the high rainfall zone (HRZ) and the medium rainfall zone (MRZ) in Zambia were designed to determine the natural occurrence of fumonisins (FB1–2) in Zambian maize hybrids, accumulation of FB1–2 resulting from artificial inoculation with Fusarium verticillioides and effects of climate and planting time on FB1–2 in maize. Combined FB1–2 concentrations varied from 0 to 13,050 ng/g, with an overall mean of 666 ng/g. Maize from the HRZ had low incidences of FB1–2-positive samples (mean 41%) which contained FB1–2 below 500 ng/g. In the MRZ, higher incidences (mean 97%) and concentrations (40% of samples >1,000 ng/g) were recorded in two out of three years. There was no correlation between mean location FB1–2 concentrations in individual years and precipitation, number of rain days or monthly precipitation. Postponing the planting time with 10 or 20 days did not significantly affect FB1–2 concentration, but it reduced the yields in some years.  相似文献   

8.
Tseng  Tsung-Che  Liu  Chen-Yi 《Mycopathologia》1997,137(1):57-61
Corn-based human foodstuffs purchased in Taiwan were analyzed for fumonisin B1 (FB1) and fumonisin B2 (FB2) using high-performance liquid chromatography. Fifty-two (33.9%) and 32 (20.9%) of 153 samples were found to contain FB1 (73–2395 ng/g) and FB2 (120–715 ng/g), respectively. The highest frequency of detection and also the highest FB1 concentrations were found in sweetcorn (50%, 1089 ng/g) and cornflour (50%, 608 ng/g), followed by corn snacks (33.3%, 2395 ng/g), miscellaneous corn products (33.3%, 73 ng/g), popcorn (31.8%, 1003 ng/g) and cornflakes (23.5%, 1281 ng/g). 16 corn snacks (= approximately 20.5% of the samples) had an average FB1 and FB2 content of 456 and 145 ng/g, respectively, while six sweetcorn (= 25%) samples were contaminated with an average of 400 ng/g of FB1 and 65 ng/g of FB2. Of the 22 pop-corn samples examined, 7 had an average of 347 ng/g and 116 ng/g of FB1 and FB2, respectively. During an analysis of the distribution pattern for the combined fumonisin levels of FB1 and FB2, it became apparent that more than 69% of tested samples had fumonisin concentrations below 100 ng/g, while 11.1% (or 17 samples) contained in excess of 600 ng toxins per g. These results clearly illustrated that commercially available corn-based foodstuffs for human consumption in Taiwan are frequently contaminated with FB1 and FB2.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

9.
Fumonisins are mycotoxins produced primarily by Fusarium moniliforme and Fusarium proliferatum in corn. In liquid culture, production of fumonisin B1 (FB1), the most common moiety of the family of fumonisins, can be obtained using a defined medium that is nitrogen-limited. Under nitrogen-limited conditions both growth and the production of FB1 were greatly influenced by pH and aeration. At pH above 5.0, F. proliferatum grew normally but produced little FB1 (<100 μg m−1). At pH below 5.0, there was less growth but substantially more FB1. Below a pH of 2.5, both growth and metabolism were slower with very little FB1 produced. When the optimal pH range of between 3.0 and 4.0 under well-aerated conditions was used, both growth and FB1 production were high. However, under oxygen-limited conditions, less growth occurred, glucose consumption was increased, and no FB1 was produced. Received 16 May 1997/ Accepted in revised form 03 September 1997  相似文献   

10.
Fumonisins B1(FB1) and B2(FB2) were isocratically separated on a fluorocarbon column without using an ion pair reagent and nonvolatile buffer during the HPLC and were detected by an o-phthalaldehyde postcolumn derivatization system using a fluorescence detector. The minimum detectable concentrations of FB1 and FB2 in corn by this system were 0.01 μg/g and 0.01 μg/g, respectively. The separated fumonisins were further identified by a directly interfaced ion trap MS using electrospray ionization. FB1 and FB2 in naturally contaminated corn were identified in the selective ion monitoring mode at concentrations of 3.75μg/g and 1.44 μg/g, respectively. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
Toxicokinetics and the toxicological effects of culture material containing fumonisin B1 (FB1) were studied in male weaned piglets by clinical, pathological, biochemical and sphingolipid analyses. The animals received a single oral dose of 5 mg FB1/kg of body weight, obtained from Fusarium verticillioides culture material. FB1 was detected by HPLC in plasma collected at 1-h intervals up to 6 h and at 12-h intervals up to 96 h. FB1 eliminated in feces and urine was quantified over a 96-h period and in liver samples collected 96 h post-intoxication. Blood samples were obtained at the beginning and end of the experiment to determine serum enzyme activity, total bilirubin, cholesterol, sphinganine (Sa), sphingosine (So) and the Sa/So ratio. FB1 was detected in plasma between 30 min and 36 h after administration. The highest concentration of FB1 was observed after 2 h, with a mean concentration of 282 μg/ml. Only 0.93% of the total FB1 was detected in urine between 75 min and 41 h after administration, the highest mean concentration (561 μg/ml) was observed during the interval after 8 at 24 h. Approximately 76.5% of FB1 was detected in feces eliminated between 8 and 84 h after administration, with the highest levels observed between 8 and 24 h. Considering the biochemical parameters, a significant increase only occurred in cholesterol, alkaline phosphatase and aspartate aminotransferase activities. In plasma and urine, the highest Sa and Sa/So ratios were obtained at 12 and 48 h, respectively.  相似文献   

12.
Fumonisins are mycotoxins produced by Fusarium moniliforme, F. proliferatum, and related Fusarium species found on corn. They occur naturally in corn-based feeds and foods and are suspected human esophageal carcinogens. Fumonisin B1 (FB1), the most common homologue, causes the animal diseases associated with F. moniliforme. Hepato- and nephrotoxicities, disrupted sphingolipid metabolism, and liver cancer have been found in rats fed FB1. To determine the in vivo effects of diets containing fumonisins B2 (FB2) or B3 (FB3), male rats were fed culture materials (CM) of FB1 non-producing F. moniliforme isolates to provide low (4.6–6.7 ppm), mid (32–49 ppm) or high (219–295 ppm) dietary levels of either FB2 (FB2CM) or FB3 (FB3CM). Other groups were fed culture material of an FB1 producing isolate (FB1CM) providing 6.9, 53 or 303~ppm total fumonisins (FB1 : FB2 : FB3 = 1.0 : 0.38 : 0.15) and a tenth group was fed a control diet having no detectable fumonisins. One-half (n = 5/group) the animals were killed after three weeks, at which time the toxicological and histopathological effects of the three culture materials were similar, mimicked the effects of FB1, and included decreased body weight gains, serum chemical indicators of hepatotoxicity, decreased kidney weights, and apoptosis of hepatocytes and kidney tubular epithelium. FB1CM, FB2CM, and FB3CM affected sphingolipids, causing increased sphinganine to sphingosine ratios (Sa/So) in both liver and kidneys. The remaining animals (n = 5/group) were fed a control diet for three additional weeks. All body weight and tissue specific effects, including increased Sa/So, induced by the FB2CM, FB3CM and low level FB1CM diets were absent following the recovery period. Except for mild biliary lesions found in the high dose FB1CM group and a few apoptotic hepatocytes present in one mid- and two high-dose FB1CM rats, no evidence of toxicity remained in these groups following the recovery period.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

13.
Fumonisin B1 (FB1) is a Fusarium mycotoxin frequently occurring in corn in combination with deoxynivalenol (DON) and zearalenone. The aim of this study was to determine if FB1, alone and combined with DON or α-zearalenol (ZEA), zearalenone major active metabolite, can affect granulosa cell proliferation, steroid production, and gene expression in swine. Porcine granulosa cells were cultured for 2 days in serum-containing medium followed by 1 or 2 days in serum-free medium with or without added treatments. Fumonisin B1 had inhibitory effects on granulosa cell proliferation. Deoxynivalenol strongly inhibited cell growth, and no significant difference was detected in combination with FB1. α-Zearalenol showed a stimulatory effect on granulosa cell numbers even in combination with FB1. Regarding steroid production, FB1 increased progesterone production, and FB1 had no effect on estradiol production. Deoxynivalenol strongly inhibited progesterone and estradiol production, and FB1 had no significant effect on this response. α-Zearalenol increased progesterone production, and its combination with FB1 produced additive effects. α-Zearalenol had no effect on estradiol production, whereas it decreased estradiol production when co-treated with FB1. Fumonisin B1 was found to decrease CYP11A1 messenger RNA abundance, and the stimulatory effect of FB1 on progesterone production was found to be not dependent on 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity suggesting that FB1 increases progesterone production through a different mechanism. The results show that these Fusarium mycotoxins can influence porcine granulosa cell proliferation and steroid production, thereby demonstrating their potential reproductive effects on swine.  相似文献   

14.
Fingerlings of Clarias gariepinus were used to evaluate the effect of dietary fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, on growth, haematological and serum biochemical parameters. The fingerlings were sorted, weighed and randomly stocked in 16 plastic tanks at the rate of 20 fingerlings per tank. Fusarium-cultured maize grains containing FB1 were used to formulate three diets containing approximately 5.0, 10.0 and 15.0 mg FB1/kg, constituting diets 2, 3, and 4 respectively. These three diets, plus diet 1, which contained non-Fusarium cultured maize grains that served as the control, were used in a 6-week feeding trial. The final weight gains by the fingerlings were significantly (P?<?0.05) influenced by FB1. The final weights of the fingerlings fed diets 2, 3 and 4 ranged from 70.07 to 87.10% of the controls. The haematocrit, erythrocytes, haemoglobin, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and the serum protein constituents (total protein, albumin and globulin) values significantly (P?<?0.05) decreased, while the leucocytes, MCV and MCH increased significantly (P?<?0.05) with increase in the dietary FB1. The total serum protein values of the fingerlings fed diets 2, 3 and 4 were 34.53, 39.42 and 50.17% lower than the total serum protein values of those fed the control diet. These results indicate that Fusarium-contaminated diets containing about 5.0 mg or more FB1/kg reduced weight gain and significantly altered haematological parameters and serum protein constituents in the fingerlings. These may have a significant impact on physiological activities and may be vital in immunosuppression in the fingerlings with a strong negative impact on subsequent performance of the fish.  相似文献   

15.
Twenty samples of unpolished (rough) rice collected in Arkansas and Texas during the 1995 harvesting season from fields exhibiting Fusarium sheath rot disease or panicle blight were previously shown to include 8 samples positive for fumonisin B1(FB1) in the range 2.2–5.2 ppm, and moniliformin (MON), but no beauvericin (BEA), deoxynivalenol, its derivatives or zearalenone were detected. Fifteen cultures of F. proliferatum were established from the 20 rough rice samples. Single spore isolates of each culture were grown on rice and tested for the production of fumonisins (FB1, FB2, FB3, etc.), MON and BEA. All 15 isolates produced FB1, FB2, MON and BEA in culture on rice. No deoxynivalenol, its derivatives orzearalenone were detected. Seven cultures produced FB1 at >50ppm (range 80–230 ppm), with therest producing FB1 in the range 14–43 ppm.FB2 was produced in the range 5–47 ppm, and those cultures which produced the most FB1 also produced the most FB2. Of the 15 cultures producing MON, 11 produced it at >100 ppm in the range 188–6018 ppm, with the rest producing in the range 7–64 ppm. BEA was produced in the range 109–1350 ppm. Other derivatives of fumonisins, including FA1, FA2 and partially hydrolyzed FB1, as well asseveral unknown metabolites including a compound with MW 414, were identified in culture extracts by continuous flow fast atom bombardment with ion spraymass spectrometry (CF/FAB/MS). Further study is needed to identify the factors that control production of FB1, MON and BEA by F.proliferatu in culture and in field samples. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

16.
Gong HZ  Ji R  Li YX  Zhang HY  Li B  Zhao Y  Sun L  Yu F  Yang J 《Mycopathologia》2009,167(1):31-36
Fumonisin B1 (FB1) is the most abundant of the fumonisin mycotoxins, mainly produced in maize by F. verticillioides and F. proliferatum. A total of 282 corn samples harvested in 2005 from six provinces, the main corn-producing areas of China, were analyzed for FB1 using high-performance liquid chromatography. All samples except one were (99.6%) positive for FB1 at levels varying from 3 to 71,121 ng/g with mean and median levels for all samples of 6,662 and 1,569 ng/g, respectively. During an analysis of the distribution pattern for FB1, it became apparent that 43.6% of tested samples had FB1 concentrations below 1,000 ng/g, while 25.2% contained in excess of 5,000 ng/g. The average exposure to FB1 (1.1 μg/kg body weight/day) is within the provisional maximum tolerable daily intake of 2 μg/kg body weight/day set by the Joint FAO/WHO Expert Committee on Food Additives.  相似文献   

17.
Fumonisins, fungal toxins found primarily in maize and produced by various Fusarium species, have been shown to cause a variety of significant adverse health effects in livestock and experimental animals, and are probable human carcinogens. Thirty-three maize samples were collected at ports from bulk shipments, which were imported into Iran from six countries during 2001–2002, and analysed by HPLC for the most abundant of the naturally occurring fumonisin analogues, namely fumonisins B1 (FB1), B2 (FB2) and B3 (FB3). Of the 33 samples, 21 (64%) were found to contain FB1 (58–512 μg/kg) at levels above 10 μg/kg. The frequency of FB1 found in maize samples imported from Uruguay and Canada was 75%, followed by China and Argentina (67%), USA (60%), and Brazil (50%). The average FB1 level was 266 and 169 μg/kg for positive and all samples, respectively. Medians were 250 and 146 μg/kg for positive and all samples, respectively. FB2 levels ranged from not detected (<10 μg/kg) to 53 μg/kg, whereas no sample had an FB3 level above the detection level (10 μg/kg). This is the first report of fumonisin contamination of imported maize in Iran. Although, the level of all detected fumonisins were below the Iranian and FDA tolerance levels for foods and feeds, It is necessary to maintain the strict rules to ensure continued safety of imported maize.  相似文献   

18.
Pristhesancus plagipennis (Walker) is a predator of larvae and nymphs of many pestiferous insects for which natural enemies are not commercially available. This paper describes a containerized mass-rearing method for P. plagipennis using hot water-killed larvae of Tenebrio molitor (L.) and Helicoverpa armigera (Hübner). In addition, the effect of P. plagipennis density during nymphal rearing and adult oviposition was investigated. The rearing method minimizes P. plagipennis cannibalism, avoids the need for live insect prey, and is space and labor efficient. Larvae of the yellow mealworm, T. molitor, were the most suitable prey for minimizing nymphal development time and mortality while producing insects with the highest body weight. When reared on a diet of T. molitor, the optimum rearing density was 20–27 nymphs per 5-liter container. This rearing density minimized nymphal mortality to 16–22%. The optimum density for oviposition was 16 adults per 5-liter container, which provided the best compromise between egg production and space utilization.  相似文献   

19.
Eight Fusarium spp. were isolated from greenhouse-grown jimsonweed (Datura stramonium L.) in Mississippi in 1990. Four isolates of Fusarium moniliforme were obtained and when grown on autoclaved rice, produced 115 to 3,200 mg/kg fumonisin B1, (FB1). Other fumonisin-related compounds, such as FB2, FB3 and FB4 were also produced at levels of 240, 210 and 160 mg/kg, respectively. F. semitectum (1 isolates) was negative for production of fumonisin and other phyto-toxins. F. oxysporutn (1 isolate) produced only 3.5 g/kg moniliformin. This is the first report of production of fumonisins by F. moniliforme isolated from weeds such as jimsonweed.  相似文献   

20.
The CO2 production of individual larvae of Apis mellifera carnica, which were incubated within their cells at a natural air humidity of 60–80%, was determined by an open-flow gas analyzer in relation to larval age and ambient temperature. In larvae incubated at 34 °C the amount of CO2 produced appeared to fall only moderately from 3.89±1.57 µl mg–1 h–1 in 0.5-day-old larvae to 2.98±0.57 µl mg–1 h–1 in 3.5-day-old larvae. The decline was steeper up to an age of 5.5 days (0.95±1.15 µl mg–1 h–1). Our measurements show that the respiration and energy turnover of larvae younger than about 80 h is considerably lower (up to 35%) than expected from extrapolations of data determined in older larvae. The temperature dependency of CO2 production was determined in 3.5-day-old larvae, which were incubated at temperatures varying from 18 to 38 °C in steps of 4 °C. The larvae generated 0.48±0.03 µl mg–1 h–1 CO2 at 18 °C, and 3.97±0.50 µl mg–1 h–1 CO2 at 38 °C. The temperature-dependent respiration rate was fitted to a logistic curve. We found that the inflection point of this curve (32.5 °C) is below the normal brood nest temperature (33–36 °C). The average Q10 was 3.13, which is higher than in freshly emerged resting honeybees but similar to adult bees. This strong temperature dependency enables the bees to speed up brood development by achieving high temperatures. On the other hand, the results suggest that the strong temperature dependency forces the bees to maintain thermal homeostasis of the brood nest to avoid delayed brood development during periods of low temperature.Abbreviations m body mass - R rate of development or respiration - TI inflexion point of a logistic (sigmoid) curve - TL lethal temperature - TO temperature of optimum (maximum) developmentCommunicated by G. Heldmaier  相似文献   

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