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Days Longer (day + longer)
Selected AbstractsSurvival and oviposition of a western corn rootworm variant feeding on soybeanENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2003Timothy R. Mabry Abstract The role of soybean, Glycine max (L.) Merril (Fabaceae), in the circumvention of crop rotation was evaluated by observing the effects of soybean herbivory on western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) survival and oviposition. Field collected D. virgifera adults resistant to annual rotation of corn, Zea mays (L.) (Poaceae), and soybean were given the opportunity to feed on a soybean pre-treatment diet prior to diet combinations of corn, soybean, and/or water. The number of days that the adults survived after removal of the diet combinations was used as a measure of insect vigor and diet quality. Willingness to feed on a soybean foliage pre-treatment did not indicate greater ability to benefit nutritionally from soybean herbivory. Adult D. virgifera previously feeding on corn, soybean, or water survived starvation for 8.3 ± 0.15 days, 5.1 ± 0.13 days, and 3.9 ± 0.14 days, respectively. Diabrotica virgifera recover from 2 days of starvation or poor diet if subsequently given access to corn tissues for 2 days. Eggs were laid within 1 day of access to poor diet or starvation. Other D. virgifera, captured as they flew from a cornfield into a soybean field, were maintained on soybean foliage or only water until they died. Of the beetles with access to soybean foliage, 24% fed within 24 h after capture and survived 1 day longer than insects given only water. Only 20% of these D. virgifera were able to lay eggs without consuming additional corn prior to death. Few D. virgifera enter soybean fields capable of immediate oviposition. Female reproductive status and diet quality influence the likelihood of oviposition following exposure to stress. The effects of soybean herbivory may contribute to the proximate mechanism of resistance to crop rotation. [source] Temperature-dependent ovariole and testis maturation in the yellow dung flyENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2005Wolf U. Blanckenhorn Abstract Temperature is one of the abiotic environmental factors most strongly affecting animal behaviour, physiology, and life history. In insects, lower temperatures generally slow down most physiological processes, reducing growth rate and prolonging the juvenile period. Here, we investigate temperature-dependent ovariole and testis maturation in the anautogenous yellow dung fly, Scathophaga stercoraria L. (Diptera: Scathophagidae), and relate it to corresponding temperature effects on pre-adult development time and the adult pre-reproductive period. Flies were reared in the laboratory at three constant temperatures (18, 22, and 26 °C), and the size of the developing ovarioles and testes (reflecting sperm production) was measured over time (i.e., age). Ovariole size increased asymptotically over the first 12 days of adult life, while the testes continued to fill after day 10. In accordance with the temperature-size rule, warmer temperatures resulted in smaller ovarioles (eggs) and smaller testes, independent of body size. Warmer temperatures also greatly reduced pre-adult development time by more than half, from 12 to 25 °C, the larger males always taking 1,3 days longer than the females. Corresponding temperature effects on the adult pre-reproductive period were small (<1 day between 15 and 25 °C), with males taking 5,6 days and females 10,13 days to first reproduction. Time lost by males during the pre-adult stage, when ovaries and testes are produced, can thus be more than compensated-for by time gained during the pre-reproductive period, when eggs and sperm are produced, so males can nevertheless start reproducing sooner than females. [source] Spatial and temporal variability of the phenological seasons in Germany from 1951 to 1996GLOBAL CHANGE BIOLOGY, Issue 6 2001Annette Menzel Abstract Various indications for shifts in plant and animal phenology resulting from climate change have been observed in Europe. This analysis of phenological seasons in Germany of more than four decades (1951,96) has several major advantages: (i) a wide and dense geographical coverage of data from the phenological network of the German Weather Service, (ii) the 16 phenophases analysed cover the whole annual cycle and, moreover, give a direct estimate of the length of the growing season for four deciduous tree species. After intensive data quality checks, two different methods ,,linear trend analyses and comparison of averages of subintervals , were applied in order to determine shifts in phenological seasons in the last 46 years. Results from both methods were similar and reveal a strong seasonal variation. There are clear advances in the key indicators of earliest and early spring (,0.18 to ,0.23 d y,1) and notable advances in the succeeding spring phenophases such as leaf unfolding of deciduous trees (,0.16 to ,0.08 d y,1). However, phenological changes are less strong during autumn (delayed by +,0.03 to +,0.10 d y,1 on average). In general, the growing season has been lengthened by up to ,0.2 d y,1 (mean linear trends) and the mean 1974,96 growing season was up to 5 days longer than in the 1951,73 period. The spatial variability of trends was analysed by statistical means and shown in maps, but these did not reveal any substantial regional differences. Although there is a high spatial variability, trends of phenological phases at single locations are mirrored by subsequent phases, but they are not necessarily identical. Results for changes in the biosphere with such a high resolution with respect to time and space can rarely be obtained by other methods such as analyses of satellite data. [source] Hydrogeologic controls on streamflow sensitivity to climate variationHYDROLOGICAL PROCESSES, Issue 22 2008Anne Jefferson Abstract Climate models project warmer temperatures for the north-west USA, which will result in reduced snowpacks and decreased summer streamflow. This paper examines how groundwater, snowmelt, and regional climate patterns control discharge at multiple time scales, using historical records from two watersheds with contrasting geological properties and drainage efficiencies. In the groundwater-dominated watershed, aquifer storage and the associated slow summer recession are responsible for sustaining discharge even when the seasonal or annual water balance is negative, while in the runoff-dominated watershed subsurface storage is exhausted every summer. There is a significant 1 year cross-correlation between precipitation and discharge in the groundwater-dominated watershed (r = 0·52), but climatic factors override geology in controlling the inter-annual variability of streamflow. Warmer winters and earlier snowmelt over the past 60 years have shifted the hydrograph, resulting in summer recessions lasting 17 days longer, August discharges declining 15%, and autumn minimum discharges declining 11%. The slow recession of groundwater-dominated streams makes them more sensitive than runoff-dominated streams to changes in snowmelt amount and timing. Copyright © 2008 John Wiley & Sons, Ltd. [source] The effects of low dietary calcium during egg-laying on eggshell formation and skeletal calcium reserves in the Zebra Finch Taeniopygia guttataIBIS, Issue 2 2001S. JAMES REYNOLDS Many small passerines forage intensively for calcium-rich foods during laying. Increased incidences of shell defects in eggs of small passerines have been reported, particularly in western Europe, and these have been explained in terms of declining calcium availability in soils, resulting from prolonged anthropogenic acid deposition. Studies in the field have provided laying birds, nesting in areas of low calcium availability, with calcium supplements. An alternative approach was adopted in this study by allowing captive Zebra Finches Taeniopygia guttata to lay first clutches on ad libitum calcium, switching them to a low calcium diet for 72 hours for the formation of all but the first egg of the second clutch and reinstating ad libitum calcium for the final clutch. Control females had access to ad libitumcalcium for all three clutches. Clutch sizes did not vary significantly between birds on low calcium and controls. The former took over three days longer to lay clutch 3 than did controls but the difference was not statistically significant. Birds on low calcium laid eggs that declined in shell ash mass with laying sequence, indicating that birds may have been calcium-limited. Although not statistically significant, eggshell thickness also declined with laying sequence in clutches laid by females on low calcium. The remaining egg measurements (shell mass, shell surface area and volume] of clutches laid by birds on low calcium did not differ significantly from those of controls. Furthermore, females on low calcium did not resort to skeletal reserves to provide sufficient calcium for egg formation. Dietary calcium appears to be of paramount importance in providing sufficient calcium for clutch formation. [source] Sex-dependent response of primary moult to simulated time constraints in the rock sparrow Petronia petroniaJOURNAL OF AVIAN BIOLOGY, Issue 3 2010Lorenzo Serra There is growing evidence that moult speed affects plumage quality. In many bird species, males and females differ in terms of breeding effort, survival expectation and the relationship between fitness and plumage quality. Consequently, differences in moult strategies between the sexes can be expected. The aim of this study was to assess whether, under simulated time constraints and with no parental investment in the previous breeding season, males and females differed in: a) timing and duration of primary moult, b) growth rates of individual primary feathers, and c) number of concurrently growing feathers. We investigated the effect of time constraints generated by a treatment consisting of two decreasing photoperiods (slow changing photoperiod, SCP=2,min,day,1 and fast changing photoperiod, FCP=8,min,day,1) on the primary post-nuptial moult of captive rock sparrows Petronia petronia. Females started to moult on average 14 and 15,days later than males in both experimental groups. Primary moult duration was 10 (FCP) and 24 (SCP) days longer in males than in females, and, within sex, 34 (females) and 48 (males) days longer in SCP birds than in FCP ones. Females renewed a larger number of primaries simultaneously (5.7% in FCP and 12.8% in SCP) and had a higher total daily feather mass grown (9.9% in FCP and 22.4% in SCP), even though daily growth rates of individual primaries did not differ between sexes. As a result, males and females completed their primary moult at the same time within treatment. The observed differences in timing, duration and energy allocation for primary moult between the sexes probably have a genetic basis, as birds did not engage in reproduction during the preceding breeding season. [source] Influence of sulphur plant nutrition on oviposition and larval performance of the cabbage root flyAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2005Cristina Marazzi Abstract 1,Oilseed rape plants (Brassica napus) (L.) (Brassicaceae) were grown under different levels of sulphur supply and tested for the oviposition preference and larval performance of cabbage root flies Delia radicum (L.) (Diptera: Anthomyiidae). 2,Adult females laid more than three-fold as many eggs on control Sn (normal field concentration) than on sulphur-free S0 plants. By contrast, no significant difference was observed between control and double normal concentration (S+) plants. 3,The larval performance was evaluated using three additional, intermediate sulphur levels between S0 and Sn, and the plants were infected with equal numbers of eggs. The percentage pupation at the end of larval feeding ranged from 6% (S0) to 32% (Sn or S+) and the average number of pupae, or of emerging flies, was significantly correlated with sulphur application. 4,The weight of emerging males and females was correlated with plant sulphur supply. 5,The duration of development from eggs to adult emergence was approximately 2 days longer in females than in males. Females originating from plants with a normal or higher sulphur supply tended to emerge 1,2 days earlier. [source] The effect of unilateral eyestalk ablation and diet on the reproductive performance of wild-caught Farfantepenaeus aztecus (Ives, 1891) using a closed recirculating maturation systemAQUACULTURE RESEARCH, Issue 6 2007Ryan L Gandy Abstract Two studies were conducted to evaluate the effects of unilateral eyestalk ablation and diet on the reproductive performance of wild populations of Farfantepenaeus aztecus. In both studies, females in two treatments were unilaterally ablated while those in the control treatment were not. Shrimp in the non-ablated treatment and one of the unilaterally ablated treatments received frozen bloodworms (8% BW day,1) and frozen squid (12% BW day,1). The bloodworm component of the diet of the third unilateral ablation treatment was replaced with frozen adult enriched Artemia sp. Ablated female population spawning per night, in both studies, was higher than non-ablated spawning (8.5 and 8.9 vs. 2.6%; 7.4 and 7.5 vs. 2.7% respectively; P<0.05). Replacement of bloodworms with adult enriched Artemia sp. had no negative effect on the number of eggs spawned per ablated female (124 000 vs. 115 000 eggs spawn,1; 144 000 vs. 151 000 eggs spawn,1 respectively; P>0.05). The life span of ablated females fed adult enriched Artemia sp. was 8 and 40 days longer than ablated females fed bloodworms for the first and second studies respectively. Replacement of bloodworms with adult enriched Artemia sp. resulted in higher hatch and larval survival rates (Nauplius 1 to Zoea 1) (55.0% vs. 46.9% and 44.8% vs. 37.2%), respectively, P<0.05. [source] Adenanthera pavonina trypsin inhibitor retard growth of Anagasta kuehniella (Lepidoptera: Pyralidae)ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2010Maria Lígia Rodrigues Macedo Abstract Anagasta kuehniella is a polyphagous pest that feeds on a wide variety of stored products. The possible roles suggested for seed proteinase inhibitors include the function as a part of the plant defensive system against pest via inhibition of their proteolytic enzymes. In this study, a trypsin inhibitor (ApTI) was purified from Adenanthera pavonina seed and was tested for insect growth regulatory effect. The chronic ingestion of ApTI did result in a significant reduction in larval survival and weight. Larval and pupal developmental time of larvae fed on ApTI diet at 1% was significantly longer; the larval period was extended by 5 days and pupal period was 10 days longer, therefore delaying by up to 20 days and resulting in a prolonged period of development from larva to adult. As a result, the ApTI diet emergence rate was only 28% while the emergence rate of control larvae was 80%. The percentage of surviving adults (%S) decreased to 62%. The fourth instar larvae reared on a diet containing 1% ApTI showed a decrease in tryptic activity of gut and that no novel proteolytic form resistant to ApTI was induced. In addition, the tryptic activity in ApTI -fed larvae was sensitive to ApTI. These results suggest that ApTI have a potential antimetabolic effect when ingested by A. kuehniella. © 2010 Wiley Periodicals, Inc. [source] Temperature-dependent development and distribution in the soil profile of pupae of greyback canegrub Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae) in Queensland sugarcaneAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2007David P Logan Abstract, The temperature-dependent development rate of pupae of greyback canegrub, Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae), a major pest of sugarcane in central and northern Queensland, was determined under six constant temperature regimes: 18, 20, 23, 25, 27 and 30°C, and for four geographically separated populations. Development rate increased significantly with increasing temperature. Parameters of the linear regression equation did not differ among populations and common coefficients were calculated. Developmental zero, at and below which no development occurs, for pupae was 12.0°C and the thermal constant was 476 day-degrees (D°). Minimum and maximum periods for pupal development were 26 days at 30°C and 75 days at 18°C, respectively. The phenology of pupae was determined in soil-filled cubicles in a shade house and in the field at Ayr (19°35,S, 147°25,E), north Queensland, using D. albohirtum field-collected as late-stage third-instar larvae and kept in containers. Pupation of D. albohirtum began in late August or early September and eclosion was complete by mid- to late October. The phenology data were used to validate the development model. Eclosion was predicted by summing hourly fractions of day-degrees until 476 D° was reached and was close to actual eclosion. As temperature, and hence pupal development rate, varies with soil depth, the distribution of the third instars in pupal cells in the soil profile was determined in recently harvested fields of sugarcane in the Burdekin sugarcane district centred on Ayr. Numbers of late third instars in pupal cells peaked at 300,400 mm, with pupae found from 30 to 700 mm. Pupal development was simulated using hourly soil temperatures measured at depths of 200 and 400 mm at Ayr and at Sarina (21°22,S, 149°13,E). The pupal stage was predicted to take up to 2,10 days longer at 200 mm deep than at 400 mm depending on pupation site and date. When pupation was simulated in late August, as is likely in the field, pupal development at 400 mm deep took 48,56 days at Ayr and 58,62 days at Sarina. [source] | |||||||||||||||||||||||||