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Demographic development of middle Dalmatian settlements: Jesenice, Mimice, Zivogosće and Zaostrog was followed during the period between 1857 and 1991. On the basis of the analysis, we can conclude that the positive trends in the number of residents were interrupted during the first decades of the 20th century, while the stagnation and decrease of the total number of residents prevailed during the following period. In other words, depopulation was established as a stable demographic process. Population's gender structure was uniform during the rolls in 1971, 1981 and 1991 in all four settlements. During the same period, the age structure of the population showed that the older residents prevailed over younger residents (prereproductive and repoductive population) in all four settlements (Jesenice, Mimice, Zivogosće and Zaostrog). Furthermore, all settlements belonged to the regressive or stationary types of age structure (neither belonging to the progressive type). We have used the LOPI model for the mathematical modeling of demographic processes of the middle Dalmatian population. On the basis of the LOPI model the results show very good accordance between the simulated data and actual values in the settlements of Zivogosće and Zaostrog. The settlements of Jesenice and Mimice showed also very good accordance between the simulated data and actual values, but only until 1920 (Jesenice) and 1910 (Mimice) year.
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To quantify populations of the corn flea beetle, Chaetocnema pulicaria Melsheimer (Coleoptera: Chrysomelidae), and refine estimates of a threshold for its control to prevent Stewart's wilt caused by Erwinia stewartii, sequential plantings of 'Jubilee' sweet corn were made at 2-wk intervals from April or May through August or September 2001 and 2002 at four locations from southern to northern Illinois: Simpson, Brownstown, Champaign, and Mendota. Densities of C. pulicaria and incidence of Stewart's wilt were monitored weekly. At Mendota, where C. pulicaria populations were decimated by cold temperatures during winter 2000-2001, densities reached 33.3 beetles per 15-cm yellow sticky trap per day by September 2002, after a mild 2001-2002 winter. Maximum incidence of Stewart's wilt in single plots at Simpson, Brownstown, Champaign, and Mendota was 22, 36, 39, and 2%, respectively, in 2001, and 33, 47, 99, and 87%, respectively, in 2002. In 24 plots where beetle densities were < or =2 per trap per day, Stewart's wilt incidence was <5% in 20 plots. We propose that two corn flea beetles per trap per day be used as a threshold for insecticide application to seedlings to control C. pulicaria and minimize subsequent incidence of Stewart's wilt in processing sweet corn. Enzyme-linked immunosorbent assays indicated that E. stewartii incidence in C. pulicaria peaked at 67, 62, and 54%, respectively, at Simpson, Brownstown, and Champaign, in 2001, and at 71, 76, and 60%, respectively, in 2002. Further studies might allow the use of areawide or field-specific estimates of E. stewartii incidence in corn flea beetles for adjusting management decisions.
A study of the density of river mollusks in six watercress groves is made. It is seen how densities of F. cubensis, intermediate host of fascioliasis in Cuba, is maintained with relative stability. The poor effectiveness of P. duryi as an agent of biologic control is demonstrated. The high density of P. cubensis, which seems to exert a certain regulatory effect on F. cubensis--particularly in the months of reproductive peaks (August and September)--is emphasized. Densities of B. havanensis and B. helophila may be affected by the density of F. cubensis and P. cubensis, which may exert certain influence in the decrease of pulmonate density. F. cubensis and P. parvulus are morphometrically compared and a high correlation between length and width of the shell (r = 0.9) is emphasized; such correlation was smaller in P. parvulus (r = 0.7).
Tsetse flies are a major constraint on animal production in about 10 million km2 of Africa through their transmission of animal trypanosomiasis. Up to 25 million people are at risk from human trypanosomiasis, or sleeping sickness. Tsetse research has been concentrated on the factors that control the distribution and abundance of these vectors and the means by which their numbers can be reduced. Eradication successes in some countries are insignificant compared with the continental scale of the problem and the long-term reduction in the area infested by tsetse has been negligible. We report here that the mortality rates of tsetse from sites in both West and East Africa, the size of male and female tsetse (related to the mortality rate of the parental female population) along a north-south transect in West Africa, and the abundance of two species of tsetse over the northern half of Côte d'Ivoire, are significantly correlated with data from meterological satellites. This information could be used to predict both the mortality rate and the abundance (key determinants of disease transmission potential) of tsetse over very large areas of the continent and to produce maps of high risk areas of disease transmission for the African trypanosomiases and, by implication, for many other vector-borne diseases.
Ozone formation is a complex function of local hydrocarbon and nitrogen oxide emissions. Therefore, trading of NOx emissions among geographically distributed facilities can lead to more or less ozone formation than across-the-board reductions. Monte Carlo simulations of trading scenarios involving 51 large NOx point sources in eastern Texas were used in a previous study by the authors to assess the effects of trading on air quality benefits, as measured by changes in ozone concentrations. The results indicated that 12% of trading scenarios would lead to greater than a 25% variation from conventional across-the-board reductions when air quality benefits are based only on changes in ozone concentration. The current study found that when benefits are based on a metric related to population exposure to ozone, two-thirds of the trading scenarios lead to changes in air quality benefits of approximately 25%. Variability in air quality benefits is not as strongly dependent on the temporal distribution of NOx emissions.
The performance of 1,312 male market turkeys (Large White, Nicholas strain) from 0 to 20 wk of age fed diets varying in feed form and energy level was measured under two stocking densities (.21 or .46 m2 per bird) and four lighting and temperature programs. The four diets were 1) corn and soybean meal with 1% supplemental fat, mash (CSM); 2) as 1, pelleted (CSP); 3) as Diet 1 but with 1, 2, 4, 6, and 8% supplemental fat during 0 to 4, 4 to 8, 8 to 12, 12 to 16, and 16 to 20 wk of age, respectively (CSF); and 4) as Diet 1 but with barely included at 0, 20, 35, 50, and 65% during the respective 4-wk age periods (CSB). The four light and temperature programs were 1) Environment A with intermittent light [4 [2 h light (L):4 h dark (D)]] in combination with cycling temperature at 7 and 21 C during light and dark photoperiod, respectively; Environment B with intermittent light, 21 C; Environment C with continuous light (18L:6D) and cycling temperature of 7 to 21 C; and Environment D with intermittent light, 7 C. Lighting and temperature programs started at 1 and 4 wk of age, respectively. Body weights at 20 wk of age decreased (P less than .05) with increasing temperature (13.86 versus 12.26 kg for Environments D and B, respectively) with cycling temperature intermediate (13.51 kg for Environment A). Intermittent light (P less than .05) improved BW and feed conversion by 3.4 and 2.0%, respectively, compared with continuous light. Rearing males at .21 m2 per bird versus .46 m2 per bird decreased weight (P less than .05) by 5.5%. Twenty-week BW of males fed the CSP (13.52 kg) and CSF (13.58 kg) diets were greater (P less than .05) than those fed CSM (12.90 kg) and CSB (12.69 kg) diets. Significant (P less than .05) interactions between diet, environment, and density were not detected for most performance characteristics. Environmental measurements indicated higher dust and ammonia levels in the warm environment (B). Isolates of aspergillus and incidence of airsacculitis at time of processing were greatest in Environment B.
Bilaterally symmetrical morphological characters with fluctuating asymmetry usually have small, random deviations from symmetry that reflect the ability of individuals to cope with genetic and environmental stress. A comparison of the level of fluctuating asymmetry in two fast-growing breeds (ScanBrid, Ross 208) with that of a slow-growing breed (La Belle Rouge) and wild jungle fowl from India revealed a positive relationship between growth rate and asymmetry. Fast-growing chickens kept at three densities (20, 24, and 28 chickens per square meter) revealed a positive association between fluctuating asymmetry and density. Large individuals generally had higher levels of fluctuating asymmetry than small individuals. Tonic immobility, which is often used as a measure of fearfulness, was weakly positively associated with the degree of fluctuating asymmetry (P < .05). Measures of fluctuating asymmetry may provide information on levels of stress experienced by domesticated animals.
At 28 days post-infection autoinfective third-stage larvae (L3a) of Strongyloides stercoralis occurred in jirds infected with 10,000 infective third-stage (L3i). Previously in the jird model of strongyloidiasis, autoinfection had been seen in immunologically immature or immunosuppressed jirds only. The heavily infected jirds described herein had a strong anti-L3i immune response at the same time the living L3a were found in their tissues. This was demonstrated by the rapid killing of L3i in subcutaneously implanted diffusion chambers. No decrease of intestinal motility was observed in these heavily infected jirds, indicating that an increased time for development was not the explanation for the presence of L3a. These larvae were found only in jirds when concomitantly a large number of first-stage larvae (L1) occurred in the intestines. We suggest that the development of L3a in the adult jird model is a rare event and thus, autoinfection occurs only when the intestinal population of L1 is very large, as was the case in the heavily infected jirds. Index Descriptors and Abbreviations. Nematode; Strongyloides stercoralis; Mongolian gerbil; Meriones unguiculatus; autoinfection; larval development; L3i, infective third-stage larva(e); L3i+, tissue migrating third-stage larva(e); L3a, autoinfective third-stage larva(e); L1, first-stage larva(e); PI, post-infection.
Home Office guidelines recommend an area of 60 cm2 per mouse for growing mice up to 30 g. However, the overall growth rate, and final adrenal weight of weanling BALB/c and MF1 strain mice was not affected by being housed at a density of down to 27 cm2 per mouse, though there was some evidence of strain differences in ability to tolerate such dense housing. The presence of cage accessories had no effect on growth rate of BALB/c and female mice, but reduced growth of MF1 and male mice, though the effect was small. It is concluded that present Home Office guidelines make a generous provision for the space requirements of growing laboratory mice, and that the use of cage accessories of varying design may be worth exploring in more detail.
In the period from April to May and September to October of 1967--1973 in the Mujun-Kum a radioactive tracing of great gerbils was carried out. In all 225 tests were conducted. The greatest intensity of parasitic contacts between the animals was noted at their average quantity. Its further rise does not result in the increase of the parasitic relations. If the number of fleas is high the parasitic contacts level even at the relatively low number of great gerbils is usually high enough for a further passing of the plague microbe. If the number of both fleas and great gerbils is low the parasitic relations provide but not always an agent transmission.
In a survey of containers infested with Aedes aegypti (L.) conducted during September and October 1979 in a substandard residential area of New Orleans, LA, infestation indices were as follows: House--35, Breteau (foci)--85, Receptacle--69, Block--100, and Larval Density--169. A mean of 48.5 water-holding containers were found per block. More than 50% of these receptacles were narrow-mouthed containers, e.g., drink bottles, that held an average of less than 0.03 mosquito immatures each. After exclusion of data on the unproductive narrow-mouthed type, the average container held 7.8 liters of water, 105 1st and 2nd instars, 69 3rd an 4th instars, and 12 pupae. With assumed constant adult survival rates of 0.85-0.90 per day, the number of females per block on any particular day was estimated from pupal production data at 362-558, and the standing crop of females 12 days and older and therefore old enough to transmit dengue fever if they are vector competent was estimated at 51-158 per block.