Average Daily Mortality Rate Research Articles

Uji Efektivitas Pestisida Nabati Ekstrak Daun Pepaya (Carica papaya L.) dan Ekstrak Ubi Gadung (Dioscorea hispida Dennst) pada Mortalitas Penghisap Buah Kakao (Helopeltis spp.)

Fruit-sucking bugs (Helopeltis spp.) are one of the main pests on cocoa plants. The damage caused by this pest is by piercing and sucking the liquid of cocoa pods and young shoots. This study aimed to obtain the effective concentration of papaya leaf extract and yam extract on the mortality of cocoa fruit-sucking bugs. This research was carried out at the Plant Production Laboratory II of the Politeknik Negeri Lampung from September 2020 to January 2021. The design used in this study was a Randomized Block Design consisting of 4 treatments and six replications. The results showed that the average daily mortality rate fluctuated in each treatment. In all treatment concentrations of papaya leaf extract and yam extract, the average mortality of cocoa fruit-sucking bugs ranged from 25.76% to 75.76%. All treatment concentrations of papaya leaf extract and yam extract were not effective in the mortality of cocoa fruit-sucking bugs.

Environmentally triggered shifts in steelhead migration behavior and consequences for survival in the mid-Columbia River.

The majority of Columbia River summer-run steelhead encounter high river temperatures (near or > 20°C) during their spawning migration. While some steelhead pass through the mid-Columbia River in a matter of days, others use tributary habitats as temperature refuges for periods that can last months. Using PIT tag detection data from adult return years 2004-2016, we fit 3-component mixture models to differentiate between "fast", "slow", and "overwintering" migration behaviors in five aggregated population groups. Fast fish migrated straight through the reach on average in ~7-9 days while slow fish delayed their migration for weeks to months, and overwintering fish generally took ~150-250 days. We then fit covariate models to examine what factors contributed to the probability of migration delay during summer months (slow or overwintering behaviors), and to explore how migration delay related to mortality. Finally, to account for the impact of extended residence times in the reach for fish that delayed, we compared patterns in estimated average daily rates of mortality between migration behaviors and across population groups. Results suggest that migration delay was primarily triggered by high river temperatures but temperature thresholds for delay were lowest just before the seasonal peak in river temperatures. While all populations groups demonstrated these general patterns, we documented substantial variability in temperature thresholds and length of average delays across population groups. Although migration delay was related to higher reach mortality, it was also related to lower average daily mortality rates due to the proportional increase in reach passage duration being larger than the associated increase in mortality. Lower daily mortality rates suggest that migration delay could help mitigate the impacts of harsh migration conditions, presumably through the use of thermal refuges, despite prolonged exposure to local fisheries. Future studies tracking individual populations from their migration through reproduction could help illuminate the full extent of the tradeoffs between different migration behaviors.

Field evaluation of Maqs® and Api-Bioxal® for late summer control of Varroa mite infestation in Northeastern Italy

The study evaluates the efficacy and effects of two organic acid-based miticides (Maqs® and Api-Bioxal®) used in late summer to reduce the population of Varroa destructor mites in colonies of Apis mellifera ligustica. The study took place in Albaredo d’Adige (Verona, Northeastern Italy). Twenty-six honey bee colonies, divided into four groups, were used for the experiment. Miticide efficacy, average daily mortality rate of adult bees, and number of bees present in the hives at specific timeframes were evaluated. The average daily efficacy of Maqs®’s miticide proved to be 96.8% compared to 93.4% for Api-Bioxal® combined with queen caging. High adult honey bee mortality was recorded after treatment with Maqs®, showing that average daily mortality was 82.4% higher than natural daily mortality. Daily mortality for Api-Bioxal® and queen caging was instead 30.1% lower than in non-treated colonies. The average decrease in the colony population of the treated groups was higher in the Maqs® (–38%) than in the Api-Bioxal® group (–28%). The fall in the latter was comparable to the values recorded in the control groups (–23% in the Api-Bioxal and –24% in the Maqs® control groups). Both veterinary medicinal products were effective for the control of V. destructor mite populations in late summer. However, the important negative effects recorded in the Maqs® group discourage the use of this miticide in geographical and climatic conditions of the type described in this study. Api-Bioxal® in combination with queen caging did instead confirm its efficacy and reliability for controlling the infestation in Northeastern Italy.

Warmer is healthier: Effects on mortality rates of changes in average fine particulate matter (PM2.5) concentrations and temperatures in 100 U.S. cities

Recent studies have indicated that reducing particulate pollution would substantially reduce average daily mortality rates, prolonging lives, especially among the elderly (age⩾75). These benefits are projected by statistical models of significant positive associations between levels of fine particulate matter (PM2.5) levels and daily mortality rates. We examine the empirical correspondence between changes in average PM2.5 levels and temperatures from 1999 to 2000, and corresponding changes in average daily mortality rates, in each of 100 U.S. cities in the National Mortality and Morbidity Air Pollution Study (NMMAPS) data base, which has extensive PM2.5, temperature, and mortality data for those 2years. Increases in average daily temperatures appear to significantly reduce average daily mortality rates, as expected from previous research. Unexpectedly, reductions in PM2.5 do not appear to cause any reductions in mortality rates. PM2.5 and mortality rates are both elevated on cold winter days, creating a significant positive statistical relation between their levels, but we find no evidence that reductions in PM2.5 concentrations cause reductions in mortality rates. For all concerned, it is crucial to use causal relations, rather than statistical associations, to project the changes in human health risks due to interventions such as reductions in particulate air pollution.

Size‐dependent predation risk in tree‐feeding insects with different colouration strategies: a field experiment

1. Body size is positively correlated with fecundity in various animals, but the factors that counterbalance the resulting selection pressure towards large size are difficult to establish. Positively size-dependent predation risk has been proposed as a selective factor potentially capable of balancing the fecundity advantage of large size. 2. To construct optimality models of insect body size, realistic estimates of size-dependent predation rates are necessary. Moreover, prey traits such as colouration should be considered, as they may substantially alter the relationship between body size and mortality risk. 3. To quantify mortality patterns, we conducted field experiments in which we exposed cryptic and conspicuous artificial larvae of different sizes to bird predators, and recorded the incidence of bird attacks. 4. The average daily mortality rate was estimated to vary between 4% and 10%. In both cryptic and conspicuous larvae, predation risk increased with prey size, but the increase tended to be steeper in the conspicuous group. No main effect of colour type was found. All the quantitative relationships were reasonably consistent across replicates. 5. Our results suggest that the size dependence of mortality risk in insect prey is primarily determined by the probability of being detected by a predator rather than by a size-dependent warning effect associated with conspicuous colouration. Our results therefore imply that warningly coloured insects do not necessarily benefit more than the cryptic species from large body size, as has been previously suggested.

Stage-specific mortality of Baltic cod (Gadus morhua L.) eggs

Summary A study on cod egg mortality was carried out in the Bornholm Basin (southern central Baltic Sea) toward the end of July 1996. An initial egg aggregation marked by a satellite-tracked drifter buoy was sampled repeatedly over an 11-day period; profiles of temperature, salinity and dissolved oxygen were concurrently recorded. Three replicate estimates of mortality were obtained for each pair of subsequent developmental stages from newly spawned eggs to early larvae. A consistent pattern of stage-specific mortality coincided well with previous experimental observations. Average daily mortality rates were 7.2% (eggs IA/IB), 38.7% (eggs (IB/II), 25.6% (eggs II/III), 40.0% (eggs III/IV), and 42.3% (eggs IV/early larvae). The cumulative mortality until hatch amounted to 99.9%. Results from hydrodynamic modelling, however, indicated that the drifter's trajectory was influenced by wind stress. Hence, the mortality rates might be biased despite the short sampling intervals; a modification of the sampling design is recommended for future studies.

POPULATION GROWTH OF ANTARCTIC FUR SEALS: LIMITATION BY A TOP PREDATOR, THE LEOPARD SEAL?

Antarctic fur seals (Arctocephalus gazella) in the South Shetland Islands are recovering from 19th-century exploitation more slowly than the main population at South Georgia. To document demographic changes associated with the recovery in the South Shetlands, we monitored fur seal abundance and reproduction in the vicinity of Elephant Island during austral summers from 1986/1987 through 1994/1995. Total births, mean and variance of birth dates, and average daily mortality rates were estimated from daily live pup counts at North Cove (NC) and North Annex (NA) colonies on Seal Island. Sightings of leopard seals (Hydrurga leptonyx) and incidents of leopard seal predation on fur seal pups were recorded opportunistically during daily fur seal research at both sites. High mortality of fur seal pups, attributed to predation by leopard seals frequently observed at NC, caused pup numbers to decline rapidly between January and March (i.e., prior to weaning) each year and probably caused a long-term decline in the size of that colony. The NA colony, where leopard seals were never observed, increased in size during the study. Pup mortality from causes other than leopard seal predation appeared to be similar at the two sites. The number of pups counted at four locations in the Elephant Island vicinity increased slowly, at an annual rate of 3.8%, compared to rates as high as 11% at other locations in the South Shetland Islands. Several lines of circumstantial evidence are consistent with the hypothesis that leopard seal predators limit the growth of the fur seal population in the Elephant Island area and perhaps in the broader population in the South Shetland Islands. The sustained growth of this fur seal population over many decades rules out certain predator–prey models, allowing inference about the interaction between leopard seals and fur seals even though it is less thoroughly studied than predator–prey systems of terrestrial vertebrates of the northern hemisphere. Top-down forces should be included in hypotheses for future research on the factors shaping the recovery of the fur seal population in the South Shetland Islands.

Population Growth of Antarctic Fur Seals: Limitation by a Top Predator, the Leopard Seal?

Antarctic fur seals (Arctocephalus gazella) in the South Shetland Islands are recovering from 19th-century exploitation more slowly than the main population at South Georgia. To document demographic changes associated with the recovery in the South Shetlands, we monitored fur seal abundance and reproduction in the vicinity of Elephant Island during austral summers from 1986/1987 through 1994/1995. Total births, mean and variance of birth dates, and average daily mortality rates were estimated from daily live pup counts at North Cove (NC) and North Annex (NA) colonies on Seal Island. Sightings of leopard seals (Hydrurga leptonyx) and incidents of leopard seal predation on fur seal pups were recorded opportunistically during daily fur seal research at both sites. High mortality of fur seal pups, attributed to predation by leopard seals frequently observed at NC, caused pup numbers to decline rapidly between January and March (i.e., prior to weaning) each year and probably caused a long-term decline in the size of that colony. The NA colony, where leopard seals were never observed, increased in size during the study. Pup mortality from causes other than leopard seal predation appeared to be similar at the two sites. The number of pups counted at four locations in the Elephant Island vicinity increased slowly, at an annual rate of 3.8%, compared to rates as high as 11% at other locations in the South Shetland Islands. Several lines of circumstantial evidence are consistent with the hypothesis that leopard seal predators limit the growth of the fur seal population in the Elephant Island area and perhaps in the broader population in the South Shetland Islands. The sustained growth of this fur seal population over many decades rules out certain predator–prey models, allowing inference about the interaction between leopard seals and fur seals even though it is less thoroughly studied than predator–prey systems of terrestrial vertebrates of the northern hemisphere. Top-down forces should be included in hypotheses for future research on the factors shaping the recovery of the fur seal population in the South Shetland Islands.

Efficacy of Sarafloxacin Hydrochloride in Treating Naturally-InducedEdwardsiella ictaluriInfections in Channel Catfish,Ictalurus punctatus

Sarafin (sarafloxacin hydrochloride), a new antibacterial, was evaluated in the field on a naturally induced infection of Edwardsiella ictaluri in channel catfish, -Ictalurus punctatus. Healthy channel catfish (mean weight = 50 g) were stocked into nine cages at 200 fish per cage in a pond with an undergoing E. ictaluri infection. Seven days after stocking, dead fish were observed in the cages with clinical signs of enteric septicemia of channel catfish (ESC). After E. ictaluri was confirmed through isolative biochemical tests, medicated feed was applied for five consecutive days. During this period, fish in three control cages received a commercial 32% protein floating feed, three other cages of fish served as positive controls and were fed Romet, and three cages received the test feed with Sarafin. Both medicated feeds reduced the increase in cumulative percent mortality. In the control cages, cumulative percent mortalities continued to increase throughout the study period. Average daily mortality rates...

From a case study to a theoretical basis for tsetse control

The paper presents a way of estimating average daily mortality rates of female tsetse from ovarian age distributions. This technique was applied to monthly biconical trap samples of G. palpalis taken during and after insecticidal campaigns in the Bouafle region of Ivory Coast. A clear inverse relationship is demonstrated between the annual mean number of females per trap per sample at 10 separate sites, and the mean annual mortality rates calculated for them. Local variation in the impact of insecticides is explained in terms of the grouping of the sites either side of a level of natural mortality above which tsetse populations cannot be sustained through reproduction alone. A theoretical model for density dependent population growth is presented and applied to a particular control situation, that of the sterile insect release method. The model demonstrates that the effectiveness of any particular level of induced sterility (or mortality) is crucially determined by the natural resilience of the target population.

The survival in nature of Wuchereria-infected Anopheles funestus Giles in North-eastern Tanzania

Hungry Anopheles funestus females were caught in CDC light traps positioned overnight in village houses in which the occupants were protected by bed nets. The sampling was performed in six huts near Muheza, in North-eastern Tanzania, September to November 1972. Parous, unfed mosquitoes were carefully examined, usually under phase-contrast optics, for the presence of developing Wuchereria bancrofti larvae. Because A. funestus seek blood meals at three-day intervals, most filariae were three, six, nine, 12 and 15 days old, and could with confidence be assigned to one of these five easily recognized age groups. Of 3,289 unfed A. funestus examined, 1,723 (52%) were parous. Developing and mature infections amongst the parous were 272 in number. Simultaneous infections of two age groups numbered 21, one mosquito was triply infected, thus there were 249 infected mosquitoes (7·57% of the total). The regression of loge number of infections ( y) on estimated age in days ( X), agreed with an hypothesis of linearity (r = −0·9967); the equation log e y = 5·25− 0·1646X suggested an average daily mortality rate of 16·46% in good agreement with the mean 15-6% observed in A. funestus by Gillies & Wilkes. The equation above affords an estimate of the probability of an A. funestus becoming infected at a single random feeding. The expected number of day 0 infections, given by the antilog of the first term of the equation and taken as a fraction of the biting population, gives the estimate. The values obtained were 0-058-0-087. Use of Macdonald's 1952 formula for the sporozoite rate provided estimates of 0-071-0-081. Age-specific worm densities in A. funestus did not vary significantly between day three and day 15 infections, and no evidence was obtained to suggest that the higher worm burdens influenced the survival of their hosts. The frequency of superinfections did not support the contention that a previously established infection inhibits the chance of a second, younger infection from becoming established.