Impact Population Growth Research Articles

Heuristics for the Intelligent Prediction of Population Growth

Population growth is a phenomenon that is inevitable in a life course and the components of population growth are fertility, mortality and migration. Because of the impact population growth exact upon the socio- economic nature of a country, it will be wise to know the future size and distribution of it so that adequate measures can be made to forestall possible problems. There are different population models and algorithms implemented to project population growth, ranging from statistical to machine learning models; these model techniques were very suitable in their time, such as the Malthusian theory, which, first and foremost, gives deeper consideration to the exponential growth model, while many implemented classification and linear regression algorithm. Linear regression machine learning algorithms were considered the most effective algorithm for population growth projection. This study tends to develop a machine learning model that is data-driven mathematically, capable of implementing the data-independent prediction model equation that was used to predict the impact of the Non-pharmaceuticals approach and pharmaceuticals approach (NPA and PA) in mitigating the spread of the Covid-19 virus, and both models were re-modified to project Nigeria population growth. The data-independent prediction model (DIPM) utilized onset data from the NPA and PA interventions to predict the probability of mitigating the spread of the virus for a specific period. The DIPM has the properties of arithmetic and exponential methods. The fusion of these two properties with the aid of machine learning model has further reveal the data-independent prediction model as a conceptualization technique to reflect how data are processed in an algorithm setting in a concrete world, with the support of the Java array list algorithm, what all the statistical models and supervised machines learning model used in the past studies could not achieve, have been accomplished succinctly. The data independent prediction model is a robust technique for both projection and forecasting future population growth as well as proffer answers to historical issues in mathematical modeling of population expansion.

Approaching a population‐level assessment of body size in pinnipeds using drones, an early warning of environmental degradation

AbstractBody mass is a fundamental indicator of animal health closely linked to survival and reproductive success. Systematic assessment of body mass for a large proportion of a population can allow early detection of changes likely to impact population growth, facilitating responsive management and a mechanistic understanding of ecological trends. One challenge with integrating body mass assessment into monitoring is sampling enough animals to detect trends and account for individual variation. Harbour seals (Phoca vitulina) are philopatric marine mammals responsive to regional environmental changes, resulting in their use as an indicator species. We present a novel method for the non‐invasive and semi‐automatic assessment of harbour seal body condition, using unoccupied aerial vehicles (UAVs/drones). Morphological parameters are automatically measured in georeferenced images and used to estimate volume, which is then translated to estimated mass. Remote observations of known individuals are utilized to calibrate the method. We achieve a high level of accuracy (mean absolute error of 4.5 kg or 10.5% for all seals and 3.2 kg or 12.7% for pups‐of‐the‐year). We systematically apply the method to wild seals during the Spring pupping season and Autumn over 2 years, achieving a near‐population‐level assessment for pups on land (82.5% measured). With reference to previous mark‐recapture work linking Autumn pup weights to survival, we estimate mean expected probability of over‐winter survival (mean = 0.89, standard deviation = 0.08). This work marks a significant step forward for the non‐invasive assessment of body condition in pinnipeds and could provide daily estimates of body mass for thousands of individuals. It can act as an early warning for deteriorating environmental conditions and be utilized as an integrative tool for wildlife monitoring. It also enables estimation of yearly variation in demographic rates which can be utilized in parameterizing models of population growth with relevance for conservation and evolutionary biology.

Analysis of Factors That Influence Fertility in Women in North Kuta District Badung Regency

Fertility is a crucial indicator in demographic studies and has direct implications for population development. The fertility rate refers to the average number of live births that a woman or a population in a specific area and time period can produce. The Total Fertility Rate (TFR) in Badung is relatively low compared to other regions, standing at 1,93. This may influence slower population growth. However, it's important to note that low TFR is not the sole factor affecting population growth. Other factors such as migration, mortality, birth rates, and population mobility can also impact population growth. This research aims to analyze the factors influencing fertility rates in the North Kuta District of Badung Regency. The variables considered in this study include education, family income, age at first marriage, and contraceptive use concerning fertility rates in the North Kuta District of Badung Regency, both simultaneously and partially. The data for this study are entirely based on primary and secondary sources. The research was conducted in the North Kuta District of Badung Regency, with a sample size of 100 couples of childbearing age, using purposive sampling. The analytical technique employed in this research is Multiple Linear Regression Analysis. The findings indicate that education has a negative and non-significant influence on fertility, while income, age at first marriage, and contraceptive use have a positive and significant impact on fertility. This research is expected to contribute significantly to improving women's reproductive health in controlling birth rates and enhancing family well-being.

Forecasting Outbreaks of Hantaviral Disease: Future Directions in Geospatial Modeling.

Hantaviral diseases have been recognized as 'place diseases' from their earliest identification and, epidemiologically, are tied to single host species with transmission occurring from infectious hosts to humans. As such, human populations are most at risk when they are in physical proximity to suitable habitats for reservoir populations, when numbers of infectious hosts are greatest. Because of the lags between improving habitat conditions and increasing infectious host abundance and spillover to humans, it should be possible to anticipate (forecast) where and when outbreaks will most likely occur. Most mammalian hosts are associated with specific habitat requirements, so identifying these habitats and the ecological drivers that impact population growth and the dispersal of viral hosts should be markers of the increased risk for disease outbreaks. These regions could be targeted for public health and medical education. This paper outlines the rationale for forecasting zoonotic outbreaks, and the information that needs to be clarified at various levels of biological organization to make the forecasting of orthohantaviruses successful. Major challenges reflect the transdisciplinary nature of forecasting zoonoses, with needs to better understand the implications of the data collected, how collections are designed, and how chosen methods impact the interpretation of results.

Growth rate and projected age at sexual maturity for immature hawksbill turtles and green turtles foraging in the remote marine protected area of Aldabra Atoll, Seychelles

Changes in marine ecosystems from human stressors, and concerns over how species will respond to these changes have emphasized the importance of understanding and monitoring crucial demographic parameters for population models. Long-lived, migratory, marine vertebrates such as sea turtles are particularly vulnerable to changes. Life-history parameters like growth-in-body size can be largely influenced by environmental processes which can impact population growth. We analyzed a 40-year (1981–2021) capture-mark-recapture dataset from the protected UNESCO World Heritage Site, Aldabra Atoll, Seychelles, to estimate key population parameters, including body growth, for immature green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata). Curved carapace length (CCL) range was 34.3–110.9 cm (mean ± SD: 51.0 ± 11.4 cm, n = 1191) for green turtles and 28.7–89.4 cm (47.7 ± 14.4 cm, n = 538) for hawksbill turtles. Recapture events, with an 11-month minimum period, revealed a mean annual growth rate of 3.2 ± 1.5 cm year−1 for green turtles (n = 75) and 2.8 ± 1.4 cm year−1 for hawksbill turtles (n = 110). Hawksbill turtles exhibited a non-monotonic growth rate while no significant growth-size relationship was detected for green turtles. Green turtle mean annual growth per 10-cm size class was highest in the larger size classes (50‒69.9 cm). Hawksbill turtle growth rate was highest in the larger size classes (50‒69.9 cm) then declined in the largest size class (70‒79.9 cm). Green turtles and hawksbill turtles may spend > 8 and 18 years, respectively, using Aldabra, Seychelles, as a foraging ground.

The cost of self-promotion: ecological and demographic implications of the mentor effect in natural plant populations.

Under the mentor effect, compatible heterospecific pollen transfer induces self-pollen germination in otherwise self-incompatible plants. The mentor effect could be considered a novel mode of reproductive interference if it negatively impacts fitness. Yet to date, this phenomenon has predominately been investigated under experimental conditions rather than insitu. We address this gap in natural populations of the self-incompatible native dandelion, Taraxacum ceratophorum, where selfing only occurs in association with hybridization from exotic Taraxacum officinale. We tested whether self-fertilization rate increases in the hybrid zone, as predicted due to the mentor effect. Using results from these investigations, we created an exponential growth model to estimate the potential demographic impacts of the mentor effect on T. ceratophorum population growth. Our results demonstrate that the strength of the mentor effect in Taraxacum depends on the prevalence of pollinator-mediated outcross pollen deposition rather than self-pollination. Demographic models suggest that reduced outcrossing in T. ceratophorum under exotic invasion could negatively impact population growth through inbreeding depression. We demonstrate the mentor effect is rare in natural populations of T. ceratophorum due to masking by early life cycle inbreeding depression, prevalent outcrossing, and ovule usurpation by heterospecific pollen.

Reproductive cycles of the oviparous sponges Cinachyrella apion (Spirophorida) and Tethya maza (Tethyida) in a tropical intertidal environment

AbstractEnvironmental factors are constantly changing in the intertidal region. Consequently, the various benthic organisms that densely colonize this ocean area had to adapt to these constant changes. Reproductive strategy might be considered one of these adaptations. However, knowledge about this aspect of the biology of marine invertebrates is still contentious for some groups, especially with regard to sponges (Porifera). Here, we investigated the effects of different environmental factors on the timing and effort of sexual and asexual reproduction in Cinachyrella apion and Tethya maza, two oviparous demosponges in Salvador, Bahia, Brazil. We analyzed the influence of humidity, atmospheric temperature, seawater temperature, photoperiod, rainfall, height of low tides, and chlorophyll‐a concentration on the density and size of oocytes and buds of these sponges. Both species reproduced aperiodically. Cinachyrella apion had a maximum 2.8 ± 4.04 oocytes/mm2 and 0.73 ± 0.15 buds/mm2, whereas T. maza had a maximum 6.0 ± 12.21 oocytes/mm2 and 0.31 ± 0.13 buds/mm2. The density of oocytes in C. apion was positively influenced by chlorophyll‐a concentration, whereas that of T. maza was negatively modulated by relative humidity. We did not observe any relationship between the environmental factors and bud density in C. apion, but bud density variation in T. maza was positively related to chlorophyll‐a concentration and to seawater temperature. It seems that individuals of both species alternated between the production of sexual and asexual propagules, suggesting a trade‐off between reproductive modes. Therefore, asexual and sexual reproduction seems to impact population growth and reproduction of both species, likely contributing to the recruitment of new sponges. In tropical intertidal regions, multiple environmental factors seem to contribute more to determining the quantity of sexual and asexual reproductive elements rather than the species' reproductive period.

How should we manage a strong Eurasian Beaver population? A comparison of population trends in Poland and Belarus.

The Eurasian beaver is currently found in at least 32 European countries, with many of these populations being established in the 1960s. In most European countries, the beaver is under protection, however, when the population is strong, the beaver becomes a game species. In Poland, the beaver is partially protected despite the species having a strong population. In this study we aimed to compare the development trends of Eurasian beaver populations in two management regimes, in Poland (protected) and Belarus (hunted), between 2004 and 2019. We compared beaver population trends in both countries, and analyzed the factors that could impact population growth. In Poland, during this period the population increased 3.5 times, while in Belarus it was only 20%. Distinct differences in the rate of population numbers increase were also observed between regions in Poland, but a stable, slight increase similar in all regions in Belarus. Our study did not show that precipitation or the density of this species influenced the rate of population development in Poland. During this period, hunting and wolf density significantly and negatively impacted beaver population growth in Belarus, but in the long-term analysis, hunting had a lower impact on beaver population growth. We concluded that we can expect a further increase in this population in Poland. Long-term hunting at a level of 13,7% (based on the analysis of population dynamics and hunting bags for Belarus) of the annual population seems to be a safe value for the beaver population. Nevertheless more detailed analysis should be carried out in the face of the large differences between regions.

POPULATION GROWTH INDUCED AND HOUSEHOLDS FINANCIAL VULNERABILITY IN NIGERIA

Nigeria has been recording a rapid increase in its population over the years. This reality has posed a serious concern for the welfare of households especially as the increase in population growth puts households at the risk of financial vulnerability. Based on this, this study is on the move to examined the impact population growth induced has on household in Nigeria. The study made use of secondary data obtained from World Bank and the Central Bank statistical bulletine spanning from 1981 to 2020 to analyze the impact of population growth induced and its financial vulnerability on household using a structural vector autoregressive model (SVAR). After the analysis, the study found out that in the long run, an increase in financial vulnerability, due to an increase in population growth decreases household welfare in Nigeria. Hence, this study recommends that the Nigerian legislature should formulate a law against rapid population growth induced to ensure that the increase in population does not outscore the means of subsistence.
 
 JEL: H10; H31
 
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Revisiting Ophidiomycosis (Snake Fungal Disease) After a Decade of Targeted Research.

Emerging infectious diseases (EIDs) are typically characterized by novelty (recent detection) and by increasing incidence, distribution, and/or pathogenicity. Ophidiomycosis, also called snake fungal disease, is caused by the fungus Ophidiomyces ophidiicola (formerly “ophiodiicola”). Ophidiomycosis has been characterized as an EID and as a potential threat to populations of Nearctic snakes, sparking over a decade of targeted research. However, the severity of this threat is unclear. We reviewed the available literature to quantify incidence and effects of ophidiomycosis in Nearctic snakes, and to evaluate whether the evidence supports the ongoing characterization of ophidiomycosis as an EID. Data from Canada remain scarce, so we supplemented the literature review with surveys for O. ophidiicola in the Canadian Great Lakes region. Peer-reviewed reports of clinical signs consistent with ophidiomycosis in free-ranging, Nearctic snakes date back to at least 1998, and retrospective molecular testing of samples extend the earliest confirmed record to 1986. Diagnostic criteria varied among publications (n = 33), confounding quantitative comparisons. Ophidiomycosis was diagnosed or suspected in 36/121 captive snakes and was fatal in over half of cases (66.7%). This result may implicate captivity-related stress as a risk factor for mortality from ophidiomycosis, but could also reflect reporting bias (i.e., infections are more likely to be detected in captive snakes, and severe cases are more likely to be reported). In contrast, ophidiomycosis was diagnosed or suspected in 441/2,384 free-ranging snakes, with mortality observed in 43 (9.8 %). Ophidiomycosis was only speculatively linked to population declines, and we found no evidence that the prevalence of the pathogen or disease increased over the past decade of targeted research. Supplemental surveys and molecular (qPCR) testing in Ontario, Canada detected O. ophidiicola on 76 of 657 free-ranging snakes sampled across ~136,000 km2. The pathogen was detected at most sites despite limited and haphazard sampling. No large-scale mortality was observed. Current evidence supports previous suggestions that the pathogen is a widespread, previously unrecognized endemic, rather than a novel pathogen. Ophidiomycosis may not pose an imminent threat to Nearctic snakes, but further research should investigate potential sublethal effects of ophidiomycosis such as altered reproductive success that could impact population growth, and explore whether shifting environmental conditions may alter host susceptibility.

Carbon Emission And Population Growth: Evidence From The Magna Cum Laude Oil Producing African Countries

Ample amount of scientific effort has been applied to question the potentials of fossil fuel combustion and other carbon emission sources which in turn has impact on human population growth. This study sought to find the extent of which carbon emissions impact population growth among the Magna cum Oil producing Africa countries. The study utilises panel data analysis within the sample period: 2000–2019 using the Pooled Ordinary Least Squares and the Feasible General Least Square. The results of the research revealed the existence of a significant and negative relationship. This therefore, makes this subject an issue of critical policy interest and requires immediate actions and makes this research very significant in recent times as it considers several countries within the study’s scope.

Evaluation of spot patterns and carapace abnormalities of an Endangered freshwater turtle, Clemmys guttata, as a potential tool for population assignment

Many of the world’s contemporary species of turtle are extinct or threatened with extinction due to habitat loss, increases in anthropogenic sources of mortality, and poaching (illegal collection). The slow life-history strategy of most turtle species magnifies the effects of poaching because the loss of even a few mature individuals can impact population growth. Returning poached turtles to their population of origin, where possible, can mitigate these effects, but identifying the origin of these individuals can be challenging. We hypothesized that spot patterns might allow assignment of Endangered spotted turtlesClemmys guttatato their population of origin. We characterized and compared spot patterns from carapace photographs of 126 individuals from 10 sites. To explore other types of information these photographs might provide, we also documented carapacial scute abnormalities and quantified their association with genetic diversity and latitude. Spot pattern similarity was not higher within populations than among populations and did not accurately differentiate populations. Carapacial scute abnormalities occurred in 82% of turtles and were not correlated with estimates of neutral genetic diversity. Abnormalities were positively correlated with latitude, implicating thermal stress during the early stages of development in the generation of some scute deformities. However, this relationship became non-significant when line (scute seam) abnormalities were excluded from the data, suggesting a different primary cause for the more severe scute deformities. Further research should continue to investigate the drivers of these deformities, as monitoring shifts in the frequency of scute deformities may provide relevant information for conservation and recovery of endangered turtles.

The Impact Population Growth on Disaggregate Energy Generation Source from (Hydro Power, Natural Gas, Oil and Coal Source) in Nigeria

This research tries to investigate the impact of population growth on energy generation in Nigeria using Auto Regressive Distributive Lag (ARDL). The study employed an econometric methodology involving the use of unit root test, cointegration test technique. The study use of different source of electricity production in Nigeria such as hydro power source (HPS), natural gas source (NGS), oil and coal sources (OCS) , as dependents variables which were regress against population and real gross domestic product (GDP) as explanatory variables which altogether serve as determinants of energy generation. The ARDL Bound test reveals that both the three equations under studies are cointegrated. Consequently, the study finds that the long run and short run dynamics of the variables involved. From the long run coefficients the study found that population growth has a positive and significant impact on energy generation from natural gas source, oil and coal source but negative impact on hydropower sources. Based on these findings some recommendations were made, Nigeria government should adequately project the growing rate of population in advance so as to generate volume of energy that will cater for the population so as to avoid the risk of energy shortage in Nigeria.

A functional trait approach to identifying life history patterns in stochastic environments.

Temporal variation in demographic processes can greatly impact population dynamics. Perturbations of statistical coefficients that describe demographic rates within matrix models have, for example, revealed that stochastic population growth rates (log(λ s)) of fast life histories are more sensitive to temporal autocorrelation of environmental conditions than those of slow life histories. Yet, we know little about the mechanisms that drive such patterns. Here, we used a mechanistic, functional trait approach to examine the functional pathways by which a typical fast life history species, the macrodetrivore Orchestia gammarellus, and a typical slow life history species, the reef manta ray Manta alfredi, differ in their sensitivity to environmental autocorrelation if (a) growth and reproduction are described mechanistically by functional traits that adhere to the principle of energy conservation, and if (b) demographic variation is determined by temporal autocorrelation in food conditions. Opposite to previous findings, we found that O. gammarellus log(λ s) was most sensitive to the frequency of good food conditions, likely because reproduction traits, which directly impact population growth, were most influential to log(λ s). Manta alfredi log(λs) was instead most sensitive to temporal autocorrelation, likely because growth parameters, which impact population growth indirectly, were most influential to log(λ s). This differential sensitivity to functional traits likely also explains why we found that O. gammarellus mean body size decreased (due to increased reproduction) but M. alfredi mean body size increased (due to increased individual growth) as food conditions became more favorable. Increasing demographic stochasticity under constant food conditions decreased O. gammarellus mean body size and increased log(λ s) due to increased reproduction, whereas M. alfredi mean body and log(λ s) decreased, likely due to decreased individual growth. Our findings signify the importance of integrating functional traits into demographic models as this provides mechanistic understanding of how environmental and demographic stochasticity affects population dynamics in stochastic environments.

Effects of territorial status and life history on Sandhill Crane (Antigone canadensis) population dynamics in south-central Wisconsin, USA

Population growth rate in long-lived bird species is often most sensitive to changes in adult survival. Sandhill Cranes (Antigone canadensis (Linnaeus, 1758)) have long life spans, small broods, and delayed first reproduction. Only territorial adult Sandhill Cranes participate in breeding, and territory acquisition reflects the interplay between the availability of suitable territories and the variation in mortality of adult birds occupying those territories. We estimated vital rates of a population at equilibrium using long-term resightings data (2000–2014; n = 451 marked individuals) in a multistate mark–resight model and used a stage-structured projection matrix to assess how strongly territorial adult survival affects population growth rate. Elasticity analysis indicated territorial birds surviving and retaining territories had a 2.58 times greater impact on population growth compared with the next most important transition rate (survival of nonterritorial adults remaining nonterritorial). Knowing how changes in vital rates of various stage classes will differentially impact population growth rate allows for targeted management actions including encouraging growth in recovering populations, assessing opportunity for recreational harvest, or maintaining populations at a desired level. This study also highlights the value of collecting demographic data for all population segments, from which one can derive reproductive output or growth rate.

Population viability analyses for threeMacrhybopsisspp. of the Lower Missouri River

Recent declines in three species of chubs that inhabit the lower Missouri River (shoal chub M. hyostoma, sicklefin chub M. meeki and sturgeon chub M. gelida) have become a concern in the management of their own populations and the endangered pallid sturgeon (Scaphirhynchus albus) that feeds on them. These chub populations encounter threats from fish predation and habitat loss. With the recent advancements in the understanding of the reproductive life history of these species, their declines have prompted development of population models and population viability analyses. For each species, we developed an age-structured population matrix model with hierarchical stochasticity, which partitions parameter total variance into sampling and temporal components. Using these models, we found population growth rate of all three chub species decreased when stochasticity was added to the model. While examining sensitivity, we found individual fish growth, as measured by length-at-age, to impact population growth rate and depending on the species, could be up to four times more influential than overall survival, the next most sensitive parameter. Current survival rates have large temporal variance; more research into accuracy and factors that influence survival rates is needed.

Direct and Indirect Effects of Resource P-Limitation Differentially Impact Population Growth, Life History and Body Elemental Composition of a Zooplankton Consumer.

One of the central tenets of ecological stoichiometry is that consumer growth rate is strongly determined by food phosphorus (P) content. In planktonic organisms population growth rates of zooplankton have repeatedly been shown to be reduced when fed with P-limited algal food sources. However, P-limitation may also affect other quality-related aspects of algae, such as biochemical composition or palatability. We studied the population growth, detailed life history and body elemental composition of the herbivorous rotifer, Brachionus calyciflorus, in response to three different food quality treatments: algae cultured in high phosphorus conditions (average algal molar C:P ≈ 112, ‘HP’), algae cultured in low P conditions (molar C:P ≈ 631, ‘LP’) and low-P cultured algae spiked with P just before feeding (molar C:P ≈ 113, ‘LP+P’). LP+P algae thus combined high P content with a history of growth under P-limited conditions. Total P content and the C:P ratio of rotifers in the LP+P treatment equaled those of rotifers in the HP treatment. Rotifer population growth rates were higher in HP than in LP and intermediate in the LP+P treatment. Similarly, many life history traits observed for animals in the LP+P treatment, such as somatic growth rate, age at maturity, and egg production rate were also intermediate to those observed in the LP and HP treatments. However, there were important deviations from this pattern: size at first reproduction and egg mortality in the LP+P treatment equaled the HP treatment, whereas size and development time of the first eggs equaled those of the LP treatment. Our results indicate that elemental limitation cannot fully explain reduced performance of consumers fed with P-limited algae and strongly suggest that indirect, non-stoichiometric effects of P-limitation, e.g., via changes in biochemical composition or morphology of the algae also play a major role. Furthermore, our study highlights that such indirect effects have a differential impact on major fitness components and may as such also determine the population dynamics and demographic structure of consumer populations.

Behavioural ecology and marine conservation: a bridge over troubled water?

AbstractBehavioural ecology is an evolutionary-based discipline that attempts to predict how animals will behave in a given set of environmental circumstances and how those behavioural decisions will impact population growth and community structure. Given the rapidly changing state of the ocean environment it seems that this approach should be a beneficial tool for marine conservation, but its promise has not been fully realized. Since many conservation issues involve alterations to an animal’s habitat, I focus on how habitat selection models developed by behavioural ecologists may be useful in thinking about these sorts of problems, and mitigating them. I then briefly consider some other potential applications of behavioural ecology to marine conservation. Finally, I emphasize that the strength of a functional approach like behavioural ecology is that it allows predictions, from first principles, of responses to environmental changes outside the range of conditions already experienced and studied, and its models may be broadly generalizable across species and ecosystems.

At Lunch with a Killer: The Effect of Weaver Ants on Host-Parasitoid Interactions on Mango.

Predator-prey interactions can affect the behaviour of the species involved, with consequences for population distribution and competitive interactions. Under predation pressure, potential prey may adopt evasive strategies. These responses can be costly and could impact population growth. As some prey species may be more affected than others, predation pressure could also alter the dynamics among species within communities. In field cages and small observation cages, we studied the interactions between a generalist predator, the African weaver ant, Oecophylla longinoda, two species of fruit flies that are primary pests of mango fruits, Ceratitis cosyra and Bactrocera dorsalis, and their two exotic parasitoids, Fopius arisanus and Diachasmimorpha longicaudata. In all experiments, either a single individual (observation cage experiments) or groups of individuals (field cage experiments) of a single species were exposed to foraging in the presence or absence of weaver ants. Weaver ant presence reduced the number of eggs laid by 75 and 50 percent in B. dorsalis and C. cosyra respectively. Similarly, parasitoid reproductive success was negatively affected by ant presence, with success of parasitism reduced by around 50 percent for both F. arisanus and D. longicaudata. The negative effect of weaver ants on both flies and parasitoids was mainly due to indirect predation effects. Encounters with weaver ant workers increased the leaving tendency in flies and parasitoids, thus reduced the time spent foraging on mango fruits. Parasitoids were impacted more strongly than fruit flies. We discuss how weaver ant predation pressure may affect the population dynamics of the fruit flies, and, in turn, how the alteration of host dynamics could impact parasitoid foraging behaviour and success.

Impacts of management on Mountain Pine Beetle spread and damage: A process-rich model

The Mountain Pine Beetle (MPB, Dendroctonus ponderosae) is a major forest pest at epidemic densities, capable of killing entire stands of mature pine. There are a variety of tactics used by forest managers to control MPB epidemics, but the ecology of the insect and the large scale of MPB infestations make it difficult to evaluate the effectiveness of any management strategy. Using a partial differential equation framework, we develop a mathematical model describing the interactions between beetles, beetle pheromone, and susceptible trees across multiple years. We use our mathematical model to examine the effectiveness of various existing management approaches used to limit the spread of the MPB. In particular, our study focuses on management activities that were used in Banff National Park, in Alberta, Canada. Comparing the indirect controls of prescribed burning and clearcutting, we found the success of these methods is critically dependent on the level of MPB attraction to, and productivity in, partially burned trees. Our analysis also indicates that pheromone baiting in combination with tree removal is successful at reducing MPB impact at high beetle densities, but may lead to greater forest impact and greater MPB population growth at low beetle densities. Finally, we found that removal of beetle-attacked trees in the absence of baiting is the most successful strategy if managers are able to locate areas with significant MPB activity.