
Steven A JulianoIllinois State University | ISU · School of Biological Sciences
Steven A Juliano
PhD
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220
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Introduction
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October 1987 - July 1988
August 1986 - September 2017
Publications
Publications (220)
Aedes eggs may hatch in synchrony, yielding individuals of similar age and size, or asynchrony, yielding individuals of different ages and sizes, depending on rainfall. Multiple freshwater species have similar variation in developmental synchrony of immatures.
We tested alternative hypotheses that asynchronous hatch modifies intraspecific competiti...
Mortality imposed on a population can interact with negatively density-dependent mortality to produce overcompensation, wherein added mortality results in more survivors. Experimental mortality can cause overcompensation in mosquito larvae, which would be counterproductive if it resulted from mosquito control in nature. We tested for different demo...
Population density can affect survival, growth, development time, and adult size and fecundity, which are collectively known as density-dependent effects. Container Aedes larvae often attain high densities in nature, and those densities may be reduced when larval control is applied. We tested the hypothesis that density-dependent effects on surviva...
Asimina triloba is replacing shade-tolerant Acer saccharum as the most abundant seedling in many Ac. saccharum-dominated forests in the midwestern USA. Selective browsing of Ac. saccharum by Odocoileus virginianus and avoidance of As. triloba contributes to this increased As. triloba abundance. However, shade tolerance may also be a factor contribu...
Understanding the relationship of population dynamics to density is central to many ecological investigations. Despite the importance of density-dependence in determining population growth, the empirical relationship between density and per capita growth remains understudied in most systems and is often assumed to be linear. In experimental studies...
For simplicity and to minimize variation, functional response experiments frequently use environments of simple physical structure and small size. Less attention is paid to similarity of the experimental environment to the natural environment where predation occurs. Assumptions about predator and prey use of space are often implied in the choice of...
Microbial control of mosquitoes via the use of symbiotic or pathogenic microbes, such as Wolbachia and entomopathogenic fungi, are promising alternatives to synthetic insecticides to tackle the rapid increase in insecticide resistance and vector-borne disease outbreaks. This study evaluated the susceptibility and host responses of two important mos...
Understanding the relationship of population dynamics to density is central to many ecological investigations. Despite the importance of density-dependence in determining population growth, the empirical relationship between density and per capita growth remains understudied in most systems and is often assumed to be linear. In experimental studies...
Parasite dilution occurs in varied systems, via multiple potential mechanisms. We used laboratory manipulation and field surveys to test for invader‐induced parasite dilution via two specific mechanisms: host–host competition and encounter reduction. In the laboratory, single Aedes triseriatus larvae were exposed to one of eight combinations of: pa...
Biological invaders often are accompanied by co-invasive parasites that can alter ecosystem function and established native host-parasite relationships. When these co-invasive parasites establish in a community, they can affect native host fitness and native parasite infection intensity, prevalence, and success within the native host. The mosquito,...
Aedes albopictus (Skuse) (Diptera: Culicidae) is one of the most invasive species globally, and has led to rapid declines and local extirpations of resident mosquitoes where it becomes established. A potential mechanism behind these displacements is the superior competitive ability of Ae. albopictus in larval habitats. Research on the context-depen...
1. Population responses to extrinsic mortality can yield no change in the number of survivors (compensation) or an increase in the number of survivors (overcompensation) when the population is regulated by negative density‐dependence. This intriguing response has been the subject of theoretical studies, but few experiments have explored how the sou...
Extrinsic mortality impinging on negative density‐dependent populations can result in no change in the number of survivors (compensation) or an increase (overcompensation) by releasing the population from density‐dependent effects on survivorship. The relationship between the level of extrinsic mortality (i.e., percentage of mortality) and the leve...
• Predators alter prey populations via direct lethality (density‐mediated effects), but in many taxa, the indirect nonlethal threat of predation may be almost as strong an effect, altering phenotypically plastic traits such as prey morphology, behavior, and life history (trait‐mediated effects). There are costs to antipredator defenses and the stre...
Non-lethal, trait-mediated effects of predation impact prey behavior and life-history traits. Studying how these effects in turn influence prey demography is crucial to understand prey life-history evolution. Mosquitoes are important vectors that claim several million lives every year worldwide by transmitting a range of pathogens. Several ecologic...
We tested the effect of the native container-dwelling predator Toxorhynchites rutilus on the codominant container-dwelling mosquitoes: native Aedes triseriatus and invasive Aedes japonicus. We established two predator treatments (predator, no predator) by removing T. rutilus from all containers, and stocking T. rutilus larvae (1/3.5 liters) in the...
1. This study investigated the effects of strong density dependence on larval growth, development, and survival of the mosquito Culex restuans (Theobald). It also tested the hypothesis that density reduction early in larval development could result in as many or more individuals surviving to adulthood (compensation or over‐compensation, respectivel...
The vector mosquitoes Aedes aegypti (L.), native to Africa, and Aedes albopictus (Skuse), native to Asia, are widespread invasives whose spatial distributions frequently overlap. Predictive models of their distributions are typically correlative rather than mechanistic, and based on only abiotic variables describing putative environmental requireme...
Overcompensation occurs when added mortality increases survival to the next life‐cycle stage. Overcompensation can contribute to the Hydra Effect, wherein added mortality increases equilibrium population size. One hypothesis for overcompensation is that added mortality eases density‐dependence, increasing survival to adulthood (“temporal separation...
Predation impacts development, behavior and morphology of prey species thereby shaping their abundances, distribution and community structure. Non-lethal threat of predation, specifically, can have a strong influence on prey lifehistory characteristics. While investigations often focus on the impact of predation threat on prey in isolation, tests o...
A growing body of literature on mosquito oviposition behavior supports the hypothesis that females place eggs in habitats that provide best available opportunity for growth, development, and maturation of their offspring. We conducted a field experiment to evaluate Culex oviposition behavior in response to the interspecific competitor Aedes triseri...
1. Per‐capita resource availability in aquatic habitats is influenced directly by consumer density via resource competition and indirectly via delayed resource competition when temporally non‐overlapping cohorts of larvae exploit the same resources. In detritus‐based systems, resources are likely to be influenced by the age of the aquatic habitat,...
1. General theory from aquatic ecology predicts that smaller aquatic habitats have shorter hydroperiods favouring species that are better resource competitors and complete development quickly. Larger habitats are predicted to have longer hydroperiods enabling longer‐lived predators to persist. Habitats with long hydroperiods and predators are predi...
1. Prey organisms can perceive cues to predation hazard and adopt low‐risk behaviours to increase survival. Animals with complex life cycles, such as insects, can exhibit such anti‐predatory behaviours in multiple life stages.
2. Cues to predation risk may induce ovipositing females to choose habitats with low predation risk. Cues to predation risk...
Modafinil (MOD) exhibits therapeutic efficacy for treating sleep and psychiatric disorders, but its mechanism is incompletely understood. Compared to other psychostimulants inhibiting dopamine (DA) uptake, MOD weakly interacts with the dopamine transporter (DAT) and modestly elevates striatal dialysate DA, suggesting additional targets besides DAT....
How does behaviour affect biological invasions? Can it explain why some animals are such successful invaders? With contributions from experts in the field, and covering a broad range of animals, this book examines the role of behaviour in biological invasions from the point of view of both invaders and native species. The chapters cover theoretical...
Previous studies have shown that the negative effects of density of Ae. albopictus on Ae. aegypti exceed those of Ae. aegypti on Ae. albopictus for population growth, adult size, survivorship, and developmental rate. This competitive superiority has been invoked to explain the displacement of Ae. aegypti by Ae. albopictus in the southeastern USA. I...
Zip file containing the dataset used in this study.
It consists of three.csv files: climate_data.csv contains the climate variables for the study period, competition_data.csv contains the data from the competition experiments, productivity_data.csv contains the total number of pupae collected during the colonization experiment.
(ZIP)
The National Ecological Observatory Network (NEON) intends to monitor mosquito populations across its broad geographical range of sites because of their prevalence in food webs, sensitivity to abiotic factors, and relevance for human health. We describe the design of mosquito population sampling in the context of NEON's long‐term continental scale...
Parasites and pathogens are increasingly recognized as signi cant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among hu- man, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term t...
Parasites and pathogens are increasingly recognized as significant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among human, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term ti...
The National Ecological Observatory Network (NEON) intends to monitor mosquito populations across its broad geographical range of sites because of their prevalence in food webs, sensitivity to abiotic factors, and relevance for human health. We describe the design of mosquito population sampling in the context of NEON's long-term continental scale...
1. Few studies have taken a comprehensive approach of measuring the impact of inter‐ and intra‐specific larval competition on adult mosquito traits. In this study, the impact of competition among Aedes aegypti ( L. ) and A. albopictus ( S kuse) was quantified over the entire life of a cohort.
2. Competitive treatments affected hatch‐to‐adult surviv...
Evolutionary theory predicts that vector-borne pathogens should have low virulence for their vector because of selection against pathogens that harm the vector sufficiently to reduce transmission. Environmental factors such as nutritional stress can alter vector-pathogen associations by making the vectors more susceptible to pathogens (condition-de...
Biotic and abiotic factors change seasonally and impact life history in temperate-zone ectotherms. Temperature and photoperiod are factors that change in predictable ways. Most studies testing for effects of temperature on vectors use constant temperatures and ignore potential correlated effects of photoperiod. In two experiments, we tested for eff...
We investigated three pathways by which predators on an intermediate trophic level may produce a trophic cascade in detritus-based systems. Predators may increase lower trophic levels (bacteria) by reducing density of bacteriovores, by altering behavior of bacteriovores, and by processing living bacteriovores into carcasses, feces, and dissolved nu...
Osteoporosis is a bone disease that commonly results in a 30% incidence of fracture in hens used to produce eggs for human consumption. One of the causes of osteoporosis is the lack of mechanical strain placed on weight-bearing bones. In conventionally-caged hens, there is inadequate space for chickens to exercise and induce mechanical strain on th...
The mosquito Aedes japonicus (Diptera: Culicidae) has spread rapidly through North America since its introduction in the 1990s. The mechanisms underlying its establishment in container communities occupied by competitors Aedes triseriatus and Aedes albopictus are unclear. Possibilities include (A) temporal separation of A. japonicus from other Aede...
Two hypotheses for how conditions for larval mosquitoes affect vectorial capacity make opposite predictions about the relationship of adult size and frequency of infection with vector-borne pathogens. Competition among larvae produces small adult females. The competition-susceptibility hypothesis postulates that small females are more susceptible t...
For organisms with complex life cycles, larval environments can modify adult phenotypes. For mosquitoes and other vectors, when physiological impacts of stressors acting on larvae carry over into the adult stage they may interact with infectious dose of a vector-borne pathogen, producing a range of phenotypes for vector potential. Investigation of...
1. Modification of behaviours in the presence of predators or predation cues is widespread among animals. The costs of a behavioural change in the presence of predators or predation cues depend on fitness effects of lost feeding opportunities and, especially when organisms are sexually dimorphic in size or timing of maturation, these costs are expe...
1. Classic studies of succession, largely dominated by plant community studies, focus on intrinsic drivers of change in community composition, such as inter‐specific competition and changes to the abiotic environment. They often do not consider extrinsic drivers of colonisation, such as seasonal phenology, that can affect community change.
2. Both...
Insects' oviposition responses to resource and larval densities can be important factors determining distributions and competitive interactions of larvae. Aedes albopictus ( S kuse) and Aedes aegypti ( L .) ( D iptera: C ulicidae) show aggregated distributions of larvae in the field, larval interactions that are affected by detritus resources, and...
Understanding mechanisms fostering coexistence between invasive and resident species is important in predicting ecological, economic, or health impacts of invasive species. The non-native mosquitoes Aedes aegypti and Culex quinquefasciatus have been resident in the southeastern United States for over a century. They coexist at some urban sites with...
Oviposition habitat choices of species with aquatic larvae are expected to be influenced by both offspring risk of mortality due to predation, and offspring growth potential. Aquatic predators may indirectly influence growth potential for prey by reducing prey density and, for filter-feeding prey, by increasing bacterial food for prey via added org...
Background: Sexual size dimorphism (SSD) in insects often accompanies a sexual difference in development time, sexual bimaturism (SBM). Goal: To determine whether three Aedes mosquito species have similar plasticity in SSD, attain sexual dimorphism through similar strategies, and whether SSD and SBM are associated. Organisms: Aedes albopictus, Aede...
Sexual size dimorphism (SSD) and sexual bimaturism (SBM) are widespread among animals, and can arise due to sexual selection, natural selection, or both. Dimorphism of size and age at maturity can be mediated by a difference in initial size, growth rate, development time, or asymptotic size of the sexes. Using Aedes mosquitoes as model organisms, t...
Overcompensatory mortality occurs when an additional source of mortality causes an increase in population (Hydra Effect). One hypothesis that accounts for this postulates that additional mortality eases density-dependent effects on remaining individuals, allowing for greater survivorship. Added mortality occurring prior to density dependent effects...
Background/Question/Methods
For organisms with complex life cycles, ecological interactions and abiotic factors acting on larval stages can have profound effects on adult population dynamics and adult physiology. Resource competition among immature stages, in particular can: prolong development; increase larval mortality; and reduce adult size, f...
Background/Question/Methods
Feeding by container-dwelling mosquito larvae may negatively affect microorganism richness or abundance. However, indirect effects of mosquito predators on microorganisms are poorly studied. Larvae of the predator Toxorhynchites rutilus prey on larval Aedes triseriatus, which feed on bacteria. We postulated that a trop...
The invasive dengue vector Aedes aegypti has persisted for > 200 years in South Florida in the United States. We tested the hypotheses that Florida's landscape creates dispersal barriers and corridors and that long-distance human-aided dispersal structures populations of Ae. aegypti. We evaluated the phylogeography of 362 individuals from Florida's...
The tradeoff between colonization and competitive ability has been proposed as a mechanism for ecological succession, and this tradeoff has been demonstrated in multiple successional communities. The tradeoff between competitive ability and predation resistance is also a widely-described phenomenon; however, this tradeoff is not usually postulated...
Amphetamine, a highly addictive drug with therapeutic efficacy, exerts paradoxical effects on the fundamental communication modes employed by dopamine neurons in modulating behavior. While amphetamine elevates tonic dopamine signaling by depleting vesicular stores and driving non-exocytotic release through reverse transport, this psychostimulant al...
Amphetamine has well-established actions on pre-synaptic dopamine signaling, such as inhibiting uptake and degradation, activating synthesis, depleting vesicular stores, and promoting dopamine-transporter reversal and non-exocytotic release. Recent in vivo studies have identified an additional mechanism: augmenting vesicular release. In this study,...
We investigated the aggregation model of coexistence as a potential mechanism explaining patterns of coexistence between container mosquitoes Aedes albopictus and Aedes aegypti in southern Florida, USA. Aedes aegypti coexists with the invasive A. albopictus in many locations despite being an inferior resource competitor under most conditions. In ag...
Two invasive, container-breeding mosquito species, Aedes aegypti (Stegomyia aegypti) and Aedes albopictus (Stegomyia albopicta) (Diptera: Culicidae), have different distribution patterns on Reunion Island. Aedes albopictus occurs in all areas and Ae. aegypti colonizes only some restricted areas already occupied by Ae. albopictus. This study investi...
Aedes oviposit in a range of water holding containers. Three common species, Aedes triseriatus, Aedes albopictus, and Aedes japonicus are known or suspected vectors of arboviruses, such as West Nile and La Crosse, that are important causes of human disease. Productivity in these containers depends on detritus input from adjacent terrestrial habitat...
Background / Purpose:
There are two alternative hypotheses for how crowded larval conditions affect frequency of virus infection of vector mosquitoes: 1). The hypothesis that crowded conditions shorten adult life predicts that probability of virus infection increases with adult size.2). The hypothesis that crowded conditions raise adult susceptib...
Resource competition theory predicts that R*, the equilibrium resource amount yielding zero growth of a consumer population, should predict species' competitive abilities for that resource. This concept has been supported for unicellular organisms, but has not been well-tested for metazoans, probably due to the difficulty of raising experimental po...
Theory shows that fluctuation of environmental conditions can produce temporal niches for inferior competitors that mitigate effects of interspecific competition and facilitate long‐term persistence of poor competitors.
In south F lorida, the mosquitoes A edes albopictus and A edes aegypti often co‐occur in water‐filled containers despite A . albop...
The Asian tiger mosquito, Aedes albopictus (Skuse), is perhaps the most successful invasive mosquito species in contemporary history. In the United States, Ae. albopictus has spread from its introduction point in southern Texas to as far north as New Jersey (i.e., a span of approximately 14 degrees latitude). This species experiences seasonal const...
Estimating a mosquito's vector competence, or likelihood of transmitting disease, if it takes an infectious bloodmeal, is an important aspect of predicting when and where outbreaks of infectious diseases will occur. Vector competence can be affected by rearing temperature and inter- and intraspecific competition experienced by the individual mosqui...
Arthropod-borne viruses (arboviruses) cause many diseases worldwide and their transmission is likely to change with land use and climate changes. La Crosse virus (LACV) is historically transmitted by the native mosquito Aedes triseriatus (Say) in the upper Midwestern US, but the invasive congeners Aedes albopictus (Skuse) and A. japonicus (Theobald...
Episodic resource inputs (i.e., pulses) can affect food web properties and community dynamics, but detailed mechanistic understanding of such effects remain elusive. Natural aquatic microsystems (e.g., tree holes, human-made containers) are colonized by invertebrates that form complex food webs dependent on episodic and sometimes sizeable inputs of...
Early embryonic exposure to maternal glucocorticoids can broadly impact physiology and behaviour across phylogenetically diverse taxa. The transfer of maternal glucocorticoids to offspring may be an inevitable cost associated with poor environmental conditions, or serve as a maternal effect that alters offspring phenotype in preparation for a stres...
Climate differences across latitude can result in seasonal constraints and selection on life-history characters. Because Aedes albopictus (Skuse) invaded North America in the mid-1980s, it has spread across a range of ≈14° latitude and populations in the north experience complete adult mortality because of cold winter temperatures that are absent i...
Background/Question/Methods
The colonization-competition tradeoff has been proposed as a mechanism that drives ecological succession in communities. However, as communities gain diversity, additional factors (habitat heterogeneity, predation) may alter the colonization-competition tradeoff as species are required to allocate resources to respond...
Coexistence of competitors may result if resources are sufficiently abundant to render competition unimportant, or if species differ in resource requirements. Detritus type has been shown to affect interspecific competitive outcomes between Aedes albopictus (Skuse) and Aedes aegypti (L.) larvae under controlled conditions. We assessed