In this study we analysed the theoretical population dynamics of C. megacephala, an exotic blowfly, kept at 25 and 30 °C, using a density-dependent mathematical model, with parametric estimates of survival and fecundity in the laboratory.... more
In this study we analysed the theoretical population dynamics of C. megacephala, an exotic blowfly, kept at 25 and 30 °C, using a density-dependent mathematical model, with parametric estimates of survival and fecundity in the laboratory. No change in terms of oscillation patterns was found for the two temperatures. The populations exhibited a two-point limit cycle, i.e. oscillations between two fixed points, at 25 and 30°C. However, a quantitative change was observed, indicating that at 25 °C the number of immatures in equilibrium is 1176 and at 30 °C, 1944. The implications of this difference in terms of equilibrium for population dynamics of C. megacephala are discussed.
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The laboratory population dynamics of Chrysomya megacephala (F.) was explored with a mathematical model of density-dependent growth. Fecundity and survival decreased significantly as a function of larval density. Parameters in the... more
The laboratory population dynamics of Chrysomya megacephala (F.) was explored with a mathematical model of density-dependent growth. Fecundity and survival decreased significantly as a function of larval density. Parameters in the exponential regressions fitted to the fecundity and survival data were incorporated into a finite-difference equation that incorporates the delayed effect of larval density on fecundity and survival of adults. The theoretical population model of C. megacephala showed cyclic behavior with a stable limit cycle of two points for adults and immatures.
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Equilibrium dynamics in experimental populations of Chrysomya megacephala (F.) and C. putoria (Wiedemann), which have recently invaded the Americas, and the native species Cochliomyia macellaria (F.), were investigated using nonlinear... more
Equilibrium dynamics in experimental populations of Chrysomya megacephala (F.) and C. putoria (Wiedemann), which have recently invaded the Americas, and the native species Cochliomyia macellaria (F.), were investigated using nonlinear difference equations. A theoretical analysis of the mathematical model using bifurcation theory established the combination of demographic parameters responsible for producing shifts in blowfly population dynamics from stable equilibria to bounded cycles and aperiodic behavior. Mathematical modeling shows that the populations of the 2 introduced Chrysomya species will form stable oscillations with numbers fluctuating 3-4 times in successive generations. However, in the native species C. macellaria, the dynamics is characterized by damping oscillations in population size, leading to a stable population level.
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A compartmental model was developed to describe the temporal course of an exotic amphipod's population, Talitroides topitotum, in an Atlantic Forest habitat in Brazil. Extensive biological information — including breeding pattern,... more
A compartmental model was developed to describe the temporal course of an exotic amphipod's population, Talitroides topitotum, in an Atlantic Forest habitat in Brazil. Extensive biological information — including breeding pattern, development and mortality rates, and temperature dependence of the parameters — were considered in the model. A genetic algorithm was used to estimate model parameters by comparing simulation results with field data. This allowed us to discuss the reproductive strategies adopted by this species and to analyze the potential influence of global climate changes on its populations dynamics.
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This book brings together nine chapters that aim to present the most recent research on the interface between ecological modelling and entomology. The chapters are summaries of research performed in different Brazilian institutions, UK... more
This book brings together nine chapters that aim to present the most recent research on the interface between ecological modelling and entomology. The chapters are summaries of research performed in different Brazilian institutions, UK and Ireland universities. The idea of the book is to present different focuses of study by aggregating theoretical ecology and applications in agricultural and medical entomology, also emphasising pest management and conservation. This chapter briefly summarises a history of the population theory applied to entomology and will introduce the reader to the topics developed in the following chapters.
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ABSTRACT
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We investigated aggregation patterns in three fruit fly species economically important in Brazil, namely Ceratitis capitata, Anastrepha fraterculus, and A. obliqua. The study was carried out in a buffer zone and two neighbourhoods by... more
We investigated aggregation patterns in three fruit fly species economically important in Brazil, namely Ceratitis capitata, Anastrepha fraterculus, and A. obliqua. The study was carried out in a buffer zone and two neighbourhoods by comparing two-time series associated with the management strategy of fruit flies (systems approach). The abundance of these three species significantly decreased over the years with a negative binomial regression model describing the relationship between abundance and time in the entire area, buffer zone, and their neighbourhoods. In addition, the negative binomial model was also well fitted to the frequency distribution data of fruit flies in all analyzed scenarios. Anastrepha obliqua showed the highest aggregation degree, considering both the entire area and time series. A. fraterculus exhibited the lowest aggregation level, and C. capitata showed an intermediate degree. The buffer zone exhibited the highest aggregation degree for all species, and nei...
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O controle de pragas por meio do uso de agrotóxicos tem sido alvo de diversas problematizações, em razão do risco de seleção de resistência em insetos, da influência negativa sobre populações de organismos não-alvo e da contaminação do... more
O controle de pragas por meio do uso de agrotóxicos tem sido alvo de diversas problematizações, em razão do risco de seleção de resistência em insetos, da influência negativa sobre populações de organismos não-alvo e da contaminação do ambiente. Nesse contexto, outras práticas, como o controle biológico, são necessárias, bem como a utilização de tecnologias alternativas, como a homeopatia, a fim de minimizar os impactos negativos da contaminação química. Nesse sentido, preparados homeopáticos, obtidos a partir de sementes secas da planta Delphinium staphisagria L. (Ranunculaceae), as quais contêm alcalóides tóxicos, têm recebido relevante atenção pela comunidade científica e de produtores, especialmente no que diz respeito ao manejo de afídeos (Hemiptera). Todavia, informações que possam dar suporte a implementação dessa prática dentro de um programa de manejo integrado de pragas ainda são incipientes. Diante desse cenário, o objetivo deste trabalho foi analisar o impacto do prepara...
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The variation in co‐occurrence between pests may influence spatio‐temporal persistence strategies of species, with implications for pest management. The co‐occurrence of Anastrepha species (Diptera: Tephritidae) in papaya orchards was... more
The variation in co‐occurrence between pests may influence spatio‐temporal persistence strategies of species, with implications for pest management. The co‐occurrence of Anastrepha species (Diptera: Tephritidae) in papaya orchards was investigated in areas at different distances from a native forest reserve in Espírito Santo, Brazil, to investigate positive, negative, or random interactions, understood as potential coexistence, interspecific competition, or neutral interactions, respectively. Data were obtained from a papaya‐growing area divided into three sub‐areas – a buffer zone bordering the forest, neighbourhood 1, and neighbourhood 2 – and the co‐occurrence results were compared with the entire area. The buffer zone along the protected native Atlantic Forest (semideciduous seasonal forest vegetation) was created to filter negative environmental impacts. Neighbourhood 1 was closer to the forest than neighbourhood 2. Based on a long‐term dataset from 1998 to 2010, co‐occurrence ...
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Species distributions are affected by landscape structure at different spatial scales. Here we study how the interplay between dispersal at different spatial scales and landscape connectivity and composition affect local species dynamics.... more
Species distributions are affected by landscape structure at different spatial scales. Here we study how the interplay between dispersal at different spatial scales and landscape connectivity and composition affect local species dynamics. Using a host-parasitoid model, we assessed host density and host occupancy on the landscape, under different parasitoid dispersal ranges and three local distributions of non-crop habitats, areas where hosts are unable to grow but parasitoids are provided with alternative hosts and food resources. Our results show distinct responses of host density to increases in non-crop area, measured by differences in slopes for different distributions of non-crop habitats, and that the effect of local landscape composition on species dynamics depends on the landscape connectivity at the regional scale. Moreover, we show how host density and occupancy are affected by increasing parasitoid dispersal ranges depending on landscape structure. Our results demonstrate...
Research Interests: Spatial Ecology, Ecology, Medicine, Multidisciplinary, Habitat, and 3 moreParasitoid, PLoS one, and Occupancy
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The egg-parasitoid wasp Telenomus podisi has received attention as a biological-control agent for one of the most important soybean pests in Brazil, the stink bug Euschistus heros. As yet, no studies have conclusively established... more
The egg-parasitoid wasp Telenomus podisi has received attention as a biological-control agent for one of the most important soybean pests in Brazil, the stink bug Euschistus heros. As yet, no studies have conclusively established strategies for the release of T. podisi. We developed a computational model employing cellular automata to investigate release strategies for T. podisi in soybean crops, in order to optimize the use of these wasps in managing E. heros. A computational model was developed, using cellular automata in the C programming language and assuming a two-dimensional grid of cells corresponding to a soybean field. The biological dynamics of E. heros and T. podisi were programmed. The following parameters for release strategy were investigated: release mode, number of releases, number of parasitoids per hectare per release, and spacing between release points or strips. The sensitivities of the release and movement parameters were analyzed. The release strategies capable...
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Plants have developed various mechanisms to respond specifically to each biotrophic attack. It has been shown that the electrical signals emitted by plants are associated with herbivory stress responses and can lead to the activation of... more
Plants have developed various mechanisms to respond specifically to each biotrophic attack. It has been shown that the electrical signals emitted by plants are associated with herbivory stress responses and can lead to the activation of multiple defences. Bt cotton is a genetically modified pest-resistant plant that produces an insecticide from Bacillus thuringiensis (Bt) to control Lepidopteran species. Surprisingly, there is no study–yet, that characterizes the signalling mechanisms in transgenic cotton plants attacked by non-target insects, such as aphids. In this study, we characterized the production of electrical signals on Bt and non-Bt cotton plants infested with Aphis gossypii and, in addition, we characterized the dispersal behaviour of aphids to correlate this behaviour to plant signalling responses. Electrical signalling of the plants was recorded with an extracellular measurement technique. Impressively, our results showed that both Bt and non-Bt cotton varieties, when ...
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Assessing the effects of a plant-host shift is important for monitoring insect populations over long time periods and for interventions in a conservation or pest management framework. In a heterogeneous environment, individuals may... more
Assessing the effects of a plant-host shift is important for monitoring insect populations over long time periods and for interventions in a conservation or pest management framework. In a heterogeneous environment, individuals may disperse between sources and sinks in order to persist. Here we propose a single-species two-patch model that aims to capture the generational movement of an insect that exhibits density-dependent dispersal, to see how shifting between hosts could alter its viability and asymptotic dynamics. We then analyse the stability and persistence properties of the model and further validate it using parameter estimates derived from laboratory experiments. In order to evaluate the potential of this model, we applied it to Drosophila suzukii (Diptera: Drosophilidae), which has become a harmful pest in several countries around the world. Although many studies have investigated the preference and attractiveness of potential hosts on this invasive drosophilid, no studie...
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Sunflower is a pollinator-dependent crop and one of the most cultivated oilseeds in the world, supporting important sectors of the agricultural industry, such as the food supply, because it is an important source of vitamin E and... more
Sunflower is a pollinator-dependent crop and one of the most cultivated oilseeds in the world, supporting important sectors of the agricultural industry, such as the food supply, because it is an important source of vitamin E and unsaturated fatty acids for human health. Although it is well stablished that bee pollination improves sunflower seed set, it is still unknown if pollinators influence the nutritional composition. Considering the economic importance of sunflowers for several Brazilian agricultural sectors, the aim of this study was to evaluate the effect of the bee community for (1) achene quality (weight and nutritional composition) and (2) market value. Exclusion experiments were performed with hybrid sunflowers and showed that bee pollination enhanced the achene weight by 91 %, the levels of vitamin E by 45 % and unsaturated fatty acids by 0.3 %. Also, it was estimated that due to the pollination services provided by bees, the grower of the sunflower cultivar used in thi...
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Background The feeding preferences of Diabrotica speciosa (Coleoptera: Chrysomelidae) cause a parent-offspring conflict, as providing the best host for the offspring development is detrimental to adult survival and fecundity.... more
Background The feeding preferences of Diabrotica speciosa (Coleoptera: Chrysomelidae) cause a parent-offspring conflict, as providing the best host for the offspring development is detrimental to adult survival and fecundity. Understanding the implications of this conflict could help entomologists to implement pest-management programs. With this in mind, the foraging behaviour of D. speciosa was investigated using an individual-based model in two distinct scenarios. Methods In an intercropping scenario, parent-offspring conflict was simulated when adult insects exploit two crops (corn and soybean) that provide different nutritional advantages for each insect stage. First, we compared three hypothetical types of adult dispersal, considering a continuous oviposition over time: diffusion, attracted to a fixed host and alternating the preference between hosts with frequency $\frac {1}{\tau }$1τ, where τ is the time in days spent foraging for each host. We also simulated two principles: ...
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Resumo. O presente estudo teve como objetivos avaliar a resposta funcional dos instares larvais e adultos de três espécies de coccinelídeos predadores [Harmonia axyridis (Pallas), Cycloneda sanguinea (Linnaeus) e Hippodamia convergens... more
Resumo. O presente estudo teve como objetivos avaliar a resposta funcional dos instares larvais e adultos de três espécies de coccinelídeos predadores [Harmonia axyridis (Pallas), Cycloneda sanguinea (Linnaeus) e Hippodamia convergens Guerin Meneville] em diferentes densidades de Brevicoryne brassicae (Linnaeus), comparando o desempenho da espécie invasora com as espécies locais. Observou-se que H. axyridis consumiu mais insetos que as outras espécies; o número de pulgões predados pelas três espécies de coccinelídeos aumentou com a troca do instares larvais e, que as fêmeas tenderam a predar mais pulgões que os machos. A voracidade das larvas de 4º instar é similar a dos adultos, às vezes até maior, como no caso da C. sanguinea. Exceto no 1º instar larval, todos os outros estágios de vida mostraram aumento do consumo de pulgões à medida que a oferta de presas aumenta. Os resultados mostraram que a resposta funcional do tipo III foi indicada apenas pelas larvas de 3º instar de H. axy...
Research Interests: Biology and Coccinellidae
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We studied the effects of landscape structure on species with resource nutritional partition between the immature and adult stages by investigating how food quality and spatial structure of a landscape may affect the invasion and... more
We studied the effects of landscape structure on species with resource nutritional partition between the immature and adult stages by investigating how food quality and spatial structure of a landscape may affect the invasion and colonization of the insect pest, Diabrotica speciosa. To this end, we formulated two bidimensional stochastic cellular automata, one for the insect immature stage and the other for the adult stage. The automata are coupled by adult oviposition and emergence. Further, each automata site has a specific culture type, which can affect differently the fitness attributes of immatures and adults, such as mortality, development and oviposition rates. We derived the mean-field approximation for these automata model, from which we obtained conditions for insect invasion. We ran numerical simulations using entomological parameters obtained from laboratory experiments (using bean, soybean, potato, and corn crops), and we compared the results of the automata with the ones given by the mean-field approximation. Finally, using artificially generated landscapes, we discussed how the structured heterogeneous landscape can affect dispersal and establishment of insect populations.
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Research Interests: Zoology, Biology, Brazil, Population Dynamics, Medicine, and 3 moreAnimals, Theoretical Models, and Diptera
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... 1, January 2007 ( C 2007) DOI: 10.1007/s10905-006-9064-x Ovipositional Behavior in Predator and Prey Blowflies Juliana Zibordi Giao1 and Wesley Augusto Conde Godoy1,2 Revised August 24, 2006; accepted December 20, 2006 Published... more
... 1, January 2007 ( C 2007) DOI: 10.1007/s10905-006-9064-x Ovipositional Behavior in Predator and Prey Blowflies Juliana Zibordi Giao1 and Wesley Augusto Conde Godoy1,2 Revised August 24, 2006; accepted December 20, 2006 Published online: January 17, 2007 ...
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In the present study, a single procedure was established to investigate the effect of the spatial distribution of immatures in patchy resources, on the outcome of larval competition for food, in experimental populations of Chrysomya... more
In the present study, a single procedure was established to investigate the effect of the spatial distribution of immatures in patchy resources, on the outcome of larval competition for food, in experimental populations of Chrysomya megacephala. A theoretical model of intraspecific competition was extended and applied to experimental data on survival to adulthood for 20 larval densities, to obtain the theoretical mean number of individuals that will survive, considering a hypothetical previous random adult oviposition in a system of homogeneous patches. The survival curve obtained suggests that the larval competition for food in C. megacephala is of the scramble/exploitative type, which corroborates results from previous studies, although the latter did not consider the correlation between local and global abundances. The present model allows that experimental data could be perfectly applicable, and it incorporates fundamental assumptions about the spatial context of competition for...
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: In this study we investigate aggregated patterns as a consequence of post‐feeding larval dispersal in three blowfly species, based on the frequency distribution of sampling units in the substrate having 0, 1, 2,…,n pupae. Statistical... more
: In this study we investigate aggregated patterns as a consequence of post‐feeding larval dispersal in three blowfly species, based on the frequency distribution of sampling units in the substrate having 0, 1, 2,…,n pupae. Statistical analysis revealed that aggregated patterns of distribution emerge as a consequence of larval dispersal, and Cochliomyia macellaria has higher levels of aggregation when compared to Chrysomya megacephala and C. putoria. Aggregation during dispersal is associated with a spatial pattern where most larvae in the species tend to pupariate near the food source. The possible consequences for the population ecology of these species are discussed.
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Dynamics of handling time and functional response by larvae of Chrysomya albiceps (Dip., Calliphoridae) on different prey species
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Research Interests: Zoology, Agronomy, Biology, Population, Intercropping, and 3 moreAphididae, Foeniculum vulgare, and Aphid
Entomologists have often used computational modeling to study the dynamics of insects in agricultural landscapes. Recently, important issues such as the movement of adults and immatures associated with insect resistance to GMO... more
Entomologists have often used computational modeling to study the dynamics of insects in agricultural landscapes. Recently, important issues such as the movement of adults and immatures associated with insect resistance to GMO (genetically modified organism) crops, have been addressed using computational models. Further studies are needed, especially of structured landscapes composed of GMO plants and alternative hosts that insect pests can exploit. We developed an individual-based model using the cellular automata approach (CA) to investigate how an intercropping system composed of transgenic maize (Bacillus thuringiensis), refuge areas (non-Bt maize), and grasses combined with off-season periods might influence the evolution of resistance in Spodoptera frugiperda (Lepidoptera: Noctuidae), one of the leading agricultural pests targeted by GMOs. We designed the Bt and non-Bt plants in two different arrangements: a) a seed mixture and b) alternate rows, adding grasses in areas adjace...
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Competition behavior involving agricultural pest species has long been viewed as a powerful selective force that drives ecological and phenotypic diversity. In this context, a Game Theory-based approach may be useful to describe the... more
Competition behavior involving agricultural pest species has long been viewed as a powerful selective force that drives ecological and phenotypic diversity. In this context, a Game Theory-based approach may be useful to describe the decision-making dilemma of a competitor with impacts to guarantee its superiority in terms of ecological dominance or sharing of the food resource with its competitor. In an attempt to elucidate the consequences of competitive dynamics for the ecological dominance of these species in refuge areas of Bt cotton, we conducted a study that was divided into two parts. The first study consisted of an evaluation of interactions involving Spodoptera frugiperda (JE Smith, 1797) and Helicoverpa armigera (Hübner, 1808) on non-Bt cotton plants in a field trial. In the second study, we explored the data matrix collected in the field to parameterize a model of Cellular Automata (CA) with update rules inspired by Game Theory. Computer simulations were analyzed in hypot...
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The diversity and abundance of necrophagous Diptera were investigated in urban, farm and wild areas in Botucatu, São Paulo State, Brazil, from March 2003 through February 2004, in order to evaluate the current distribution and abundance... more
The diversity and abundance of necrophagous Diptera were investigated in urban, farm and wild areas in Botucatu, São Paulo State, Brazil, from March 2003 through February 2004, in order to evaluate the current distribution and abundance of flies important in a forensic context. Members of the family Sarcophagidae were most abundant, followed by Drosophilidae, Calliphoridae and Phoridae. Members of Muscidae were least abundant. Flies were more abundant in spring and summer than in fall and winter. Members of Sarcophagidae, Calliphoridae and Phoridae were most abundant in urban areas. Chrysomya albiceps was the most abundant calliphorid species, followed by Lucilia eximia, Chrysomya megacephala, Cochliomyia macellaria and Lucilia cuprina. The implications of these results for the necrophagous fauna structure are discussed. _____________________________________________________________________________________________________________
High dispersal of Lepidoptera larvae between non-Bt and Bt cotton plants can favour the evolution of insect resistance; however, information on host acceptance of neonates in tropical transgenic crops is scarce. Therefore, the purposes of... more
High dispersal of Lepidoptera larvae between non-Bt and Bt cotton plants can favour the evolution of insect resistance; however, information on host acceptance of neonates in tropical transgenic crops is scarce. Therefore, the purposes of this study were as follows: (i) to investigate the feeding behaviour of susceptible and Cry1F-resistant strains of Spodoptera frugiperda (J.E. Smith) on Bt and non-Bt cotton (Gossypium hirsutum L.) varieties and (ii) to understand the possible effects of cotton field contamination on the dispersal and infestation capacity of S. frugiperda larvae by using an individual-based model. The main results of this paper are as follows: (1) the highest post-feeding larval dispersal of the Cry1F-resistant strain occurred at an exposure time of 18-24 h; (2) via video tracking assays, we found that the least distance moved was by larvae resistant to Cry1F on non-Bt cotton; and (3) the model indicated differences in mobility capacity between Bt and non-Bt cotton...
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Population dynamics of aphids have been studied in sole and intercropping systems. These studies have required the use of more precise analytical tools in order to better understand patterns in quantitative data. Mathematical models are... more
Population dynamics of aphids have been studied in sole and intercropping systems. These studies have required the use of more precise analytical tools in order to better understand patterns in quantitative data. Mathematical models are among the most important tools to explain the dynamics of insect populations. This study investigated the population dynamics of aphids Aphis gossypii and Aphis craccivora over time, using mathematical models composed of a set of differential equations as a helpful analytical tool to understand the population dynamics of aphids in arrangements of cotton and cowpea. The treatments were sole cotton, sole cowpea, and three arrangements of cotton intercropped with cowpea (t1, t2 and t3). The plants were infested with two aphid species and were evaluated at 7, 14, 28, 35, 42, and 49 days after the infestations. Mathematical models were used to fit the population dynamics of two aphid species. There were good fits for aphid dynamics by mathematical model o...
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The intercropping is an important cultural practice commonly used in pest management. It is based on the principle that increased plant diversity in the agro-ecosystem can lead to reductions of pest populations in the crop. The current... more
The intercropping is an important cultural practice commonly used in pest management. It is based on the principle that increased plant diversity in the agro-ecosystem can lead to reductions of pest populations in the crop. The current study aimed to assess the impact the colored fiber cotton-cowpea intercropped systems on Aphis gossypii and Aphis craccivora and on their predator Cycloneda sanguinea and the losses and the dispersion behavior of these aphids and their predator in these cropping systems. The experiment had a randomized block experimental design with two bioassays and four treatments. The number of apterous and alate aphids (A. gossypii) per cotton plant was 1.46 and 1.73 or 1.97 and 2.19 times highest in the solid cotton system than that found in the cotton-cowpea intercropped systems (S1) and (S2), respectively. On the other hand, the cotton-cowpea intercropped systems (S1 and S2) reduced, respectively, in 43% and 31% the number of apterousA. gossypiiper cotton plant...
Research Interests: Agronomy, Nonparametric Statistics, Biology, Medicine, Multidisciplinary, and 15 moreCoccinellidae, Animals, Aphids, Coleoptera, Intercropping, Predator, Vigna, Analysis of Variance, Aphididae, Biological Pest Control, Predatory Behavior, Biological Assay, Aphis Craccivora, Aphis gossypii, and Gossypium
In this study we analyzed the effect of migration on the persistence time of coupled local populations of Tribolium in different environments. Four treatments were set up to compare different levels of environmental heterogeneity. We... more
In this study we analyzed the effect of migration on the persistence time of coupled local populations of Tribolium in different environments. Four treatments were set up to compare different levels of environmental heterogeneity. We established high, low, moderate, and no heterogeneity. These levels were estimated by the different amounts of food offered to each population. To investigate how risk spreading works, a stochastic model for two subpopulations was employed. The high heterogeneity treatment resulted in the longest persistence, even though survival analysis revealed no significant difference among treatments. The magnitude of differences in growth rates among subpopulations is probably associated with persistence.