Native to Asia, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is an invasive non-native ladybird in Europe and North America, where it was widely introduced as a biological control agent of aphids and coccids. There were three main objectives of this study: firstly, to investigate the spread and distribution of H. axyridis in Europe from the start of the invasion process; secondly, to study its ecology in Great Britain; and thirdly, to examine its effects on native ladybirds in Britain. In Europe, collaborations with a network of scientists allowed the collation of H. axyridis occurrence data from across the continent. In Great Britain, a web-based public survey (www.harlequin-survey.org) was used, leading to the receipt of over 10,000 verified records of H. axyridis between 2004 and 2008. National land cover data enabled the habitats used by H. axyridis to be identified across Great Britain. These datasets were analysed in order to study the spread and ecology of H. axyridis in Europe and Britain. Fieldwork over a three year period (2006 to 2008) was carried out to examine changes in ladybird species assemblages during the invasion phase of H. axyridis in eastern England. Laboratory work was conducted to detect intraguild predation by H. axyridis, through PCR analyses of gut contents of field-collected ladybirds. In Europe, H. axyridis has spread since 2001 at the rate of approximately 200km yr-1. It has become established in at least 23 European countries. The established range extends from Norway in the north to southern France in the south, and from Ukraine in the east to Great Britain in the west. In the first five years of establishment H. axyridis spread north through Britain at the rate of 105km yr-1 and west at the rate of 145km yr-1. Evidence of the production of two generations per year was found, giving H. axyridis an advantage over most native ladybirds in Britain. Although H. axyridis was very common in urban habitats, it increasingly used semi-natural habitats. In addition, whilst the species was most common on deciduous trees, it was increasingly found on herbaceous plants. Aceraceae, Rosaceae and Malvaceae were the dominant plant families used by H. axyridis, especially for breeding. In eastern England H. axyridis increased from 0.1% to 40% of total ladybirds in three years, whilst native aphidophagous ladybirds declined from 84% to 41% of total ladybirds in the same period. Three species in particular experienced declines: Adalia 2-punctata, Coccinella 7-punctata and Propylea 14-punctata. Harmonia axyridis was the most abundant species by the end of the study. Detection of intraguild predation by one coccinellid on another, in the field in Europe, was shown for the first time using PCR techniques: A. 2-punctata DNA was detected in the gut of one of 112 field-collected H. axyridis. Harmonia axyridis has spread very quickly since 2001 and has become one of the most widely distributed coccinellids in Europe. Populations of native aphidophagous ladybirds were negatively affected by the arrival of H. axyridis, partly through intraguild predation.

In this thesis I have investigated the effects of invading top and intermediate consumers in a size-structured fish community, using a combination of field studies, a lake invasion experiment and smaller scale pond and aquaria experiments. The lake invasion experiment was based on introductions of an intermediate consumer, ninespine stickleback (Pungitius pungitius L.), in to allopatric populations of an omnivorous top predator, Arctic char (Salvelinus alpinus L.). The invasion experiment was performed in two tundra lakes and in two birch forest lakes to investigate the effect of climate on the invasion success. I found that the effect of sticklebacks on char was size dependent. Small char suffered reduced growth from resource competition with sticklebacks whereas the maximum size of adult char increased from the addition of a larger prey resource, stickleback. The negative effect of sticklebacks on the growth of small char suggests that sticklebacks may be a better resource competitor than char, which was also supported by the pond and aquaria experiments. The pond experiments also suggested that char were more efficient cannibals than interspecific predators on sticklebacks. Cannibalism in char may limit the recruitment of char and decrease both their predatory and competitive effect on coexisting species and thereby also promote the coexistence of char and sticklebacks. The successful invasion by sticklebacks and their subsequent increases in density suggest that the absence of sticklebacks in char lakes in this region is not caused by biotic interactions with char. Instead, it may be suggested that co-occurrence of sticklebacks and char in the region is limited by dispersal. The char – stickleback system resembles an intraguild predation system with char as the top consumer and stickleback as the intermediate consumer. The effects of the stickleback invasion is also contrasted with a field study of a northern pike (Esox lucius L.) invasion into a system with coexisting char and stickleback, where pike can be viewed as the top consumer and char as the intermediate consumer both feeding on sticklebacks. In this case pike excluded char. The identity of the invading species and the relative strength of the predatory and competitive interactions in the two contrasting systems are discussed in relation to coexistence in intraguild predation systems. I found that the identity of the invading species is of crucial importance for the response at the ecosystem level, and that the inherent size dependency of competitive and predatory interactions in fish communities is important for attaining a mechanistical understanding of the effects of invasive species in lake ecosystems.

Made available in DSpace on 2014-06-11T19:32:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-01Bitstream added on 2014-06-13T18:42:57Z : No. of bitstreams: 1 correa_lrb_dr_jabo.pdf: 1543048 bytes, checksum: a8f8dbb9edf2e1247f77433aae591f2e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se avaliar aspectos biológicos de Aphis gossypii em três cultivares de algodoeiro colorido, estudar a biologia e a interação dos predadores Harmonia axyridis e Eriopis connexa alimentados com o pulgão A. gossypii criado nas cultivares, avaliar a densidade de tricomas e glândulas de gossipol das folhas das cultivares e elaborar tabelas de vida de A. gossypii, H. axyridis e E. connexa. As cultivares de algodoeiro colorido utilizadas foram: BRS Rubi, BRS Safira e BRS Verde (Gossypium hirsutum L.r. latifolium Hutch., herbáceo). Os ensaios foram conduzidos em câmara climatizada regulada a 25 ± 2ºC, UR de 70 ± 10% e fotofase de 12 horas. Os substratos alimentares avaliados afetaram a fase ninfal de A. gossypii, sendo que na cultivar BRS Verde verificou-se o menor tempo de duração e na BRS Safira ocorreu o oposto. Em BRS Verde, cultivar com menor densidade de tricomas, observou-se elevada produção de ninfas e a maior taxa líquida de reprodução (R0) por A. gossypii. Os coccinelídeos E. connexa e H. axyridis apresentaram maior número de ovos com elevada viabilidade quando alimentados com pulgões oriundos de BRS Safira, cultivar com baixa densidade de glândulas de gossipol nas folhas. A maior taxa de canibalismo entre as larvas de E. connexa e H. axyridis foi obtida em BRS Verde. Não foi observada predação das larvas de H. axyridis por E. connexa em nenhum dos tratamentos. Portanto, a cultivar BRS Verde favorece os maiores padrões de fecundidade de A. gossypii. BRS Safira proporciona elevada fecundidade de E. connexa e H. axyridis. O coccinelídeo H. axyridis prevalece como predador intraguilda na relação com E. connexa / The aim was to evaluate biological aspects of Aphis gossypii in three colored cotton cultivars, to study the biology and interaction of the predator Harmonia axyridis and Eriopis connexa fed with the aphid A. gossypii reared on the cultivars, evaluate the density of trichomes and gossypol glands in leaves of cultivars and prepare life tables of A. gossypii, H. axyridis and E. connexa. The following colored cotton cultivars were used: BRS Rubi, BRS Safira and BRS Verde (Gossypium hirsutum latifolium Hutch Lr., herbaceous). The tests were conducted in climatized chamber at 25±2 ºC, RH 70± 10% and photophase of 12 hours. The feed substrates evaluated affected the nymphal stage of A. gossypii, and in BRS Verde observed the lowest duration and BRS Safira was the opposite. In BRS Verde with lowest density of trichomes observed high production of nymphs and the highest net reproductive rate (R0) by A. gossypii. The coccinellids E. connexa and H. axyridis had higher numbers of eggs with high viability when fed with aphids from BRS Safira, gossypol glands low density cultivar. The highest rate of cannibalism among larvae of E. connexa and H. axyridis was observed in BRS Verde. It was not observed predation on larvae of H. axyridis by E. connexa in all treatments. Therefore, BRS Safira cultivar supports the hightest fertility patterns of A. gossypii. The BRS Safira provides the high fecundity of E. connexa and H. axyridis. The coccinellid H. axyridis acts as intraguild predator in relation with E. connexa

Made available in DSpace on 2014-06-11T19:22:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2009Bitstream added on 2014-06-13T19:49:19Z : No. of bitstreams: 1 galindo_la_dr_botib.pdf: 1002192 bytes, checksum: efafdb9e0e1cd36e8c2d273acc8df569 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As interações interespecíficas em dípteros califorídeos de importância forense resultam de processos biológicos complexos, envolvendo comportamentos específicos capazes de influenciar tanto a abundância como a diversidade de insetos presentes nos substratos orgânicos em decomposição. Nesse sentido, a presença de determinadas espécies com forte ação interativa, como por exemplo, predadores, competidores ou parasitóides, pode interferir substancialmente na composição da fauna decompositora de cadáveres, com sérias implicações para a estimativa de intervalo pós-morte em investigações criminais. Em estudo prévio foi investigado em laboratório o comportamento de oviposição em L. eximia, C. megacephala e C. albiceps na tentativa de esclarecer se a postura de ovos em moscas-varejeiras ocorre meramente ao acaso, ou se a presença prévia de diferentes espécies pode influenciar a desova por parte das espécies que chegaram ao local subsequentemente. Os resultados encontrados indicam que as espécies L. eximia e C. megacephala escolhem sítios de oviposição em que não há a presença prévia de larvas de C. albiceps, uma espécie predadora intraguilda. Esses resultados sugerem estudos mais aprofundados, preferencialmente em populações naturais, focalizando sobre a interação entre larvas e adultos de moscas-varejeiras, já que há evidências de que fêmeas adultas são capazes de detectar a presença de larvas predadoras, o que influi na decisão oviposicional. Este estudo teve o objetivo geral de investigar a abundância, diversidade e dinâmica comportamental em populações de moscas-varejeiras no contexto de recursos alimentares efêmeros e limitados, considerando a ação da predação intraguilda. A proposta do estudo é criar duas frentes de investigação no contexto de ecologia comportamental, experimentação em campo e modelagem matemática populacional / The interspecific interactions in calliphorid flies of forensic impoltance result of complex biological processes, involving specific behaviors capable of influencing both the abundance and the diversity of insects in organic substrates in decomposition. The presence of certain species with a strong interactive action, such as predators, competitors or parasitoids, can interfere substantially in the composition of the decomposer fauna of corpses, with serious implications for the postmortem interval estimate in criminal inquiries. In a previous study the oviposition behavior in L. eximia, C. megacephala and C. albiceps was investigated in laboratory in the attempt to clarify if the egg laying in blowflies occurs at random, or if the previous presence of different species may influence the oviposition of the species that had arrived subsequently at the substrate. The results suggest that the species L. eximia and C megacephala prefer oviposition substrates, without the previous presence of C. albiceps larvae, an intraguild predator species. These results suggest further studies, preferably in natural populations, focusing on the interaction between larvae and adult of blowflies, since there is evidence that females are able to detect the presence of predator. This study had the general objective of investigating the abundance, diversity and behavioral dynamic in populations of blowflies in the context of limited and ephemeral food resources, considering the effect of intraguild predation. The proposal of the study is to create two fronts of investigation in the context of behavioral ecology, experimentation in field and population mathematical modeling

Orientador: Francisco Jorge Cividanes / Banca: Brigida de Souza / Banca: Valter Arthur / Banca: Nilza Maria Martinelli / Banca: Ricardo Antonio Polanczyk / Resumo: Objetivou-se avaliar aspectos biológicos de Aphis gossypii em três cultivares de algodoeiro colorido, estudar a biologia e a interação dos predadores Harmonia axyridis e Eriopis connexa alimentados com o pulgão A. gossypii criado nas cultivares, avaliar a densidade de tricomas e glândulas de gossipol das folhas das cultivares e elaborar tabelas de vida de A. gossypii, H. axyridis e E. connexa. As cultivares de algodoeiro colorido utilizadas foram: BRS Rubi, BRS Safira e BRS Verde (Gossypium hirsutum L.r. latifolium Hutch., herbáceo). Os ensaios foram conduzidos em câmara climatizada regulada a 25 ± 2ºC, UR de 70 ± 10% e fotofase de 12 horas. Os substratos alimentares avaliados afetaram a fase ninfal de A. gossypii, sendo que na cultivar BRS Verde verificou-se o menor tempo de duração e na BRS Safira ocorreu o oposto. Em BRS Verde, cultivar com menor densidade de tricomas, observou-se elevada produção de ninfas e a maior taxa líquida de reprodução (R0) por A. gossypii. Os coccinelídeos E. connexa e H. axyridis apresentaram maior número de ovos com elevada viabilidade quando alimentados com pulgões oriundos de BRS Safira, cultivar com baixa densidade de glândulas de gossipol nas folhas. A maior taxa de canibalismo entre as larvas de E. connexa e H. axyridis foi obtida em BRS Verde. Não foi observada predação das larvas de H. axyridis por E. connexa em nenhum dos tratamentos. Portanto, a cultivar BRS Verde favorece os maiores padrões de fecundidade de A. gossypii. BRS Safira proporciona elevada fecundidade de E. connexa e H. axyridis. O coccinelídeo H. axyridis prevalece como predador intraguilda na relação com E. connexa / Abstract: The aim was to evaluate biological aspects of Aphis gossypii in three colored cotton cultivars, to study the biology and interaction of the predator Harmonia axyridis and Eriopis connexa fed with the aphid A. gossypii reared on the cultivars, evaluate the density of trichomes and gossypol glands in leaves of cultivars and prepare life tables of A. gossypii, H. axyridis and E. connexa. The following colored cotton cultivars were used: BRS Rubi, BRS Safira and BRS Verde (Gossypium hirsutum latifolium Hutch Lr., herbaceous). The tests were conducted in climatized chamber at 25±2 ºC, RH 70± 10% and photophase of 12 hours. The feed substrates evaluated affected the nymphal stage of A. gossypii, and in BRS Verde observed the lowest duration and BRS Safira was the opposite. In BRS Verde with lowest density of trichomes observed high production of nymphs and the highest net reproductive rate (R0) by A. gossypii. The coccinellids E. connexa and H. axyridis had higher numbers of eggs with high viability when fed with aphids from BRS Safira, gossypol glands low density cultivar. The highest rate of cannibalism among larvae of E. connexa and H. axyridis was observed in BRS Verde. It was not observed predation on larvae of H. axyridis by E. connexa in all treatments. Therefore, BRS Safira cultivar supports the hightest fertility patterns of A. gossypii. The BRS Safira provides the high fecundity of E. connexa and H. axyridis. The coccinellid H. axyridis acts as intraguild predator in relation with E. connexa / Doutor

abstract: A functioning food web is the basis of a functioning community and ecosystem. Thus, it is important to understand the dynamics that control species behaviors and interactions. Alterations to the fundamental dynamics can prove detrimental to the future success of our environment. Research and analysis focus on the global dynamics involved in intraguild predation (IGP), a three species subsystem involving both competition and predation. A mathematical model is derived using differential equations based on pre-existing models to accurately predict species behavior. Analyses provide sufficient conditions for species persistence and extinction that can be used to explain global dynamics. Dynamics are compared for two separate models, one involving a specialist predator and the second involving a generalist predator, where systems involving a specialist predator are prone to unstable dynamics. Analyses have implications in biological conservation tactics including various methods of prevention and preservation. Simulations are used to compare dynamics between models involving continuous time and those involving discrete time. Furthermore, we derive a semi-discrete model that utilizes both continuous and discrete time series dynamics. Simulations imply that Holling's Type III functional response controls the potential for three species persistence. Complicated dynamics govern the IGP subsystem involving the white-footed mouse, gypsy moth, and oak, and they ultimately cause the synchronized defoliation of forests across the Northeastern United States. Acorn mast seasons occur every 4-5 years, and they occur simultaneously across a vast geographic region due to universal cues. Research confirms that synchronization can be transferred across trophic levels to explain how this IGP system ultimately leads to gypsy moth outbreaks. Geographically referenced data is used to track and slow the spread of gypsy moths further into the United States. Geographic Information Systems (GIS) are used to create visual, readily accessible, displays of trap records, defoliation frequency, and susceptible forest stands. Mathematical models can be used to explain both changes in population densities and geographic movement. Analyses utilizing GIS softwares offer a different, but promising, way of approaching the vast topic of conservation biology. Simulations and maps are produced that can predict the effects of conservation efforts. / Dissertation/Thesis / M.S. Applied Biological Sciences 2012

Without an adequate understanding of complex interactions between native and non-native species, management of invasive species can result in unforeseen detrimental impacts. I used both field and laboratory experiments to study reciprocal species interactions between the endangered Mohave tui chub (Siphateles bicolor mohavensis) and invasive western mosquitofish (Gambusia affinis). I also examined the impacts of both fish species on the aquatic invertebrate communities in desert springs. I demonstrate a case of intraguild predation (IGP) as a mechanism facilitating co-persistence of the endangered Mohave tui chub with invasive mosquitofish using field mesocosm experiments. In this case of IGP, adult tui chub prey on adult and juvenile mosquitofish, while adult mosquitofish prey on tui chub eggs and/or larvae. I conducted laboratory predation trials to assess if IGP was size-structured due to predator gape-limitation. I explored sex specific differences in gape-size limitation in mosquitofish, because mosquitofish are sexually dimorphic. Larval tui chubs had lower survival in the presence of female mosquitofish than in the presence of males. Reciprocally, male mosquitofish had lower survival than the females in the presence of Mohave tui chub. These results combined with vulnerability modeling supported that IGP in this system is size structured based on gape-size limitation. These results collectively suggest size-structured IGP may facilitate the co-persistence of these two fish species. My findings also suggest that mosquitofish may not be a limiting factor for the persistence of the endangered Mohave tui chub. Further, habitats currently harboring mosquitofish were considered as future refuge habitats for Mohave tui chub, a management option previously un-available. In addition to such reciprocal interactions between fish species, recently established fish populations may impact unique invertebrate communities. Mesocosm experiments with sympatric and allopatric populations of tui chub and mosquitofish showed negative impacts of both fish species on changes of invertebrate community structure. Specifically, fish caused population declines and, in some cases, extirpations of various invertebrate taxa. These results suggest important conservation implications of invasive fish as well as protected fish transplants into fishless desert springs. Overall my research emphasizes the complexity of ecological interactions between native and non-native fish species in desert aquatic systems.

Lethal interactions between carnivorans (interspecific killing) may influence their population dynamics, behavior, and other important aspects of their ecology. In this study, I expand upon previous research on the broad-scale patterns of interspecific killing in Carnivora (Palomares & Caro 1999, Donadio & Buskirk 2006) with a greatly expanded dataset (inclusion of scat and stomach data and more intensive sampling of the literature), and suggest avenues for future research. While like previous studies, I found a positive effect of relative body size between killer species and killed species on the likelihood of forming a killing interaction, I failed to find evidence that this effect had a body size ratio threshold above which interactions become less common, suggesting a greater role of non-competitive killing than previously believed. I also found evidence for a positive influence of range overlap and dietary overlap on species interactions, but found mixed effects of phylogeny. This study suggests that our previous understanding of the broad-scale dynamics interspecific killing in Carnivora was, due to limited sampling, incomplete in scope. Incidental killing, whereby killing interactions occur as a byproduct of opportunistic lethal encounters caused by the hyperpredatory behavior of carnivorans, has a number of interesting implications for our understanding of interspecies aggression, including research on intraguild predation and its effects.

Changes in abundance of interactive species can have cascading, community-wide effects (Soule et al. 2003). Raccoons (Procyon lotor) prey on a competitor for marine turtle eggs, the Atlantic ghost crab (Ocypode quadrata). Conservation of marine turtles often includes managing raccoons-the most obvious egg predator-which may have broader ecological effects, and unknown effects on egg predation. Neither the relationship between raccoons and ghost crab density nor the effects of ghost crab density on egg predation are well understood. I studied raccoon-ghost crab interactions and the effects of environmental variation on their activity during the 2007 marine turtle nesting season on Canaveral National Seashore, FL. My goal was to model predator activity and identify efficient management strategies to reduce egg predation. Raccoon activity increased with increasing habitat diversity and edge of the dominant cover type, coastal strand. Raccoon activity increased locally and became less variable near segments of beach accessed for human recreation, but activity was greater on undeveloped beach, where habitat diversity and edge were greater. Ghost crab density and size were primarily affected by sand characteristics and recreation but decreased with increasing raccoon activity in June, which may have contributed to sustained declines in ghost crab density. Hatching success of marine turtles decreased with increasing ghost crab egg predation, suggesting ghost crabs are an important cause of egg mortality and not merely scavengers on unhatched eggs. Egg predation by ghost crabs was unrelated to ghost crab density or size, likely a result of monitoring limitations, but raccoon activity increased with increasing egg predation by ghost crabs, supporting previous research and experimental evidence suggesting ghost crabs can facilitate secondary nest predation by raccoons. This indirect interaction has strong implications for marine turtle conservation, because its strength may increase with increasing ghost crab density, potentially negating the effects of raccoon removal.

No description available.