Mass mortality events (MMEs) can affect communities through large amounts of carcass biomass and significant reductions in population sizes. I conducted laboratory experiments to compare effects of predator and herbivore MMEs on a community using a study system of convergent lady beetles (Hippodamia convergens), pea aphids (Acyrthosiphon pisum), and fava beans (Vicia faba). I used a factorial design crossing input (addition of carcasses) and mortality (removing 75% of the population) of aphids and lady beetles. Lady beetle mortality reduced the top-down pressure on the aphid population, which increased aphid abundance and decreased plant height. Input of aphid carcasses increased aphid abundance. Input and mortality of aphids caused the aphid population to diminish suggesting that top-down effects of mortality were more significant than bottom-up effects of carcasses. My results show that MMEs can have effects through both bottom-up and top-down processes, which is dependent upon who experiences the MME.

Coccinella septempunctata L. (Coleoptera: Coccinellidae) has been introduced to North America in recent decades, raising concerns of adverse impacts on native lady beetles, including the congeneric C. transversoguttata richardsoni (Brown). The central focus of my dissertation is to understand the importance of reproduction, in particular, in promoting invasion of C. septempunctata and its replacement of native lady beetles in alfalfa fields of western North America. Studies were conducted to compare reproductive tactics of the invasive C. septempunctata and the native C. transversoguttata, by addressing: 1) maximum rate of reproduction of overwintered lady beetles, 2) population dynamics of the invasive and native lady beetles and their aphid prey, and seasonal reproductive patterns, over a 3-year period (2004'2006) in alfalfa fields, 3) reproductive tactics and plasticity in response to various prey availabilities, and 4) ovarian dynamics and observation of oosorption in response to prey removal. The invasive C. septempunctata gained a reproductive advantage over native, North American lady beetles from its larger body size when feeding on abundant prey. The invasive species gained additional advantage by its allocation of prey to larger numbers of relatively small eggs. In alfalfa fields, females of C. septempunctata reproduced more readily and laid more eggs than females of C. transversoguttata even at low prey density. C. septempunctata females collected from the field were also more successful in approaching their maximum body weights and reproduction, as observed under ideal conditions, than were females of native C. transversoguttata. In the laboratory, C. septempunctata females produced larger numbers of relatively small eggs, and they maintained their body weights even as they were producing eggs at low rates when aphids were provided in limited numbers. More immediate adjustment of reproductive effort with prey removal, and higher recovery of reproductive rate when prey again became available, were observed in C. septempunctata, compared with C. transcersoguttata. These reproductive abilities of C. septempucntata may contribute to its invasion success and dominance in alfalfa fields. Further studies are needed to determine why females of C. septempunctata are in better physiological condition than are females of C. transversoguttata in spring alfalfa fields.

Populations of striped cucumber beetles (<i>Acalymma vittatum</i> Fabr.), spotted cucumber beetles (<i>Diabrotica undecimpunctata howardi</i> Barber), western cucumber beetles (<i>Acalymma trivittatum</i> Mann.), Pennsylvania leatherwings (<i>Chauliognathus pennsylvanicus</i> DeGeer), Diptera (Order: Diptera), lady beetles (Order: Coleoptera, Family: Coccinellidae), hymenoptera (Order: Hymenoptera), and spiders (Order: Araneae) in a cucumber field and a bordering field of uncultivated vegetation were assessed using yellow sticky traps to determine: 1) the relative abundances of target insects across the uncultivated vegetation and the crop field, 2) relationships between target insects and plant species. In both years populations striped and spotted cucumber beetles and Pennsylvania leatherwings (only in 1995) increased significantly and Diptera decreased significantly in the direction of the crop. The strength of these relationships increased over the season to a peak in August in 1995 and July in 1996 and then decreased in September in both years. There were significant correlations between Diptera and sweet-vernal grass in 1995. In 1996, cucumber beetles were correlated with wild violet (<i>Viola</i> spp.) and white clover (<i>Trifolium repens</i>); Diptera with wild violets; and the lady beetle <i>Coleomegilla maculata</i> with goldenrod (<i>Solidago</i> spp.), English plantain (<i>Plantago lanceolata</i>), and marjoram (<i>Origanum</i> spp.) in 1996. This study demonstrated the potential value of increasing the diversity of a cucumber field to control insect pests (and thus reduce pesticide useage) as well as suggested specific plants that influenced insect populations. / Master of Science

Master of Science / Department of Entomology / Brian P. McCornack / Winter canola production in the south-central US is commonly threatened by a complex of aphid species that can cause up to 70% in yield loss. Aphid species vary in their life-history traits, performance (sequestration/excretion of secondary compounds; glucosinolates), vertical distribution within the plant, and temporal dynamics across the growing season. Colonizing behavior of these aphids may be affected by intrinsic characteristics of the host plant (bottom-up effects), such as nutritional value, secondary compounds, or plant architecture. Understanding bottom-up effects may enable the evaluation of plant-level interactions that are influencing predator-prey dynamics. The goal of my research project is to understand aphid population dynamics in different canola plant structures, assess whether aphid quality (sequestration/ excretion of glucosinolates) is influenced by feeding location on the canola plant, and if so, assess the impact on the existing predator communities, specifically the development and fitness of immature and adult Hippodamia convergens. A combination of filed and greenhouse experiments provided novel contributions that will help shape our understanding of key factors regulating aphid population growth in canola fields, which will lead to more judicious use of insecticides and better sampling strategies.

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2018-09-26T12:19:08Z No. of bitstreams: 1 2013 - Alice Teodorio Lixa.pdf: 7684993 bytes, checksum: f6675b748532a5b5835d14d6a4480870 (MD5) / Made available in DSpace on 2018-09-26T12:19:08Z (GMT). No. of bitstreams: 1 2013 - Alice Teodorio Lixa.pdf: 7684993 bytes, checksum: f6675b748532a5b5835d14d6a4480870 (MD5) Previous issue date: 2013-02-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Coccinellid predators are natural enemies of agricultural pests such as aphids and scale insects. They are known colloquially as ladybirds, ladybugs or lady beetles. Some species only complete their development and produce viable eggs and offspring when they consume their preferred prey. However, in the absence of this prey, or in presence with lower nutritional quality prey, the ladybugs tend to consume alternative foods, such as pollen and nectar, to ensure their survival. Thus, the choice and maintenance of useful floral resources to ladybugs in agroecosystems is a strategy favorable to the conservation of natural enemy populations in the production environment. Another line is the use of pesticides that cause fewer negative impacts on natural enemies of pests. This study worked on these two fronts, seeking to know floral species beneficial in situ conservation of biodiversity of ladybugs, and to evaluable the impact of pesticides used in organic agriculture on these insects. The thesis is organized in three chapters. Chapter I aimed to identify plant families and/or plant species are natural sources of pollen grains for predatory ladybug adults in diversified organic system. Adults were collected from 26 August 2010 to 22 August 2011, at area of Integrated Agroecological Production System (IAPS), in Serop?dica, RJ, Brazil. Baker's legs and wings have been removed to avoid contamination with pollen attached to the outside of the insects, the remainder of the body subjected to acetolysis analysis, aiming at the identification of pollen possibly ingested. We identified pollen from different plant species: star fruit (Averrhoa carambola, Oxalidaceae), coriander (Coriandrum sativum, Apiaceae), sunflower (Helianthus annuus, Asteraceae), maize (Zea mays, Poaceae), elderberry (Sambucus nigra, Adoxaceae), and different families: coming from Amaranthaceae, Asteraceae, Fabaceae, Malvaceae, Myrtaceae, and Passifloraceae. Pollens were found in seven species of ladybugs. Just Cycloneda sanguinea ingested pollen of all these families, and pollen unidentified families. Chapter II aimed to determine the diversity of adult ladybugs community in the area of IAPS, and characterize the population structure by faunistic indexes. Species richness was equal to seven [Cycloneda sanguinea, Hippodamia convergens, Coleomegilla maculate, Coleomegilla quadrifasciata, Eriopis connexa, Harmonia axyridis, and Olla v-nigrum]. C. sanguinea, H. convergens, and C. maculata were classified as dominant, being the first constant and others accessories. In Chapter III, the studies were conducted with C. maculata at laboratory conditions, with the objective of evaluating the effect of different concentrations of alternative pesticides used in organic agriculture (Natuneem?, Nim-I-Go?, Rotenat?, Lime sulfur, and Agrobio?) on biological aspects of this insect. The two neem based products (Natuneem and Nim-I-Go) to 2 % and the ?timb?? based product (Rotenat) 1% and 2 % decreased egg viability of C. maculata. Nim-I-Go at concentrations of 1% and 2% caused higher mortality than the control treatment (water) in all larval instars. Except Agrobio, all pesticides adversely affected the reproduction of C. maculata. The neem based products should be used sparingly to avoid negative effects on the development of C. maculata. / Dentre os inimigos naturais das pragas agr?colas, destacam-se os coccinel?deos predadores, tamb?m conhecidos como joaninhas. Algumas esp?cies s? completam seu desenvolvimento e produzem ovos e prog?nies vi?veis quando consomem sua presa preferencial. Todavia, na aus?ncia dessa presa ou na presen?a de uma presa com qualidade nutricional inferior, as joaninhas tendem a consumir alimentos alternativos, tais como p?len e n?ctar, para garantir sua sobreviv?ncia. Desse modo, a escolha e a manuten??o de recursos florais ?teis ?s joaninhas no agroecossistema ? uma estrat?gia favor?vel ? conserva??o de popula??es dos inimigos naturais no ambiente de produ??o. Outra linha ? o uso de defensivos que causem menos impactos negativos aos inimigos naturais das pragas. O presente trabalho atuou nessas duas frentes, buscando conhecer esp?cies florais ben?ficas a conserva??o in situ da biodiversidade das joaninhas e defensivos agr?colas, usados na agricultura org?nica, menos danosos a esses insetos. A tese foi organizada em tr?s cap?tulos. No Cap?tulo I objetivou-se identificar, em sistema org?nico diversificado, quais fam?lias e/ou esp?cies bot?nicas s?o fontes naturais de gr?os de p?len para adultos de joaninhas predadoras. Os adultos foram coletados de 26 de agosto de 2010 a 22 de agosto de 2011, em ?rea do Sistema Integrado de Produ??o Agroecol?gica (SIPA), em Serop?dica, RJ. Asas e pernas das joaninhas foram retiradas a fim de evitar contamina??es por polens presos ? parte externa dos insetos, sendo o restante do corpo submetido ? an?lise de acet?lise, objetivando a identifica??o dos polens possivelmente ingeridos. Foram identificados polens de diferentes esp?cies bot?nicas: carambola (Averrhoa carambola, Oxalidaceae), coentro (Coriandrum sativum, Apiaceae), girassol (Helianthus annuus, Asteraceae), milho (Zea mays, Poaceae), sabugueiro (Sambucus nigra, Adoxaceae); e de diferentes fam?lias: oriundos de Amaranthaceae, Asteraceae, Fabaceae, Malvaceae, Myrtaceae e Passifloraceae. Os polens foram encontrados em sete esp?cies de joaninhas afid?fagas. Apenas a Cycloneda sanguinea ingeriu p?len de todas essas fam?lias, al?m de polens de fam?lias n?o identificadas. No Cap?tulo II, objetivou-se determinar a diversidade comunidade de joaninhas adultas, em ?rea do SIPA, e caracterizar a estrutura das popula??es por meio da an?lise faun?stica. A riqueza de esp?cies foi igual a sete [Cycloneda sanguinea, Hippodamia convergens, Coleomegilla maculata, Coleomegilla quadrifasciata, Eriopis connexa, Harmonia axyridis e Olla v-nigrum]. C. sangu?nea, H. convergens e C. maculata foram classificadas como dominantes, sendo a primeira constante e as demais acess?rias. No Cap?tulo III, os estudos foram conduzidos com C. maculata, em condi??es de laborat?rio, com o objetivo de avaliar o efeito de diferentes concentra??es de produtos fitossanit?rios alternativos usados em agricultura org?nica (Natuneem?, Nim-I-Go?, Rotenat?, Calda sulfoc?lcica e Agrobio?), sobre aspectos biol?gicos desse inseto. Os dois produtos ? base de nim (Natuneem e Nim-I-Go) a 2% e o produto ? base de timb? (Rotenat) a 1% e 2% diminu?ram a viabilidade dos ovos de C. maculata. Nim-I-Go nas concentra??es de 1% e 2% causou maior mortalidade do que o tratamento controle (?gua) em todos os instares larvais. Com exce??o do Agrobio todos os produtos fitossanit?rios influenciaram negativamente a reprodu??o de C. maculata. Os produtos ? base de nim devem ser utilizados com parcim?nia para evitar efeitos negativos ao desenvolvimento de C. maculata.

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