The apple snail, Pomacea canaliculata has made a tremendous threat to agricultural crops as well as environmental ecology in Taiwan. Although various control methods are available, there are certain limitations in each of the applications. The present study was conducted to evaluate the application potential of food preference in attractant usage to apple snails. It has been found that apple snails actively searched animal materials. Fish blood and egg glair were as attractive as banana (Musa sp.). With equal weight, blood clots from cobia (Rachycentron canadum) and pig (Sus sp.) were more attractive than banana, and cooked pig blood was as attractive as banana. The response of snails to concentrated extracts from fish blood (with molecular weight > 5000) was stronger than banana. There were no significant differences in snails¡¦ responses to blood from pig, cobia, freshwater and seawater milk fish (Chanos chanos). Furthermore, protein was probably the attractive source to apple snails and frozen-treated blood increased attractive response. As expected, blood clots from cobia and pig were more attractive than banana in the field. In summary, the results show that animal protein is potentially applicable as attractive components for apple snails.

Feral hogs (Sus scrofa) are considered an exotic, free-ranging ungulate distributed within numerous countries and continents to include the United States. The reproductive efficiency, lack of predators, land use practices for domestic livestock (e.g., feeding stations, introduced water sources, intense cropping practices, etc.), and diet are leading factors in the expansion of feral hogs throughout their range. Feral hogs negatively impact floral and faunal communities, agricultural lands, and residential and recreational areas to include concerns with public safety and disease transmission. My study objectives were to (1) assess feral hog abatement strategies by (A) evaluating trap designs with the inclusion of electrical fencing, and (B) evaluating candidate baits for feral hog-specificity, and (2) assess prevalence levels for feral hog diseases. I evaluated 3 corral trap designs differing in the addition of electric fence configurations. Feral hog capture success data were collected and used to determine trap design efficacy. Treatments evaluated included (A) control corral trap with no electrical configurations, (B) corral trap with 1 electrical leg, and (C) corral trap with 2 electrical legs. ANOVA analyses suggest no differences (df = 2, P = 0.758) between trap designs; however, length of trapping effort (i.e., the number of days that trapping occurred) was a significant (df = 6, P < 0.001) factor in determining trap success. Pre-baiting was an important factor in observed trapping success. Trapping success declined after fourth day of continuous trapping. I recommend short, intensive trapping efforts (e.g., <4 days) when using corral traps in feral hog abatement programs. I also evaluated 14 candidate baits (with and without repellant) replicated 40 times to determine feral hog specificity. Three evaluated baits (i.e., PIGOUT™ strawberry, corn, and rice) were selected (df = 2, P < 0.05) more frequently by feral hogs than other combinations. Non-target species (e.g., raccoons) visited baits with repellants less (df = 2, P < 0.05) than baits without repellants. Repellant had no direct impact on feral hog visitation at bait sites. Trapping data also suggests that grains commonly farmed in local or regional areas are more likely to be consumed by feral hogs and, therefore considered in baiting options. Finally, of 412 feral hogs captured, 86 were sampled for prevalence of pseudorabies and Brucella suis. The prevalence of pseudorabies and B. suis was 20.9% and 13.9%, respectively within the study area. Based on disease study results, I recommend that natural resource managers take necessary precautions to protect themselves by wearing protective equipment and equipment and properly cooking feral hog meat. Additionally, resource managers should properly administer vaccinations to domestic and companion animals, and restricting domestic and companion animals from areas of high risk (e.g., carcasses of dead hogs and wallows).

Sinorhizobium meliloti (Ensifer meliloti) is a bacterium that will exist saprotrophically in the soil and rhizosphere or as a differentiated bacteroid inside root nodules of the legume genera Medicago, Melilotus, and Trigonella. It exists in symbiosis when inside a host plant and will fix gaseous N2 into ammonium for the plant. In return, a population of the bacteria is harbored inside the plant where it can proliferate beyond what would be possible in the rhizosphere or bulk soil. This symbiosis is a defining feature of the Fabaceae (legume) family, a clade that diverged approximately 60 million years ago and is now the 5th largest plant family by species count. Each legume species pairs with one or several strains of bacteria, referred to broadly as rhizobia. The rhizobia identify their proper host plant by a cocktail of secondary metabolites called flavonoids released from specific parts of the roots. Initiation of the symbiosis may only occur at the tips of young root hairs. Therefore, the means rhizobia take to localize themselves to these sites must be the inceptive step in the symbiotic interaction. The studies here examine the mechanisms and priorities rhizobia use to achieve this goal. Movement of bacteria is referred to as motility and is achieved via (in rhizobia, multiple) rotating flagella, proteinaceous extracellular appendages that propel the cell through liquid environments. On their own, flagella may only move but not guide the cell. Navigation is achieved through sensors that detect chemical attractant or repellent cues in the environment and an intracellular signaling system that relays information to appropriately control locomotion. This sensing is called chemotaxis. A research focus is directed on the sensing aspect of chemotaxis to understand which chemical compounds are the preferred attractants for S. meliloti. An emphasis is placed on those compounds released from germinating host seeds. Chapter 2 spearheads our research goals by examining the chemotactic potential of host-derived flavonoids, the compounds that induce the symbiotic signaling in the rhizobial symbiont. While a logical place to start, this study reveals that our strain of rhizobia is not attracted to flavonoids. We determined that the best chemoattractants are hydrophilic in nature and that hydrophobic compounds, such as flavonoids, are not effective chemoattractants. In addition, we discuss the nature of chemotactic agents and symbiosis inducers to fortify our understanding of how classes of compounds contribute to the rhizobia-plant interaction. In chapter 3, we characterize the sensor protein, McpV, and its ligand profile for carboxylates. The protein is first screened using a high-throughput assay to test numerous possible ligands simultaneously. We confirm positive reactions using direct binding studies and quantify dissociation constants. Then, the phenotypic response to these ligands is measured using capillary chemotaxis assays, and the role mcpV plays in this response is confirmed using deletion mutants. Last, the symbiotic context is addressed by quantifying these ligands in exudates of the host alfalfa. These experiments show that McpV is a chemotactic sensor dedicated to detecting 2 – 4 C monocarboxylates. Only one of the compounds found in the ligand profile, glycolate, was detected in seed exudates, so the contribution of McpV to host sensing is yet to be expounded. Chapter 4 follows the model of chapter 2 but is complicated when the ligand screen used previously gives ambiguous results. Using direct binding studies, we were able to confirm the true ligand amidst numerous false positives. Analytical gel filtration suggests that McpT exists as a dimer regardless of ligand binding. Capillary chemotaxis assays quantified the responses mediated by McpT to di- and tri-carboxylates, which were slightly weaker, but still on-par with the responses to McpV ligands. Strains with mcpT deletions showed strongly reduced, but in some cases, not abolished, chemotaxis to carboxylates. Chapter 5 examines McpX – the chemoreceptor already known to be a sensor of quaternary ammonium compounds. This is a structural investigation into the binding of McpX to its ligands. A crystal structure of the ligand binding region of the protein is resolved to understand how ligands fit into the binding pocket of McpX and what determines its structurally diverse ligand profile. The contribution of certain residues to ligand binding are further probed using direct binding studies on single point variants of McpX. The analysis of chemoreceptor functions hint at what kinds of molecules are most important to bacterial survival and reproduction. Knowing what the bacterium is tuned to seek out grants understanding of what niches they prefer, and how they thrive in those niches. For S. meliloti and other rhizobia, the preeminent niche is one in symbiosis with a host plant. The sum of this knowledge we have accrued with S. meliloti lends itself to agricultural goals of soil enrichment, legume inoculation, nutrient cycling, and environmentally safe and efficient crop fertilization. / Doctor of Philosophy / Sinorhizobium meliloti and other soil-dwelling bacteria termed rhizobia are crucial to the cultivation of leguminous crops such as alfalfa, soy, pea, lentil, peanut, and many more. The bacterium can be internalized by the plant host's roots where it will supply the plant with nitrogen. This is a great boon to crops when they need to accumulate more protein in seed stores, or for plants that survive in nutrient depleted soils. The bacterium must begin seeking out the host plant by sensing chemical cues. It can navigate to the proper location by using a process called chemotaxis. This process is centered around chemoreceptors that can be likened to the nose of the bacterium. Using these chemoreceptors, the bacterium will seek out compounds that benefits it – these are usually food sources. Identifying what each individual chemoreceptor senses allows us to understand what the bacterium needs to seek out to survive. We correlate this information with compounds that the plant secretes and find that many chemoreceptors have evolved to sense signals that will lead the bacterium to a plant root. This interaction is a key part of how the symbiosis is propagated and ultimately benefits the agriculture of leguminous plants.

This study investigated spatial learning in Caenorabditis elegans; the ability to associate reinforcing cues with a location. Naive, wildtype C. elegans were trained in a microfluidic t-maze in the presence of diacetyl (a volatile attractant associated with food) and subsequently tested to see if they could associate diacetyl with one arm of the t-maze. 70-80% of the subjects chemotaxed towards diacetyl during training phase, but they randomly chose left or right when diacetyl was absent (number of subjects that chose diacetyl being under 65%). From our experiments, it is unlikely that the worms are associating diacetyl with one arm of the t-maze, but appears to be using some component of the atmosphere as a cue.

This study examined the role of olfactory and visual cues in host finding of the pine bark beetles Hylastes ater and Hylurgus ligniperda and the burnt pine longhorn beetle Arhopalus ferus. The ultimate aim of this research was to provide new information on attractant and repellent (such as non-host leaf volatiles) stimuli to improve monitoring methods and reduce the attack by wood-boring and bark beetle species. A field trapping trial of visual and olfactory cues near Nelson caught 7842 H. ater, 274,594 H. ligniperda and 16,301 A. ferus adults. There were significant effects of both visual (colour and sihoutte) and olfactory (host and non-host volatiles) cues for all three species. The highest catches were in black (host mimicking), panel flight intercept traps baited with attractant (α-pinene and ethanol) and the lowest in clear or white (non-host mimicking) control traps. The repellent, green leaf volatiles (GLV) ((E)-2-hexen-1-ol & (Z)-3-hexen-1-ol) when present on traps with attractant reduced catches significantly but modestly in H. ater and H. ligniperda, but had no significant effect on A. ferus. A field trial near Christchurch found that GLV applied as a topical repellent halved the number of beetles attacking Pinus radiata logs. This reduction was significant in H. ligniperda, but not quite (P = 0.07) in H. ater. Placing logs among broadleaved plants (natural sources of non-host volatiles) significantly reduced attack of H. ligniperda by about 75% compared to logs in the open, but had no effect on H. ater. Attack by H. ater was found on 4% of 500 P. radiata seedlings in a field trial near Dunedin. Treatment of seedlings with GLV significantly affected the severity and proportion of seedlings attacked by H. ater, compared with insecticide-treated and control seedlings, but the treatment effect was apparently driven by an unexpected direct damaging effect of GLV on the health of seedlings. It is recommended that future research explores the use of non-host volatiles from natural sources that influence host finding in wood–boring and bark beetle species for the protection of plantation forests in New Zealand.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-06-20T20:36:51Z No. of bitstreams: 1 2012 - Vinicius de Abreu D'?vila.pdf: 623654 bytes, checksum: 2c91585552193e53bcefc6b559fe2a2f (MD5) / Made available in DSpace on 2017-06-20T20:36:51Z (GMT). No. of bitstreams: 1 2012 - Vinicius de Abreu D'?vila.pdf: 623654 bytes, checksum: 2c91585552193e53bcefc6b559fe2a2f (MD5) Previous issue date: 2012-08-31 / CAPES / The biological control is as important method to regulate the pest populations in a system of sustainable agricultural production, because it is a promising alternative to the use of the organic synthetic pesticides that cause great ecotoxicological impacts. The predator ladybeetles are part of the biological control agents of agricultural pests, could be management by the three biocontrol strategies: classical, conservative and augmentative. In the present work, it was tried to generate knowledge for using the aphidophagous predator ladybeetle Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) under the perspective of the last two strategies. The conservative biological control involving predator insects bases on the fact that in the absence or scarceness of their preferential prey or in the presence of the other preys with inferior nutritional quality, they may use alternative foods, such as pollen, to guarantee their survivorship and, sometimes, their reproduction, and because of that botanical species that provide this floral resource might integrate the agricultural landscape, inside and/or around the agricultural property; meanwhile the augmentative control requests the multiplication of the predator in the laboratory, using natural or artificial preys. Even though some authors proved the visitation of the flowers of some species of Apiaceae by C. maculata, there are no records in the literature of the ingestion of pollen grains of this botanical family by this ladybeetle. In this context, this work was carried out with the aim to select the plant species whose flowers are source of pollen as alternative or complementary food to C. maculata in the perspective to compose the vegetation of the agroecosystems to contribute in the conservation of this ladybeetle, and /or to aid in its mass rearing in the laboratory conditions. The objective of the chapter I was to prove the ingestion of pollen of three species of the family Apiaceae [coriander (Coriandrum sativum L.), dill (Anethum graveolens L.), and fennel (Foeniculum vulgare Mill.)] from the provision of their flowers to the larvae of the 4th instar and adults of C. maculata. It was observed the presence of pollen grains in the five replicates of all treatments, proving the ingestion of the pollen of these three species of Apiaceae from their flowers by C. maculata. At 24 hours of exposition, adults fed on average more pollen of dill than pollens of coriander and fennel, while the larvae consumed more pollen of fennel. The objective of the chapter II was to determine the suitability of nine diets to C. maculata, including provision of pollen of the two species of Apiaceae (coriander and dill), under controlled conditions of the laboratory. Even though the diets with only flowers of these two Apiaceae did not provided the full development of C. maculata, they used as complementary food with eggs of Anagasta kuehniella Zeller (Lepidoptera: Pyralidae) resulted in reduction of larval period, increased the egg number by cluster, and increased the body weight. The diet with alive larvae of Drosophila melanogaster Meigen (Diptera: Drosophilidae) was proved to be an essential food as well as resulted in adults with higher body weight, and the number of eggs per cluster increased in comparison with the feeding with only eggs of A. kuehniella. / O controle biol?gico ? um importante m?todo para regular as populac?es de pragas em um sistema de produ??o agr?cola sustent?vel, pois ? uma alternativa promissora ao uso de agrot?xicos org?nicos sint?ticos que causam grandes impactos ecotoxicol?gicos. As joaninhas predadoras fazem parte dos agentes de controle biol?gico de pragas agr?colas, podendo ser manejadas pelas tr?s estrat?gias de controle biol?gico: cl?ssico, conservativo e aumentativo. No presente trabalho, buscou-se gerar conhecimento para uso da joaninha predadora afid?faga Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) sob a perspectiva das duas ?ltimas estrat?gias. O controle biol?gico conservativo envolvendo insetos predadores baseia-se no fato de que, na aus?ncia ou escassez da presa preferencial ou na presen?a de outras presas de qualidade inferior, podem usar alimentos alternativos, tais como p?len, para garantir sua sobreviv?ncia e, por vezes, sua reprodu??o e, por isso, esp?cies bot?nicas provedoras desse recurso floral devem integrar a paisagem agr?cola, dentro e/ou no entorno da propriedade agr?cola; enquanto o controle aumentativo requer a multiplica??o do predador no laborat?rio, podendo se valer de presas naturais ou artificiais. Apesar de alguns autores comprovarem a visita??o das flores de algumas esp?cies de Apiaceae por C. maculata, n?o h? relatos na literatura da ingest?o de gr?os de p?len dessa fam?lia bot?nica por essa joaninha. Nesse contexto, este trabalho foi conduzido a fim de selecionar esp?cies de plantas cujas flores sejam fonte de p?len como alimento alternativo ou complementar para C. maculata na perspectiva de compor a vegeta??o dos agroecossistemas para contribuir na conserva??o dessa joaninha, e/ou auxiliar na cria??o massal da mesma em condi??es de laborat?rio. O objetivo do cap?tulo I foi comprovar a ingest?o de p?len de tr?s esp?cies da fam?lia Apiaceae [coentro (Coriandrum sativum L.), endro (Anethum graveolens L.) e erva-doce (Foeniculum vulgare Mill.)] a partir da oferta de suas flores para larvas de 4? instar e adultos de C. maculata. Constatou-se a presen?a de gr?os de p?len nas cinco repeti??es de todos os tratamentos, comprovando a ingest?o de p?len dessas tr?s Apiaceae a partir de suas flores por C. maculata. Em 24 horas de exposi??o, os adultos consumiram em m?dia mais p?len de endro em compara??o aos polens de coentro e erva-doce, enquanto que as larvas consumiram mais p?len de erva-doce. O objetivo do capitulo II foi determinar a adequabilidade de nove dietas para C. maculata, incluindo oferta de p?len de duas esp?cies de Apiaceae (coentro e endro), em condi??es controladas de laborat?rio. Apesar das dietas apenas com flores dessas duas Apiaceae n?o proporcionarem o desenvolvimento completo de C. maculata, elas usadas com complementa??o da alimenta??o com ovos de Anagasta kuehniella Zeller (Lepidoptera: Pyralidae) possibilitam a redu??o do per?odo larval, aumento no n?mero de ovos por postura e aumento do peso corp?reo. A dieta com larvas vivas de Drosophila melanogaster Meigen (Diptera: Drosophilidae) n?o foi s? comprovada como alimento essencial como tamb?m resultou em adultos de maior peso corp?reo e um aumento no n?mero de ovos por postura em compara??o ? alimenta??o apenas com ovos de A. kuehniella.