The processes influencing larval fish survival in the low-latitude open ocean are poorly understood, especially with regard to feeding. As part of a large-scale study that included two years of monthly sampling in the Straits of Florida (SOF), the objectives of this dissertation were to elucidate the larval fish feeding behaviors and strategies of 1) istiophorid billfishes, 2) tunas, and 3) coral reef fishes, while also 4) characterizing the feeding environment, synthesizing the dominant trophic pathways to fish larvae, and reviewing the literature for evidence of latitudinal distinctions in larval fish trophodynamics. Larval billfishes exhibited highly selective feeding, and their diets were numerically dominated (90%) by two genera of crustaceans, Farranula copepods and Evadne cladocerans. These prey were consumed throughout early larval ontogeny, from first-feeding through piscivorous lengths (> 5 mm), until piscivory became exclusive near 12 mm. High feeding incidence (0.94) and rapid digestion (~3.5 hrs) suggests frequent and successful feeding by billfish larvae. For tunas, nearly all larvae examined (>98%) contained prey. Thunnus spp. exhibited a mixed diet, while skipjack, little tunny, and Auxis spp. nearly exclusively consumed appendicularians. All four tuna taxa co-occurred in the western SOF where prey was more abundant, while in the central and eastern SOF (where prey availability was lower), only Thunnus spp. and skipjack were present. Additionally, these two taxa exhibited significantly different vertical distributions. Estimates of predatory impact indicated the potential for depletion of resources in the absence of the spatial and dietary niches of larval tunas. Coral reef fish families examined included Serranidae, Lutjanidae, Mullidae, Pomacentridae, Labridae, Scaridae, and Acanthuridae. Feeding incidences were high (0.94 to 1.0) for all taxa except scarids (0.04), and diets were narrow and predator-specific. Cluster analysis yielded clear groupings based on the selective feeding exhibited by the taxa, while within taxa, canonical correspondence analysis illustrated the change in diet with a variety of variables. The physical and biological environment varied markedly across the SOF, largely influenced by the Florida Current. Characteristics examined included thermocline depth, fluorescence, and abundances of total plankton and copepod nauplii. The feeding ecologies of the 21 taxa of fish larvae in this work were synthesized into qualitative and quantitative webs that illustrate the variable trophodynamic strategies of larvae in the SOF and the levels of community reliance upon zooplankton prey types. A review of 170 investigations on larval fish feeding revealed notable distinctions between high- and low-latitude regions, highlighting the substantial variability across environments in the role of larval fishes within the planktonic food web.

The diamondback moth (Plutella xylostella L.) is a major pest of crucifer crops worldwide. It is a particularly important problem in Southeast Asia where climatic conditions favor a short generation time and rapid proliferation. In countries such as Thailand, the diamondback moth has apparently become resistant to all classes of insecticides, even the newest ones. The first part of this thesis is the development of a computer database of all the available information on diamondback moth toxicology. About 1,550 records were extracted from more than 235 published or unpublished documents. These records include information on the geographical location of experiments, the insecticide evaluated, the testing method and the results observed. Most records in the database are from the last decade, and are predominantly from Taiwan, Thailand, the USA and Japan. Trends in the use of various classes of insecticides can easily be followed. Thirty three records have been found of insecticide resistance of more than a thousandfold. An the known mechanisms of resistance are found, and the diamondback moth has become resistant to all the classes of insecticides, including Bacillus thuringiensis but excluding abamectin. Case studies made possible by the use of the database showed a rapid succession in the use of 29 insecticides in the last 26 years in a single country (Thailand). Although this rapid succession is usually ascribed to the development of resistance, a case study on the regional differences in resistance to five insecticides showed marked variations in the level of resistance over distances of 20 miles or more. The possibility of managing insecticide resistance at the local level, already suggested by studies in Hawaii, is thus supported by this analysis. In the second part of this thesis, the toxicity of Bacillus thuringiensis var. aizawai and of the bacterial toxin abamectin was tested by two bioassay techniques on populations of the diamondback moth from two Chinese kale fields at locations in Thailand at which the highest levels of resistance to most insecticides have been reported. The leaf-dip bioassay was found to be superior to a residue-vial assay or to the FAO-recommended assay. More than 70-fold resistance to Bacillus thuringiensis var. aizawai was observed in the populations of DBM collected from these two fields, suporting the theory that resistance resulted in the control failures reported by growers. Resistance did not explain control failures with abamectin as no resistance to this compound could be detected. The third part of this thesis analyzes the intraplant distribution of the diamondback moth larvae in an effort to explain the control failures with abamectin on Chinese kale. Extensive sampling of the various larval instars of the diamondback moth revealed that a majority of second instar larvae were sheltered on the young folded leaves of Chinese kale. The majority of fourth instar larvae and pupae were found on mature (lower) leaves. Inefficient spraying practices observed in the field with high volume, low pressure hydraulic pump sprayers may allow the young larvae to escape pesticide exposure possibly explaining control failures in the absence of physiological resistance. This study shows that resistance in the diamondback moth is a worldwide problem of major proportions. The rapid development of resistance to Bacillus thuringiensis in the field is of practical concern. Resistance management programs in developing countries should include mechanisms to optimize insecticide delivery to the protected habitats of diamondback moth on Chinese kale. / Graduation date: 1992

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Predation is a strong dective force on invertebrate prey. Asellus aquaticus differs in pigmentation reed and submerged vegetation habitats in lakes. Light pigmented individuals al vegetation dominated by Chara sp. while dark pigmented individuals dominate in the reeds. These differences have been hypothesized to result from background matching. Predation pressure from fish is belived to be highest in Chara sp., while invertebrate predators are more common in the reeds. In this study I investigatedif predation from perch and damselfly larvae create different se1ection pressure on pigmentation and size of the Asellus, and if selection is affected by the structure of the habitat. The study vas carried out in aquaria in a loboratory. Regarding predation from perch a tendancy to be selective against dark pigmented individuals in Chara substrate was seen. Mortality increased with body size in Asellus, regardless of pigmentation. In the experiment mortality of Asellus decreased with body length. The results illdicate that it is not as important for Asellus to be cryptic in the reeds since it is not exposed to visual predation on the same level as in the Chara sp. where it is preferable to be small and cryptic. In the reed, large individuals are probably favorued since common predators, such as damselfly larvae, are size-limited in their prey choice.

Mercury (Hg) compounds are some of the most toxic compounds of any heavy metal on earth. Due to long-range transport from point sources Hg can be found world-wide in air, soil, water, and living organisms. Mercury compounds can cause a number of adverse effects, with the unborn fetus, infants, and children being most susceptible. Zebrafish (Danio rerio) are an excellent vertebrate model system for toxicological studies, including developmental effects. The overall objective of this research was to investigate the effects of inorganic forms of Hg in zebrafish larvae. Unique accumulation patterns were observed using synchrotron X-ray fluorescence imaging after zebrafish were exposed to one of four Hg compounds (i.e. mercuric chloride, mercury bis-L-cysteineate, methylmercury chloride, methylmercury L-cysteineate). Specifically, we noted chemical form dependant and tissue-specific Hg accumulation including the sensory cells of the olfactory epithelia and the neuromasts. Phenylthiourea (PTU) is commonly used to block zebrafish melanogenesis to generate transparent larvae to aid with enhanced visualization of immunohistochemical and vital stains. It was determined that PTU dramatically alters Hg toxicity through chemical interaction with Hg so that further studies were conducted in the absence of PTU. To investigate the effects of Hg on primary neurons, the immunohistochemistry protocol using anti-acetylated tubulin was performed and the results demonstrated that mercuric chloride damages primary neurons particularly in the olfactory pits. To study potential detoxification of Hg in zebrafish we examined the efficacy of two sequestration agents, dimercaptosuccinic acid and alpha lipoic acid, as well as endogenous selenium. The levels of Hg were not significantly lower following treatment with either sequestration agent under the conditions used in this research. Previous work examining the antagonistic relationship between Hg and selenium has been conducted by dosing animals with both Hg and selenium (Se). We discovered a mixed chalcogenide of the general form HgSxSe(1-x) forming in vivo following exposure to mercuric chloride without the addition of selenium. Indeed the selenium may have been remobilized from natural stores in the pigment spots. The research presented herein demonstrates that the target tissues for Hg depend strongly on chemical form. In particular inorganic Hg can accumulate in a number of important tissues including sensory systems. The formation of insoluble and non-toxic HgSxSe(1-x) in zebrafish larvae suggests that endogenous selenium may play critical roles in modulating toxicity.

The effects of the toxic dinoflagellate, karenia brevis (Wilson clone), on larval survival and development of the northern quahog (=hard clam, Mercenaria mercenaria), eastern oyster (Crassostrea virginica) and bay scallop (Argopecten irradians) were studied in the laboratory. The effects of K. brevis on feeding activities of juveniles from these species plus the green mussel (Perna viridis) were also examined. Finally, adult bay scallops were exposed to K. brevis for two weeks to investigate possible cytotoxic effects. Survival of 3-day-old larvae was generally > 85% for all shellfish species at Karenia brevis densities of 100 cells . ml-1 or less, and not significantly different between whole and lysed culture. At 1,000 cells . ml-1, survival was significantly less in lysed culture than whole culture for both M. mercenaria and C. virginica. Survival of 7-day-old larvae in all species was not significantly affected at densities up to 1,000 cells . ml-1. At 5,000 cells . ml-1, however, survival was reduced to 37, 26 and 19% for A. irradians, M. mercenaria and C. virginica, respectively. Development of C. virginica and M. mercenaria larvae was protracted at K. brevis densities of 1,000 cells . ml-1. Clearance rates of juveniles were determined under static and flow-through conditions using whole and lysed cultures of K. brevis. The bay scallop was most sensitive, exhibiting a 79% reduction in clearance rate at 1,000 cells . ml-1 of whole culture. The eastern oyster was least responsive, showing a 38% reduction in clearance rate between the same treatments. The green mussel and the northern quahog displayed intermediate responses. Similar results were observed during longer (2 day) exposures to a continuous supply of K. brevis. Bay scallops showed a significant decline in clearance rate at 100 cells . ml-1 after 24 hr exposure; clearance rate of oysters was not affected by K. brevis at this concentration. No mortality was observed for any species during these brief exposures. Adult bay scallops exposed to K. brevis for two weeks showed degenerative and inflammatory changes in the digestive gland, including reduced thickness of the epithelium, increased size of digestive tubule lumens and hemocytic infiltration. The prospect for recovery of bay scallop populations in Florida may be hampered by recurring blooms of K. brevis.

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Efficient disposal methods are needed to manage manure produced by industrial animal production. Saprophagous fly larvae could potentially convert manure into fertilizer and produce protein; however, the process is not well studied. Musca domestica, Hydrotaea aenescens, and Coproica hirtula were investigated to determine the most suitable species and conditions that facilitate efficient poultry manure conversion. The objectives were to (1) develop laboratory protocols and timelines for fly production; (2) identify environmental conditions that affect conversion; and (3) determine the ideal manure moisture content, depth, and fly egg-to-manure ratio for manure conversion and protein production. Mass-production was possible for every species and timelines were established for all species except C. hirtula. The most promising species for use in a conversion system was M. domestica and the presence of C. hirtula facilitated complete conversion. When using these species simultaneously the ideal initial conditions were: 77.5% moisture, 2.9cm deep and 0.82g eggs/kg manure. / OMAFRA/ University of Guelph partnership

Magistratūros studijų baigiamajame darbe pateikiama 2012 metais Aleksandro Stulginskio universiteto Agronomijos fakulteto Biologijos ir augalų biotechnologijos instituto Augalų apsaugos metodų laboratorijoje tirti veiksniai, kaip skirtingi spragšių (Elateridae) lervų kiekiai įtakoja žemės ūkio augalų vystymąsi. Darbo objektas - Agriotes sp., Selatosomus sp. ir Cidnopus sp. lervos. Darbo metodai: buvo vykdomi 3 bandymai norint išsiaiškinti spragšių lervų daromą žalą įvairiems žemės ūkio augalams. Pirmojo bandymo metu buvo stebima kaip Agriotes sp., Selatosomus sp. ir Cidnopus sp. skirtingi 2, 4 ir 6 lervų kiekiai įtakos kukurūzų, kviečių ir miežių vystymosi procesus. Antrojo bandymo metu buvo stebima kaip 3, 5 ir 7 Agriotes sp. lervos paveiks morkas, runkelius ir rapsus. Trečiojo bandymo metu stebėta kaip skirtingi 3, 5, ir 7 lervų kiekiai paveiks morkų, runkelių ir rapsų vystymąsi. Visuose bandymuose kontroliniame variante lervų naudota nebuvo. Eksperimentai buvo vykdomi trimis pakartojimais, pažeidimai augaluose stebėti 5 kartus, kas 5 dienas. Duomenys statistiškai įvertinti naudojant programą ANOVA iš paketo SELEKCIJA. Darbo rezultatai: 2012 m. Aleksandro Stulginskio universiteto Agronomijos fakulteto Augalų apsaugos laboratorijoje atlikus stebėjimus, kaip spragšių lervos įtakoja augalų vystymąsi gauti rezultatai parodė, kad didžiausias esminis kukurūzų pažeidimų skaičius lyginat su kontrolinių variantu buvo Selatosomus sp. 6 lervų variante. Pažeistų augalų buvo rasta... [toliau žr. visą tekstą] / Master's thesis submitted in 2012, Alexander Stulginskio University, Faculty of Agronomy in the laboratory to investigate factors such as different gaps (Elateridae) larvae affect the amounts of crop development. The object of the work - Agriotes sp. Selatosomus sp. and Cidnopus sp. larvae. Methods of the work - was carried out three tests for identifying gaps larval damage to various crops. The first test was observed as Agriotes sp. Selatosomus sp. and Cidnopus sp. Different 2, 4 and 6 of the larvae of the influence of corn, wheat and barley development processes. Second test was observed as 3, 5 and 7 Agriotes sp. larvae affect carrots, beet and oilseed rape. The third test was seen as different 3, 5, and 7 larvae affect the amounts of carrot, beet and oilseed rape development. All of the tests in the control larvae were used. Experiments were carried out in three replications, damage plants monitored 5 times every 5 days. Statistically evaluated using ANOVA program from the package SELEKCIJA. The results: 2012. Aleksandras Stulginskis University, Faculty of Agronomy Plant protection laboratory observations carried out as a gap in the larval development of the plant influences the results obtained showed that the highest corn substantial number of violations compared to the control variant was Selatosomus sp. 6 larvae version. Infected plants were found as much as 46 percent. Abundantly as much as 50 percent. damaged wheat was 6 Selatosomus sp. larvae version. Most barley... [to full text]