Developmental Time, Longevity, and Lifetime Fertility of Three Introduced Parasitoids of the Mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae)

Developmental time, longevity, and lifetime fertility of three previously introduced parasitoids (Acerophagus papayae Noyes and Schauff, Anagyrus loecki Noyes and Menezes, and Pseudleptomastix mexicana Noyes and Schauff) (Hymenoptera: Encyrtidae) of the mealybug Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae) were studied in the laboratory to understand the outcome of their recovery in field studies conducted in the United States. The developmental time of both male and female A. papayae and A. loecki was shorter than the developmental time of male and female P. mexicana. Male parasitoids of all three species had a shorter developmental time than their females. All parasitoids had a shorter developmental time in adult-female mealybugs than in second instars. Mating status (unmated and mated) had no effect on the male longevity. Unmated and mated females that were not allowed to oviposit had similar longevity and lived longer than those that were allowed to oviposit. Virgin females produced male only progeny with higher number of males from A. loecki or P. mexicana than from A. papayae. The number of females and the cumulative progeny was smaller for A. papayae than for A. loecki or P. mexicana. The progeny sex ratio (proportion of females) was not different among the parasitoids. A. papayae had the shortest reproductive period followed by A. loecki and P. mexicana, respectively. This information is important in evaluating the efficiency, recovery and establishment of A. papayae, A. loecki, and P. mexicana

Host Instar Susceptibility and Selection and Interspecific Competition of Three Introduced Parasitoids of the Mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae)

Three previously introduced parasitoids (Acerophagus papayae Noyes and Schauff, Anagyrus loecki Noyes and Menezes, and Pseudleptomastix mexicana Noyes and Schauff [Hymenoptera: Encyrtidae]) of the mealybug Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae) were studied for their host instar susceptibility and sex ratio, host instar selection, and interspecific competition in the laboratory. All three parasitoids were able to develop in the second instars, third-instar females, and adult females of P. marginatus. No progeny emerged from first-instar mealybugs. The proportion of female emergence was increased with increasing host size. Parasitoids selected their host instars for oviposition when they had a choice. Between second- and third-instar hosts, A. papayae and P. mexicana had significantly higher parasitism in second-instar mealybugs, whereas A. loecki had higher parasitism in the third-instar mealybugs. When competed with either one or two parasitoid species, A. papayae was significantly more successful in second-instar hosts and A. loecki was significantly more successful in third-instar mealybugs. P. mexicana was significantly less competitive when with A. papayae in both second and third instars, with A. loecki in third instars and with both A. papayae and A. loecki in second and third instars. Overall, A. papayae provided a better control of the host, when present singly or with the other two parasitoids. This information is important in evaluating the efficiency of A. papayae, A. loecki, and P. mexicana and understanding the outcome of their recovery and establishment in field studies conducted in Florida

Life History of Paracoccus marginatus (Hemiptera: Pseudococcidae) on Four Host Plant Species Under Laboratory Conditions

Life history of the mealybug, Paracoccus marginatus Williams and Granara de Willink, on three ornamental plants [Hibiscus rosa-sinensis L., Acalypha wilkesiana (Muell.-Arg.), and Plumeria rubra L.] and one weed species (Parthenium hysterophorus L.) was studied under laboratory conditions. Mealybugs were able to develop, survive, and reproduce on all four hosts; however, there were differences in the life history parameters. Adult females that developed on acalypha and parthenium emerged ≈1 d earlier than those that developed on hibiscus and plumeria. Adult males had a longer developmental time on plumeria than on the other hosts. Survival of first- and second-instar nymphs and cumulative adult survival were lowest on plumeria. Longevity was not affected by hosts for males and females and averaged 2.3 ± 0.1 and 21.2 ± 0.1 d, respectively. On plumeria, 58.9 ± 1.7% of the adults were females, which was a higher female percentage than on the other hosts. No egg production occurred in virgin females. Prereproductive and reproductive periods of the females were not affected by hosts and averaged 6.3 ± 0.1 and 11.2 ± 0.1 d, respectively. Mean fecundity of 186.3 ± 1.8 eggs on plumeria was lower than on the other three plant species. Life history parameters of P. marginatus on hibiscus, acalypha, plumeria, and parthenium show its ability to develop, survive, and reproduce on a wide variety of plant species

The study of DNA dynamics on glassy carbon electrode surfaces

Master of ScienceDepartment of ChemistryDaniel A. HigginsThe potential-dependent reorientation dynamics of double stranded DNA (ds-DNA) covalently attached to planar glassy carbon electrode (GCE) surfaces were studied in this thesis. The orientation of ds-DNA was investigated via the distance-dependent quenching of fluorescence from a 6–carboxyfluorescein (FAM6) flurophore to the electrode surface. The fluorophore was covalently bound to the distal end of the DNA. Fluorescence microscopy was employed for optical detection of FAM6 fluorescence and hence the DNA dynamics. The variation of the fluorescence from the dye with electrode potential is attributed to distance-dependent dipole-electrode energy transfer. Application of positive potentials (i.e., +0.2 V vs. open circuit potential, OCP) to the GCE caused the ds-DNA to align approximately parallel to the surface, yielding strong FAM6-electrode energy transfer and low fluorescence intensity. With the switching of the potential towards negative values (i.e., -0.4 V vs. OCP) the ds-DNA realigned perpendicular to the GCE surface leading to a reduction in energy transfer and high fluorescence intensity. Initial DNA reorientation upon a change in electrode potential is very fast. These fast dynamics have been observed and characterized in a number of previous publications. We have observed subsequent slow dynamics that we attribute to slow orientational relaxation of the DNA. Our observations were first reported by Q. Li, et al., J. Am. Chem. Soc. 2012, 134, 14467. In this thesis, this prior work is extended to verify the reproducibility of these new dynamics and to eliminate the possibility of certain artifacts as their source. Specifically, the experiments are repeated using a new cell design and a different buffer. In the primary experiments performed in this thesis, the dependence of the DNA reorientation dynamics on surface coverage was investigated by observing the fluorescence modulation as a function of probe concentration in the functionalization bath. Concentrations of 0.25, 1.0 and 1.5 µM 35-mer ds-DNA were employed. Electrodes functionalized at these concentrations have ds-DNA surface coverages of 1.18 x 10[superscript]12, 3.24 x 10[superscript]12 and 4.26 x 10[superscript]12 cm[superscript]-2, respectively. With increasing concentration of the DNA probe, the reorientation time constant at positive applied bias (vs. OCP) increased, indicting reorientation was slowed. In contrast, the time constant decreased with the negative applied bias (vs. OCP) indicating faster orientational relaxation. The possible origins for the observed trends in the reorientation time constant are discussed

Enhancing Employability of Management Graduates of State Universities in Sri Lanka: An Examination of Job Market Requirements

Higher education helps in enhancing the human resources required for development. Universities and higher education institutes play a vital role in disseminating and creating knowledge through teaching and research, contributing to the development of any country. The quality and relevance of the output (graduates) of higher education institutes need to be enhanced to increase graduates’ employability. Graduate unemployment has become a significant problem in Sri Lanka. If graduates are unemployed, this will directly and negatively influence economic development. The main objectives of this study are to identify job market requirements of the industry and factors affecting the success of the graduates’ interviews. This study used qualitative research methods as a mono method.  Data were collected using advertisements from two selected leading English and Sinhala weekend newspapers published from October 2019 to January 2020, and in-depth interviews were conducted with selected Human Resource managers. Newspaper analysis and job market requirement analysis were done using an inductive thematic analysis approach. Five core skills were identified as the job market requirements, namely, problem-solving skills, communication skills, numeracy skills, computer skills, and interpersonal skills. Leadership qualities, communication and presentation ability, teamwork, interpersonal relations, practical knowledge, positive attitudes, hardworking characteristics, well-preparedness at the interview, and a clear understanding of the graduate's career path mainly affect the graduate interview's success. The study proposes policy measures to improve the employability of management graduates of state universities in Sri Lanka.  Keywords: Employability, Management Graduates, State Universities, job market requirements, Sri Lank

The relative importance of olfactory signaling to fly-moss spore dispersal network structure of two sympatric moss species in Newfoundland, Canada

In Newfoundland, Splachnum ampullaceum (herbivore dung scent mimic) and S. pensylvanicum (omnivore dung scent mimic) grow in bogs on summer moose (Alces alces L.) dung and via olfactory and visual deception have their spores dispersed to dung by flies. In Chapter 2, the addition of carnivore and herbivore-mimicking scent increased the number of visiting flies, and the addition of carnivore scent attracted carrion flies, and this effect was greatest for S. pensylvanicum. In Chapter three consecutive years of fly trapping data for both species of moss were compared using Network analyses. Results showed that both mosses attract a generalized fly fauna (lower network specialization (H₂average) 0.171), most of which are also associated with summer moose dung (average connectance low 0.799). Also, the fly faunas of S. ampullaceum and S. pensylvanicum did not differ from each other in all three years

Species Composition and Visiting Frequencies of Flower Visitors of Chromolaena odorata

Plant-animal interaction has been a major theme in ecology as it has helped ecologists to rule out different patterns they observed in the surrounding environments. Chromolaena odorata is another plant species that is studied extensively as it has become a major troublesome weed in many parts of the tropics. But, handful of studies are available on pollination of this invasive plant species in dry forests and its function as a pollinator sink in these environments. The current study was carried out in a dry zone secondary forest patch in North-Central Sri Lanka to assess the diversity, abundance, and pollination strength of flower visitors associated with the C. odorata. The results suggest that the diversity of Hymenoptera and Lepidoptera is higher than the other insect orders that visited C. odorata, but all species exerted equal pollination strength on the plant. The attraction of large numbers of insects is concluded to as one of the factors that contribute to the reproductive success of C. odorata in dry zone forests

Study on Involvement in Aesthetic Activities and Academic Performance of Undergraduates The Case of the Faculty of Management Studies and Commerce of University of Sri Jayewardenepura in Sri Lanka

Enhancing knowledge seems to be a partial objective in any education process inthe contemporary society. The ultimate goal of the education should be the creation of agood citizen. It is widely believed perception that the involvement in aesthetic activitiesin the learning process helps to enhance various talents of students and nurture positiveattitudes. Several researches confirmed that there is a positive relationship betweeninvolving in Aesthetic activities and academic performance of students in educationalinstitutions.This study examines the relationship between involvement in Aestheticactivities and academic performance of the undergraduates of the Faculty ofManagement Studies and Commerce of the University of Sri Jayewardenepura in SriLanka. The study was done through a self-administrated structured questionnaire of asample of 200 undergraduates (around 5% of the total population) for the year 2010.Thesample consists of first, second, third and fourth year undergraduates, representing bothstudents who engaged in aesthetic activities and who did not.Correlation analysis wasdone to examine the relationship between academic performance and the involvementof Aesthetic activities of the undergraduates of the Faculty. It was found that there is aninsignificant weak positive relationship between the involvement in aesthetic activitiesand the accumulated Grade Point Average of the undergraduates. To identify reasonsfor this phenomenon, ten in-depth interviews were undertaken with students who havehigher academic performance at the end semester examinations conducted by theFaculty. The qualitative analysis revealed several interrelated factors in this regard.Some major reasons are; heavy work load of the students (five subjects with manyassignments within a very limited time period per semester), students‟ involvement inprofessional examinations and training programs (due to the competition of the job market), the involvement in any job due to their financial difficulties, a strongdetermination to obtain a (first) class etc. Due to these reasons, many undergraduates ofthe Faculty have given their least priority to aesthetic activities during their educationalprocess.This situation leads to produce graduates with lack of essential qualities such ascreativity and sensitivity which violate the ultimate goal of education- that is “creatinggood citizens”. Finally, policy measures are suggested to overcome this situation.Keywords: Aesthetic Activities, Academic performance, Management, Undergraduate

Developmental Time, Longevity, and Lifetime Fertility of Three Introduced Parasitoids of the Mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae)

Developmental time, longevity, and lifetime fertility of three previously introduced parasitoids (Acerophagus papayae Noyes and Schauff, Anagyrus loecki Noyes and Menezes, and Pseudleptomastix mexicana Noyes and Schauff) (Hymenoptera: Encyrtidae) of the mealybug Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae) were studied in the laboratory to understand the outcome of their recovery in field studies conducted in the United States. The developmental time of both male and female A. papayae and A. loecki was shorter than the developmental time of male and female P. mexicana. Male parasitoids of all three species had a shorter developmental time than their females. All parasitoids had a shorter developmental time in adult-female mealybugs than in second instars. Mating status (unmated and mated) had no effect on the male longevity. Unmated and mated females that were not allowed to oviposit had similar longevity and lived longer than those that were allowed to oviposit. Virgin females produced male only progeny with higher number of males from A. loecki or P. mexicana than from A. papayae. The number of females and the cumulative progeny was smaller for A. papayae than for A. loecki or P. mexicana. The progeny sex ratio (proportion of females) was not different among the parasitoids. A. papayae had the shortest reproductive period followed by A. loecki and P. mexicana, respectively. This information is important in evaluating the efficiency, recovery and establishment of A. papayae, A. loecki, and P. mexicana.Keywords: biological control, mealybug, parasitoids, parasitis

Using plant volatile traps to develop phenology models for natural enemies: An example using Chrysopa nigricornis (Burmeister) (Neuroptera: Chrysopidae)

A model predicting phenology of adult Chrysopa nigricornis (Burmeister) (Neuroptera: Chrysopidae) in orchards was developed from field (trapping) data supplemented with development data collected under laboratory conditions. Lower and upper thresholds of 10.1°C and 29.9°C, respectively, were estimated from published and unpublished laboratory observations, and were used to develop a phenology model. Season-long field data were collected using white delta traps that had been baited with squalene, a volatile shown previously to be highly attractive to C. nigricornis. The model was developed from data collected in three Washington apple orchards, and was validated using independent data sets collected from apple, sweet cherry, pear, and walnut orchards over a 2–4year period across a much wider geographic region. We found that the mean absolute deviation across all crops and years was 39.7±1.2day-degrees (DD), or 4.4±0.14days. Populations of C. nigricornis from walnut orchards in California emerged 105DD later than those in Oregon and Washington, thus requiring correction of average time of first trap catch in California to synchronize models. The ability to use a single model across multiple crops, different prey species and abundances, and different pesticide regimes demonstrates that phenology models for generalist predators may have broader application to IPM programs in other cropping systems