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Aspects of the biology and control of old man's beard (Clematis vitalba) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Palmerston North, New Zealand
(Massey University, 2023) Jarvis-Lowry, Brenda
Old man’s beard (Clematis vitalba) is an increasingly problematic liana in New Zealand, but the factors that contribute to its invasiveness are not fully understood. The work in this thesis investigated elements of old man’s beard seed biology and ecology, seedling establishment, and vegetative reproduction that were unclear or unknown. The findings point to a reproductive diversification strategy that contributes to old man’s beard’s success as an invasive plant, due in part to dual dispersal mechanisms (by wind and water), dual seed banks (aerial and soil), dual seed dormancies (physiological and morphological), and dual reproductive modes (seeds and vegetative spread). Summary of findings regarding the biology • The aerial seed bank is transient: half of all achenes tagged and monitored were dispersed via anemochory during complete dormancy in autumn, and all but 5% of the remainder were gone by early spring. • The likelihood of secondary water dispersal is high, as seeds tolerated up to 6 weeks of immersion, germinated readily in water, and produced seedlings that remained robust, if removed from water within the 6-week period. • Pre-chilling was found to be unnecessary for germination, even for seeds that had not undergone a full winter of after-ripening: although it increased the speed at which seeds incubated at constant temperatures germinated, it did not promote total germination as successfully as a fluctuating temperature regime without pre-chilling. • Seeds collected off the vine and tested for germination over a 2-year period were fully physiologically dormant until completely senesced. Thereafter, dormancy declined during winter, and seeds were largely non-dormant by early spring. However, morphological dormancy did not change until seeds were exposed for several days to suitable germination conditions. Fewer than 72% of seeds were ultimately viable. • The soil seed bank was confirmed to be relatively small but persists at least for two years. Seeds in the soil experience the same cyclic physiological dormancy changes as those in the aerial seed bank, though can also enter a secondary dormancy when appropriate germination conditions are not met. • Seedlings were not able to survive competition exerted by established perennial grass cover unless the cover was very sparse. However, seedlings that survived began producing multiple, elongating stems within six months of emergence. • Vegetative growth produces an extensive network of creeping stems on the ground. Also, two-node woody stem fragments from both creeping and climbing stems are capable of rooting and growing vigorously as individual, clonal plants. Current management of old man’s beard infestations necessarily involves chemical control. The efficacy of two types of herbicide control was also assessed. As a precision technique for climbing vines that avoids non-target damage, the basal bark method with triclopyr in oil provides highly effective chemical control of individual stems, with >95% mortality. The cut stem method, using a 45% glyphosate gel formulation was less effective (55% mortality). For creeping stems, triclopyr alone and a triclopyr/picloram/aminopyralid mixture were effective herbicide sprays that preserved grass cover. Favouring a dense grass cover can help suppress subsequent establishment of old man’s beard by seed. Management should also consider that waterways are potential conduits of propagule spread, and that mechanical fragmentation of stems serves to produce more individuals, due to regeneration.
Developing a risk prediction model for the seasonality of Lucilia spp. in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand
(Massey University, 2023) Brett, Paul Thomas James
Flystrike of sheep in New Zealand is principally caused by Lucilia cuprina and Lucilia sericata. A series of studies were conducted to develop models to describe and predict the seasonal occurrence of these Lucilia spp. in New Zealand. Dipterans were collected on a weekly basis on eight farms across New Zealand over three fly seasons (2018/2019, 2019/2020, 2020/2021) using the LuciTrap® with a Stickytrap attachment (Lucilia spp. n = 10,559). Covid 19 travel restrictions restricted the collection of samples during the 2019/2020 and 2020/2021 seasons. Dipterans were initially identified using morphological characteristics, with further validation using the nuclear 28s rRNA and the mitochondrial ND4 gene. The morphological identification had an accuracy of 71 % for L. cuprina and 55 % for L. sericata, compared to the molecular method (p < 0.05). Consequently, the counts of both species were combined for modelling purposes. The seasonality of Lucilia spp. adult flies span from early October until late May with variability of weeks duration between farms and three weeks between seasons for individual farms. A hurdle model was used to describe the occurrence of Lucilia spp. from the 2018/2019 season (p < 0.05). Significant variables include soil temperature, rainfall, maximum temperature and photoperiod with lag times of one to seven weeks. A second model used the 2018/2019 seasonal data to predict the start of the 2019/2020 season using a mixed-effects logistic regression model using weather data from the closest Virtual Climate Station. 10 cm soil temperature and Soil Moisture Deficit Index predicted the start of the season within two weeks of the observed season (p < 0.05). Four trap and bait combinations were compared to help choose a supplementary on-farm technique to confirm model predictions. A negative binomial model fitted for Lucilia spp. catch data found no difference between LuciTrap® combined with LuciLures and the Western Australian Trap combined with sheep liver preserved in 30 % sodium sulphide (p > 0.05). While the other two trap and bait combinations were significantly worse for catching Lucilia spp. (p < 0.05). These models should provide information to allow farmers to make more informed decisions for flystrike control.
Unravelling the molecular basis of subcuticular host-colonization by the apple scab fungus, Venturia inaequalis : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy (PhD) in Plant Science, School of Agriculture and Environment, Massey University
(Massey University, 2023) Rocafort Ferrer, Mercedes
Scab, caused by the fungal pathogen V. inaequalis (Vi), is the most economically important apple disease. During infection, Vi occupies the subcuticular environment, where it develops specialized infection structures, called stromata and runner hyphae. These structures are thought to be important for fungal nutrition and the delivery of proteins, with many of these anticipated to function as virulence factors (effectors) in promoting host infection or avirulence factors (Avr effectors) in triggering host resistance. To date, nothing is known about how these structures are differentiated and protected from recognition by the host immune system. Likewise, little is known about the identity and function of Vi effector proteins. To better control scab, a greater understanding of the molecular mechanisms underpinning infection structure differentiation and protection, as well as Vi virulence and avirulence, is first needed. In Chapter 2, a comprehensive review of apoplastic effector proteins from plant-associated fungi (and oomycetes) was provided. Given that Vi is an extracellular pathogen, this review provided insights into the potential types of effector proteins secreted by Vi into the subcuticular environment. Then, in Chapter 3, a multidisciplinary approach based on bioinformatics, transcriptomics, and structural biology was used to identify and characterize Vi effector candidates (ECs). This revealed that ECs were predominantly expressed in two temporal waves, and that many belonged to expanded protein families with predicted structural similarity to virulence and avirulence effectors from other plant-pathogenic fungi. This analysis helped to generate a list of ECs for further study and contributed to a better understanding of effector biology and evolution. Next, in Chapter 4, a multidisciplinary approach based on transcriptomics, proteomics, glycomics, and confocal microscopy was used to study Vi cell wall carbohydrate composition during the differentiation of infection structures. This iii revealed that Vi down-regulates genes putatively associated with the biosynthesis of immunogenic carbohydrates, and deacetylates surface-exposed chitin to the less immunogenic carbohydrate, chitosan. Finally, in Chapter 5, CRISPR-Cas9 technology was applied to Vi for the first time, which will enable genes identified in this study to be functionally characterized. Altogether, this thesis has furthered our understanding of the Vi –apple pathosystem and has provided novel data that can be used to inform the development of new scab control strategies against Vi.
Minimising non-target impacts of anticoagulant rodenticide use for a highly susceptible species, the New Zealand lesser short-tailed bat (Mystacina tuberculata) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Manawatū, New Zealand
(Massey University, 2019) Dennis, Gillian Clare
Anticoagulant rodenticides may cause mortality in non-target wildlife. In New Zealand, broad-scale anticoagulant use is essential for wildlife conservation, but also poses risks to threatened species. In 2009, >100 endemic lesser short-tailed bats (Mystacina tuberculata) died during a rodent control operation. In this thesis I confirm that these bats were intoxicated with the first-generation anticoagulant rodenticide diphacinone, and present several lines of research investigating the route of exposure, the effectiveness of management changes at minimising exposure and mortalities and the potential consequences of such non-target impacts on bat population viability. I used infra-red video cameras at non-toxic baits in wild and captive settings to determine that the route of exposure of the bats to diphacinone was most likely through ingestion of contaminated arthropods. In a field trial, analysis of communal guano deposits revealed that an alternative baiting method reduced but did not prevent exposure of bats to diphacinone. However, this exposure was subclinical, as prolongation of mean blood prothrombin time was not evident. Furthermore, mark-recapture analysis of passive integrated transponder (PIT) tagged bats indicated zero to negligible effect of exposure on population survival. Despite this result, sublethal exposure to anticoagulants is of concern because of the unknown effects on bat fitness and reproduction. An abundance estimate using closed-population mark-recapture analysis revealed that the study population was small (c.780 adults) relative to other lesser short-tailed bat populations, and thus particularly vulnerable to reductions. I developed a model describing the population dynamics of the bats to explore the potential effects of chronic reduction of survival and productivity on population viability. While model projections highlighted the need to suppress rodents in bat habitat, they also demonstrated that small annual reductions in survival could threaten population persistence. This study has contributed to bat conservation management in New Zealand and highlights the delicate balance that needs to be achieved between managing invasive vertebrates and protecting native species that are highly susceptible to vertebrate pesticides. Investigating the effects of sublethal exposure of bats to anticoagulant rodenticides should be a conservation priority as there are global implications for health and viability of other insectivorous bat species.
The ability of detainment bunds to mitigate the impact of pastoral agriculture on surface water quality in the Lake Rotorua catchment : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Palmerston North, New Zealand
(Massey University, 2020) Levine, Brian
Identifying and implementing cost-effective mitigation strategies are necessary to achieve reductions in the anthropogenic phosphorus (P) and nitrogen (N) loads that contribute to eutrophication and toxic algal blooms in Lake Rotorua, in the Bay of Plenty Region on the North Island of New Zealand. Storm generated surface runoff from grazed pastures, that cover ~48% of Lake Rotorua’s catchment, contribute 67% of the total N (TN) and 43% of the total P (TP) loads delivered from the catchment to the lake. Detainment bunds (DBs) are a novel mitigation strategy targeted at decreasing nutrient and sediment losses by impeding and temporarily ponding stormflows for up to 3 days. A DB is an earthen, stormwater retention structure, approximately 1.5-2 m high and 20-80 m long, constructed on pastures across the flow path of targeted low-order ephemeral streams. Two DBs on pastures in the Lake Rotorua catchment, with 20 and 55 ha catchments, were monitored over 12 months. Nearly 20 storm events resulted in ponding at each site. Detailed hydrological analyses were conducted for each storm in order to establish water balances, as well as to analyse contaminate loads delivered to, and discharged from the DBs. Surface runoff flows were measured, and samples were collected, to determine the DB mitigation performance and to identify the processes affecting the outcomes. The DBs prevented an estimated 51-59% of the annual suspended sediment loads, 47-68% of the annual TP loads, and 57-72% of the annual TN loads delivered to the DBs in runoff, from reaching the lake. An estimated 43-63% of the annual surface runoff delivered to the DBs infiltrated the soil, as a result of increased residence times of surface runoff on well-drained pasture soils. Soil infiltration was mainly responsible for decreased contaminant loads delivered to surface waters downstream of the bunds, while sorption and sedimentation also contributed to some load reductions. The inability to impound only portions of the runoff generated during rare, high magnitude storm events limited the performance of DBs. Furthermore, declining soil infiltration rates and increasing soil P concentrations in the ponding areas could affect the longer-term performance of DBs. A cost: benefit analysis of the DB strategy was conducted in order to compare the cost-effectiveness of DBs to other nutrient migration strategies, with results demonstrating that the DB strategy is a highly cost-effective edge of field mitigation option available to pastoral farmers in the Lake Rotorua catchment.
Landscape genetics for conservation management : brushtail possums (Trichosurus vulpecula) in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, New Zealand
(Massey University, 2019) Pattabiraman, Nimeshika
The negative impact of brushtail possums (Trichosurus vulpecula) on New Zealand ecosystems became apparent soon after their introduction from Australia in 1858. Possums not only denude native vegetation but prey on native birds and invertebrates. They also carry bovine tuberculosis (TB) impacting the dairy industry and consequently the New Zealand economy. New Zealand possum populations have spread from several introduction sites and densities have increased. The resulting complex patterns of gene flow influences regional diversity, and potentially the effectiveness of control measures. Currently, ~100 million dollars are spent on 1080 management per year, mostly in response to Tb risk, but there is little information about the migration rates associated with resulting population density fluctuations. To determine whether the potential for intermixing between populations since their introductions could have caused a homogenizing effect on the genetic diversity across New Zealand, I began a detailed population genetic analysis by genotyping possums from 19 locations using nuclear microsatellites and mitochondrial DNA haplotyping from across the country to estimate population structure. Initial introductions of possums from multiple locations resulted in genetic and fur colour diversity but, in comparison to natural Australian populations, it appears that only a subset of genetic variants was brought to New Zealand from Australia. Mitochondrial sequence variation analyses showed overall high haplotype diversity with substantial differences among samples in haplotype frequencies, but with relatively low nucleotide diversity. Similarly, analysis of nuclear markers (microsatellite genotypes with Naïve Bayesian clustering) reveals that while there has been admixture between populations in various locations, indicated by shared genotypes, there are genetically distinct regional populations. Concordance of genetic and geographically distant sampling shows a well-developed population structure of possums across New Zealand. These results are also supported by pairwise Fst comparisons between all pairs of populations; although nearly all populations showed significant differences, there was no signature of isolation by distance as expected from their history of introductions. This study provides a foundation for further research into spatial structure of brushtail possums which will enable the effective targeting of management and is essential for modelling population recovery, disease spread, and potentially the emergence of toxin resistance. Predator-free 2050 is an ambitious objective considering current circumstances. In order to achieve its goals, even for the targeted species, we need to efficiently manage our resources and improve the accuracy of control measures to maintain long-term effects.
Insecticide resistance in diamondback moth (Plutella xylostella) (Lepidoptera: Plutellidae) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Plant Health at Massey University
(Massey University, 1992) Bell, Peter Daryl
Diamondback moth is a cosmopolitan species of considerable importance as a pest of cruciferous plants. It is capable of rapid growth in numbers and has a high potential for the development of insecticide resistance. By 1986 resistance had been confirmed to 23 insecticides in 16 countries. A susceptible population was identified from a forage brassica crop on a Massey University farm. Insects collected were used to establish a susceptible laboratory colony. Full dose mortality curves for a range of insecticides were constructed for this colony using leaf dip bioassays. The LD9 values were determined for each of the 7 insecticides tested and used as diagnostic doses to screen field populations for resistance. Field populations regularly exposed to insecticides were sampled at five locations in intensive market garden areas in the North Island. Larvae and pupae collected from these sites were reared to the Fl generation in the laboratory. Third instar larvae were then tested for resistance using leaf dip bioassays treated with the diagnostic doses. Some insecticide resistance was detected at each of the five sites. Insect survival for the site showing the highest resistance levels ranged from 82% to 16% when exposed to the diagnostic dose (LD9 for the susceptible population). Only one site showed resistance to all of the insecticides screened and there seemed to be no pattern to the cross resistance each site. All five sites had spectra encounted on different histories of pesticide usage. Two of the five sites were in close proximity but they were geographically isolated from the remaining 3 sites which were isolated from each other. High levels of parasitism by Diadegma semiclausum was evident in all of the field populations tested. The impact that this is having on the development of resistance is unknown but warrants further study. Even though resistant insects were found, their numbers were low and the crop loss too small to be of concern to the growers. However in the light of experience in South East Asia it would be prudent to formulate resistance management tactics for New Zealand conditions. I suggest that a number of reccomendations should be made to growers with respect to their diamondback moth control programmes. Pyrethroid use should be restricted to one application per brassica crop. The use of control action threasholds should be encouraged as should the use of less persistent insecticides such as dichlorvos and mevinphos. Urgent attention should be given to the development of an efficient grower operated monitoring programme. The feasibility of operating an integrated pest management programme should also be investigated.
The influence of cultural practices on soil organic matter, soil biomass size and nitrogen leaching : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science (Agricultural Environmental Science) at Massey University, New Zealand
(Massey University, 1994) Mapfumo, Phillimon
The effects of bare fallow, cultivation and nitrogen application on soil organic matter, soil biomass and nitrogen leaching were compared against the backgrounds of permanent grass pasture and grass/clover pasture. Cultivated plots were dug annually to a depth of 15cm. All plots received an annual dressing of 300kg ha·1 of Potassic Super. The Nitrogen treatment was applied as two equal applications of 100kg ha·1 Calcium Ammonium Nitrate in November and December each year. The results indicated that both bare fallowing and cultivation reduced soil organic matter and soil microbial biomass. The use of N-fertilizer did not promote either the soil organic matter or soil microbial biomass; this is contrary to the general finding. Legume nitrogen was found to leach as readily as the applied nitrogen and hence posed an environmental threat to groundwater quality. In all cultural practices the largest concentration of nitrate nitrogen (NO3-N) was observed at the 50 - 100m depth, below the root zone. Vertical movement of groundwater was estimated at lm year·1 This confirmed the concern of possible groundwater pollution by nitrate nitrogen from agricultural activities.
An evaluation of pest and disease control practices in field process tomatoes in Hawkes Bay and opportunities for improved pest management : a thesis in partial fulfilment of the requirement for the degree of Master of Horticultural Science at Massey University
(Massey University, 1992) Bland, Susanne
The spray practices of seven process tomatoes growers in the Hawkes Bay were evaluated during the 1990/1991 season by analysis of spray diaries, field surveys, and weather data. In very few instances were calendar spray systems, weather or insect thresholds used to determine spray scheduling. Use of monitoring and forecasting systems already available will help decrease the number of sprays applied providing adequate research is done to adapt them to local conditions. It is concluded that there is potential for pest management and integrated pest management systems to be introduced into the process tomato crops.
Host-finding behaviour of female apple leaf curling midge, Dasineura mali Kieffer (Diptera: Cecidomyiidae) : a thesis presented in partial fulfilment of the requirements for the degree of Masters [i.e. Master] of Applied Science in Plant Health at Massey University, Palmerston North, New Zealand
(Massey University, 1996) Galanihe, Lalitha Damayanthi
In the past few years New Zealand populations of apple leaf curling midge, Dasineura mali Kieffer (Diptera: Cecidomyiidae) (hereafter referred to as ALCM) have exploded, making control in commercial apple orchards more difficult. The present studies were initiated to generate information about the basic biology and behaviour of adult female ALCM. Experiments were conducted in the laboratory during two consecutive summer seasons in 1994/95 and 1995/96 at Massey University, Palmerston North and at HortResearch, Mt. Albert Research Center, Auckland, respectively. The diel emergence patterns of adult ALCM males and females were synchronized. Adults of both sexes started emerging at 05.00 h, with approximately 95% of adults emerging before noon. Females exhibited calling behaviour (a posture associated with the release of sex pheromone) within minutes after emergence. After mating females ceased calling. When tested in a wind tunnel containing apple foliage, mated females were rarely active before 10.00 h. After this, greater numbers of females flew upwind and landed on apple foliage, with peak responses to apple foliage occurring after 14.00 h. When given a choice between apple and pear foliage, female ALCM oviposited four times more eggs on apple than on pear. However, when given no choice between plant species females oviposited similar numbers of eggs on the two plant species. Female ALCM laid more eggs on immature apple leaves and buds than on mature apple leaves. Chemical cues from apple foliage were found to be of major importance in the host-finding behaviour of ALCM females. Volatile chemicals from apple foliage triggered upwind flight, approach and landing. Volatile chemicals from a non-host plant, pear, stimulated only half as many females to fly upwind and rarely stimulated approach or landing. Females were more responsive to chemical stimuli from immature foliage of apple than to stimuli from mature foliage. A dichloromethane extract of apple leaves increased the percentages of females flying upwind and approaching extract treated filter papers six and thirty times, respectively, over filter papers treated with dichloromethane. Out of the females that flew upwind to apple foliar extracts, 48.7% landed and 23% exhibited post-landing plant-examination behaviours. No females landed on filter papers treated with dichloromethane.

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