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Biological control ecology of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) on Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Plant Science (Entomology) at Massey University, Manawatū, New Zealand
(Massey University, 2023) Chen, Chen
Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) is an important primary parasitoid of tomato-potato psyllid Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), a serious invasive pest of solanaceous crops. It kills its hosts by both feeding and parasitisation. However, its biological control ecology is still not well known, making it difficult to develop an effective biological control programme using this parasitoid. In this thesis, I investigated adult circadian rhythms, diets, life history strategies, and host selection behaviour in T. triozae. My results show that most emergence occurred in the morning and most mating took place early the next morning. Oviposition only occurred during the daytime, peaking between mid-morning and mid-afternoon while host feeding had three peaks in the early morning, late afternoon, and dawn. Adults fed with honey for four days with no access to hosts or with water or yeast for one day followed by host feeding for three days had similar longevity and lifetime pest killing ability. Adults fed with only water for one day immediately before release had significantly greater intrinsic rate of increase, shorter doubling time, and higher daily fecundity peak. Adults fed with honey or yeast for one day followed by host feeding for three days significantly flattened their daily oviposition curves. T. triozae females could feed on nymphs of all instars but preferred mid-aged ones for feeding. Most parasitisation occurred on older nymphs. Host feeding and parasitism peaked during the first week of female life and declined markedly after two weeks. Parasitoids allocated more fertilised eggs to older and larger nymphs. The oviposition of fertilised eggs peaked when females were four to five days old, with > 90 % of daughters produced during the first half of their life. There was a positive relationship between the host size at parasitisation and parasitoid offspring fitness. The parasitoid behaviours consisted of encounter, evaluation, piercing for feeding, feeding, oviposition probing, and oviposition, and host defence behaviours included body swaying and escaping. Female wasps were more likely to encounter and evaluate older and larger hosts. However, encounter and evaluation did not necessarily translate into feeding and oviposition success. Older nymphs had more resources, thicker integument and stronger defence ability and the opposite was the case for younger ones. The present study provides novel knowledge for development of effective T. triozae mass rearing, shipment, and release programmes for the control of B. cockerelli.
Interactions between Anystis baccarum (Acari: Anystidae), a generalist predatory mite, and larvae of Epiphyas postvittana (Walker (Lepidoptera: Tortricidae), a pest of apples : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science in Plant Health at Massey University
(Massey University, 1995) Ekanayake, Nayana Kumudini
A large numbers of Anystis baccarum (Acari: Anystidae) were discovered living alongside of Epiphyas postvittana (Lepidoptera: Tortricidae) larvae known as light brown apple moth (LBAM) in shelter belt of acacia, Acacia reva (Leguminoseae: Sub family Mimosoidae). Few questions that needed to be answered were whether the mites actually feed on the LBAM larvae and what are their interactions. The objective of my study was to investigate the general characteristics of mite feeding on LBAM larvae, and to study the age, density, webs and defence behaviour of larvae as exogenous factors, and the effect of level of starvation and experience of mites as endogenous factors on foraging behaviour of A. baccarum. Eleven experiments were conducted under laboratory conditions. At 20 c, the average daily consumption rate of A. baccarum was 11.5 ± 52.68 neonate E. postvittana larvae of 1.484 mm in lenght and 0.231 mm in width. The predator spent 1106 ± 309 seconds mean feeding time, feeding on a neonate larvae of E. postvittana. A. baccarum is cannabalistic and survived 6.1 ± 2.28 days totaly deprived of food and water. Webs of E. postvittana larvae act as a physical barrier to attack of A. baccarum. When the webs were removed larvae upto eight days of age were consumed by A. baccarum, however survival from capture by mite increased with age. When the mite was given a choice between three different age groups of larvae, a higher number of neonate faivae were taken as the first choice, but the overall results showed the choice depends on random encounters between the predator and prey and prey avoidence behaviour of larvae. Spinning was the most frequent avoidence behaviour of larvae without webs. Spinning response occured less frequently with increased age of the larvae. The most common response of larvae in webs was quick movement fonnards or backwards. Starvation for 24 hours did not significantly increase walking speed of A. baccarum over walking speed of non-starved mites, but walking speed was decreased at 48 hr and 72 hr starvation. However, starvation increased prey capture of A. baccarum compared to non starved condition. Starvation also had a significant effect on number of captures at first encounter. A. baccarum with no experience of prey on apple shoots prefered to rest on branch of apple than leaf and fruit given that area of the branch is low, preference was even greater. On their search of alternative walking and resting periods, A. baccarum spent significantly more time walking than resting. When given experience of feeding a neonate larva of LBAM on branch, leaf or fruit, A. baccarum spent significantly more time walking on the location they were fed. In conclusion, the larvae of E. postvittana includes in to the list of prey of A- baccarum. If encounterd during their dispersal phase after hatching, possibilities are high that neonate larvae of E. postvittana to be preyed by A. baccarum ocurring in large numbers in orchid ecosystems in New Zealand. Studies on this predator-prey interaction opens new venues of research on generalised predator-prey interactions.
Bio-prospecting for endophytes of Brassica : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatu, New Zealand
(Massey University, 2019) Roodi, Davood
Disease and insect pests are major limiting factors for crop production worldwide. Farmers are often heavily reliant on synthetic biochemicals and fertilisers to mitigate the negative impact of pests and disease and to increase crop yield. However, the extensive use of chemicals has led to environmental concerns due to contamination of soil and water, human health issues, disturbance of macro and microorganisms balance and the development of resistance by both insects and fungal pathogens. Use of biological control agents including endophytic microorganisms is an alternative control option to combat these problems. Many endophytes are able to provide their host with beneficial traits such as resistance against insect-pests and pathogens and enhance crop performance under abiotic stresses. Although beneficial microorganisms of brassica crops have been discovered, endophytes of wild brassica’s, particularly those associated with the seed, have been ignored. In this study, we screened seed of various brassica species with a worldwide distribution and isolated 131 bacterial and two fungal species. Molecular identification of bacterial isolates indicates that most seed accessions harboured endophytic bacteria belonging to 17 species. Among these isolates, two species, identified as Methylobacterium fujisawaense and Me. phyllosphaerae were dominant and widespread across the majority of accessions sampled, and originated from different species and locations. The inoculation of oilseed rape (Brassica napus) root with these endophytic bacteria significantly increased the fresh weight of the seedlings. The fungal endophyte species identified were Beauveria bassiana and Geomyces pannorum, isolated from two different accession of a wild brassica species (B. rapa). Inoculation of the seeds of three brassica species, B. napus, B. rapa and B. oleracea with these fungal endophytes resulted in infection of below and above ground tissues of inoculated seedlings but colonisation of the next generation seeds/seedlings did not occur. Seed inoculation, foliar application and soil drenching when the plants were grown on non-sterile soil also did not result in plant colonisation. A dual culture test was performed to study the antagonistic effect of these bacterial and fungal endophytes against Leptosphaeria maculans, the causal agent of phoma stem canker in brassica crops. The highest inhibition rate was recorded for Stenotrophomonas rhizophila, Novosphingobium resinovorum, Pseudomonas azotoformans, Plantibacter flavus, Me. fujisawaense and Me. phyllosphaerae which produced a significant inhibition zone indicating the antagonistic ability of these species. The fungal endophytes also suppressed the growth of the pathogen and created an inhibition zone. In planta tests in which the fungal endophytes were inoculated on to seed of a susceptible oilseed rape cultivar were also undertaken. At the cotyledon leaf stage, the leaf was punctured and spore suspension of L. maculans was placed on the wound site. Inoculated seedlings particularly B. bassiana, significantly decreased phoma stem canker disease symptoms on the cotyledon. To our knowledge, this is the first study that screen the fungal and bacterial endophytes of wild brassica species associated with the seeds and demonstrate their beneficial characteristic when inoculated to brassica crops.
Assessing the effect of plant surface on the predatory ability of Orius vicinus : a potential biological control agent of the tomato-potato psyllid (Bactericera cockerelli) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand
(Massey University, 2019) Gamarra Landa, Abel
The tomato-potato psyllid (TPP), Bactericera cockerelli (Sulc), is a pest to solanaceous crops (e.g. potato, tomato, peppers, and eggplant) and is associated with economically important plant diseases. Subsequently, chemical control is the preferred management option. However, chemical reliance is associated with a host of issues. The development of biological control methods is vital to implementing Integrated Pest Management (IPM) programs as an alternative to broad-spectrum insecticide usage. The predatory bug Orius vicinus (Ribaut) is a potential biological control agent that is capable of consuming all nymphal life stages of TPP. In order to be a commercially viable management option, potential biological control agents of TPP have to cope with the different morphological plant features of the pest’s wide range of host plants. Tomato and capsicum plant surfaces were selected as the experimental surfaces for my thesis because they differ significantly in their substrate morphology. Tomato plant surfaces can be a hostile environment for potential biological control agents due to the negative effect tomato trichomes have on their foraging performance. Alternatively, because capsicum plant surfaces are virtually void of trichomes they appear to be more suitable for effective biological control agent deployment. I exposed the predatory bug to a variety of TPP nymph densities (10, 20, 30 and 40 individuals) in order to determine the functional response of O. vicinus. Furthermore, the predatory bug was exposed to all five TPP nymphal stages simultaneously. The predatory performance of O. vicinus was also assessed on experimental arenas varying in complexity (leaflet vs. small plant environments). The functional response was determined to be Type II on both plant surfaces. Nymph consumption at higher prey densities (30 and 40 nymphs) was significantly greater on capsicum than on tomato. Nymph consumption at lower prey densities (10 and 20 nymphs) was only significantly greater on capsicum when the complexity of the experimental arena increased from leaflet to small plant. The influence of O. vicinus in nymph dispersal was also assessed. My results revealed that the presence of O. vicinus increased the dispersal of nymphs to lower leaf surfaces and that nymph dispersal was significantly greater on capsicum than on tomato. TPP nymph size preference by O. vicinus was determined in my study. I established that the predatory bug is capable of killing all nymphal stages. My study strongly indicated that the predatory bug is more likely to target and consume medium (3rd instars) and large nymphs (4th and 5th instars) over small nymphs (1st and 2nd instars). I investigated the behaviour of O. vicinus adults and TPP nymphs during their interactions via video recordings. The predatory bug spent a significantly greater amount of time investigating TPP nymphs on capsicum than on tomato. There was significantly higher number of attacks recorded on capsicum. The greater killing percentage on tomato suggests that the defensive capabilities of TPP nymphs appear to have been negatively affected by the tomato substrate. The results from my study indicate that augmentative releases of O. vicinus, in the presence of smaller TPP nymphs, could be a viable biological control option on capsicum plants. However, the predatory bug will likely struggle if deployed on tomato plants. Future studies should be conducted in settings such as open field or glasshouses using multiple predatory bugs in the presence of susceptible life stages to assess augmentative release efficiency.
The potential ability of Stethorus bifidus (Kapur) to regulate populations of Tetranychus lintearius (Dufour) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University
(Massey University, 1993) Peterson, Paul Gordon
Tetranychus lintearius Dufour (Acari; Tetranychidae) was released in New Zealand, in 1989, to assist in the regulation of gorse (Ulex europaeus). The present study was initiated to determine why colonies of GSM are consistently failing to establish above parallel 39°S and the possibility that Stethorus bifidus may be regulating populations of T.lintearius (GSM). Predation by S.bifidus was investigated by examining both numerical and functional responses to prey density. - Development of S.bifidus is described by a linear relationship with temperature between 8.5°C and 27.5°C (numerical response). Oviposition and temperature are linearly related and independent of GSM density. Measurements of temperature under GSM webbing showed an elevation of 1- 20 C above ambient. - The feeding rate of S.bifidus increased in a non-linear fashion between 6.5°C and 32.5°C (functional response). - Handling time decreased with increasing prey density demonstrating that S.bifidus is an effective predator at high mite densities. This investigation suggests that the role of S.bifidus in regulating GSM is more important in northern regions of New Zealand.
Ecological factors affecting the establishment of the biological control agent Gargaphia decoris Drake (Hemiptera: Tingidae) : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatu, New Zealand
(Massey University, 2017) Falla, Cecilia María
The Brazilian lace bug (Gargaphia decoris Drake (Hemiptera:Tingidae)) was released in New Zealand in 2010 for the biological control of the invasive weed woolly nightshade (Solanum mauritianum Scopoli (Solanaceae)). Currently there is scarce information about the potential effect of ecological factors on the establishment of this biological control agent. This study investigated: 1) the effect of maternal care and aggregation on nymphal survival and development; 2) the effect of temperature, photoperiod and humidity on G. decoris performance; and 3) the effect of light intensity on S. mauritianum and G. decoris performance. Maternal care and aggregation are characteristic behaviours of G. decoris. These behaviours have an adaptive significance for the offspring and are key determinants for the survival of the species under natural conditions. Maternal care is reported to increase the survival and development of offspring under field conditions, and higher aggregations to increase the survival of the offspring. However, in this study, maternal care negatively affected the survival and development of the offspring, and higher aggregations had no significant impact on offspring survival. The availability of host plants under laboratory conditions may have influenced the expression of these behaviours. Climate is a factor that constrains insect development and therefore establishment. In this study, temperature affected the survival, nymphal development, life cycle, adult longevity, female reproductive success (i.e. total number of eggs, number of eggs laid per female, number of egg batches, number of eggs per batch, pre-oviposition period, percent females that oviposited successfully, number of eggs in the first batch and percentage of eggs that hatched from the first batch) and population growth parameters (i.e. life table). Temperatures between 20 – 25 °C were the optimal temperatures for G. decoris establishment. Photoperiod affected the mean percentage of egg hatch (i.e. emergence of nymphs in egg batch collected from colony) and total nymphal survival (i.e. egg to adult emergence), adult longevity and population growth parameters. The photoperiod 16L:8D was the optimal photoperiod for insect establishment. Humidity affected the mean percentage of egg hatch, adult longevity and population growth parameters. G. decoris population growth was highest at 70 ± 10% RH but the population growth was faster at 50 ± 10%. The CLIMEX model predicted that G. decoris could occupy broader regions not only on its native range (i.e. Brazil and Argentina) but also other regions where S. mauritianum is considered invasive (i.e. New Zealand and South Africa). G. decoris is predicted to be able to establish optimally in most of New Zealand North Island, except in regions with altitudes higher than 1300 meters above sea level. Most of the South Island is considered unsuitable for G. decoris establishment, except parts of the West Coast, Nelson and the Tasman region, which are predicted to be moderately to marginally suitable. Light intensity and plant age (i.e. day of harvest) affected host plant quality and had an indirect impact on insect establishment. Light intensity and plant age affected key physiological, morphological and defensive traits of S. mauritianum. Three compounds appeared to be involved, and were positively identified as glycoalkaloids: α-solamargine/β-solamarine, solauricine/solasonine, and unknown-954. The reproductive performance of G. decoris was affected because females avoided ovipositing on unshaded plants. The presence of trichomes and an increase in concentration of glycoalkaloids in the second harvest affected the nymphal performance and was reflected in adults, which had smaller bodies and wings. The results of my study have implications for using the Brazilian lace bug G. decoris in biological control programmes. The ecological factors included in this study work synergistically rather than independently and are important to consider when deciding the best locations in which the insect could be liberated.
Biological control ecology of Aphidius colemani Viereck (Hymenoptera: Braconidae: Aphidiinae) on Myzus persicae (Sulzer) (Hemiptera: Aphididae) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Sciences (Entomology) at Massey University, Palmerston North, New Zealand
(Massey University, 2017) Khatri, Diwas
The solitary and koinobiont endoparasitoid, Aphidius colemani Viereck, is produced commercially for biological control of green peach aphid Myzus persicae (Sulzer) and cotton aphid Aphis gossypii Glover around the world. However, its production cost is still high and biological control efficiency is still uncertain, probably due to the lack of knowledge on its biological control ecology. To fill the knowledge gap, I investigated the biological control ecology of the A. colemani-M. persicae system. My results show that most emergence and reproductive activities of A. colemani occur during the photophase. After emergence, both sexes need about 2 hours for sex maturation, but once sexually mature, age of neither sex has any significant effect on mating success. Food supply to adult females is essential to mating success. The mating behavioural sequence is similar to that of many other braconid parasitoids. My findings suggest that A. colemani is an effective biological control agent of M. persicae because reproductive outputs of the parasitoid are twice as high as the aphid, the parasitoid reaches the maximum lifetime reproductive potential about a week earlier than the aphid, and parasitised aphids contribute little to their population growth and make limited damage to plants. The parasitoid prefers to attack larger hosts but such preference is counterbalanced by greater defensive ability of larger hosts, resulting in similar parasitism rate on hosts of all ages. As a result, parasitising mid-aged hosts allows A. colemani females to gain maximum fitness in developmental period, body size and parasitism of their progeny. Finally, my study confirms that A. colemani has a Type II functional response. However, it can still successfully control M. persicae regardless of pest density probably because parasitoid density has significantly more effect than host density on parasitoid reproductive fitness and the low mutual interference among the searching parasitoids encourages aggregation of the parasitoids on host patches of high density. The present study provides basic knowledge on the biology of A. colemani for development of effective measures for laboratory handling, rearing, and field release, and brings insight into the success of aphid biological control programmes using the parasitoid augmentation approach.
Acaricide resistance and genetic affinities of some selected populations of Tetranychus urticae Koch in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science (Horticultural) in Entomology at Massey University
(Massey University, 1973) Ong, S. H.
A study of resistance to acaricides in a number of populations of the two-spotted spider mite, Tetranychus urticae, in New Zealand had been carried out. Natural genetic and cytoplasmic incompatibilities between populations were also investigated with a view to possible biological control of the pest. Facets of acaricide resistance that were studied included multi-resistance, cross-resistance, negatively correlated resistance and the inheritance of resistance. Chemicals used included an organophosphate representative (parathion-methyl), a carbamate (formetanate), an ungrouped compound (tricyclohexyltin hydroxide) and an organochlorine (dicofol). Cross-resistance was demonstrated between parathion-methyl and formetanate in five populations obtained from widely separate areas of New Zealand. The resistance to parathion of three strains was found to be inherited as a single dominant character and transmissible by both sexes. Cytoplasmic factors (or nucleo-cytoplasmic interactions) and minor genes were found to contribute slightly to the expression of total resistance. No resistance to tricyclohexyltin hydroxide (Plictran) and dicofol (Kelthane) was detected. High degrees of incompatibility (haploid egg lethality) were observed in the hybrids of crosses between the various populations. Chromosomal rearrangements in balanced, heterozygous conditions, in conjunction with the cytoplasm, were considered to be important factors determining the interpopulational sterilities. The interpopulational incompatibility phenomenon was found to be multi-factorial and not associated with the resistance factor. The egg mortalities of some backcross series which remained constantly high in spite of several crossings, implicated that the introduction of normal males to a resistant mite population in an enclosed area (e.g. in a glasshouse) might be a worthwhile proposition in the integrated control of spider mites. Backcross hybrids, on allowing to multiply randomly, were capable of forming new gene combinations, leading consequently to the formation of new strains which were genetically different from the original parents used in the backcross series.
Tracer studies of a subsurface flow wetland : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Technology in Environmental Engineering, Massey University
(Massey University, 1996) Prasad, Julius Narendra
The use of constructed wetlands represents an innovative approach to wastewater treatment. However, the treatment performance of constructed wetlands has been variable due to an incomplete knowledge of the hydraulic characteristics. Current design methods idealise constructed wetlands as plug flow reactors ignoring the existence of longitudinal dispersion, short-circuiting and stagnant regions. The overall effect will be a reduction of treatment efficiency at the outlet. This thesis investigates the hydraulic characteristics of a subsurface flow wetland using a fluorescence dye tracer so as to determine the difference between theoretical and actual retention times and their effect on treatment efficiency. A thorough review of the literature is undertaken, firstly examining wetland systems and their treatment mechanisms, it then reviews their hydraulic characteristics and design considerations while finally discussing dye tracing studies. A series of dye tracing trials were undertaken on a pilot scale gravel bed wetland with a theoretical retention time of four days. The results from this research are presented as plots of dye concentration versus time at the outlet. These results are analysed in terms of chemical reactor theory and their implications on performance of various treatment mechanisms is discussed.
Planning and control of IPM for greenhouse tomato growers : processes used by expert consultants : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Agricultural Systems & Management at Massey University
(Massey University, 1999) Singgih, Shinta Milasari
Given the clean, green image used to promote New Zealand produce, greenhouse tomato growers are under pressure to shift from conventional pest control to more environmentally-friendly methods such as IPM. However, growers often lack the specific knowledge required to tailor IPM strategies to their properties. Greenhouse consultants with expertise in IPM may provide a valuable source of assistance in terms of IPM adoption. However, little is known about how expert greenhouse consultants conduct this task. This study investigated the processes used by expert greenhouse consultants to assist greenhouse tomato growers with the planning and control of IPM strategies. A Multiple case study research method was selected as the most appropriate method for meeting the study objectives. Following the review of the literature, two expert greenhouse consultants were selected, and the data were collected using semi-structured interviews, field observations, and relevant documentation. Qualitative data analysis techniques were used to analyse the data. The two consultants were found to use similar IPM consultancy processes which, for the purpose of this study, have been separated into the physical activities, and planning and control processes. Both consultants perform similar physical activities (telephone calls and visits) to those used by farm management consultants. However, the two consultants studied distinguish between planning and control purpose telephone calls and visits, which the farm management consultants do not. In addition, both consultants use additional communication tools during the control stage. Throughout the consultancy processes, rapport is considered important to enable a trusting relationship to be built between the client and the consultant. The study highlights the presence of three phases during the consultancy processes, which were not mentioned in other farm management consultancy literature. The "screening" phase is used to ensure the development of the client's favourable attitudes toward IPM in the planning process. The "provision of information" phase, which occurs throughout the processes, is critical due to the complex nature of IPM. The "validation" phase is used to confirm the existence of the problems in the control process. During the planning and control processes, the client and the consultant share several roles and responsibilities. As the clients own the problem, they are responsible for making the decisions, implementing the plans, and undertaking monitoring. In order to do this, the clients act as the information providers and receivers for the consultant. The consultant is responsible for understanding the clients' system, providing the information required by the clients and designing the preventative IPM strategies during the planning stage. At this stage, the consultant also provides a monitoring strategy and contingency plans to be used by the clients. During control, the consultant is responsible for validating and diagnosing existence of the problems, providing information about the causal effect of the problems and designing the curative IPM strategies to solve the problems. During the design phase, the consultant uses decision rules to modify his IPM template, according to the need of each client. Factors such as type of crop, greenhouse age, crop age, whitefly population levels, the ability to heat, season, stud height, and persistence period are mentally structured to come up with various Encarsia introduction rates. In contrast, the IPM manual suggests a single Encarsia rate is used for all situations. The Encarsia introduction rates comprise the initial and maintenance rates. Case Study One starts with low rates of Encarsia for 2-4 weeks, followed by increasing the rates. Case Study Two starts with high rates of Encarsia for 6-10 weeks, followed by reducing the rates. Introduction is discontinued when the sustainable level of whitefly parasitism has been achieved. A more detailed IPM manual which allows for the specific circumstances in greenhouse tomato growers' properties is required to assist growers in the adoption of IPM strategies Key words: consultancy, planning, control, IPM, greenhouse tomatoes, Encarsia formosa, multiple case studies.

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