Invasive weeds are threatening ecosystem function and productivity all over the world by outcompeting desirable vegetation and reducing species diversity. One option for long-term control of such weeds is biological control using natural insect enemies. Such a program has been developed for management of Dalmatian toadflax (Linaria dalmatica (L.) Miller (Plantaginaceae)) in North America using a stem-mining weevil, Mecinus janthiniformis Toševski and Caldara (Coleoptera: Curculionidae). Although widely effective in northern regions, such as in British Columbia and in the American northwest, this insect has been slow to suppress Dalmatian toadflax in southern most regions of their current range, including areas in Utah and Colorado, and little is known of the limiting factors leading to slow weed suppression in these areas. Using field assessments of insect and plant activity over two growing seasons at several sites, this study aimed to provide degree-day and calendar-date descriptions of insect phenology. In addition, dead, overwintered Dalmatian toadflax stems were dissected to determine overwintering mortality of weevil adults before spring emergence, and living stems were dissected to determine development stages and mortality of weevils during summer development. Degree-day and calendar-date based models independently resulted in consistent trends in weevil phenology between sites and between years in this study, although the degree-day model is likely to be most useful for purposes of predicting weevil life cycle timing. Interestingly, the sexes differed in their phenology in that males consistently emerged from overwintering sites and were found on Dalmatian toadflax stems considerably earlier than females in the spring. Females as well as males tended to peak in abundance on stems in late-May when Dalmatian toadflax stems reached full maturity. Overall mortality of M. janthiniformis during a lifecycle was low for all samples; approximately 83% of adults successfully emerged from overwintered stems in the following spring, and greater than 65% of larvae survived to adulthood before overwintering. This resulted in >50% of weevils surviving larval development, overwintering, and spring emergence as adults. The majority of M. janthiniformis deaths (51%) resulted from parasitism by chalcidoid wasps during summer development to adulthood. These parasitoid wasps, and also M. janthiniformis adults, likely created the peculiar exit holes that were observed in live Dalmatian toadflax stems during the summer. Although M. janthiniformis populations were slow to provide effective control of Dalmatian toadflax at sites in Utah, this study indicates that the phenology and survivorship of M. janthiniformis individuals in Utah are well suited for successful biocontrol. If given enough time to build populations, M. janthiniformis appears to be capable of providing effective Dalmatian toadflax control in southern regions, but other limiting factors, such as precipitation and host plant quality, should be considered in future studies to explain slow weed suppression. Phenology models and estimates of mortality of M. janthiniformis generated by this study at sites in Utah may be helpful in implementing future biocontrol programs of Dalmatian toadflax.

Dentre os parasitoides utilizados no controle biológico de pragas está Habrobracon hebetor Say, 1857 (Hymenoptera: Braconidae), um ectoparasitoide frequentemente encontrado em armazéns de grãos e que parasita espécies de lepidópteros que atacam produtos armazenados. Dada a sua agressividade e pela sua ação em laboratório é um potencial agente de controle biológico de diversas espécies de lagartas que causam prejuízos econômicos. Portanto, no presente trabalho buscou-se avaliar o potencial de parasitismo de H. hebetor, parasitoide já existente no Brasil, sobre diferentes pragas agrícolas pertencentes às famílias Noctuidae (9 espécies), Erebidae e Crambidae, em relação à duas espécies de Pyralidae (controles), com base na paralisação e no tempo de tal paralisação em lagartas de diferentes tamanhos, com diferentes densidades do parasitoide, bem como seu desenvolvimento nas espécies escolhidas pelo potencial observado. Foram estudadas as espécies Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) (controle 1), Corcyra cephalonica (Staiton, 1865) (Lepidoptera: Pyralidae) (controle 2), Helicoverpa armigera (Hübner, 1809) (Lepidoptera: Noctuidae), Chloridea virescens (Fabricius, 1777) (Lepidoptera: Noctuidae), Spodoptera cosmioides (Walker, 1858) (Lepidoptera: Noctuidae), Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae), Spodoptera albula (Walker, 1857) (Lepidoptera: Noctuidae), Spodoptera eridania (Cramer, 1782) (Lepidoptera: Noctuidae), Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae), Helicoverpa zea (Boddie, 1850) (Lepidoptera: Noctuidae), Anticarsia gemmatalis Hübner, 1818 (Lepidoptera: Erebidae), Agrotis ipsilon (Hufnagel, 1767) (Lepidoptera: Noctuidae). Foram avaliados o tempo e a porcentagem de paralisação das lagartas, assim como a correlação dessas variáveis com o tamanho do hospedeiro (2º ou 4º ínstar) e o número de parasitoides (1, 2 e 4), sendo as espécies mais paralisadas e no menor tempo, selecionadas como melhores por meio de uma análise de componentes principais. Estudou-se a preferência do parasitoide sobre as melhores espécies de lagartas por meio de um teste de livre escolha, observando-se a paralisação e o tempo gasto para tal paralisação. Avaliou-se o efeito da densidade de lagartas na paralisação por H. hebetor durante 4 dias. Posteriormente foi realizada a biologia das espécies selecionadas avaliando-se a duração dos estágios evolutivos assim como a viabilidade das melhores espécies e o número de ovos colocados em 3 dias. Não houve relação entre a paralisação e o parasitismo por H. hebetor. Quanto maior a paralisação do hospedeiro, menor foi o tempo para tal paralisação. O número de parasitoides e os ínstares mais avançados reduziram significativamente o tempo de paralisação. Houve grande variação na paralisação entre as espécies das 3 famílias estudadas (Noctuidae, Erebidae, Crambidae) e dentro de uma mesma espécie. Das três espécies selecionadas com base na paralisação, S. cosmioides, A. ipsilon e D. saccharalis, apenas esta última se apresentou como potencial hospedeiro para parasitismo de H. hebetor. Existe um potencial de utilização de H. hebetor no controle de D. saccharalis, com base nos resultados obtidos, exigindo uma validação em condições de campo. / Among the parasitoids used in biological pest control is Habrobracon hebetor Say, 1857 (Hymenoptera: Braconidae), an ectoparasitoid often found in grain stores and parasitizing lepidopteran species that attack stored products. Given its aggressiveness and its action in the laboratory is a potential agent of biological control of several species of caterpillars that cause economic losses. Therefore, the present work aimed to evaluate the parasitism potential of H. hebetor, a parasitoid already present in Brazil, on different agricultural pests belonging to the families Noctuidae (9 species), Erebidae and Crambidae, in relation to 2 Pyralidae species as control, based on the paralyzation and the time of such paralysis in caterpillars of different sizes, with different parasitoid densities, as well as their development in the species with potential. The species studied were: Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) (control 1), Corcyra cephalonica (Staiton, 1865) (Lepidoptera: Pyralidae) (control 2), Helicoverpa armigera (Hübner, 1809) (Lepidoptera: Noctuidae) , Chloridea virescens (Fabricius, 1777) (Lepidoptera: Noctuidae), Spodoptera cosmioides (Walker, 1858) (Lepidoptera: Noctuidae), Spodoptera frugiperda (JE Smith, 1797) (Lepidoptera: Noctuidae), Chrysodeixis includens (Lepidoptera: Noctuidae), Spodoptera albula (Walker, 1857) (Lepidoptera: Noctuidae), Spodoptera eridania (Cramer, 1782) (Lepidoptera: Noctuidae), Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae), Helicoverpa zea (Boddie, 1850) (Lepidoptera: Noctuidae), Anticarsia gemmatalis Hübner, 1818 (Lepidoptera: Erebidae), Agrotis ipsilon (Hufnagel, 1767) (Lepidoptera: Noctuidae). The time and percentage of caterpillar paralysis were evaluated, as well as the correlation of these variables with the host size (2nd or 4th instar) and the number of parasitoids (1, 2 and 4), with the species being more paralyzed and, in less time, selected as the best by means of a principal component analysis. The preference of the parasitoid on the best caterpillar species was studied by means of a free choice test, observing the paralyzation and the paralyzation time. The effect of caterpillar density on H. hebetor paralyzation was evaluated for 4 days. Afterwards the biology of the selected species was evaluated, evaluating the duration of the evolutionary stages as well as the viability of the best species and the number of eggs placed in 3 days. There was no relationship between paralyzation and parasitism by H. hebetor. The greater the host paralysis, the longer the paralyzation delay. The number of parasitoids and the more advanced instars significantly reduced the standstill time. There was a great variation of paralysis among the species of the three families studied (Noctuidae, Erebidae, Crambidae) and within the same species. The three species selected based on the paralyzation, S. cosmioides, A. ipsilon and D. saccharalis, only the sugarcane borer presented as a potential host for H. hebetor parasitism. There is a potential of using H. hebetor in the control of D. saccharalis, based on the results obtained, requiring validation under field conditions.

Brown and Penicillium rot (blue and green mould) are the most common postharvest diseases in New Zealand, causing significant postharvest fruit losses. Current practice uses fungicides to control the postharvest diseases; however there are perceived health risks associated with the use of such chemicals. Recently, there has been substantial interest in chemicals that are considered Generally Regarded as Safe or GRAS and natural products as alternative postharvest treatments to replace currently used fungicides. In this study, ethanol (GRAS chemical) and the natural products honey, milk and essential oils (lemon, lemongrass, manuka and orange) were assessed as potential alternative treatments to replace the currently used fungicides on both peaches and oranges. In pilot studies ethanol was applied to the fruit by either vapour or dipping (30 seconds or 1.5 minutes). Honey, milk and essential oils were applied by dipping at 30 seconds. Essential oils were also tested using a microtiter assay. Exposing fruit to ethanol vapour proved effective at inhibiting fungal growth, but impacted negatively on fruit quality. Peaches that were exposed to 70% to 100% ethanol vapour were protected against fungal infection for up to 30 days when stored at either 4ºC or room temperature. This is compared to two days for untreated peaches and three days for fungicide -treated peaches. However, the ethanol-treated peaches suffered from severe browning. In contrast, 20% ethanol protected peaches for ten days when stored at 4ºC and two days at room temperature. The fruit that were exposed to 20% ethanol did not brown as a result of the treatment. Oranges that were exposed to 20%, 50%, 70% and 100% ethanol vapour were protected from fungal inhibition for 30 days at both 4ºC and room temperature, but they too suffered from severe browning. Dipping was not as effective as vapour at protecting against fungal infection, but had a little effect on fruit quality. Peaches dipped in 20% to 100% ethanol were completely rotten by ten days when stored at room temperature, but the peaches experienced little to no browning. Untreated and fungicide-treated fruit were protected for one day and two days, respectively. Milk and honey do not appear to have potential as postharvest treatments. Peaches that were treated with 20%, 50% and 100% whole milk and 50% manuka honey showed greater degree of fungal infection compared to untreated peaches after both room temperature and 4ºC storage. At room temperature, peaches that were exposed to 20%, 50% and 100% milk were completely rotten at eight days, compared with ten days for untreated peaches. In contrast, at 4ºC, peaches that were treated with 100% milk were completely rotten at 30 days, while only a slight fungal infection observed on untreated fruit. Similar to milk, honey-treated peaches were also completely rotten at 30 days at 4ºC storage.In vitro (microtiter) assay of the essential oils showed that orange and manuka oils appeared to be effective only at high concentrations. In contrast, lemongrass and lemon oils appeared to be effective even at low concentrations. Of the essential oils tested in the in vivo assay, lemongrass and lemon oils have the greatest potential. Oranges that were exposed to 0.05% lemongrass oil, 0.25% and 0.5% lemon oil were protected for 30 days when stored at 4ºC or room temperature. They provided the best antifungal activity compared to the other concentrations of all four essential oils tested as well as fungicide treatment for 30 days. Of all the treatment tested, 0.05% lemongrass oil, 0.25% and 0.5% lemon oil appeared to be the most promising treatments. However, these treatments need to be tested for antifungal effects, fruit quality, flavour and nutritional effects in large scale experiments before they can be applied as replacements to currently used fungicides. Also, essential oils are complex compounds; therefore it would be of interest to determine the active compound(s) of the lemongrass and lemon oils.

Includes two journal articles with contributions by the author Bibliography: leaves 145-154

There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320930 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320930 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Bibliography: leaves 221-240. This thesis deals with the introduction of "Aphidius rosae" as a classical biological control agent into South-Eastern Australia. Appropriate host specificity tests are carried out. Laboratory experiments are also completed to gain a better understanding of the interactions between host and parasitoid in the field. The study aims to monitor the performance of the control agent in the Adelaide environment for the first two years after initial release. It is also planned to invent an experimental field technique to estimate the impact of the control agent on rose aphid populations.

The cinnabar moth, Tyria jacobaeae (L.) (Lepidoptera:Arctiidae), was released in 1959 to control the grassland weed tansy ragwort, Senecio jacobaea L. (Asteraceae), despite evidence that caterpillars of this species can feed on native plants within the genera Senecio and Packera. Previous studies confirmed the moth's ability to develop on the native Senecio triangularis Hook., although no systematic study has been conducted to determine the extent of non-target impact on all potential host species. To address the lack of systematic studies we conducted a regional survey to determine the consequences of exposure of non-target plants to cinnabar moth caterpillars. We also conducted a local field experiment to determine the influence of habitat on the patterns of association of the moth and non-target plants. In the regional survey, we mapped the potential distribution of the cinnabar moth in Oregon to determine the extent of exposure of native Senecio and Packera species, and systematically sampled exposed species to assess the frequency and severity of feeding on these plants. We found that nine of the 20 native non-target species in Oregon were exposed to the cinnabar moth, three of the 10 native Senecio and six of the 10 native Packera. Ten of the native species escaped exposure because they occur east of the Cascade Mountain Range where the cinnabar moth does not occur. We found feeding damage on three of the nine exposed species: Packera cymbalarioides, P. pseudaurea, and S. triangularis were attacked at one of three (33%), two of six (33%), and seven of 15 (47%) sites that supported populations of each species, respectively. Within sites, attack frequency of stems was 33% (of six total stems sampled) for P. cymbalarioides, and ranged from 53% to 56% (of 20 to 108 total stems sampled) for P. pseudaurea and 7% to 64.5% (of 32 to 458 total stems sampled) for S. triangularis. Conditional median damage per site (median of attacked stems only) was 10% in P. cymbalarioides, 5% to 17.5% in P. pseudaurea, and 5% to 37.5% in S. triangularis. The attack rate on non-target plants (7.1 to 64.5 percent of stems attacked at a singe site) was equal to or greater than on the target weed (8.3 to 50.0 percent of stems attacked at a single site). At three sites, caterpillars attacked non-target plants but the target weed was absent, and at one site, the target was present but caterpillars fed on non-target plants only. We conclude that attack frequency and severity on the three species is not high, but equaled or exceeded the level of attack on the target weed. We also conducted a mark-release-recapture experiment to relate habitat preference to patterns of non-target host use in the field. We compared adult moth dispersal patterns and larval development between a meadow habitat and a forest habitat. We found that long-term dispersal distance (spanning days) was similar in both habitats but we recaptured a higher percentage of moths from the meadow (47%) compared to the forest (10%). Short-term displacements, based on direct observations of flights immediately after release, differed between habitats: moths in the meadow flew short distances (8.5m ± 1.5, n=13) at or below the herbaceous canopy (0.8 m ± 0.2, n=13) while moths in the forest flew longer horizontal (22.8 m ± 2.8, n=15) and vertical distances (5.9 m ± 0.9, n=15). We recovered seven fifth instar larvae (of 278 eggs) from the meadow habitat but no larvae beyond the second instar (of 119 eggs) were recovered from the forest habitat. We conclude that the cinnabar moth is limited to meadow habitats because adult moths display movement patterns that remove them from forest habitats (possibly due to disorientation) and larvae are unable to survive on plants growing in the forest. Taken together, the regional survey and the local field-experiment indicate that the cinnabar moth uses only a small proportion of available non-target host plant species. Other species are likely unused because of geographic isolation from the moth, habitat selection by the moth, or phenological differences between the moth and non-target plants. / Graduation date: 2003

Knowledge of how individual organisms behave in their environment can provide a greater understanding of population dynamics. In a predator-prey system, the choices made by predators when foraging for prey are important aspects of behavior. Particularly in the case of a stage-structured prey population, how the predator selects prey stages once a prey patch has been located can have implications for prey population growth, predator development and fecundity, and predator-prey system dynamics. Predaceous mites of the family Phytoseiidae are important biological control agents of Tetranychus spider mites in agricultural settings worldwide. Phytoseiid species range from specialists that require Tetranychus spider mite prey in order to develop and reproduce to generalist omnivores. In studies with 13 phytoseiid species, specialized species tended to prefer T. urticae eggs as prey or have no prey-stage preference while more generalist species tended to have no prey-stage preference or prey more often on mobile immatures. Further testing with a subset of these species suggested variability among species with regard to genetic and environmental influences on prey-stage preference. The specialist Phytoseiulus persimilis also preferred to forage and oviposit in patches containing egg-biased stage distributions rather than in adjacent mobile immature-biased patches. No benefits to offspring developing in either type of patch were found in terms of developmental time or subsequent adult fecundity. However, the results of both manipulative experiments and nonlinear population models indicated potential benefits of egg-biased predation in terms of current adult female fecundity, a less severe impact of predation on the prey population, and an increased number of predator descendents during the predator-prey interaction. Considering both subjective factors and discriminant analyses, prey-stage preference performed well as an indicator for the ecological classification of phytoseiid species. The classifications of four phytoseiid species occurring on apple in central and eastern Oregon, USA, were evaluated accordingly. / Graduation date: 2004

The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is the most devastating foliage-feeding pest of potatoes in the United States. Potential biological control agents include the nematodes Heterorhabditis marelatus Liu & Berry and Steinernema riobrave Cabanillas, Poinar & Raulston, which provided nearly 100% CPB control in previous laboratory trials. In the present study, laboratory assays tested survival and infection by the two species under the soil temperatures CPB are exposed to, from 4-37°C. H. marelatus survived from 4-31°C, and S. riobrave from 4-37°C. Both species infected and developed in waxworm hosts from 13-31°C, but H. marelatus rarely infected hosts above 25°C, and S. riobrave rarely infected hosts below 19°C. H. marelatus infected an average of 5.8% of hosts from 13- 31°C, whereas S. riobrave infected 1.4%. Although H. marelatus could not survive at temperatures as high as S. riobrave. H. marelatus infected more hosts so is preferable for use in CPB control. Heterorhabditis marelatus rarely reproduced in CPB. Preliminary laboratory trials suggested the addition of nitrogen to CPB host plants improved nematode reproduction. Field studies testing nitrogen fertilizer effects on nematode reproduction in CPB indicated that increasing nitrogen from 226 kg/ha to 678 kg/ha produced 25% higher foliar levels of the alkaloids solanine and chaconine. However, the increased alkaloids did not affect nematode infection of, nor reproduction in, CPB prepupae. Nematodes applied to field plot soil at 50 infective juveniles/cm² reduced adult CPB by 50%, and increased numbers of dead prepupae in soil samples up to five times more than in non-nematode plots. Laboratory studies of H. marelatus and its symbiotic bacteria in CPB hemolymph indicated that immune responses did not limit nematode reproduction. A 58kD CPB hemolymph protein apparently caused the symbiotic bacteria to switch to the secondary form, which does not produce antibiotics and enzymes necessary for nematode growth and reproduction. Despite heat denaturation of the protein, the nematodes did not reproduce unless lipids were added to the hemolymph. Therefore, while H. marelatus may provide high levels of CPB control, nutritional constraints on the nematode and its bacteria inhibit reproduction in CPB and limit long-term multi-generation control. / Graduation date: 2003