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Diachasmimorpha kraussii (Hymenoptera: Braconidae: Opiinae) is a koinobiont larval parasitoid of dacine fruit flies of the genus Bactrocera (Diptera: Tephritidae) in its native range (Australia, Papua New Guinea, Solomon Islands). The wasp is a potentially important control agent for pest fruit flies, having been considered for both classical and inundative biological control releases. I investigated the host searching, selection and utilisation mechanisms of the wasp against native host flies within its native range (Australia). Such studies are rare in opiine research where the majority of studies, because of the applied nature of the research, have been carried out using host flies and environments which are novel to the wasps. Diachasmimorpha kraussii oviposited equally into maggots of four fruit fly species, all of which coexist with the wasp in its native range (Australia), when tested in a choice trial using a uniform artificial diet media. While eggs laid into Bactrocera tryoni and B. jarvisi developed successfully through to adult wasps, eggs laid into B. cucumis and B. cacuminata were encapsulated. These results suggest that direct larval cues are not an important element in host selection by D. kraussii. Further exploring how D. kraussii locates suitable host larvae, I investigated the role of plant cues in host searching and selection. This was examined in a laboratory choice trial using uninfested fruit or fruit infested with either B. tryoni or B. jarvisi maggots. The results showed a consistent preference ranking among infested fruits by the wasp, with guava and peach most preferred, but with no response to uninfested fruits. Thus, it appears the wasp uses chemical cues emitted in response to fruit fly larval infestation for host location, but does not use cues from uninfested fruits. To further tease apart the role of (i) suitable and non-suitable maggots, (ii) infested and uninfested fruits of different plant species, and (iii) adult flies, in wasp host location and selection, I carried out a series of behavioural tests where I manipulated these attributes in a field cage. These trials confirmed that D. kraussii did not respond to cues in uninfested fruits, that there were consistent preferences by the wasps for different maggot infested fruits, that fruit preference did not vary depending on whether the maggots were physiologically suitable or not suitable for wasp offspring development, and finally, that adult flies appear to play a secondary role as indicators of larval infestation. To investigate wasp behaviour in an unrestrained environment, I concurrently observed diurnal foraging behaviours of both the wasp and one of its host fly in a small nectarine orchard. Wasp behaviour, both spatially and temporally, was not correlated with adult fruit fly behaviour or abundance. This study reinforced the point that infested fruit seems to be the primary cue used by foraging wasps. Wasp and fly feeding and mating was not observed in the orchard, implying these activities are occurring elsewhere. It is highly unlikely that these behaviours were happening within the orchard during the night as both insects are diurnal. As the final component of investigating host location, I carried out a habitat preference study for the wasp at the landscape scale. Using infested sentinel fruits, I tested the parasitism rate of B. tryoni in eucalyptus sclerophyll forest, rainforest and suburbia in South East Queensland. Although, rainforest is the likely endemic habitat of both B. tryoni and D. kraussii, B. tryoni abundance is significantly greater in suburban environments followed by eucalyptus sclerophyll forest. Parasitism rate was found to be higher in suburbia than in the eucalyptus sclerophyll forest, while no parasitism was recorded in the rainforest. This result suggests that wasps orient within the landscape towards areas of high host density and are not restricted by habitat types. Results from the different experiments suggest that host searching, selection and utilisation behaviour of D. kraussii are strongly influenced by cues associated with fruit fly larval feeding. Cues from uninfested fruits, the host larvae themselves, and the adult host flies play minimal roles. The discussion focuses on the fit of D. kraussii to Vinson’s classical parasitoid host location model and the implications of results for biological control, including recommendations for host and plant preference screening protocols and release regimes.

Aphidophagous lady beetles rely on multiple sources of food in their environment. Alfalfa fields provide both aphids and many alternate foods, such as other arthropod prey, pollen, and fungi. Alfalfa fields (Medicago sativa L.) in Utah have low aphid densities, which may require lady beetles to consume alternative sources of food. Many methods can be used to determine these diets; frass analysis is used here to compare the diets of the introduced species Coccinella septempunctata L. with two native species, C. transversoguttata richardsoni Brown and Hippodamia convergens Guérin-Méneville, that occur in the Utah alfalfa habitat. In initial laboratory experiments to examine the feasibility of frass analysis, 48 hours at 20oC was sufficient time for adult lady beetles to pass prey cuticle through their guts. When consumed by these adults, pea aphids (Acyrthosiphon pisum [Harris]), alfalfa weevil larvae (Hypera postica [Gyllenhall]), and C. septempunctata larvae produced distinctive fragments in the frass. Such fragments could also be distinguished in frass collected in a field experiment in which aphid densities in plots of alfalfa were manipulated. Furthermore, additional consumed foods could be distinguished in the field experiment, including pollen, fungi, and other types of arthropods. Frass analysis demonstrated higher use of aphid prey by C. septempunctata adults collected from high versus low aphid density plots during the field experiment. Use of other types of prey, such as alfalfa weevil larvae, other arthropods, pollen and fungi, was similar between plots with high and low aphid densities. A field census was performed over two years to track the diets of the three species of lady beetles during the first crop of alfalfa, when two sources of prey in particular were present, aphids and alfalfa weevil larvae. Comparisons of diets revealed that the three species utilized different types of prey to similar degree during both years. In general, however, higher percentages of C. septempunctata adults were found to have consumed aphids and weevils during both years. Also, C. septempunctata was found to produce more frass and consume larger quantities of prey than either native species during the second year.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2015-10-26T13:53:50Z No. of bitstreams: 2 Dissertação - Paola Arielle Ferreira Nobre - 2015.pdf: 2865061 bytes, checksum: eb60843824dc4bc74edc88795332bc18 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-26T14:09:22Z (GMT) No. of bitstreams: 2 Dissertação - Paola Arielle Ferreira Nobre - 2015.pdf: 2865061 bytes, checksum: eb60843824dc4bc74edc88795332bc18 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-26T14:09:22Z (GMT). No. of bitstreams: 2 Dissertação - Paola Arielle Ferreira Nobre - 2015.pdf: 2865061 bytes, checksum: eb60843824dc4bc74edc88795332bc18 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / the factors that influence the choice of egg-laying sites by adult insects is critical in order to identify the major drivers of host-plant use by insects. The abundance of different plant species and the level of feeding specialization of insects have been considered as determinants of the preferential use of host-plants by herbivorous insects. We analyzed the host use patterns of endophagous insects that feed on Asteraceae flower-heads to test the following hypotheses: (i) the abundance of a plant species has a positive effect on the preference of herbivorous insects for that plant species, and (ii) the relative importance of plant abundance in determining preferential use is greater for herbivorous species that use a wider range of host-plant species. We used data on the interactions between herbivorous insects and Asteraceae host-plants family sampled in 20 Cerrado areas in São Paulo State. We analyzed 11 species of endophagous insects and 12 host-plant species. For eight species of herbivorous insects, plant species abundance showed a positive influence on herbivore preference. Three insect species did not respond to any influence of plant abundance on feeding preferences, but one of them showed a positive effect of plant species identity. Furthermore, both the most specialized and the most generalist insect species presented a stronger positive effect of plant species abundance in their choice of a host-plant. Therefore, our study shows that the abundance of plant species is a major factor determining the preferential use of hostplants by the endophagous insects of Asteraceae. Moreover, we show that herbivore diet breadth mediates the relationship between host use and plant abundance. / Estudos abordando interações entre insetos herbívoros e plantas hospedeiras abrangem uma vasta gama de aspectos ecológicos. Boa parte desses aspectos pode ser relacionada diretamente ou indiretamente com a alta dependência que os herbívoros apresentam em relação às suas plantas hospedeiras. Devido a essa alta dependência os insetos herbívoros respondem tanto à riqueza e densidade, quanto ao arranjo espacial das hospedeiras no habitat (Wright and Samways 1999, Summerville and Crist 2001, Tsharntke and Brandl 2004). Além das plantas hospedeiras proporcionarem recurso alimentar para os insetos, elas também fornecem abrigo e microclima adequado para o desenvolvimento dos imaturos (Gaston et al. 1992). Insetos herbívoros não consomem indiscriminadamente as plantas, havendo geralmente alguma preferência por poucas espécies de plantas hospedeiras (Futuyma and Gould 1979). Assim, mudanças, por exemplo, em aspectos quantitativo e qualitativo, nessas hospedeiras podem ter grandes efeitos sobre as populações desses herbívoros. Nesse contexto, pode-se dizer que a amplitude da dieta é um componente fundamental do nicho das espécies de insetos herbívoros, influenciando desde sua dinâmica populacional e suscetibilidade à extinção (Brown 1984), até sua distribuição geográfica (Strong et al. 1984).

To refine our knowledge and to adequately test hypotheses concerning theoretical and applied aspects of invasion biology, successful and unsuccessful invaders should be compared. This study investigated insect establishment patterns by comparing the climatic preferences and biological attributes of two groups of polyphagous insect species that are constantly intercepted at New Zealand's border. One group of species is established in New Zealand (n = 15), the other group comprised species that are not established (n = 21). In the present study the two groups were considered to represent successful and unsuccessful invaders. To provide background for interpretation of results of the comparative analysis, global areas that are climatically analogous to sites in New Zealand were identified by an eco-climatic assessment model, CLIMEX, to determine possible sources of insect pest invasion. It was found that south east Australia is one of the regions that are climatically very similar to New Zealand. Furthermore, New Zealand shares 90% of its insect pest species with that region. South east Australia has close trade and tourism links with New Zealand and because of its proximity a new incursion in that analogous climate should alert biosecurity authorities in New Zealand. Other regions in western Europe and the east coast of the United States are also climatically similar and share a high proportion of pest species with New Zealand. Principal component analysis was used to investigate patterns in insect global distributions of the two groups of species in relation to climate. Climate variables were reduced to temperature and moisture based principal components defining four climate regions, that were identified in the present study as, warm/dry, warm/wet, cool/dry and cool/moist. Most of the insect species established in New Zealand had a wide distribution in all four climate regions defined by the principal components and their global distributions overlapped into the cool/moist, temperate climate where all the New Zealand sites belong. The insect species that have not established in New Zealand had narrow distributions within the warm/wet, tropical climates. Discriminant analysis was then used to identify which climate variables best discriminate between species presence/absence at a site in relation to climate. The discriminant analysis classified the presence and absence of most insect species significantly better than chance. Late spring and early summer temperatures correctly classified a high proportion of sites where many insect species were present. Soil moisture and winter rainfall were less effective discriminating the presence of the insect species studied here. Biological attributes were compared between the two groups of species. It was found that the species established in New Zealand had a significantly wider host plant range than species that have not established. The lower developmental threshold temperature was on average, 4°C lower for established species compared with non-established species. These data suggest that species that establish well in New Zealand have a wide host range and can tolerate lower temperatures compared with those that have not established. No firm conclusions could be drawn about the importance of propagule pressure, body size, fecundity or phylogeny for successful establishment because data availability constrained sample sizes and the data were highly variable. The predictive capacity of a new tool that has potential for eco-climatic assessment, the artificial neural network (ANN), was compared with other well used models. Using climate variables as predictors, artificial neural network predictions were compared with binary logistic regression and CLIMEX. Using bootstrapping, artificial neural networks predicted insect presence and absence significantly better than the binary logistic regression model. When model prediction success was assessed by the kappa statistic there were also significant differences in prediction performance between the two groups of study insects. For established species, the models were able to provide predictions that were in moderate agreement with the observed data. For non-established species, model predictions were on average only slightly better than chance. The predictions of CLIMEX and artificial neural networks when given novel data, were difficult to compare because both models have different theoretical bases and different climate databases. However, it is clear that both models have potential to give insights into invasive species distributions. Finally the results of the studies in this thesis were drawn together to provide a framework for a prototype pest risk assessment decision support system. Future research is needed to refine the analyses and models that are the components of this system.