Species of Lissothrips and Williamsiella from mosses and lichens in Australia and New Zealand (Thysanoptera, Phlaeothripinae)

Species of Lissothrips and Williamsiella live in association with mosses and lichens. Their gut contents are commonly blue-green, suggesting that they possibly feed on blue-green algae. Three species of Lissothrips are known from New Zealand, of which two are here recorded from Australia together with six new species. Williamsiella is recorded from Australia for the first time, with one new species.

New synonymies for Australian Cleridae (Coleoptera)

The following synonymies are proposed based on examination of primary types (lectotypes are designated for all taxa except those marked with a '*'): Lemidia spinnipennis Lea, 1907 syn. n. and Lemidia bicolor Schenkling, 1906 syn. n. = Lemidia biaculeata (Westwood); Lemidia mastersi Lea, 1907 syn. n. = Lemidia circumcincta Schenkling, 1906; Lemidia albonotata Pic, 1941 syn. n. = Lemidia laticeps Lea, 1907; Lemidia australiae Lea, 1907 syn. n. = Lemidia maculata Schenkling, 1902; Lemidia bilineatra Lea, 1907 syn. n. = Lemidia maculicollis Gorham, 1877; Lemidia decolor Pic, 1941 syn. n. = Lemidia munda Blackburn, 1892; *Phlogistus conspiciendus Elston, 1926 syn. n. = Mimolesterus ventralis (Westwood); Thanasimus cursorius Westwood, 1853 syn. n. and Stigmatium dispar Kuwert, 1894 syn. n. = Stigmatium acerbum (Newman); Stigmatium fasciatoventre Chevrolat, 1874 syn. n., Stigmatium flavescens Chevrolat, 1874 syn. n. and *Xestonotus eximius Kuwert, 1894 syn. n. = Stigmatium laevium Macleay, 1872; Stigmatium versipelle Gorham, 1876 syn. n. and Xestonotus (Cyclotomocerus) australicus Kuwert, 1894 syn. n. = Stigmatium varipes Chevrolat, 1876; Tarsostenus pulcher Macleay, 1872 syn. n. = *Tarsostenus carus (Newman, 1840). The available name Tarsosternus pulcher Macleay, 1872 is deemed a lapsus calami and emended to Tarsostenus pulcher Macleay, 1872.

The host specificity and climatic suitability of the gall flyCecidochares connexa(Diptera: Tephritidae), a potential biological control agent for Chromolaena odorata(Asteraceae) in Australia

The gall fly Cecidochares connexa (Diptera: Tephritidae) is a potential biological control agent for Chromolaena odorata in Australia. Its host specificity was determined against 18 species in the tribe Eupatorieae (Family Asteraceae) in which C. odorata belongs, in quarantine in Brisbane, Australia. Oviposition occurred and flies developed on only C. odorata and Praxelis clematidea, both of which are in the subtribe Praxelinae. P. clematidea is considered a weed outside tropical America. In both multiple-species-minus-C. odorata choice tests and single-species no-choice tests, the mean number of galls/plant was significantly greater on C. odorata (48 and 41, respectively) than on P. clematidea (2 and 9, respectively). There were also significantly more adults emerging from C. odorata (mean 129 and 169, respectively) in the two types of tests than from P. clematidea (1 and 8, respectively). Paired choice, multiple generation (continuation) and time dependent tests further clarified the extent that C. connexa could develop on P. clematidea. In these tests, the mean number of galls formed and the mean number of emerging adults were consistently less for P. clematidea than C. odorata and populations of C. connexa could not be maintained on P. clematidea. Galls were not seen on any other plant species tested. This study supports the results of host specificity testing conducted in seven other countries and confirms that C. connexa poses little risk to other plant species in Australia. C. connexa has been released in 10 countries and an application seeking approval to release in Australia has been submitted to the Australian Government.

Developmental biology and prey preference of Diomus notescens Blackburn (Coleoptera: Coccinellidae): A predator of Aphis gossypii Glover (Hemiptera: Aphididae)

The minute two-spotted ladybeetle, Diomus notescens Blackburn is a common predator of aphids and other pests in Australian agricultural crops, however little is known about the biology of D. notescens. The aim of this study was to provide information on the life cycle of this predator and improve our understanding of its biological control potential, particularly against one of the major pests of cotton, Aphis gossypii Glover. In laboratory experiments, juvenile development, prey consumption, as well as adult lifespan and fecundity were studied. Results from this study revealed that D. notescens could successfully complete development on A. gossypii, which at 25 °C required 21 days and during this period they each consume 129 ± 5.2 aphids. At 25 °C adult lifespan was 77 ± 9.6 days, with a mean daily prey consumption of 28 ± 1.8 aphids and a mean daily fecundity of 8 ± 0.5 eggs. Net reproductive rate was estimated as 187 ± 25.1 females and the intrinsic rate of increase was estimated as 0.14. Juvenile development was recorded at four constant temperatures (15, 21, 26 and 27 °C) and using a linear model, the lower threshold for D. notescens development was estimated to be 10 ± 0.6 °C with 285 ± 4.7 degree days required to complete development. A prey choice experiment studying predation rates revealed a strong preference for A. gossypii nymphs compared to Bemisia tabaci Gennadius eggs.

The host range of four new biotypes of Dactylopius tomentosus (Hemiptera: Dactylopiidae) from southern USA and their potential as biological control agents of Cylindropuntiaspp.(Cactaceae) in Australia: Part II.

Eight Cylindropuntia species have naturalised in Australia and pose serious economic, environmental and social impacts. Two biotypes of Dactylopius tomentosus have been used as bio-control agents to control different Cylindropuntia species. The host range of four additional biotypes of Dactylopius tomentosus from southern USA was investigated. Feeding and development were restricted to the genus Cylindropuntia. However, they showed differences in specificity within this genus and some biotypes discriminated between the provenances of C. rosea and C. tunicata. Efficacy trials were conducted to determine whether populations of each biotype could be sustained on the naturalised Cylindropuntia species and if these populations could retard the growth or kill these plants. The acanthocarpa biotype offers potential control of C. rosea (Lorne Station), while the cylindropuntia sp. biotype shows great potential to control C. rosea (Grawin). The cylindropuntia sp. biotype also had a high impact on C. kleiniae and C. imbricata, and a moderate impact on C. leptocaulis and C. prolifera. The acanthocarpa X echinocarpa biotype had its greatest impact on C. tunicata (Grawin), killing this plant in 18 weeks. A fourth biotype, leptocaulis, was damaging to some species, but was less effective than the other biotypes. Cylindropuntia spinosior is the only naturalised species in Australia where no effective biocontrol agent has been found.

Flow field and traverse times for fan forced injection of fumigant via circular or annular inlet into stored grain

Fan forced injection of phosphine gas fumigant into stored grain is a common method to treat infestation by insects. For low injection velocities the transport of fumigant can be modelled as Darcy flow in a porous medium where the gas pressure satisfies Laplace's equation. Using this approach, a closed form series solution is derived for the pressure, velocity and streamlines in a cylindrically stored grain bed with either a circular or annular inlet, from which traverse times are numerically computed. A leading order closed form expression for the traverse time is also obtained and found to be reasonable for inlet configurations close to the central axis of the grain storage. Results are interpreted for the case of a representative 6m high farm wheat store, where the time to advect the phosphine to almost the entire grain bed is found to be approximately one hour.

Mathematical modelling and numerical simulation of phosphine flow during grain fumigation in leaky cylindrical silos

The phosphine distribution in a cylindrical silo containing grain is predicted. A three-dimensional mathematical model, which accounts for multicomponent gas phase transport and the sorption of phosphine into the grain kernel is developed. In addition, a simple model is presented to describe the death of insects within the grain as a function of their exposure to phosphine gas. The proposed model is solved using the commercially available computational fluid dynamics (CFD) software, FLUENT, together with our own C code to customize the solver in order to incorporate the models for sorption and insect extinction. Two types of fumigation delivery are studied, namely, fan- forced from the base of the silo and tablet from the top of the silo. An analysis of the predicted phosphine distribution shows that during fan forced fumigation, the position of the leaky area is very important to the development of the gas flow field and the phosphine distribution in the silo. If the leak is in the lower section of the silo, insects that exist near the top of the silo may not be eradicated. However, the position of a leak does not affect phosphine distribution during tablet fumigation. For such fumigation in a typical silo configuration, phosphine concentrations remain low near the base of the silo. Furthermore, we find that half-life pressure test readings are not an indicator of phosphine distribution during tablet fumigation.

Causes and consequences of inbreeding in the ant Formica exsecta

Human actions cause destruction and fragmentation of natural habitats, predisposing populations to loss of genetic diversity and inbreeding, which may further decrease their fitness and survival. Understanding these processes is a main concern in conservation genetics. Yet data from natural populations is scarce, particularly on invertebrates, owing to difficulties in measuring both fitness and inbreeding in the wild. Ants are social insects, and a prime example of an ecologically important group for which the effects of inbreeding remain largely unstudied. Social insects serve key roles in all terrestrial ecosystems, and the division of labor between the females in the colonies queens reproduce, workers tend to the developing brood probably is central to their ecological success. Sociality also has important implications for the effects of inbreeding. Despite their relative abundance, the effective population sizes of social insects tend to be small, owing to the low numbers of reproductive individuals relative to the numbers of sterile workers. This may subject social insects to loss of genetic diversity and subsequent inbreeding depression. Moreover, both the workers and queens can be inbred, with different and possibly multiplicative consequences. The aim of this study was to investigate causes and consequences of inbreeding in a natural population of ants. I used a combination of long-term field and genetic data from colonies of the narrow-headed ant Formica exsecta to examine dispersal, mating behavior and the occurrence of inbreeding, and its consequences on individual and colony traits. Mating in this species takes place in nuptial flights that have been assumed to be population-wide and panmictic. My results, however, show that dispersal is local, with queens establishing new colonies as close as 60 meters from their natal colony. Even though actual sib-mating was rare, individuals from different but related colonies pair, which causes the population to be inbred. Furthermore, multiple mates of queens were related to each other, which also indicates localized mating flights. Hence, known mechanisms of inbreeding avoidance, dispersal and multiple mating, were not effective in this population, as neither reduced inbreeding level of the future colony. Inbreeding had negative consequences both at the individual and colony level. A queen that has mated with a related male produces inbred workers, which impairs the colony s reproductive success. The inbred colonies were less productive and, specifically, produced fewer new queens, possibly owing to effects of inbreeding on the caste determination of female larvae. A striking finding was that males raised in colonies with inbred workers were smaller, which reflects an effect of the social environment as males, being haploid, cannot be inbred themselves. The queens produced in the inbred colonies, in contrast, were not smaller, but their immune response was up-regulated. Inbreeding had no effect on queen dispersal, but inbred queens had a lower probability of successfully founding a new colony. Ultimately, queens that survived through the colony founding phase had a shorter lifespan. This supports the idea that inbreeding imposes a genetic stress, leading to inbreeding depression on both the queen and the colony level. My results show that inbreeding can have profound consequences on insects in the wild, and that in social species the effects of inbreeding may be multiplicative and mediated through the diversity of the social environment, as well as the genetic makeup of the individuals themselves. This emphasizes the need to take into account all levels of organization when assessing the effects of genetic diversity in social animals.

Behavioural, population, and genetic processes affecting metapopulation dynamics of the Glanville fritillary butterfly

In my thesis I have been studying the effects of population fragmentation and extinction-recolonization dynamics on genetic and evolutionary processes in the Glanville fritillary butterfly (Melitaea cinxia). By conducting crosses within and among newly-colonized populations and using several fitness measures, I found a strong decrease in fitness following colonization by a few related individuals, and a strong negative relationship between parental relatedness and offspring fitness. Thereafter, I was interested in determining the number and relatedness of individuals colonizing new populations, which I did using a set of microsatellites I had previously developed for this species. Additionally, I am interested in the evolution of key life-history traits. By following the lifetime reproductive success of males emerging at different times in a semi-natural setup, I demonstrated that protandry is adaptive in males, and I was able to rule out, for M. cinxia, alternative incidental hypotheses evoked to explain the evolution of protandry in insects. Finally, in work I did together with Prof. Hanna Kokko, I am proposing bet-hedging as a new mechanism that could explain the evolution of polyandry in M. cinxia.

The range expansion of the European map butterfly in Finland

Climate change will influence the living conditions of all life on Earth. For some species the change in the environmental conditions that has occurred so far has already increased the risk of extinction, and the extinction risk is predicted to increase for large numbers of species in the future. Some species may have time to adapt to the changing environmental conditions, but the rate and magnitude of the change are too great to allow many species to survive via evolutionary changes. Species responses to climate change have been documented for some decades. Some groups of species, like many insects, respond readily to changes in temperature conditions and have shifted their distributions northwards to new climatically suitable regions. Such range shifts have been well documented especially in temperate zones. In this context, butterflies have been studied more than any other group of species, partly for the reason that their past geographical ranges are well documented, which facilitates species-climate modelling and other analyses. The aim of the modelling studies is to examine to what extent shifts in species distributions can be explained by climatic and other factors. Models can also be used to predict the future distributions of species. In this thesis, I have studied the response to climate change of one species of butterfly within one geographically restricted area. The study species, the European map butterfly (Araschnia levana), has expanded rapidly northwards in Finland during the last two decades. I used statistical and dynamic modelling approaches in combination with field studies to analyse the effects of climate warming and landscape structure on the expansion. I studied possible role of molecular variation in phosphoglucose isomerase (PGI), a glycolytic enzyme affecting flight metabolism and thereby flight performance, in the observed expansion of the map butterfly at two separate expansion fronts in Finland. The expansion rate of the map butterfly was shown to be correlated with the frequency of warmer than average summers during the study period. The result is in line with the greater probability of occurrence of the second generation during warm summers and previous results on this species showing greater mobility of the second than first generation individuals. The results of a field study in this thesis indicated low mobility of the first generation butterflies. Climatic variables alone were not sufficient to explain the observed expansion in Finland. There are also problems in transferring the climate model to new regions from the ones from which data were available to construct the model. The climate model predicted a wider distribution in the south-western part of Finland than what has been observed. Dynamic modelling of the expansion in response to landscape structure suggested that habitat and landscape structure influence the rate of expansion. In southern Finland the landscape structure may have slowed down the expansion rate. The results on PGI suggested that allelic variation in this enzyme may influence flight performance and thereby the rate of expansion. Genetic differences of the populations at the two expansion fronts may explain at least partly the observed differences in the rate of expansion. Individuals with the genotype associated with high flight metabolic rate were most frequent in eastern Finland, where the rate of range expansion has been highest.

Social evolution - Has nature ever rewound the tape?

Social insects such as ants, bees, wasps and termites exhibit extreme forms of altruism where some individuals remain sterile and assist other individuals in reproduction. Hamilton's inclusive fitness theory provides a powerful framework for investigating the evolution of such altruism. Using the paper wasp Ropalidia marginata, we have quantified and delineated the role of ecological, physiological, genetic and demographic factors in social evolution. An interesting feature of the models we have developed is their symmetry so that either altruism or selfishness can evolve, depending on the numerical values of various parameters. This suggests that selfish/solitary behaviour must occasionally re-emerge even from the eusocial state, It is useful to contemplate expected intermediate states during such potential reversals. We can perhaps envisage three successive steps in such a hypothetical process: i) workers revolt against the hegemony of the queen and challenge her status as the sole reproductive, ii) workers stop producing queens and one or more of them function as egg layers (functional queen/s) capable of producing both haploid as well as diploid offspring and iii) social evolution reverses completely so that a eusocial species becomes solitary, at least facultatively. It appears that the third step, namely transition from eusociality to the solitary state, is rare and has been restricted to transitions from the primitively eusocial state only. The absence of transitions from the highly eusocial state to the solitary state may be attributed to a number of 'preventing mechanisms' such as (a) queen control of workers (b) loss of spermathecae and ability to mate (c) morphological specialization (d) caste polyethism and (e) homeostasis, which must each make the transition difficult and, taken together, perhaps very difficult. However, the discovery of a transition from the highly eusocial to the solitary state can hardly he ruled out, given that little or no effort has gone into its detection. In this paper I discuss social evolution and its possible reversal and cite potential examples of stages in the transition from the social to the solitary.

Flight metabolic rate in the Glanville fritillary butterfly

Dispersal is a highly important life history trait. In fragmented landscapes the long-term persistence of populations depends on dispersal. Evolution of dispersal is affected by costs and benefits and these may differ between different landscapes. This results in differences in the strength and direction of natural selection on dispersal in fragmented landscapes. Dispersal has been shown to be a nonrandom process that is associated with traits such as flight ability in insects. This thesis examines genetic and physiological traits affecting dispersal in the Glanville fritillary butterfly (Melitaea cinxia). Flight metabolic rate is a repeatable trait representing flight ability. Unlike in many vertebrates, resting metabolic rate cannot be used as a surrogate of maximum metabolic rate as no strong correlation between the two was found in the Glanville fritillary. Resting and flight metabolic rate are affected by environmental variables, most notably temperature. However, only flight metabolic rate has a strong genetic component. Molecular variation in the much-studied candidate locus phosphoglucose isomerase (Pgi), which encodes the glycolytic enzyme PGI, has an effect on carbohydrate metabolism in flight. This effect is temperature dependent: in low to moderate temperatures individuals with the heterozygous genotype at the single nucleotide polymorphism (SNP) AA111 have higher flight metabolic rate than the common homozygous genotype. At high temperatures the situation is reversed. This finding suggests that variation in enzyme properties is indeed translated to organismal performance. High-resolution data on individual female Glanville fritillaries moving freely in the field were recorded using harmonic radar. There was a strong positive correlation between flight metabolic rate and dispersal rate. Flight metabolic rate explained one third of the observed variation in the one-hour movement distance. A fine-scaled analysis of mobility showed that mobility peaked at intermediate ambient temperatures but the two common Pgi genotypes differed in their reaction norms to temperature. As with flight metabolic rate, heterozygotes at SNP AA111 were the most active genotype in low to moderate temperatures. The results show that molecular variation is associated with variation in dispersal rate through the link of flight physiology under the influence of environmental conditions. The evolutionary pressures for dispersal differ between males and females. The effect of flight metabolic rate on dispersal was examined in both sexes in field and laboratory conditions. The relationship between flight metabolic rate and dispersal rate in the field and flight duration in the laboratory were found to differ between the two sexes. In females the relationship was positive, but in males the longest distances and flight durations were recorded for individuals with low flight metabolic rate. These findings may reflect male investment in mate locating. Instead of dispersing, males with high flight metabolic rate may establish territories and follow a perching strategy when locating females and hence move less on the landscape level. Males with low metabolic rate may be forced to disperse due to low competitive success or may show adaptations to an alternative strategy: patrolling. In the light of life history trade-offs and the rate of living theory having high metabolic rate may carry a cost in the form of shortened lifespan. Experiments relating flight metabolic rate to longevity showed a clear correlation in the opposite direction: high flight metabolic rate was associated with long lifespan. This suggests that individuals with high metabolic rate do not pay an extra physiological cost for their high flight capacity, rather there are positive correlations between different measures of fitness. These results highlight the importance of condition.

Spatial ecology of a specialist insect herbivore : the leaf-mining moth Tischeria ekebladella on the pedunculate oak Quercus robur

Herbivorous insects comprise a major part of terrestrial biodiversity, and their interactions with their host plants and natural enemies are of vast ecological importance. A large body of research demonstrates that the ecology and evolution of these insects may be affected by trophic interactions, by abiotic influences, and by intraspecific processes, but so far research on these individual aspects has rarely been combined. This thesis uses the leaf-mining moth Tischeria ekebladella and the pedunculate oak (Quercus robur) as a case study to assess how spatial variation in trophic interactions and the physical distribution of host trees jointly affect the distribution, dynamics and evolution of a host-specific herbivore. With respect to habitat quality, Tischeria ekebladella experiences abundant variation at several spatial scales. Most of this variation occurs at small scales notably among leaves and shoots within individual trees. While hypothetically this could cause moths to evolve an ability to select leaves and shoots of high quality, I did not find any coupling between female preference and offspring performance. Based on my studies on temporal variation in resource quality I therefore propose that unpredictable temporal changes in the relative rankings of individual resource units may render it difficult for females to predict the fate of their developing offspring. With respect to intraspecific processes, my results suggest that limited moth dispersal in relation to the spatial distribution of oak trees plays a key role in determining the regional distribution of Tischeria ekebladella. The distribution of the moth is aggregated at the landscape level, where local leaf miner populations are less likely to be present where oaks are scarce. A modelling exercise based on empirical dispersal estimates revealed that the moth population on Wattkast an island in south-western Finland is spatially structured overall, but that the relative importance of local and regional processes on tree-specific moth dynamics varies drastically across the landscape. To conclude, my work in the oak-Tischeria ekebladella system demonstrates that the local abundance and regional distribution of a herbivore may be more strongly influenced by the spatial location of host trees than by their relative quality. Hence, it reveals the importance of considering spatial context in the study of herbivorous insects, and forms a bridge between the classical fields of plant-insect interactions and spatial ecology.

Spatial ecology of an oak-associated herbivore community : A metacommunity of herbivores

Habitat fragmentation is currently affecting many species throughout the world. As a consequence, an increasing number of species are structured as metapopulations, i.e. as local populations connected by dispersal. While excellent studies of metapopulations have accumulated over the past 20 years, the focus has recently shifted from single species to studies of multiple species. This has created the concept of metacommunities, where local communities are connected by the dispersal of one or several of their member species. To understand this higher level of organisation, we need to address not only the properties of single species, but also establish the importance of interspecific interactions. However, studies of metacommunities are so far heavily biased towards laboratory-based systems, and empirical data from natural systems are urgently needed. My thesis focuses on a metacommunity of insect herbivores on the pedunculate oak Quercus robur a tree species known for its high diversity of host-specific insects. Taking advantage of the amenability of this system to both observational and experimental studies, I quantify and compare the importance of local and regional factors in structuring herbivore communities. Most importantly, I contrast the impact of direct and indirect competition, host plant genotype and local adaptation (i.e. local factors) to that of regional processes (as reflected by the spatial context of the local community). As a key approach, I use general theory to generate testable hypotheses, controlled experiments to establish causal relations, and observational data to validate the role played by the pinpointed processes in nature. As the central outcome of my thesis, I am able to relegate local forces to a secondary role in structuring oak-based insect communities. While controlled experiments show that direct competition does occur among both conspecifics and heterospecifics, that indirect interactions can be mediated by both the host plant and the parasitoids, and that host plant genotype may affect local adaptation, the size of these effects is much smaller than that of spatial context. Hence, I conclude that dispersal between habitat patches plays a prime role in structuring the insect community, and that the distribution and abundance of the target species can only be understood in a spatial framework. By extension, I suggest that the majority of herbivore communities are dependent on the spatial structure of their landscape and urge fellow ecologists working on other herbivore systems to either support or refute my generalization.

Population structure and evolution in the ant Plagiolepis pygmaea and its two social parasites Plagiolepis xene and Plagiolepis grassei

Social behaviour affects dispersal of animals and is an important modifier of genetic population structures. The female sex is often philopatric, which maintains coancestry within the breeding groups and promotes cooperative behaviours. This enables also inclusive fitness returns from altruism and explains why some individuals sacrifice personal reproduction for the good of others in social insects such as ants. However, reduced dispersal and population substructuring at the level of colonies may also entail inbreeding, loss of genetic diversity, and vulnerability. In addition, the most vulnerable ants are species that are evolved to parasitize colonies of other ants, and which compromise between abilities to disperse and the efficiency to parasitize the host. On the other hand, certain social organisations of ant colonies may facilitate a species to disperse outside its natural range and become a pest. Altogether, knowledge on genetic structuring of ant populations, as well as the evolution of their life histories can contribute to conservation biology and population management. The aim of this thesis was to investigate population structures and phylogenetic evolution of the ant Plagiolepis pygmaea and its two obligatory, workerless social parasites (inquilines) P. xene and P. grassei with genetic markers and DNA sequence data. The results support the general assumption that populations of inquiline parasites are highly fragmented and genetically vulnerable. Comparison of the two parasites suggests that differences in their relative abundance may follow from their interaction with the host, i.e. how well the species is adapted to reproduce in the host colonies. The results also indicate that the most recent free living ancestor to these two parasite species is their common host. This is considered to provide evidence for the controversial issue of sympatric speciation. Further, given that the level of adaptations to parasitic life history depends on the evolutionary time since the free-living ancestor, the results establish a link between species rarity and its evolutionary age. The populations of the host species P. pygmaea displayed significantly reduced dispersal both among the females (queens) and males, and high levels of inbreeding which may enhance worker altruism. In addition, the queens were found to mate with multiple males. Given the high relatedness between the queens and their mates, this occurs probably for non-genetic reasons, e.g. without benefits associated in genetically more diverse offspring. The results hence caution that the contribution of non-genetic factors to the prevailing mating patterns and genetic population structures should not be underestimated.