Viral infection changes the expression of personality traits in an insect species reared for consumption.

Disease-induced personality change results from endogenous and adaptive host responses or parasitic manipulation. Within animal husbandry systems understanding the connection between behaviour and disease is important for health monitoring and for designing systems considerate to animal welfare. However, understanding these relationships within insect mass-rearing systems is still in its infancy. We used a simple repeated behavioural-emergence test to examine parasite-induced differences in group personality traits in the house cricket Acheta domesticus, by comparing the behaviours of 37 individuals infected with the Acheta domesticus densovirus (AdDV) and 50 virus-free individuals. AdDV-infected animals had a much lower emergence probability, longer times until emergence, and did not change their behaviour with experience compared to the virus-free animals. AdDV-infected animals also had lower variation in their probability of emergence within the population, most likely related to animals displaying a relatively uniform sickness response. These infected animals also had higher variation in their response to experimental trial experience; this greater variation resulted from a difference between males and females. Infected females responded to experience in a similar way as virus-free animals, while AdDV-infected males showed a response to experience in the opposite direction: i.e., while all other groups reduced emergence time with experience, infected males always increased their mean emergence time as trials progressed. Our results are important not only in the context of animal personality research, but also with regards to creating husbandry systems and disease monitoring within the insects-as-food industry that are considerate to both production traits and animal welfare.

Capturing the dynamics of small populations: A retrospective assessment using long-term data for an island reintroduction.

The art of population modelling is to incorporate factors essential for capturing a population's dynamics while otherwise keeping the model as simple as possible. However, it is unclear how optimal model complexity should be assessed, and whether this optimal complexity has been affected by recent advances in modelling methodology. This issue is particularly relevant to small populations because they are subject to complex dynamics but inferences about those dynamics are often constrained by small sample sizes. We fitted Bayesian hierarchical models to long-term data on vital rates (survival and reproduction) for the toutouwai Petroica longipes population reintroduced to Tiritiri Matangi, a 220-ha New Zealand island, and quantified the performance of those models in terms of their likelihood of replicating the observed population dynamics. These dynamics consisted of overall growth from 33 (±0.3) to 160 (±6) birds from 1992-2018, including recoveries following five harvest events for further reintroductions to other sites. We initially included all factors found to affect vital rates, which included inbreeding, post-release effects (PRE), density-dependence, sex, age and random annual variation, then progressively removed these factors. We also compared performance of models where data analysis and simulations were done simultaneously to those produced with the traditional two-step approach, where vital rates are estimated first then fed into a separate simulation model. Parametric uncertainty and demographic stochasticity were incorporated in all projections. The essential factors for replicating the population's dynamics were density-dependence in juvenile survival and PRE, i.e. initial depression of survival and reproduction in translocated birds. Inclusion of other factors reduced the precision of projections, and therefore the likelihood of matching observed dynamics. However, this reduction was modest when the modelling was done in an integrated framework. In contrast, projections were much less precise when done with a two-step modelling approach, and the cost of additional parameters was much higher under the two-step approach. These results suggest that minimization of complexity may be less important than accounting for covariances in parameter estimates, which is facilitated by integrating data analysis and population projections using Bayesian methods.

Virus Diversity and Loads in Crickets Reared for Feed: Implications for Husbandry.

Insects generally have high reproductive rates leading to rapid population growth and high local densities; ideal conditions for disease epidemics. The parasites and diseases that naturally regulate wild insect populations can also impact when these insects are produced commercially, on farms. While insects produced for human or animal consumption are often reared under high density conditions, very little is known about the microbes associated with these insects, particularly those with pathogenic potential. In this study we used both target-free and targeted screening approaches to explore the virome of two cricket species commonly reared for feed and food, Acheta domesticus and Gryllus bimaculatus. The target-free screening of DNA and RNA from a single A. domesticus frass sample revealed that only 1% of the nucleic acid reads belonged to viruses, including known cricket, insect, bacterial and plant pathogens, as well as a diverse selection of novel viruses. The targeted screening revealed relatively high levels of Acheta domesticus densovirus, invertebrate iridovirus 6 and a novel iflavirus, as well as low levels of Acheta domesticus volvovirus, in insect and frass samples from several retailers. Our findings highlight the value of multiple screening approaches for a comprehensive and robust cricket disease monitoring and management strategy. This will become particularly relevant as-and-when cricket rearing facilities scale up and transform from producing insects for animal feed to producing insects for human consumption.

Virus Prospecting in Crickets-Discovery and Strain Divergence of a Novel Iflavirus in Wild and Cultivated Acheta domesticus.

Orthopteran insects have high reproductive rates leading to boom-bust population dynamics with high local densities that are ideal for short, episodic disease epidemics. Viruses are particularly well suited for such host population dynamics, due to their supreme ability to adapt to changing transmission criteria. However, very little is known about the viruses of Orthopteran insects. Since Orthopterans are increasingly reared commercially, for animal feed and human consumption, there is a risk that viruses naturally associated with these insects can adapt to commercial rearing conditions, and cause disease. We therefore explored the virome of the house cricket Acheta domesticus, which is both part of the natural Swedish landscape and reared commercially for the pet feed market. Only 1% of the faecal RNA and DNA from wild-caught A. domesticus consisted of viruses. These included both known and novel viruses associated with crickets/insects, their bacterial-fungal microbiome, or their plant food. Relatively abundant among these viral Operational Taxonomic Units (OTUs) was a novel Iflavirus, tentatively named Acheta domesticus Iflavirus (AdIV). Quantitative analyses showed that AdIV was also abundant in frass and insect samples from commercially reared crickets. Interestingly, the wild and commercial AdIV strains had short, extremely divergent variation hotspots throughout the genome, which may indicate specific adaptation to their hosts' distinct rearing environments.

Using long-term data for a reintroduced population to empirically estimate future consequences of inbreeding.

Inbreeding depression is an important long-term threat to reintroduced populations. However, the strength of inbreeding depression is difficult to estimate in wild populations because pedigree data are inevitably incomplete and because good data are needed on survival and reproduction. Predicting future population consequences is especially difficult because this also requires projecting future inbreeding levels and their impacts on long-term population dynamics, which are subject to many uncertainties. We illustrate how such projections can be derived through Bayesian state-space modeling methods based on a 26-year data set for North Island Robins (Petroica longipes) reintroduced to Tiritiri Matangi Island in 1992. We used pedigree data to model increases in the average inbreeding level (F) over time based on kinship of possible breeding pairs and to estimate empirically Ne /N (effective/census population size). We used multiple imputation to model the unknown components of inbreeding coefficients, which allowed us to estimate effects of inbreeding on survival for all 1458 birds in the data set while modeling density dependence and environmental stochasticity. This modeling indicated that inbreeding reduced juvenile survival (1.83 lethal equivalents [SE 0.81]) and may have reduced subsequent adult survival (0.44 lethal equivalents [0.81]) but had no apparent effect on numbers of fledglings produced. Average inbreeding level increased to 0.10 (SE 0.001) as the population grew from 33 (0.3) to 160 (6) individuals over the 25 years, giving a Ne/N ratio of 0.56 (0.01). Based on a model that also incorporated habitat regeneration, the population was projected to reach a maximum of 331-1144 birds (median 726) in 2130, then to begin a slow decline. Without inbreeding, the population would be expected stabilize at 887-1465 birds (median 1131). Such analysis, therefore, makes it possible to empirically derive the information needed for rational decisions about inbreeding management while accounting for multiple sources of uncertainty.

Uso de Datos a Largo Plazo de una Población Reintroducida para Estimar Empíricamente las Consecuencias Futuras de la Endogamia Resumen La depresión endogámica es una amenaza importante a largo plazo para las poblaciones reintroducidas. Sin embargo, es complicado estimar la fuerza de la depresión endogámica en las poblaciones silvestres porque los datos sobre el linaje sin duda estarán incompletos y porque se necesitan datos sólidos sobre la supervivencia y la reproducción. Es especialmente difícil predecir las consecuencias poblacionales a futuro pues esto requiere proyectar a futuro los niveles de endogamia y sus impactos sobre las dinámicas poblacionales a largo plazo, las cuales están sujetas a muchas incertidumbres. Ilustramos cómo dichas proyecciones pueden derivarse mediante métodos de modelado bayesiano de estado-espacio basados en un conjunto de datos obtenidos durante 26 años para los tordos de la Isla del Norte (Petroica longipes) reintroducidos a la isla Tiritiri Matangi en 1992. Usamos datos de linaje para modelar los incrementos en el nivel promedio de endogamia ( F̲ ) a lo largo del tiempo con base en el parentesco de las posibles parejas reproductoras y para estimar empíricamente Ne/N (tamaño poblacional efectivo/por censo). Usamos una imputación múltiple para modelar los componentes desconocidos de los coeficientes de endogamia, lo que nos permitió estimar los efectos de la endogamia sobre la supervivencia para todas las aves (1458) incluidas en el conjunto de datos a la vez que modelamos la dependencia de la densidad y la estocasticidad ambiental. Este modelado indicó que la endogamia redujo la supervivencia juvenil (1.83 equivalentes letales [SE 0.81]) y podría haber reducido la subsecuente supervivencia adulta (0.44 equivalentes letales [0.81]) pero no tuvo un efecto aparente sobre los números de polluelos producidos. El nivel promedio de endogamia incrementó a 0.10 (SE 0.001) conforme la población creció de 33 (0.3) a 160 (6) individuos a lo largo de los 25 años, lo que resultó en una proporción Ne/N de 0.56 (0.01). Con base en un modelo que también incorporó la regeneración del hábitat, se proyectó que la población alcanzaría un máximo de 331-1144 aves (mediana: 726) para 2130 y después comenzaría una lenta disminución. Sin la endogamia, se esperaría que la población se estabilizaría con 887-1465 (mediana: 1131) aves. Por lo tanto, dicho análisis hace posible la derivación empírica de la información necesaria para las decisiones racionales sobre el manejo de la endogamia a la vez que considera a varias fuentes de incertidumbre.

Gene flow relates to evolutionary divergence among populations at the range margin.

BACKGROUND: Morphological differentiation between populations resulting from local adaptations to environmental conditions is likely to be more pronounced in populations with increasing genetic isolation. In a previous study a positive clinal variation in body size was observed in isolated Roesel's bush-cricket, Metrioptera roeselii, populations, but were absent from populations within a continuous distribution at the same latitudinal range. This observational study inferred that there was a phenotypic effect of gene flow on climate-induced selection in this species. METHODS: To disentangle genetic versus environmental drivers of population differences in morphology, we measured the size of four different body traits in wild-caught individuals from the two most distinct latitudinally-matched pairs of populations occurring at about 60°N latitude in northern Europe, characterised by either restricted or continuous gene flow, and corresponding individuals raised under laboratory conditions. RESULTS: Individuals that originated from the genetically isolated populations were always bigger (femur, pronotum and genital appendages) when compared to individuals from latitudinally-matched areas characterised by continuous gene flow between populations. The magnitude of this effect was similar for wild-caught and laboratory-reared individuals. We found that previously observed size cline variation in both male and female crickets was likely to be the result of local genetic adaptation rather than phenotypic plasticity. CONCLUSIONS: This strongly suggests that restricted gene flow is of major importance for frequencies of alleles that participate in climate-induced selection acting to favour larger phenotypes in isolated populations towards colder latitudes.

Ant schnapps for health and pleasure: the use of Formica rufa L. (Hymenoptera: Formicidae) to flavour aquavit.

BACKGROUND: The relationship between humans and insects goes long back and is important. Insects provide a multitude of ecosystem services for humans, e g. by pollinating crops and decomposing matter. Our current knowledge about the cultural ecosystem services that insects provide is limited and not much examined. METHOD: Scattered ethnographical descriptions and folklore records from pre-modern Sweden and other Scandinavian countries give us insights into local knowledge and use of insects among the peasantry in various parts of the country. These data have been analysed and critically reviewed. Source pluralism has been used as a method. RESULTS: The mound-building red wood ant, Formica rufa L., is one of the species that were used in Sweden for their healing properties. It was a widespread belief that the formic acid could be used to cure various diseases, especially gout and rheumatism. Both anthills and the ants themselves were used for that purpose. It was also common to flavour distilled liquor (brännvin) with ants; a remedy used for medicinal purposes. However, already in the eighteenth century, this was also used as schnapps. The cultural services provided by this species stretches throughout history and still exists today. CONCLUSION: While the use of ants in medicine has vanished, the custom of making homemade ant flavoured alcoholic beverage survives in Sweden. Nowadays it is a hobby among people who flavour their own aquavit. It is appreciated as a tasty and interesting drink.

Approaching Ecological Sustainability in the Emerging Insects-as-Food Industry.

The emerging insects-as-food industry is increasingly promoted as a sustainable alternative to other animal protein production systems. However, the exact nature of its environmental benefits are uncertain because of the overwhelming lack of knowledge concerning almost every aspect of production: from suitable species, their housing and feed requirements, and potential for accidental release. If ecological sustainability is to be a hallmark of mass insect rearing for consumption, ecologists need to engage in research related to sustainability criteria that are directly linked to key elements of the development of the industry. There is more to this subject than simply comparing feed-conversion ratios (FCRs) of insects to traditional livestock production, and we highlight areas where research needs to be immediately focused.

Diagnostic protocols for the detection of Acheta domesticus densovirus (AdDV) in cricket frass.

The European house cricket (Acheta domesticus) is a species of interest for the emerging insect-as-food industry. Acheta domesticus densovirus (AdDV) is a member of the Parvoviridae virus family which infects A. domesticus, causing widespread mortality and even extinction of local cricket populations. Despite the well-known detrimental effects of AdDV in commercial rearing of A. domesticus there are no optimized protocols to accurately and non-destructively detect and quantify the virus. This study establishes a new protocol for the detection of AdDV in faecal material from A.domesticus. The protocol includes methodological improvements, such as upgrading from conventional PCR to quantitative real-time PCR and is much more sensitive than previously published protocols. Moreover, this study shows that cricket faeces are a suitable, non-destructive sample substrate to infer reliably if a cricket population is infected with AdDV or not. Early detection of lethal or economic threats, such as disease-causing viruses, is an essential part of commercial cricket management as well as for monitoring the risk of spread to wild cricket populations or to (human) consumers.

Spatially structured environmental filtering of collembolan traits in late successional salt marsh vegetation.

Both the environment and the spatial configuration of habitat patches are important factors that shape community composition and affect species diversity patterns. Species have traits that allow them to respond to their environment. Our current knowledge on environment to species traits relationships is limited in spite of its potential importance for understanding community assembly and ecosystem function. The aim of our study was to examine the relative roles of environmental and spatial variables for the small-scale variation in Collembola (springtail) communities in a Dutch salt marsh. We used a trait-based approach in combination with spatial statistics and variance partitioning, between environmental and spatial variables, to examine the important ecological factors that drive community composition. Turnover of trait diversity across space was lower than for species diversity. Most of the variation in community composition was explained by small-scale spatial variation in topography, on a scale of 4-6 m, most likely because it determines the effect of inundation, which restricts where habitat generalists can persist. There were only small pure spatial effects on species and trait diversity, indicating that biotic interactions or dispersal limitation probably were less important for structuring the community at this scale. Our results suggest that for springtails, life form (i.e. whether they live in the soil or litter or on the surface/in vegetation) is an important and useful trait to understand community assembly. Hence, using traits in addition to species identity when analysing environment-organism relationships results in a better understanding of the factors affecting community composition.

Evaluating range-expansion models for calculating nonnative species' expansion rate.

Species range shifts associated with environmental change or biological invasions are increasingly important study areas. However, quantifying range expansion rates may be heavily influenced by methodology and/or sampling bias. We compared expansion rate estimates of Roesel's bush-cricket (Metrioptera roeselii, Hagenbach 1822), a nonnative species currently expanding its range in south-central Sweden, from range statistic models based on distance measures (mean, median, 95(th) gamma quantile, marginal mean, maximum, and conditional maximum) and an area-based method (grid occupancy). We used sampling simulations to determine the sensitivity of the different methods to incomplete sampling across the species' range. For periods when we had comprehensive survey data, range expansion estimates clustered into two groups: (1) those calculated from range margin statistics (gamma, marginal mean, maximum, and conditional maximum: ˜3 km/year), and (2) those calculated from the central tendency (mean and median) and the area-based method of grid occupancy (˜1.5 km/year). Range statistic measures differed greatly in their sensitivity to sampling effort; the proportion of sampling required to achieve an estimate within 10% of the true value ranged from 0.17 to 0.9. Grid occupancy and median were most sensitive to sampling effort, and the maximum and gamma quantile the least. If periods with incomplete sampling were included in the range expansion calculations, this generally lowered the estimates (range 16-72%), with exception of the gamma quantile that was slightly higher (6%). Care should be taken when interpreting rate expansion estimates from data sampled from only a fraction of the full distribution. Methods based on the central tendency will give rates approximately half that of methods based on the range margin. The gamma quantile method appears to be the most robust to incomplete sampling bias and should be considered as the method of choice when sampling the entire distribution is not possible.

Genetic diversity of a successful colonizer: isolated populations of Metrioptera roeselii regain variation at an unusually rapid rate.

Newly founded isolated populations need to overcome detrimental effects of low genetic diversity. The establishment success of a population may therefore depend on various mechanisms such as assortative mating, purging of deleterious alleles, creation of new mutations and/or repeated inflow of new genotypes to reduce the effects of inbreeding and further loss of genetic variation. We compared the level of genetic variation in introduced populations of an insect species (Metrioptera roeselii) far beyond its natural distribution with levels found in their respective founder populations and coupled the data with timing since establishment. This allowed us to analyze if the introduced populations showed signs of temporal changes in genetic variation and have made it possible to evaluate underlying mechanisms. For this, we used neutral genetic markers, seven microsatellite loci and a 676-bp-long sequence of the mtDNA COI gene. All tested indices (allelic richness, unbiased expected heterozygosity, effective size, haplotype diversity, and nucleotide diversity) except inbreeding coefficient had significantly higher values in populations within the founding populations inside the continuous area of the species distribution compared with the introduced populations. A logarithmic model showed a significant correlation of both allelic richness and unbiased expected heterozygosity with age of the isolated populations. Considering the species' inferred colonization history and likely introduction pathways, we suggest that multiple introductions are the main mechanism behind the temporal pattern observed. However, we argue that influences of assortative mating, directional selection, and effects of an exceptional high intrapopulation mutation rate may have impacts. The ability to regain genetic diversity at this level may be one of the main reasons why M. roeselii successfully continue to colonize northern Europe.

Causes behind insect folivory patterns in latitudinal gradients.

1.Adams and Zhang recently published one of the best studies so far of patterns of insect folivory along a latitudinal (climatic) gradient. They show clear negative trends in foliage loss in relation to temperature for certain groups of insect herbivores.2.Although their suggestion that the plant-herbivore interaction may be more important in cooler climates could be valid, they did not bring up the complementary explanation that interactions between predators and herbivores could also vary with climate. There are indications that insect natural enemies may respond more positively than insect herbivores to an increase in temperature. We argue that higher predator pressure in warmer climates may partly explain the patterns observed by Adams and Zhang.3.Synthesis.To further develop the important research concerning herbivory in a changing climate, both theoretically and empirically, plant ecologists and entomologists would mutually benefit from joining forces.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 October 2009-30 November 2009.

This article documents the addition of 411 microsatellite marker loci and 15 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Acanthopagrus schlegeli, Anopheles lesteri, Aspergillus clavatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus oryzae, Aspergillus terreus, Branchiostoma japonicum, Branchiostoma belcheri, Colias behrii, Coryphopterus personatus, Cynogolssus semilaevis, Cynoglossus semilaevis, Dendrobium officinale, Dendrobium officinale, Dysoxylum malabaricum, Metrioptera roeselii, Myrmeciza exsul, Ochotona thibetana, Neosartorya fischeri, Nothofagus pumilio, Onychodactylus fischeri, Phoenicopterus roseus, Salvia officinalis L., Scylla paramamosain, Silene latifo, Sula sula, and Vulpes vulpes. These loci were cross-tested on the following species: Aspergillus giganteus, Colias pelidne, Colias interior, Colias meadii, Colias eurytheme, Coryphopterus lipernes, Coryphopterus glaucofrenum, Coryphopterus eidolon, Gnatholepis thompsoni, Elacatinus evelynae, Dendrobium loddigesii Dendrobium devonianum, Dysoxylum binectariferum, Nothofagus antarctica, Nothofagus dombeyii, Nothofagus nervosa, Nothofagus obliqua, Sula nebouxii, and Sula variegata. This article also documents the addition of 39 sequencing primer pairs and 15 allele specific primers or probes for Paralithodes camtschaticus.

Delayed plumage maturation increases overwinter survival in North Island robins.

Many bird species show delayed plumage maturation (DPM), retaining sub-adult plumage until after their first breeding season. Most explanations assume that DPM increases fitness over the breeding season. However, unless birds undergo a full moult before breeding, DPM could also be an adaptation to increase survival over the previous winter. The winter adaptation hypothesis has never been tested owing to the difficulty of measuring overwinter survival. We experimentally tested this hypothesis in North Island robins (Petroica longipes) using a closed island population where we could accurately estimate survival. The experiment involved dyeing 41 juveniles to mimic adult males, and comparing their survival with 41 control juveniles treated with the same peroxide base minus the pigment. The population was monitored with a series of resighting surveys, and mark-recapture analysis used to estimate overwinter survival. Survival probability was estimated to be 10% for dyed birds versus 61% for control birds in 2001, and 29% for dyed birds versus 40% for control birds in the winter of 2002, supporting the winter adaptation hypothesis for DPM. Access to suitable habitat is the key factor limiting juvenile survival in this population, and the locations where dyed juveniles were sighted suggest that they were often excluded from suitable areas.

WWW design code - a new tool for colour estimation in animal studies.

BACKGROUND: The colour of animals' skin, fur, feathers or cuticula has been estimated in a large number of studies. The methods used to do so are diverse, with some being costly and not available to all researchers. In a study to measure plumage colour in a bird species, a new method of creating a colour chart was developed. While colour-charts have their own limitations, these can be minimised when they have the following properties: 1) being readily available to the majority of biologists, 2) containing a large array of colours to allow accurate recording and differentiation of subtle colour differences, 3) low cost, 4) adhering to a world-wide standard, and 5) being available in both hard-copy and digital formats to allow for various analytical methods. The method described below satisfies all of these requirements. RESULTS: Colour charts estimated to fit the range of the species' plumage colours were created on the computer screen using web software that allowed for HTML-coding (in this case Dreamweavertrade mark). The charts were adjusted using feathers from dead specimens until a satisfying range of darker and lighter colours were found. The resulting chart was printed out and was successfully used in the field to determine the plumage colour of hand-held birds. CONCLUSION: Access to a computer and printer, and the software to enable the creation of a chart, is within the reach of the vast majority of biologists. The numbers of colours that can be generated should suit most studies, with the advantage of the method being that the chart can be individually tailored to the species under study. HTML colour coding is a worldwide standard, thus the colours used in studies can be described in the methods section of journal articles using the six-digit alphanumeric code. We believe this method is very useful as a low-tech method for future estimation of individual colour.