Laboratory-reared Populations Research Articles

Population-specific responses to developmental temperature in the arboviral vector Aedes albopictus: Implications for climate change.

The increase of environmental temperature due to current global warming is not only favouring the expansion of the distribution range of many insect species, but it is also changing their phenology. Insect phenology is tightly linked to developmental timing, which is regulated by environmental temperatures. However, the degree to which the effects of developmental temperatures extend across developmental stages and their inter-stage relationships have not been thoroughly quantified in mosquitoes. Here, we used the mosquito Aedes albopictus, which is an aggressive invasive species and an arboviral vector, to study how developmental temperature influences fitness across developmental stages, thermal traits, energy reserves, transcriptome and Wolbachia prevalence in laboratory-reared populations originally collected from either temperate or tropical regions. We show that hatchability, larval and pupal viability and developmental speed are strongly influenced by temperature, and these effects extend to wing length, body mass, longevity and content of water, protein and lipids in adults in a population-specific manner. On the contrary, neither adult thermal preference nor heat resistance significantly change with temperature. Wolbachia density was generally lower in adult mosquitoes reared at 18°C than at other tested temperatures, and transcriptome analysis showed enrichment for functions linked to stress responses (i.e. cuticle proteins and chitin, cytochrome p450 and heat shock proteins) in mosquitoes reared at both 18 and 32°C. Our data showed an overall reduced vector fitness performance when mosquitoes were reared at 32°C, and the absence of isomorphy in the relationship between developmental stages and temperature in the laboratory population deriving from larvae collected in northern Italy. Altogether, these results have important implications for reliable model projections of the invasion potentials of Ae. albopictus and its epidemiological impact.

Predicting the Temperature-Driven Development of Stage-Structured Insect Populations with a Bayesian Hierarchical Model

The management of forest pests relies on an accurate understanding of the species’ phenology. Thermal performance curves (TPCs) have traditionally been used to model insect phenology. Many such models have been proposed and fitted to data from both wild and laboratory-reared populations. Using Hamiltonian Monte Carlo for estimation, we implement and fit an individual-level, Bayesian hierarchical model of insect development to the observed larval stage durations of a population reared in a laboratory at constant temperatures. This hierarchical model handles interval censoring and temperature transfers between two constant temperatures during rearing. It also incorporates individual variation, quadratic variation in development rates across insects’ larval stages, and “flexibility” parameters that allow for deviations from a parametric TPC. Using a Bayesian method ensures a proper propagation of parameter uncertainty into predictions and provides insights into the model at hand. The model is applied to a population of eastern spruce budworm (Choristoneura fumiferana) reared at 7 constant temperatures. Resulting posterior distributions can be incorporated into a workflow that provides prediction intervals for the timing of life stages under different temperature regimes. We provide a basic example for the spruce budworm using a year of hourly temperature data from Timmins, Ontario, Canada. Supplementary materials accompanying this paper appear on-line.

Investigation of the fall armyworm (Spodoptera frugiperda) gut microbiome and entomopathogenic fungus-induced pathobiome

The gut microflora plays an important role in insect development and physiology. The gut bacterial microbiome of the fall armyworm (FAW), Spodoptera frugiperda, in both cornfield and laboratory-reared populations was investigated using a 16S metagenomic approach. The alpha- and beta-diversity of the cornfield FAW populations varied among sampling sites and were higher than those of the laboratory-reared FAW population, indicating that different diets and environments influence the gut bacterial composition. To better understand the interaction between the microbiome and entomopathogenic fungi (EPF), FAWs from organic and conventionally managed corn fields and from the laboratory-reared colony were inoculated with Beauveria bassiana NCHU-153 (Bb-NCHU-153). A longer median lethal time (LT50) was observed in the Bb-NCHU-153-infected cornfield FAW population than in the laboratory-reared FAWs. In terms of the microbiome, three Bb-NCHU-153-infected FAW groups showed different gut bacterial compositions compared to noninfected FAW. Further investigation of the cooccurrence network and linear discriminant analysis (LDA) of effect size (LEfSe) revealed that the enriched bacterial genera, such as Enterococcus, Serratia, Achromobacter, and Tsukamurella, in the gut might play the role of opportunistic pathogens after fungal infection; in contrast, some gut bacteria of Methylobacterium, Marinomonas, Paenochrobactrum, Pseudomonas, Acinetobacter, Delftia, Dietzia, Gordonia, Leucobacter, Paracoccus, and Stenotrophomonas might be probiotics against EPF infection. These results indicated that EPF infection can change the gut bacterial composition and lead to a pathobiome in the FAW and that some bacterial species might protect the FAW from EPF infection. These findings could be applied to the design of pathobiome-inducing biocontrol strategies.

Diols and sugar substitutes in attractive toxic sugar baits targeting Aedes aegypti and Aedes albopictus (Diptera: Culicidae) mosquitoes.

Around the world, mosquitoes continue to transmit disease-causing pathogens and develop resistance to insecticides. We previously discovered that a generally regarded as safe (GRAS) compound, 1,2-propanediol, reduces adult mosquito survivorship when ingested. In this study, we assess and compare 5 more chemically related compounds for mosquito lethality and 8 GRAS sugar substitutes to determine toxicity. We conducted a series of feeding assays to determine if ingesting the compounds influenced mosquito mean survivorship in locally collected lab-reared populations of Aedes aegypti (Diptera, Culicidae, Linnaeus, 1762) and Aedes albopictus (Diptera, Culicidae, Skuse, 1894) mosquitoes. Our results indicate that 1,2-propanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, DL-dithiothreitol, acesulfame potassium, allulose, erythritol, sodium saccharin, stevia, and sucralose significantly reduced the mean survivorship of one or both species. Short-term trials with the most toxic compounds revealed that they could substantially affect survivorship after 24 h. We also found that there were different responses in the 2 species and that in several experimental conditions, male mosquitoes expired to a greater extent than female mosquitoes. These findings indicate that several of the compounds are toxic to mosquitoes. Further study is required to determine their effectiveness in attractive toxic sugar baits (ATSBs) as a potential component of population control strategies.

Algorithm for Experimental Estimation of the Conditional Threshold for the Duration of Low Temperatures Exposure on the Example of the Laboratory-Reared Population of Lymanrtia Dispar

The paper substantiates the introduction of a new parameter into the development model of the laboratory-reared population of Lymantria dispar, formulates and mathematically formalizes the parameter, and develops an algorithm for its experimental evaluation. It increases the correctness and adequacy of the mathematical description of the population development in terms of assessing the main parameters of its development used earlier in the model. The obtained results can be used to study the development of laboratory-reared populations of Lymantria dispar, as well as to understand the dynamics of population development in the natural environment.

Does Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida: Trypanosomatidae) modify the antennal phenotype of Triatoma dimidiata (Latreille, 1811) (Hemiptera: Triatominae)?

BackgroundTriatoma dimidiata is a vector of the protozoan parasite Trypanosoma cruzi, the etiologic agent of Chagas disease. Phenotypic plasticity allows an organism to adjust its phenotype in response to stimuli or environmental conditions. Understanding the effect of T. cruzi on the phenotypic plasticity of its vectors, known as triatomines, has attracted great interest because of the implications of the parasite–triatomine interactions in the eco-epidemiology and transmission of the etiologic agent of Chagas disease. We investigated if the infection of the vector with T. cruzi may be associated with a change in the antennal phenotype of sylvatic, domestic, and laboratory-reared populations of T. dimidiata.MethodsThe abundance of each type of sensillum (bristles, basiconic, thick- and thin-walled trichoid) on the antennae of T.cruzi-infected and non-infected T.dimidiata reared in the laboratory or collected in sylvatic and domestic ecotopes were measured under light microscopy and compared using Kruskal–Wallis non-parametric tests and permutational multivariate analysis of variance.ResultsWe found significant differences between sensilla patterns of infected and non-infected insects within sylvatic and domestic populations. Conversely, we found no significant differences between sensilla patterns of infected and non-infected insects within the laboratory-reared population. Besides, for sylvatic and domestic populations, sexual dimorphism tended to be increased in infected insects.ConclusionThe differences observed in infected insects could be linked to higher efficiency in the perception of odor molecules related to the search for distant mates and hosts and the flight dispersal in search of new habitats. In addition, these insects could have a positive effect on population dynamics and the transmission of T.cruzi.Graphical

Non-linear relationships between density and demographic traits in three Aedes species

Understanding the relationship of population dynamics to density is central to many ecological investigations. Despite the importance of density-dependence in determining population growth, the empirical relationship between density and per capita growth remains understudied in most systems and is often assumed to be linear. In experimental studies of interspecific competition, investigators often evaluate the predicted outcomes by assuming such linear relationships, fitting linear functions, and estimating parameters of competition models. In this paper, we experimentally describe the shape of the relationship between estimated population rate of change and initial density using laboratory-reared populations of three mosquito species. We estimated per capita growth rate for these experimental populations over a 30-fold range of larval densities at a standard resource abundance. We then compared fits of linear models and several different nonlinear models for the relationship of estimated rate of change and density. We find that that the relationship between density and per capita growth is strongly non-linear in Aedes aegypti (Linnaeus), Aedes albopictus (Skuse), and Aedes triseriatus (Say) mosquitoes. Components of population growth (survivorship, development time, adult size) are also nonlinearly related to initial density. The causes and consequences of this nonlinearity are likely to be important issues for population and community ecology.

Flight Capability and the Low Temperature Threshold of a Chinese Field Population of the Fall Armyworm Spodoptera frugiperda.

Simple SummaryThe fall armyworm (FAW), an invasive migratory pest from the Americas, has been rapidly spreading through the Old World recently. Although it cannot survive winter periods in temperate and subtropical regions, adults re-invade these areas each spring or summer by virtue of their migratory capability. Therefore, it is important to evaluate the flight capability of FAW moths for monitoring and predicting the range and timing of this migration. In this study, we demonstrate that the potential migration duration (and thus distance) of a field population of FAW from South China is significantly greater than previously estimated. A strong migratory tendency was observed in 58% of individuals, and the longest self-powered flight distance was 116.7 km with a cumulative flight duration of 36.51 h during a 48-h period. Furthermore, our study documented that the low temperature threshold for flight of FAW was 13.1 °C. The results of this paper will be helpful to further understand the migratory rules and flight behavior of FAW, and to provide a theoretical basis for pest forecasting and pest control.The fall armyworm, Spodoptera frugiperda (J. E. Smith), is capable of long-distance migration; thus, evaluation of its flight capability is relevant to the design of monitoring and control strategies for this pest. Previous studies have quantified the flight ability of lab-reared populations under controlled conditions, but less is known about the flight capability of natural populations. In addition, the low temperature threshold for flight in natural populations also needs to be determined. In this study, the flight capability of S. frugiperda adults emerging from field-collected larvae in South China was measured by a flight mill system. The results show that the flight capability of S. frugiperda moths varied greatly between individuals, and that some adults are capable of flying great distances. The longest self-powered flight distance was 116.7 km with a cumulative flight duration of 36.51 h during a 48-h period. Typically, the flight activity of tethered individuals was relatively stable during the first 12 h, indicating that migrating moths can fly through an entire night. Based on the accumulated flight duration in the first 12 h, moths can be clearly divided into two groups (<5 h and ≥5 h flight duration), and 58% of individuals belonged to the latter group with strong migratory tendency. Further, flight activity under low temperature conditions was tested, and the results of a logit generalized linear model indicate that the low temperature flight threshold of S. frugiperda is 13.1 °C under declining temperatures. Our results provide a scientific basis for further elucidating the flight biology and migration mechanism of S. frugiperda.

Susceptibility of a Mexican Field-Collected Wild Population of Diaphorina citri (Hemiptera: Liviidae) to Selected Insecticides

Abstract The Asian citrus psyllid, Diaphorina citri (Kuwayama) (Hemiptera: Liviidae), is a severe pest of citrus orchards worldwide. Its control is based mainly on the use of conventional insecticides, and resistance to many of those compounds is widespread. Phenotypic bioassays to detect resistance compare the response of a field-collected population with a laboratory-reared population that is susceptible to insecticides. This comparison usually does not involve a susceptible field-collected counterpart since its existence is currently rare. We found an isolated field population of D. citri living on a wild host, orange jasmine (Murraya paniculata [L.] Jack). Considering its lifetime fly capacity, gene flow with any insecticide-treated population was nonexistent or negligible. Thus, we determined the response in fourth-instar nymphs and unsexed 2- to 5-d-old adults in bioassays of commercial formulations of the commonly used insecticides chlorpyrifos, malathion, imidacloprid, and spinosad. In the bioassays, insects were placed on leaf discs previously immersed for 10 s in the respective insecticide concentrations. For adults, the lowest concentration–mortality response was with chlorpyrifos (lethal concentration 50 [LC50] of 0.72 mg L-1 and lethal concentration 95 [LC95] of 1.02 mg L-1). The highest toxicity response was with malathion (LC95 of 0.05 mg L-1). The highest toxicity response with fourth-instar nymphs was observed with spinosad (LC50 of 0.007, LC95 of 0.021 mg L-1). The estimated LC50 and LC95 values for chlorpyrifos, malathion, and spinosad were lower than those documented worldwide for these insecticides in susceptible populations of D. citri.

Active and Covert Infections of Cricket Iridovirus and Acheta domesticus Densovirus in Reared Gryllodes sigillatus Crickets.

Interest in developing food, feed, and other useful products from farmed insects has gained remarkable momentum in the past decade. Crickets are an especially popular group of farmed insects due to their nutritional quality, ease of rearing, and utility. However, production of crickets as an emerging commodity has been severely impacted by entomopathogenic infections, about which we know little. Here, we identified and characterized an unknown entomopathogen causing mass mortality in a lab-reared population of Gryllodes sigillatus crickets, a species used as an alternative to the popular Acheta domesticus due to its claimed tolerance to prevalent entomopathogenic viruses. Microdissection of sick and healthy crickets coupled with metagenomics-based identification and real-time qPCR viral quantification indicated high levels of cricket iridovirus (CrIV) in a symptomatic population, and evidence of covert CrIV infections in a healthy population. Our study also identified covert infections of Acheta domesticus densovirus (AdDNV) in both populations of G. sigillatus. These results add to the foundational research needed to better understand the pathology of mass-reared insects and ultimately develop the prevention, mitigation, and intervention strategies needed for economical production of insects as a commodity.

Tri-Trophic Relationship among Sugarcane White Leaf Disease Phytoplasma (WLDP), &lt;em&gt;Deltocephalus menoni&lt;/em&gt; (Homoptera: Cicadellidae) and Sugarcane Plant in Secondary Transmission of the Disease

Purpose: Sugarcane White Leaf Disease (WLD) is one of the most devastative diseases in cane-sugar industry in Sri Lanka and the causative agent is a distinct phytoplasma (WLDP) strain within the 16SrXI. White Leaf Disease spreads through infected seed cane and insect vector; Deltocephalus menoni (Hemiptera: Cicadellidae). This paper presents the tri-trophic relationship of the plant, vector and pathogen in disease transmission. Research Method: Four-month-old sugarcane plants of the variety SL 96 128 and laboratory-reared populations of D. menoni were used for this study. Performance of D. menoni on healthy plants and WLD plants was examined in relation to the aggregation, amount of feeding, fecundity, number of nymphs emerged, nymphal period, survival of nymph and adult’s longevity. The plant architecture, leaf histological and physiological aspects were also studied. Findings: Except for nymphal period, all behavioural characteristics were significantly-high in WLDinfected plants in 10, 14, 30, 8, 12 and 17 percent, respectively. The nymphal period of D. menoni was significantly-reduced by 12.78 percent. Number of shoots (41.83 percent) and leaves (18.96 percent) were high and distance between two leaves tends to be reduced by 32.85 percent in diseased-plants altering plant architecture into a profuse and bushy nature. Sucking distance, thicknesses of lower epidermis and phloem fibre layer in leaves were significantly reduced in infected plants. Leaf N, P, K and moisture content increased (24.89, 34.78, 28.64 and 3.85percent) while leaf wax content was reduced by 4.93 percent. Originality/value: Disease infected plants are augmenting its vector; D. menoni by attracting, enhancing survival and population build-up which promotes the transmission of WLD phytoplasma itself. There by regular inspection and rogueing out of WLD infected clumps make a great impact on secondary transmission of WLD by D. menoni.

Comprehensive analysis of male-free reproduction in Monomorium triviale (Formicidae: Myrmicinae).

We report comprehensive evidence for obligatory thelytokous parthenogenesis in an ant Monomorium triviale. This species is characterized by distinct queen-worker dimorphism with strict reproductive division of labor: queens produce both workers and new queens without mating, whereas workers are completely sterile. We collected 333 nests of this species from 14 localities and three laboratory-reared populations in Japan. All wild queens dissected had no sperm in their spermathecae. Laboratory observation confirmed that virgin queens produced workers without mating. Furthermore, microsatellite genotyping showed identical heterozygous genotypes between mothers and their respective daughters, suggesting an extremely low probability of sexual reproduction. Microbial analysis detected no bacterial genera that are known to induce thelytokous parthenogenesis in Hymenoptera. Finally, the lack of variation in partial sequences of mitochondrial DNA among individuals sampled from across Japan suggests recent rapid spread or selective sweep. M. triviale would be a promising model system of superorganism-like adaptation through comparative analysis with well-studied sexual congeners, including the pharaoh ant M. pharaonis.

Shifting microbiomes complement life stage transitions and diet of the bird parasite Philornis downsi from the Galapagos Islands.

Domestication disconnects an animal from its natural environment and diet, imposing changes in the attendant microbial community. We examine these changes in Philornis downsi (Muscidae), an invasive parasitic fly of land birds in the Galapagos Islands. Using a 16S rDNA profiling approach we studied the microbiome of larvae and adults of wild and laboratory-reared populations. These populations diverged in their microbiomes, significantly more so in larval than in adult flies. In field-collected second-instar larvae, Klebsiella (70.3%) was the most abundant taxon, while in the laboratory Ignatzschineria and Providencia made up 89.2% of the community. In adults, Gilliamella and Dysgonomonas were key members of the core microbiome of field-derived females and males but had no or very low representation in the laboratory. Adult flies harbour sex-specific microbial consortia in their gut, as male core microbiomes were significantly dominated by Klebsiella. Thus, P. downsi microbiomes are dynamic and shift correspondingly with life cycle and diet. Sex-specific foraging behaviour of adult flies and nest conditions, which are absent in the laboratory, may contribute to shaping distinct larval, and adult male and female microbiomes. We discuss these findings in the context of microbe-host co-evolution and the implications for control measures.

Genetic structure and symbiotic profile of worldwide natural populations of the Mediterranean fruit fly, Ceratitis capitata

BackgroundThe Mediterranean fruit fly, Ceratitis capitata, is a cosmopolitan agricultural pest of worldwide economic importance and a model for the development of the Sterile Insect Technique (SIT) for fruit flies of the Tephritidae family (Diptera). SIT relies on the effective mating of laboratory-reared strains and natural populations, and therefore requires an efficient mass-rearing system that will allow for the production of high-quality males. Adaptation of wild flies to an artificial laboratory environment can be accompanied by negative effects on several life history traits through changes in their genetic diversity and symbiotic communities. Such changes may lead to reduced biological quality and mating competitiveness in respect to the wild populations. Profiling wild populations can help understand, and maybe reverse, deleterious effects accompanying laboratory domestication thus providing insects that can efficiently and effectively support SIT application.ResultsIn the present study, we analyzed both the genetic structure and gut symbiotic communities of natural medfly populations of worldwide distribution, including Europe, Africa, Australia, and the Americas. The genetic structure of 408 individuals from 15 distinct populations was analyzed with a set of commonly used microsatellite markers. The symbiotic communities of a subset of 265 individuals from 11 populations were analyzed using the 16S rRNA gene-based amplicon sequencing of single individuals (adults). Genetic differentiation was detected among geographically distant populations while adults originated from neighboring areas were genetically closer. Alpha and beta diversity of bacterial communities pointed to an overall reduced symbiotic diversity and the influence of the geographic location on the bacterial profile.ConclusionsOur analysis revealed differences both in the genetic profile and the structure of gut symbiotic communities of medfly natural populations. The genetic analysis expanded our knowledge to populations not analyzed before and our results were in accordance with the existing scenarios regarding this species expansion and colonization pathways. At the same time, the bacterial communities from different natural medfly populations have been characterized, thus broadening our knowledge on the microbiota of the species across its range. Genetic and symbiotic differences between natural and laboratory populations must be considered when designing AW-IPM approaches with a SIT component, since they may impact mating compatibility and mating competitiveness of the laboratory-reared males. In parallel, enrichment from wild populations and/or symbiotic supplementation could increase rearing productivity, biological quality, and mating competitiveness of SIT-important laboratory strains.

Biological aspects and populational preference of Cotesia flavipes between Diatraea saccharalis and Diatraea flavipennella

Biological aspects of wild and laboratory-reared populations of Cotesia flavipes was assessed parasitizing Diatraea saccharalis and Diatraea flavipennella. The experiments were conducted using a climate-controlled room adjusted to 26 ± 2 °C, relative humidity of 70 ± 10%, and 12:12 h (Light: Dark) photoperiod. The choice and no-choice tests were run using arenas holding infested pieces of stalks with parasitoid release inside the arena and allowed a searching time of 6 h. After this period, the stalks were opened and the larvae single reared until molting to pupa or forming parasitoid pupae. An experimental design completely randomized in a 2 × 2 factorial arrangement was performed. The wild population of C. flavipes exhibited preference and better performance parasitizing D. flavipennella. Research to evaluate the parasitism efficiency and quality of the parasitoids crossing wild and laboratory populations of C. flavipes is necessary to enhance field release success.

Ecomorphological divergence and habitat lability in the context of robust patterns of modularity in the cichlid feeding apparatus

BackgroundAdaptive radiations are characterized by extreme and/or iterative phenotypic divergence; however, such variation does not accumulate evenly across an organism. Instead, it is often partitioned into sub-units, or modules, which can differentially respond to selection. While it is recognized that changing the pattern of modularity or the strength of covariation (integration) can influence the range or rate of morphological evolution, the relationship between shape variation and covariation remains unclear. For example, it is possible that rapid phenotypic change requires concomitant changes to the underlying covariance structure. Alternatively, repeated shifts between phenotypic states may be facilitated by a conserved covariance structure. Distinguishing between these scenarios will contribute to a better understanding of the factors that shape biodiversity. Here, we explore these questions using a diverse Lake Malawi cichlid species complex, Tropheops, that appears to partition habitat by depth.ResultsWe construct a phylogeny of Tropheops populations and use 3D geometric morphometrics to assess the shape of four bones involved in feeding (mandible, pharyngeal jaw, maxilla, pre-maxilla) in populations that inhabit deep versus shallow habitats. We next test numerous modularity hypotheses to understand whether fish at different depths are characterized by conserved or divergent patterns of modularity. We further examine rates of morphological evolution and disparity between habitats and among modules. Finally, we raise a single Tropheops species in environments mimicking deep or shallow habitats to discover whether plasticity can replicate the pattern of morphology, disparity, or modularity observed in natural populations.ConclusionsOur data support the hypothesis that conserved patterns of modularity permit the evolution of divergent morphologies and may facilitate the repeated transitions between habitats. In addition, we find the lab-reared populations replicate many trends in the natural populations, which suggests that plasticity may be an important force in initiating depth transitions, priming the feeding apparatus for evolutionary change.

Genetic and Morphologic Variation in a Potential Mosquito Biocontrol Agent, Hydrochara Affinis (Coleoptera: Hydrophilidae)

Hydrochara affinis (Coleoptera: Hydrophilidae), a water scavenger beetle, was recently identified as a natural and effective agent for biological mosquito control; it was reported to exhibit high rates of mosquito larvae predation. However, maintaining the quality (i.e., natural ecological attributes, such as genetic variation) of laboratory-reared populations is essential for ensuring the long-term success of biological control programs. Accordingly, here, we aimed to use mitochondrial Cytochrome c oxidase subunit I (COI) sequences to document the genetic diversity, population structure, and phylogenetic position of natural and lab-reared H. affinis populations in South Korea and use geometric morphometric analysis to investigate the populations’ morphological divergence. The natural H. affinis populations possessed high genetic diversity and numerous COI haplotypes, suggesting that these populations were healthy and could be directly applied to mosquito habitats without alterations to their natural genetic attributes. The lab-reared populations also possessed high genetic diversity and, thus, the potential for high adaptive capacity to new environments. Although no distinct population genetic structures were observed, quantitative variation was observed in the body shape of both the natural and lab-reared populations. The high levels of genetic and morphologic variation observed in the H. affinis populations examined here indicate the species’ favorable conservation status, genetic diversity, adaptive capacity, and, thus, “suitability” for field application as an effective mosquito control agent.

Establishment of a Colony of Phlebotomus argentipes under Laboratory Conditions and Morphometric Variation between Wild-Caught and Laboratory-Reared Populations.

The field-based studies on sand flies are not adequate to uncover information required for the control of the leishmaniasis through reduction of vector populations. Therefore, establishment and maintenance of laboratory colonies of sand flies is an essential step in leishmaniasis research. In the current study, a colony of P. argentipes was established from wild-caught sand flies following standard procedures from the published literature. Morphological measurements of laboratory-reared and wild-caught individual sand flies were compared to assess the difference between two groups. The colony was successfully established under confined laboratory conditions. The comparison of morphometric parameters revealed that the laboratory-reared sand flies are significantly larger than those caught from wild, suggesting a possibility of increased fitness of sand flies under favorable environmental conditions which may cause higher prevalence in the disease. The current study reports the first successful attempt in colonizing sand flies under laboratory conditions. However, the colony data suggest that the conditions extracted from the published literature need to be optimized to suit local settings in order to achieve maximum population sizes within the available amount of resources.

Unraveling Assemblage, Functions and Stability of the Gut Microbiota of Blattella germanica by Antibiotic Treatment.

Symbiosis between prokaryotes and eukaryotes is a widespread phenomenon that has contributed to the evolution of eukaryotes. In cockroaches, two types of symbionts coexist: an endosymbiont in the fat body (Blattabacterium), and a rich gut microbiota. The transmission mode of Blattabacterium is vertical, while the gut microbiota of a new generation is mainly formed by bacterial species present in feces. We have carried out a metagenomic analysis of Blattella germanica populations, treated and non-treated with two antibiotics (vancomycin and ampicillin) over two generations to (1) determine the core of bacterial communities and potential functions of the gut microbiota and (2) to gain insights into the mechanisms of resistance and resilience of the gut microbiota. Our results indicate that the composition and functions of the bacteria were affected by treatment, more severely in the case of vancomycin. Further results demonstrated that in an untreated second-generation population that comes from antibiotic-treated first-generation, the microbiota is not yet stabilized at nymphal stages but can fully recover in adults when feces of a control population were added to the diet. This signifies the existence of a stable core in either composition and functions in lab-reared populations. The high microbiota diversity as well as the observed functional redundancy point toward the microbiota of cockroach hindguts as a robust ecosystem that can recover from perturbations, with recovery being faster when feces are added to the diet.

Effects of the winter temperature regime on survival, body mass loss and post-winter starvation resistance in laboratory-reared and field-collected ladybirds

Ongoing climate change results in increasing temperatures throughout the seasons. The effects of climate change on insect performance are less studied during the winter season than during the growing season. Here, we investigated the effects of various winter temperature regimes (warm, normal and cold) on the winter performance of the invasive ladybird Harmonia axyridis (Coleoptera: Coccinellidae). Winter survival, body mass loss and post-winter starvation resistance were measured for a laboratory-reared population as well as three populations collected from the field prior to overwintering. The warm winter regime increased the survival rate and body mass loss and reduced post-winter starvation resistance compared to those of the ladybirds in the cold winter regime. The effects of the temperature regime were qualitatively similar for the laboratory-reared and field-collected beetles; however, there were significant quantitative differences in all measured overwintering parameters between the laboratory-reared and field-collected populations. The winter survival of the laboratory-reared beetles was much lower than that of the field-collected beetles. The laboratory-reared beetles also lost a larger proportion of their body mass and had reduced post-winter starvation resistance. Winter survival was similar between the females and males, but compared to the males, the females lost a smaller proportion of their body mass and had better post-winter starvation resistance. The pre-overwintering body mass positively affected winter survival and post-winter starvation resistance in both the laboratory-reared and field-collected ladybirds. The significant differences between the laboratory-reared and field-collected individuals indicate that quantitative conclusions derived from studies investigating solely laboratory-reared individuals cannot be directly extrapolated to field situations.