Benefits of insect colours: a review from social insect studies

Unveiling Arthropod Responses to Climate Change: A Functional Trait Analysis in Intensive Pastures

This study investigates the impact of elevated temperatures on arthropod communities in intensively managed pastures on the volcanic island of Terceira, Azores (Portugal), using a functional trait approach. Open Top Chambers (OTCs) were employed to simulate increased temperatures, and the functional traits of ground dwelling arthropods were analyzed along a small elevation gradient (180-400 m) during winter and summer. Key findings include lower abundances of herbivores, coprophagous organisms, detritivores, and fungivores at high elevations in summer, with predators showing a peak at middle elevations. Larger-bodied arthropods were more prevalent at higher elevations during winter, while beetles exhibited distinct ecological traits, with larger species peaking at middle elevations. The OTCs significantly affected the arthropod communities, increasing the abundance of herbivores, predators, coprophagous organisms, and fungivores during winter by alleviating environmental stressors. Notably, iridescent beetles decreased with elevation and were more common inside OTCs at lower elevations, suggesting a thermoregulatory advantage. The study underscores the importance of considering functional traits in assessing the impacts of climate change on arthropod communities and highlights the complex, species-specific nature of their responses to environmental changes.

Overview on tyrosinases: Genetics, molecular biology, phylogenetic relationship

Tyrosinases (TYRs) are enzymes found in various organisms that are crucial for melanin biosynthesis, coloration, and UV protection. They play vital roles in insect cuticle sclerotization, mollusk shell formation, fungal and bacterial pigmentation, biofilm formation, and virulence. Structurally, TYRs feature copper-binding sites that are essential for catalytic activity, facilitating substrate oxidation via interactions with conserved histidine residues. TYRs exhibit diversity across animals, plants, fungi, mollusks, and bacteria, reflecting their roles and function. Eukaryotic TYRs undergo post-translational modifications, such as glycosylation, which affect protein folding and activity. Bacterial TYRs are categorized into five types based on their structural variation, domain organization and enzymatic properties, showing versatility across bacterial species. Moreover, bacterial TYRs, akin to fungal TYRs, have been implicated in the synthesis of secondary metabolites with antimicrobial properties. TYRs share significant sequence homology with hemocyanins, oxygen-carrier proteins in mollusks and arthropods, highlighting their evolutionary relationships. The evolution of TYRs underscores the dynamic nature of these enzymes and reflects adaptive strategies across diverse taxa.

Variety is the spice: The role of morphological variation of Triatoma infestans (Hemiptera, Reduviidae) at a macro-scale

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi (Chagas, 1909). One of the primary vectors of T. cruzi in South America is Triatoma infestans (Klug, 1834). This triatomine species is distributed across a huge latitudinal gradient, inhabiting domiciliary , peridomiciliary , and wild environments. Its wide geographic distribution provides an excellent opportunity to study the relationships between environmental gradients and intraspecific morphological variation. In this study, we investigated variations in wing size and shape in T. infestans across six ecoregions. We aimed to address the following questions: How do wing size and shape vary on a regional scale, does morphological variation follow specific patterns along an environmental or latitudinal gradient, and what environmental factors might contribute to wing variation? Geometric morphometric methods were applied to the wings of 162 females belonging to 21 T. infestans populations, 13 from Argentina (n = 105), 5 from Bolivia (n = 42), and 3 from Paraguay (n = 15). A comparison of wing centroid size across the 21 populations showed significant differences. Canonical Variate Analysis (CVA) revealed significant differences in wing shape between the populations from Argentina, Bolivia, and Paraguay, although there was a considerable overlap, especially among the Argentinian populations. Well-structured populations were observed for the Bolivian and Paraguayan groups. Two analyses were performed to assess the association between wing size and shape, geographic and climatic variables: multiple linear regression analysis (MRA) for size and Partial Least Squares (PLS) regression for shape. The MRA showed a significant general model fit. Six temperature-related variables, one precipitation-related variable, and the latitude showed significant associations with wing size. The PLS analysis revealed a significant correlation between wing shape with latitude, longitude, temperature-related, and rainfall-related variables. Wing size and shape in T. infestans populations varied across geographic distribution. Our findings demonstrate that geographic and climatic variables significantly influence T. infestans wing morphology.

The Use of Insect Pigment in Art Works

In this compilation, the focus is on the Cochineal insect (Dactylopius coccus Costa, 1835 (Hemiptera: Dactylopiidae)), a creature native to South America that produces a potent natural red pigment known as "carmine". This pigment, utilized for obtaining the color red, has been an integral part of the art world for thousands of years. Indigenous cultures, in particular, have employed the dye extracted from this insect in the creation of textile dyes and paintings. Moreover, the Cochineal insect and its unique pigments have not only supported artistic expression but also captivated and inspired artists. During the Renaissance period, artists preferred the carmine pigment produced by the females of the Cochineal insect for obtaining bright and vivid red tones. This study delves into the history of the Cochineal insect, its role in art, and its perception in the modern world. Famous paintings created with dyes obtained from the Cochineal insect are discussed, exploring how pigments have found a place in the art world and how artists have utilized this extraordinary source to create distinctive works.

Utilization of microbial fuel cells as a dual approach for landfill leachate treatment and power production: a review

Landfill leachate, which is a complicated organic sewage water, presents substantial dangers to human health and the environment if not properly handled. Electrochemical technology has arisen as a promising strategy for effectively mitigating contaminants in landfill leachate. In this comprehensive review, we explore various theoretical and practical aspects of methods for treating landfill leachate. This exploration includes examining their performance, mechanisms, applications, associated challenges, existing issues, and potential strategies for enhancement, particularly in terms of cost-effectiveness. In addition, this critique provides a comparative investigation between these treatment approaches and the utilization of diverse kinds of microbial fuel cells (MFCs) in terms of their effectiveness in treating landfill leachate and generating power. The examination of these technologies also extends to their use in diverse global contexts, providing insights into operational parameters and regional variations. This extensive assessment serves the primary goal of assisting researchers in understanding the optimal methods for treating landfill leachate and comparing them to different types of MFCs. It offers a valuable resource for the large-scale design and implementation of processes that ensure both the safe treatment of landfill leachate and the generation of electricity. The review not only provides an overview of the current state of landfill leachate treatment but also identifies key challenges and sets the stage for future research directions, ultimately contributing to more sustainable and effective solutions in the management of this critical environmental issue.

Unraveling the Role of Cuticular Protein 3-like (HvCP3L) in the Chitin Pathway through RNAi and Methoxyfenozide Stress Response in Heortia vitessoides Moore

Cuticle proteins (CPs) constitute a multifunctional family; however, the physiological role of Cuticle Protein 3-like (CP3L) in Heortia vitessoides Moore remains largely unclear. In this study, we cloned the HvCP3L gene from the transcriptional library of Heortia vitessoides Moore. RT-qPCR results revealed that HvCP3L exhibited high expression levels during the larval stage of Heortia vitessoides Moore, particularly at the L5D1 stage, observed in both larval and adult heads. Through RNA interference, we successfully silenced the HvCP3L gene, resulting in a significant reduction in the survival rate of Heortia vitessoides Moore, with the survival rate from larvae to adults plummeting to a mere 17.7%, accompanied by phenotypic abnormalities. Additionally, we observed that the knockdown of HvCP3L led to the inhibition of genes in the chitin pathway. Following exposure to methoxyfenozide stress, the HvCP3L gene exhibited significant overexpression, coinciding with phenotypic abnormalities. These findings underscore the pivotal role of HvCP3L in the growth and development of Heortia vitessoides Moore.

Temperature differently affects body pigmentation of the paper wasp Polistes dominula along an urban and a wider geographical gradient

In insects, different pigments, such as melanins and pterins, are involved in thermoregulation. The degree of melanisation often varies along geographical gradients, according to the so-called thermal melanism hypothesis, i.e. darker forms are found in colder places because they can warm up more quickly. Similarly, pterins work as heat sinks and thus are expected to be more abundant in colder sites. Cities, which are warmer than surrounding areas (Urban Heat Island (UHI) effect), might also be expected to influence pigmentation, although studies are lacking. Here, we sampled workers of the social paper wasp Polistes dominula (Christ, 1791) (Vespidae) across an urbanisation gradient in an Italian metropolis and used iNaturalist pictures of this species across Italy to study pigmentation patterns at both urban and larger geographical scales. We found a lower yellow intensity of abdominal spots at warmer locations. Scanning Electron Microscopy strongly suggested that yellow colouration is due xanthopterin, known to be the heat sink molecule in other social vespids. Thus, wasps from warmer (i.e., urban) environments are likely to have fewer xanthopterin granules, in line with the lack of need for heat storage due to the local thermal gradient (UHI effect). At the country level, we found that wasps at higher latitudes had smaller yellow spots on the thorax and only two spots instead of four at higher altitudes, in full accordance with the thermal melanism hypothesis. In conclusion, climatic conditions seem to affect insect colour patterns both along urban and wider geographical gradients, although colour changes may affect different body parts and pigments likely according to different needs.

Infection with a non-lethal fungal parasite is associated with increased immune investment in the ant Myrmica scabrinodis

Social insects, such as ants, are preferred host organisms of pathogens and parasites because colonies are densely populated, and the number of potential hosts is high in the same place and time. Within a colony, individuals are exposed differentially to risks according to their function and age. Thus, older individuals forage and are therefore the most exposed to infection, predation, or physical stress, while young workers mostly stay inside the sheltered nest being less exposed. Immune investment is considered to be dependent on an individual's age and pathogen pressure. Long-term exposure to a parasite could affect the immune activity of individuals in an intriguing way that interferes with the age-dependent decline in immunocompetence. However, there are only few cases in which such interferences can be studied. The myrmecopathogenic fungus Rickia wasmannii, which infects entire colonies without killing the workers, is a suitable candidate for such studies. We investigated the general immunocompetence of Myrmica scabrinodis ant workers associated with non-lethal fungal infection by measuring the levels of active phenoloxidase (PO) and total PO (PPO) (reflecting the amount of both active and inactive forms of the enzyme) in two age classes. The level of PO proved to be higher in infected workers than in uninfected ones, while the level of PPO increased with age but was not affected by infection. Overall, these results indicate that a long-term infection could go hand in hand with increased immune activity of ant workers, conferring them higher level of protection.

Optical multiband polarimetric modulation sensing for gender and species identification of flying native solitary pollinators

Native pollinators are crucial to local ecosystems but are under threat with the introduction of managed pollinators, e.g., honeybees (Apis mellifera). We explored the feasibility of employing the entomological lidar technique in native pollinator abundance studies. This study included individuals of both genders of three common solitary bee species, Osmia californica, Osmia lignaria, and Osmia ribifloris, native to North America. Properties including optical cross-section, degree of linear polarization, and wingbeat power spectra at all three wavelengths have been extracted from the insect signals collected by a compact stand-off sensing system. These properties are then used in the classification analysis. For species with temporal and spatial overlapping, the highest accuracies of our method exceed 96% (O. ribifloris & O. lignaria) and 93% (O. lignaria & O. californica). The benefit of employing the seasonal activity and foraging preference information in enhancing identification accuracy has been emphasized.

Establishing Age-Based Color Changes for the American Burying Beetle, Nicrophorus americanus Olivier, with Implications for Conservation Efforts

The American burying beetle, Nicrophorus americanus Olivier, is a federally protected insect that once occupied most of eastern North America. Adult beetles feature distinct, recognizable markings on the pronotum and elytra, and color changes with age have been observed. Among the challenges faced by research scientists and conservation practitioners is the ability to determine beetle age in the field between and including teneral (young) and senescent (old) adult stages. Using 20 (10 male and 10 female) captive-bred beetles, we characterized the change in greyscale and red, green, and blue (RGB) color channels over the lifespan of each beetle for field-aging applications. Individual beetles were photographed at set intervals from eclosion to death, and color data were extracted using open-source ImageJ Version 1.54f software. A series of linear mixed-effects models determined that red color showed the steepest decrease among all color channels in the pronotum and elytral markings, with a more significant decrease in the pronotum. The change in greyscale between the pronotum and elytral markings was visibly different, with more rapid darkening in the pronotum. The resulting pronotum color chart was tested under field conditions in Oklahoma, aging 299 adult N. americanus, and six age categories (day range) were discernable by eye: teneral (0-15), late teneral (15-31), early mature (31-45), mature (45-59), early senescent (59-76), and senescent (76-90). The ability to more precisely estimate age will improve population structure estimates, laboratory breeding programs, and potential reintroduction efforts.

Optimizing total ammonia-nitrogen concentration for enhanced microbial fuel cell performance in landfill leachate treatment: a bibliometric analysis and future directions

Untreated landfill leachate can harm the environment and human health due to its organic debris, heavy metals, and nitrogen molecules like ammonia. Microbial fuel cells (MFCs) have emerged as a promising technology for treating landfill leachate and generating energy. However, high concentrations of total ammonia-nitrogen (TAN), which includes both ammonia and the ammonium ion, can impede MFC performance. Therefore, maintaining an adequate TAN concentration is crucial, as both excess and insufficient levels can reduce power generation. To evaluate the worldwide research on MFCs using landfill leachate as a substrate, bibliometric analysis was conducted to assess publication output, author-country co-authorship, and author keyword co-occurrence. Scopus and Web of Science retrieved 98 journal articles on this topic during 2011-2022; 18 were specifically evaluated and analysed for MFC ammonia inhibition. The results showed that research on MFC using landfill leachate as a substrate began in 2011, and the number of related papers has consistently increased every 2 years, totaling 4060 references. China, India, and the USA accounted for approximately 60% of all global publications, while the remaining 40% was contributed by 70 other countries/territories. Chongqing University emerged as one of the top contributors among this subject's ten most productive universities. Most studies found that maintaining TAN concentrations in the 400-800 mg L-1 in MFC operation produced good power density, pollution elimination, and microbial acclimatization. However, the database has few articles on MFC and landfill leachate; MFC ammonia inhibition remains the main factor impacting system performance. This bibliographic analysis provides excellent references and future research directions, highlighting the current limitations of MFC research in this area.

Müllerian mimicry among bees and wasps: a review of current knowledge and future avenues of research

Many bees and stinging wasps, or aculeates, exhibit striking colour patterns or conspicuous coloration, such as black and yellow stripes. Such coloration is often interpreted as an aposematic signal advertising aculeate defences: the venomous sting. Aposematism can lead to Müllerian mimicry, the convergence of signals among different species unpalatable to predators. Müllerian mimicry has been extensively studied, notably on Neotropical butterflies and poison frogs. However, although a very high number of aculeate species harbour putative aposematic signals, aculeates are under-represented in mimicry studies. Here, we review the literature on mimicry rings that include bee and stinging wasp species. We report over a hundred described mimicry rings, involving a thousand species that belong to 19 aculeate families. These mimicry rings are found all throughout the world. Most importantly, we identify remaining knowledge gaps and unanswered questions related to the study of Müllerian mimicry in aculeates. Some of these questions are specific to aculeate models, such as the impact of sociality and of sexual dimorphism in defence levels on mimicry dynamics. Our review shows that aculeates may be one of the most diverse groups of organisms engaging in Müllerian mimicry and that the diversity of aculeate Müllerian mimetic interactions is currently under-explored. Thus, aculeates represent a new and major model system to study the evolution of Müllerian mimicry. Finally, aculeates are important pollinators and the global decline of pollinating insects raises considerable concern. In this context, a better understanding of the impact of Müllerian mimicry on aculeate communities may help design strategies for pollinator conservation, thereby providing future directions for evolutionary research.

Sex recognition does not modulate aggression toward nest intruders in a paper wasp

During social interactions, the behavior of an individual often depends on the sex of its social partner. Many animal societies have males and females that play very different behavioral roles, although they coexist and interact non-sexually. At specific phases of the colony cycle, social wasp females and males are contemporaries within a nest, they often interact, although mating occurs mostly off the nest, therefore providing an opportunity to test sex discrimination in contexts other than classical sexual ones. We performed a lure presentation experiment to test if Mischocyttarus metathoracicus discriminate between conspecifics of the 2 sexes during on-nest social interactions. Female wasps discriminated conspecific sex during experimentally simulated nest intrusions. Visual and chemical cues may account for this sex discrimination. Despite sex discrimination (evidenced by differential inspective behavior from the nest females toward the female and the male lures), female wasps were as aggressive toward lures of both sexes. In the female-dominated hymenopteran societies, males are often subordinate and not aggressive on nest, resulting in females directing less aggression to them compared to other females. Instead, M. metathoracicus males and females are both aggressive toward nestmates, so they might be perceived as similar threat during on-nest social interactions.

Cholesteric Liquid Crystal Polymeric Coatings for Colorful Artificial Muscles and Motile Humidity Sensor Skin Integrated with Magnetic Composites

Structural colorful cholesterics show impressive susceptibility to external stimulation, leading to applications in electro/mechano-chromic devices. However, out-of-plane actuation of structural colorful actuators based on cholesterics and the integration with other stimulation remains underdeveloped. Herein, colorful actuators and motile humidity sensors are developed using humidity-responsive cholesteric liquid crystal networks (CLCNs) and magnetic composites. The developed colorful actuator can exhibit synergistic out-of-plane shape morphing and color change in response to humidity, with CLCNs as colorful artificial muscles. Through the integration with magnetic control, the motile sensor can be navigated to open and confined spaces with the aid of friction to detect local relative humidity. The integration of multi-stimulation actuation of cholesteric magnetic actuators will expand the research frontier of structural colorful actuators and motile sensors for confined spaces.

Global Catastrophic Biological Risks in the Post-COVID-19 World: Time to Act Is Now

Global Catastrophic Biological Risks (GCBRs) refer to events with biological agents that can result in unprecedented or catastrophic disasters that are beyond the collective response-abilities of nation-states and the existing governance instruments of global governance and international affairs. This article offers a narrative review, with a view to new hypothesis development to rethink GCBRs after coronavirus disease 2019 (COVID-19) so as to better prepare for future pandemics and ecological crises, if not to completely prevent them. To determine GCBRs' spatiotemporal contexts, define causality, impacts, differentiate the risk and the event, would improve theorization of GCBRs compared to the impact-centric current definition. This could in turn lead to improvements in preparedness, response, allocation of resources, and possibly deterrence, while actively discouraging lack of due biosecurity diligence. Critical governance of GCBRs in ways that unpack the political power-related dimensions could be particularly valuable because the future global catastrophic events might be different in quality, scale, and actors. Theorization of GCBRs remains an important task going forward in the 21st century in ways that draw from experiences in the field, while integrating flexibility, versatility, and critically informed responses to GCBRs.

New Color-Patterned Species of Microtendipes Kieffer, 1913 (Diptera: Chironomidae) and a Deep Intraspecific Divergence of Species by DNA Barcodes

The genus Microtendipes Kieffer (Diptera: Chironomidae) has a nearly worldwide distribution, comprising more than 60 species, which are further divided into two species groups based on larval stage. However, species delimitation and identification among the adults of this genus are controversial and uncertain. For instance, previous studies have provided many synonymies based on conspecific color pattern variations in Microtendipes species. Here, we used DNA barcode data to address Microtendipes species delimitation as well as to test whether color pattern variations can be diagnostic characters for interspecific identification. The 151 DNA barcodes used, 51 of which were contributed by our laboratory, represent 21 morphospecies. Species with specific color patterns could be accurately separated based on DNA barcodes. Consequently, the color patterns of adult males could be important diagnostic characters. The average intraspecific and interspecific sequence divergences were 2.8% and 12.5%, respectively, and several species exhibited deep intraspecific divergences higher than 5%. Molecular operational taxonomic units (OTUs) ranged from 21 to 73, based on methods including phylogenetic trees, the assemble species by automatic partitioning method, the Poisson tree process (PTP), and the general mixed Yule-coalescent (GMYC) method. As a result of these analyses, five new species were recognized (M. baishanzuensis sp. nov., M. bimaculatus sp. nov., M. nigrithorax sp. nov., M. robustus sp. nov., and M. wuyiensis sp. nov.).

Comparative Analysis of Facial Coloration between Introduced and Source Populations of the Red Wood Ant Formica paralugubris

The variation in the typical black-reddish color of red wood ants (Formica rufa group) has been recently suggested as a good indicator of habitat quality, being dependent on environmental conditions. However, the relative contribution of external factors and heritability in shaping this trait is poorly investigated. In this study, we compared the facial coloration of workers from four introduced populations of Formica paralugubris with those of the two Alpine populations from which they had been taken. We used a Relative Warp Analysis to describe the variations in the shape of this trait. We expected each introduced population to be more similar to its population of origin if the color pattern was predominantly genetically determined. On the contrary, due to the considerable differences in habitat type and climate between the Alps and the Apennines, we expected to observe differences between the introduced population and their origin population if the coloration was mostly environmentally determined. With one exception that we discuss, the results showed that ants from the two source populations had different phenotypes, and that the introduced populations had a shape similar to the population of origin, suggesting a stable genetic background. Surprisingly, the habitat type seems to have a less clear effect, even if within-population differences suggest the influence of very localized environmental factors. Finally, we found that the facial coloration shape is affected by the ant’s size, a result in line with previous studies.

Color, activity period, and eye structure in four lineages of ants: Pale, nocturnal species have evolved larger eyes and larger facets than their dark, diurnal congeners

The eyes of insects display an incredible diversity of adaptations to enhance vision across the gamut of light levels that they experience. One commonly studied contrast is the difference in eye structure between nocturnal and diurnal species, with nocturnal species typically having features that enhance eye sensitivity such as larger eyes, larger eye facets, and larger ocelli. In this study, we compared eye structure between workers of closely related nocturnal and diurnal above ground foraging ant species (Hymenoptera: Formicidae) in four genera (Myrmecocystus, Aphaenogaster, Temnothorax, Veromessor). In all four genera, nocturnal species tend to have little cuticular pigment (pale), while diurnal species are heavily pigmented (dark), hence we could use cuticle coloration as a surrogate for activity pattern. Across three genera (Myrmecocystus, Aphaenogaster, Temnothorax), pale species, as expected for nocturnally active animals, had larger eyes, larger facet diameters, and larger visual spans compared to their dark, more day active congeners. This same pattern occurred for one pale species of Veromessor, but not the other. There were no consistent differences between nocturnal and diurnal species in interommatidial angles and eye parameters both within and among genera. Hence, the evolution of eye features that enhance sensitivity in low light levels do not appear to have consistent correlated effects on features related to visual acuity. A survey across several additional ant genera found numerous other pale species with enlarged eyes, suggesting these traits evolved multiple times within and across genera. We also compared the size of the anterior ocellus in workers of pale versus dark species of Myrmecocystus. In species with larger workers, the anterior ocellus was smaller in pale than in dark species, but this difference mostly disappeared for species with smaller workers. Presence of the anterior ocellus also was size-dependent in the two largest pale species.

Climate and body size have differential roles on melanism evolution across workers in a worldwide ant genus

One of the main aspects associated with the diversity in animal colour is the variation in melanization levels. In ectotherms, melanism can be advantageous in aiding thermoregulation through heat absorption. Darker bodies may also serve as a shield from harmful UV-B radiation. Melanism may also confer protection against parasites and predators through improving immunity responses and camouflage in regions with high precipitation, with complex and shaded vegetations and greater diversity of pathogens and parasites. We studied melanism evolution in the globally distributed ant genus Pheidole under the pressures of temperature, UV-B radiation and precipitation, while considering the effects of body size and nest habit, traits that are commonly overlooked. More importantly, we account for worker caste polymorphism, which is marked by distinct roles and behaviours. We revealed for the first time distinct evolutionary trajectories for each worker subcaste. As expected, major workers from species inhabiting locations with lower temperatures and higher precipitation tend to be more melanised. Curiously, we show a slight trend where minor workers of larger species also tend to have darker bodies when inhabiting regions with higher precipitation. Lastly, we did not find evidence for the effects of UV-B radiation and nest habit in the lightness variation of workers. Our paper explores the evolution of ant melanization considering a marked ant worker polymorphism and a wide range of ecological factors. We discuss our findings under the light of the Thermal Melanism Hypothesis, the Photoprotection Hypothesis and the Gloger's Rule.

Effects of eri silkworm (Samia ricini) pupae inclusion in broiler diets on growth performances, health, carcass characteristics and meat quality

OBJECTIVE

The objective of this study was to determine the appropriate amount of eri silkworm pupae meal (Samia ricini) to add to the broiler diet.

METHODS

Two hundred 1-day-old male chicks with initial weight at 50.03±0.56 g/chick were divided into four groups (five replicates per group and ten chicks per replicate): a control group fed a corn-soybean diet and experimental groups supplemented with 5%, 10%, or 15% eri silkworm pupae meal. All experimental diets were isocaloric and isonitrogenous and formulated respecting nutrient requirements. Growth performances were collected during the experimental period and other parameters were collected at the end of experiment when broilers reached thirty-eight days old.

RESULTS

A higher cold carcass weight and skin yellowness in the broilers fed 10% eri silkworm pupae meal compared with the other groups (p<0.05). Therefore, supplementation with 10% eri silkworm pupae meal is suggested for the broiler diet formulation because it did not cause any serious negative consequences on growth performance, health status, carcass characteristics and meat quality. However, the usage of eri silkworm pupae meal at 15% is not recommend because it led to negative outcomes.

CONCLUSION

The addition of eri silkworm pupae at 10% can be used as an alternative protein sources for broiler chickens which provided benefits on cold carcass weight and skin yellowness without adverse effects.

Preservation and Taphonomy of Fossil Insects from the Earliest Eocene of Denmark

Simple Summary

Insect fossils dating 55 million-years-old from the Stolleklint Clay and Fur Formation of Denmark are known to preserve both fine morphological details and color patterns. To enhance our understanding on how such fragile animals are retained in the fossil record, we examined a pair of beetle elytra, a wasp and a damselfly using sensitive analytical techniques. In our paper, we demonstrate that all three insect fossils are composed of cuticular remains (that is, traces of the exoskeleton) that, in turn, are dominated by the natural pigment eumelanin. In addition, the beetle elytra show evidence of a delicate lamellar structure comparable to multilayered reflectors that produce metallic hues in modern insects. Our results contribute to improved knowledge on the process of fossilization of insect body fossils in marine environments.

Abstract

Marine sediments of the lowermost Eocene Stolleklint Clay and Fur Formation of north-western Denmark have yielded abundant well-preserved insects. However, despite a long history of research, in-depth information pertaining to preservational modes and taphonomic pathways of these exceptional animal fossils remains scarce. In this paper, we use a combination of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to assess the ultrastructural and molecular composition of three insect fossils: a wasp (Hymenoptera), a damselfly (Odonata) and a pair of beetle elytra (Coleoptera). Our analyses show that all specimens are preserved as organic remnants that originate from the exoskeleton, with the elytra displaying a greater level of morphological fidelity than the other fossils. TEM analysis of the elytra revealed minute features, including a multilayered epicuticle comparable to those nanostructures that generate metallic colors in modern insects. Additionally, ToF-SIMS analyses provided spectral evidence for chemical residues of the pigment eumelanin as part of the cuticular remains. To the best of our knowledge, this is the first occasion where both structural colors and chemical traces of an endogenous pigment have been documented in a single fossil specimen. Overall, our results provide novel insights into the nature of insect body fossils and additionally shed light on exceptionally preserved terrestrial insect faunas found in marine paleoenvironments.

Phenotypic Plasticity of Common Wasps in an Industrially Polluted Environment in Southwestern Finland

Simple Summary

Social insects are ecologically and economically important as ecosystem engineers, agricultural pest predators, pollinators, and seed dispersers. Many of the vespid wasps are social insects. Our study species, Common wasp Vespula vulgaris, is native to Finland and classified as invasive in some other parts of the world. The Common wasp have conspicuous yellow and black pigmentation. Their functions and activities in the environment expose the species to environmental pollutants and this study assessed the effect of heavy-metals on common wasps collected from the vicinity of a metal smelter in southwestern Finland. The samples collected were analyzed using various methods such as color morph categorization, electron microscopy, metal analysis, and energy dispersive X-ray analysis (EDX). The methods were used to understand the effects of metal pollution on the species and the adaptive response. Our results indicated phenotypic variation between common wasp samples across the pollution gradient and an adaptive melanin encapsulation process.

Abstract

Insects vary in the degree of their adaptability to environmental contamination. Determining the responses with phenotypic plasticity in ecologically important species in polluted environments will ease further conservation and control actions. Here, we investigated morphological characteristics such as body size, body mass, and color of the common wasp Vespula vulgaris in an industrially polluted environment, considering different levels of metal pollution, and we studied the localization of contaminants in the guts of wasps. We revealed some differences in morphological characteristics and melanization of wasps collected in habitats with high, moderate, and low levels of pollution. The results indicated that V. vulgaris from highly polluted environments had reduced melanin pigmentation on the face but increased melanin pigmentation on the 2nd tergite of the abdomen. In addition, with transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX), we found metal particles from the midgut of wasps originating from the polluted environment. Most of the particles were encapsulated with melanin pigment. This finding confirmed that in wasps, ingested metal particles are accumulated in guts and covered by melanin layers. Our data suggest that wasps can tolerate metal contamination but respond phenotypically with modification of their size, coloration, and probably with the directions of the melanin investments (immunity or coloration). Thus, in industrially polluted areas, wasps might probably survive by engaging phenotypic plasticity with no significant or visible impact on the population.

The evolution and genetics of lepidopteran egg and caterpillar coloration

Insect colors and color patterns have fascinated biologists for centuries. While extensive research has focused on the adult colors of Drosophila and butterflies, our understanding of how colors are generated and diversified in embryonic and larval stages remains limited, especially, the genetics behind the protective coloration of the immobile embryonic and larval stages. Lepidoptera, one of the most widespread and species-rich insect orders, are extremely helpful uncovering those mechanisms due to their remarkable diverse colors in eggs and caterpillars within or among species, and these colors usually are variable in different developmental stages or in response to different environments. Here we review the recent progress on coloration of lepidopteran eggs and caterpillars, focusing on the genetic basis, developmental mechanisms, ecology, and evolution underlying the remarkable color diversity.

Immune function differences between two color morphs of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae) at different life stages

Several studies demonstrated that in insects cuticle melanism is interrelated with pathogen resistance, as melanin-based coloration and innate immunity possess similar physiological pathways. For some insects, higher pathogen resistance was observed in darker individuals than in individuals with lighter cuticular coloration. Here, we investigated the difference in immune response between two color morphs (black and red) and between the life stages (pupa and adult) of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae). Here in this study, cuticle thickness, microbial test (antimicrobial activity, phenoloxidase activity, and hemocyte density), and immune-related gene expression were evaluated at different stages of RPW. Study results revealed that cuticle thickness of black phenotype was thicker than red phenotype at old-pupa stage, while no significant difference found at adult stage. These results may relate to the development processes of epidermis in different stages of RPW. The results of antimicrobial activity, phenoloxidase (PO) activity, and hemocyte density analyses showed that adults with a red phenotype had stronger pathogen resistance than those with a black phenotype. In addition to antimicrobial activity and PO activity, we tested relative gene expression in the fat body of old pupae. The results of hemolymph antimicrobial analysis showed that old pupae with a red phenotype were significantly different from those with a black phenotype at 12 hr after Staphylococcus aureus injection, suggesting that red phenotype pupae were more sensitive to S. aureus. Examination of gene expression in the fat body also revealed that the red phenotype had a higher immune response than the black phenotype. Our results were inconsistent with the previous conclusion that dark insects had increased immune function, suggesting that the relationship between cuticle pigmentation and immune function in insects was not a direct link. Additional possible factors that are associated with the immune response, such as life-history, developmental, physiological factors also need to be considered.

Pigmentation and color pattern diversity in Odonata

The order Odonata (dragonflies and damselflies) comprises diurnal insects with well-developed vision, showing diverse colors in adult wings and bodies. It is one of the most ancestral winged insect groups. Because Odonata species use visual cues to recognize each other, color patterns have been investigated from ecological and evolutionary viewpoints. Here we review the recent progress on molecular mechanisms of pigmentation, especially focused on light-blue coloration. Results from histology and pigment analysis showed that ommochrome pigments on the proximal layer and pteridine pigments on the distal layer of the epidermis are essential for light-blue coloration. We also summarize genes involved in the biosynthesis of three major insect pigments conserved across insects and discuss that gene-functional analysis deserves future studies.