Genetic basis of chemical communication in eusocial insects.

Social behavior is one of the most fascinating and complex behaviors in humans and animals. A fundamental process of social behavior is communication among individuals. It relies on the capability of the nervous system to sense, process, and interpret various signals (e.g., pheromones) and respond with appropriate decisions and actions. Eusocial insects, including ants, some bees, some wasps, and termites, display intriguing cooperative social behavior. Recent advances in genetic and genomic studies have revealed key genes that are involved in pheromone synthesis, chemosensory perception, and physiological and behavioral responses to varied pheromones. In this review, we highlight the genes and pathways that regulate queen pheromone-mediated social communication, discuss the evolutionary changes in genetic systems, and outline prospects of functional studies in sociobiology.

Cyclopropane Hydrocarbons from the Springtail Vertagopus sarekensis─A New Class of Cuticular Lipids from Arthropods.

The epicuticle of insects is usually coated with a complex mixture of hydrocarbons, primarily straight-chain and methyl-branched alkanes and alkenes. We were interested in whether springtails (Collembola), a sister class of the insects, also use such compounds. We focused here on Vertagopus sarekensis, an abundant Isotomidae species in European high alpine regions, exhibiting coordinated group behavior and migration. This coordination, suggesting chemical communication, made the species interesting for our study on epicuticular hydrocarbons in springtails with different degrees of group behavior. We isolated a single hydrocarbon from its surface, which is the major epicuticular lipid. The structure was deduced by NMR analysis and GC/MS including derivatization. Total synthesis confirmed the structure as cis,cis-3,4,13,14-bismethylene-24-methyldotriacontane (4, sarekensane). The GC/MS analyses of some other cyclopropane hydrocarbons also synthesized showed the close similarity of both mass spectra and gas chromatographic retention indices of alkenes and cyclopropanes. Therefore, analyses of cuticular alkenes must be performed with appropriate derivatization to distinguish these two types of cuticular hydrocarbons. Sarekensane (4) is the first nonterpenoid cuticular hydrocarbon from Collembola that is biosynthesized via the fatty acid pathway, as are insect hydrocarbons, and contains unprecedented cyclopropane rings in the chain, not previously reported from arthropods.

Cryo-EM structure of the insect olfactory receptor Orco.

The olfactory system must recognize and discriminate amongst an enormous variety of chemicals in the environment. To contend with such diversity, insects have evolved a family of odorant-gated ion channels comprised of a highly conserved co-receptor (Orco) and a divergent odorant receptor (OR) that confers chemical specificity. Here, we present the single-particle cryo-electron microscopy structure of an Orco homomer from the parasitic fig wasp Apocrypta bakeri at 3.5 Å resolution, providing structural insight into this receptor family. Orco possesses a novel channel architecture, with four subunits symmetrically arranged around a central pore that diverges into four lateral conduits that open to the cytosol. The Orco tetramer has few inter-subunit interactions within the membrane and is bound together by a small cytoplasmic anchor domain. The minimal sequence conservation among ORs maps largely to the pore and anchor domain, shedding light on how the architecture of this receptor family accommodates its remarkable sequence diversity and facilitates the evolution of odour tuning.

Alternative protein sources of plant, algal, fungal and insect origins for dietary diversification in search of nutrition and health.

This review aimed to compare alternative protein sources in terms of nutritional composition and health benefits with the purpose of disseminating up-to-date knowledge and contribute for diversification of the food marked and consumers decision-making. Plant-based is the most well-established category of alternative proteins, but there is still room for diversification. Less conventional species such as chia seeds are prominent sources of ω-3 (∼60% total lipids), while hempseed and quinoa are notable sources of ω-6 (up to 58% and 61%, respectively). Edible insects and microalgae are alternative foods rich in protein (up to 70%), fibers (∼30%), as well as peptides and polysaccharides with antimicrobial, antioxidant, anti-hypertensive, antidiabetic, antidepressant, antitumor, and immunomodulatory activities. Additionally, lipid contents in insect larvae can be as high as 50%, on a dry weight basis, containing fatty acids with anti-inflammatory and antitumor properties. In contrast, edible fungi have low lipid contents (∼2%), but are rich in carbohydrates (up to 79%) and have balanced amino acid profiles. The results suggest that food formulations combining different alternative protein sources can meet dietary requirements. Further studies on flavoring and texturing processes will help to create meat and dairy analogs, thus helping to broaden acceptance and applicability of alternative protein sources.

Edible Insects an Alternative Nutritional Source of Bioactive Compounds: A Review.

Edible insects have the potential to become one of the major future foods. In fact, they can be considered cheap, highly nutritious, and healthy food sources. International agencies, such as the Food and Agriculture Organization (FAO), have focused their attention on the consumption of edible insects, in particular, regarding their nutritional value and possible biological, toxicological, and allergenic risks, wishing the development of analytical methods to verify the authenticity, quality, and safety of insect-based products. Edible insects are rich in proteins, fats, fiber, vitamins, and minerals but also seem to contain large amounts of polyphenols able to have a key role in specific bioactivities. Therefore, this review is an overview of the potential of edible insects as a source of bioactive compounds, such as polyphenols, that can be a function of diet but also related to insect chemical defense. Currently, insect phenolic compounds have mostly been assayed for their antioxidant bioactivity; however, they also exert other activities, such as anti-inflammatory and anticancer activity, antityrosinase, antigenotoxic, and pancreatic lipase inhibitory activities.

Nutritional Qualities and Enhancement of Edible Insects.

Over the last decade, the urgency to find alternative and sustainable protein sources has prompted an exponential increase in the interest in insects as a human food source. Edible insects contribute suitable amounts of energy and protein, fatty acids, and micronutrients to the human diet. Nutritional values of insects can be manipulated to meet specific needs. Edible insects in food-insecure countries can contribute to improving diets and preventing undernutrition. Bioactive compounds in insects may reduce health risks. Food safety risks are low and mainly relate to those of allergenicity. Strategies to overcome barriers to the consumption of insect products include emphasizing their sustainability, increasing their tastiness, and developing the ability to disguise insects in familiar products. A new sector of insects as food and feed is emerging. Major challenges include legislation, lowering prices by automation and cheap substrates, developing insect products that appeal to consumers, and exploring the health benefits.

Potential health benefits of edible insects.

Animal-based foods have traditionally been viewed as dietary staples because they provide many essential nutrients; however, edible insects have the potential to serve as healthy, sustainable alternatives to these because of their nutrient contents. Edible insects may have superior health benefits due to their high levels of vitamin B12, iron, zinc, fiber, essential amino acids, omega-3 and omega-6 fatty acids, and antioxidants. The addition of edible insects such as crickets to the human diet could offer a myriad of environmental and nutritional benefits including an overall reduction in greenhouse gas emissions, decreased agricultural use of land and water, improved prevention and management of chronic diseases like diabetes, cancer, and cardiovascular disease, and enhanced immune function. Future research should aim to understand the beneficial effects of whole insects or insect isolates in comparison to traditional animal- and plant-based foodstuffs. Ultimately, insects have the potential to be used as meat substitutes or dietary supplements, resulting in human health and environmental benefits. The purpose of this review is to provide additional insight on the nutrient composition of edible insects, their potential use as meat substitutes or dietary supplements, the associated health and wellness benefits, and their potential role in exercise performance.

New Eco-Sustainable Feed in Aquaculture: Influence of Insect-Based Diets on the Content of Potentially Toxic Elements in the Experimental Model Zebrafish (Danio rerio).

According to the concept of circular economy, insects represent good candidates as aquafeed ingredients. Nevertheless, there are some potential chemical risks linked with insect consumption. In this study, we reared the teleost Danio rerio, used as an experimental model, with five experimental diets characterized by increasing levels (0%, 25%, 50%, 75%, and 100%) of full-fat Hermetia illucens (Hi) prepupae, substituting for fish meal (FM) and fish oil (FO). We investigated the presence of potentially toxic elements (PTEs) Cd, Pb, Ni, As, and Hg in larval (20 days), juvenile (2 months), and adult (6 months) fish. Quantitative determinations of Cd, Pb, Ni, and As were made with an atomic absorption spectrometer; the total mercury content was determined by a direct mercury analyzer. The substitution of FM and FO with Hermetia illucens meal led to a reduction in the content of some PTEs, such as Pb, As, and Ni, in fishfeed, leading to concentrations below the legal limit of undesirable substances in animal feed. By increasing the Hi meal dietary content, we observed in the Danio rerio specimens an increase in Cd, Pb, and Ni content and a reduction in As content for all life stages. Moreover, a general increase in the content of Cd, Pb, Hg, and Ni from larvae to juvenile was measured, while the shift of Danio rerio from the juvenile to the adult stage involved a significant increase in the content of Pb, Hg, and Ni. Larvae had a reduced ability to bioaccumulate metal(loid)s compared to juveniles and adults. In conclusion, the content of PTEs in Danio rerio is influenced both by the type of diet administered and by the life stage of the animal itself. This research demonstrates the possibility of using Hi prepupae as an aquafeed ingredient without exposing fish to a chemical risk and, in perspective, allows applying these eco-sustainable diets for the breeding of edible fish species, without endangering human health.

Chemical Ecology, Biochemistry, and Molecular Biology of Insect Hydrocarbons.

Insect cuticular hydrocarbons (CHCs) consist of complex mixtures of straight-chain alkanes and alkenes, and methyl-branched hydrocarbons. In addition to restricting water loss through the cuticle and preventing desiccation, they have secondarily evolved to serve a variety of functions in chemical communication and play critical roles as signals mediating the life histories of insects. In this review, we describe the physical properties of CHCs that allow for both waterproofing and signaling functions, summarize their roles as inter- and intraspecific chemical signals, and discuss the influences of diet and environment on CHC profiles. We also present advances in our understanding of hydrocarbon biosynthesis. Hydrocarbons are biosynthesized in oenocytes and transported to the cuticle by lipophorin proteins. Recent work on the synthesis of fatty acids and their ultimate reductive decarbonylation to hydrocarbons has taken advantage of powerful new tools of molecular biology, including genomics and RNA interference knockdown of specific genes, to provide new insights into the biosynthesis of hydrocarbons.

Naturally-derived targeted therapy for wound healing: Beyond classical strategies.

This review summarizes the four processes of wound healing in the human body (hemostasis, inflammatory, proliferation, and remodeling) and the most current research on the most important factors affecting cutaneous wound healing and the underlying cellular and/or molecular pathways. Local factors, including temperature, oxygenation, and infection, and systemic factors, such as age, diabetes, sex hormones, genetic components, autoimmune diseases, psychological stress, smoking and obesity are also addressed. A better understanding of the role of these factors in wound repair could result in the development of therapeutics that promote wound healing and resolve affected wounds. Additionally, natural products obtained from plants and animals are critical targets for the discovery of novel biologically significant pharmacophores, such as medicines and agrochemicals. This review outlines the most recent advances in naturally derived targeted treatment for wound healing. These are plant-derived natural products, insect-derived natural products, marine-derived natural products, nanomaterial-based wound-healing therapeutics (metal- and non-metal-based nanoparticles), and natural product-based nanomedicine to improve the future direction of wound healing. Natural products extracted from plants and animals have advanced significantly, particularly in the treatment of wound healing. As a result, the isolation and extraction of bioactive compounds from a variety of sources can continue to advance our understanding of wound healing. Undescribed bioactive compounds or unexplored formulations that could have a role in today's medicinal arsenal may be contained in the abundance of natural products and natural product derivatives.

An insect isoscape of UK and Ireland.

RATIONALE: The study of insect migration is problematic due to the small size of insects. Stable isotope analysis can be used to elucidate movement, either by geographic assignment of location of a species, or by simply distinguishing migrant from resident populations. There are few isoscapes of any kind in the UK/Ireland available for interrogation. Thus, I have measured stable isotope ratios (of H, C, N and S) of 299 individuals of the non-migratory Brimstone moth (Opisthograptis luteolata) collected from 93 locations around the UK and Ireland by citizen scientists. METHODS: After removing lipids, stable isotope ratios were measured by continuous flow isotope ratio mass spectrometry, using either a conventional elemental analyser (C, N and S) or a high-temperature, thermal conversion elemental analyser in reductive mode. RESULTS: Maps (isoscapes) were constructed that illustrate the stable isotope spatial distribution of this insect. These are the first isoscapes of H, C, N and S of biological samples covering both UK and Ireland. CONCLUSIONS: The insect isoscape patterns can be explained from what we know of moth diet, climate and geology. Sulfur isotopes may be of particular use for distinguishing individuals from areas of unique geology. Isoscape patterns may (with care) predict isotope compositions of other, herbivorous, non-aquatic, chitinous taxa. Such isoscapes, when extended beyond the UK and Ireland, would provide a useful tool to elucidate insect migration.

Volatilome and Essential Oil of Ulomoides dermestoides: A Broad-Spectrum Medical Insect.

Ulomoides dermestoides are used as a broad-spectrum medical insect in the alternative treatment of various diseases. Preliminary volatilome studies carried out to date have shown, as the main components, methyl-1,4-benzoquinone, ethyl-1,4-benzoquinone, 1-tridecene, 1-pentadecene, and limonene. This work focused on the production of metabolites and their metabolic variations in U. dermestoides under stress conditions to provide additional valuable information to help better understand the broad-spectrum medical uses. To this end, VOCs were characterized by HS-SPME with PEG and CAR/PDMS fibers, and the first reported insect essential oils were obtained. In HS-SMPE, we found 17 terpenes, six quinones, five alkenes, and four aromatic compounds; in the essential oils, 53 terpenes, 54 carboxylic acids and derivatives, three alkynes, 12 alkenes (1-Pentadecene, EOT1: 77.6% and EOT2: 57.9%), 28 alkanes, nine alkyl disulfides, three aromatic compounds, 19 alcohols, three quinones, and 12 aldehydes were identified. Between both study approaches, a total of 171 secondary metabolites were identified with no previous report for U. dermestoides. A considerable number of the identified metabolites showed previous studies of the activity of pharmacological interest. Therefore, considering the wide variety of activities reported for these metabolites, this work allows a broader vision of the therapeutic potential of U. dermestoides in traditional medicine.

Parvaxanthines D-F and Asponguanosines C and D, Racemic Natural Hybrids from the Insect Cyclopelta parva.

Five new compounds including three pairs of enantiomeric xanthine analogues, parvaxanthines D-F (1-3), two new guanosine derivatives, asponguanosines C and D (6 and 7), along with two known adenine derivatives were isolated from the insect Cyclopelta parva. Racemic 1-3 were further separated by chiral HPLC. Their absolute configurations were assigned by spectroscopic and computational methods. It is interesting that all of these isolates are natural product hybrids. Antiviral, immunosuppressive, antitumor and anti-inflammatory properties of all the isolates were evaluated.

Analysing Sr isotopes in low-Sr samples such as single insects with inductively coupled plasma tandem mass spectrometry using N2 O as a reaction gas for in-line Rb separation.

RATIONALE: Strontium isotopes are valuable markers of provenance in a range of disciplines. Limited amounts of Sr in low-mass samples such as insects mean that conventional Sr isotope analysis precludes their use for geographic origins in many ecological studies or in applications such as biosecurity. Here we test the viability of using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with N2 O as a reaction gas for accurately determining Sr isotopes in insects with Sr < 100 ng. METHODS: Strontium isotopes were determined in solution mode using ICP-MS/MS with 0.14 L/min N2 O as a reaction gas to convert Sr+ into SrO+ for in-line separation of 87 Sr from 87 Rb. The Sr isotope reference standards NIST SRM 987, NIST SRM 1570a and NIST SRM 1547 were used to assess accuracy and reproducibility. Ten insect species collected from the wild as a proof-of-principle application were analysed for Sr concentration and Sr isotopes. RESULTS: Using ICP-MS/MS we show for the first time that internal mass bias correction of 87 Sr16 O/86 Sr16 O based on 88 Sr16 O/86 Sr16 O works to give for NIST SRM 987 a 87 Sr/86 Sr ratio of 0.7101 ± 0.012 (RSD = 0.17%) and for NIST SRM 1570a a 87 Sr/86 Sr ratio of 0.7100 ± 0.009 (RSD = 0.12%), which are within error of the accepted values. The first 87 Sr/86 Sr ratio of NIST SRM 1547 is 0.7596 ± 0.0014. Strontium analyses were run on 0.8 mL of 0.25-0.5 ppb Sr, which equates to 2-4 ng of Sr. Strontium isotope analysis with a precision of >99.8% can be achieved with in-line separation of 87 Sr from 87 Rb at least up to solutions with 25 ppb Rb. CONCLUSIONS: A minimum of 5 mg of insect tissue is required for Sr isotope analysis. This new ICP-MS/MS method enables Sr isotope analysis in single insects, allowing population-scale studies to be feasible and making possible applications with time-critical uses such as biosecurity.

Juvenile hormone III skipped bisepoxide, not its stereoisomers, as a juvenile hormone of the bean bug Riptortus pedestris.

Juvenile hormone (JH) plays a pivotal role in many aspects of insect physiology. Although its presence was first reported in a blood-sucking bug belonging to the suborder Heteroptera (true bugs), JH species in the group has long been controversial. Although some recent studies proposed a putative JH molecular species in several Heteropteran species, it is not conclusive because physicochemical analyses were insufficient in most cases. Here, we studied this issue with an ultraperformance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) equipped with C18 and chiral columns in the bean bug Riptortus pedestris (Heteroptera, Alydidae), in which the JH species has long been controversial. Although a recent study describes JHSB3 as the major JH of this species, that finding was not conclusive because its chirality has not been clarified. In the present study, we detected methyl (2R,3S,10R)-2,3;10,11-bisepoxyfarnesoate, commonly named juvenile hormone III skipped bisepoxide (JHSB3), in the culture media of the corpora cardiaca-corpus allatum (CC-CA) complex and in the hemolymph of this species by a chiral ultraperformance liquid chromatography- tandem mass spectrometer (UPLC-MS/MS). Other JHSB3 stereoisomers were not detected. Topical application of JHSB3 effectively averted diapause. These results indicate that JHSB3 is the major JH of R. pedestris. The present study further revealed that JHSB3 and its (2R,3S,10S) isomer are more potent than (2S,3R,10R) and (2S,3R,10S) isomers, which suggests that there is a significance to the configuration of the 2,3-epoxide moiety in JH action. We further found a supplemental significance to the configuration of the 10-position.

Insect C-Type Lectins in Microbial Infections.

C-type lectins (CTLs) are a family of carbohydrate-recognition domain (CRD)-containing proteins that bind to ligands in a calcium-dependent manner. CTLs act as important components of insect innate immune responses, such as pattern recognition, agglutination, encapsulation, melanization, phagocytosis and prophenoloxidase activation, as well as gut microbiome homeostasis maintenance, to defend against pathogens. Besides, some insect CTLs can facilitate pathogen infection and colonization. In this review, we describe the properties of insect CTLs and focus on explaining their role in viral, bacterial, parasitic and fungal infections.

The Potential of Insects as Alternative Sources of Chitin: An Overview on the Chemical Method of Extraction from Various Sources.

Chitin, being the second most abundant biopolymer after cellulose, has been gaining popularity since its initial discovery by Braconot in 1811. However, fundamental knowledge and literature on chitin and its derivatives from insects are difficult to obtain. The most common and sought-after sources of chitin are shellfish (especially crustaceans) and other aquatic invertebrates. The amount of shellfish available is obviously restricted by the amount of food waste that is allowed; hence, it is a limited resource. Therefore, insects are the best choices since, out of 1.3 million species in the world, 900,000 are insects, making them the most abundant species in the world. In this review, a total of 82 samples from shellfish-crustaceans and mollusks (n = 46), insects (n = 23), and others (n = 13)-have been collected and studied for their chemical extraction of chitin and its derivatives. The aim of this paper is to review the extraction method of chitin and chitosan for a comparison of the optimal demineralization and deproteinization processes, with a consideration of insects as alternative sources of chitin. The methods employed in this review are based on comprehensive bibliographic research. Based on previous data, the chitin and chitosan contents of insects in past studies favorably compare and compete with those of commercial chitin and chitosan-for example, 45% in Bombyx eri, 36.6% in Periostracum cicadae (cicada sloughs), and 26.2% in Chyrysomya megacephala. Therefore, according to the data reported by previous researchers, demonstrating comparable yield values to those of crustacean chitin and the great interest in insects as alternative sources, efforts towards comprehensive knowledge in this field are relevant.

Review on Structures of Pesticide Targets.

Molecular targets play important roles in agrochemical discovery. Numerous pesticides target the key proteins in pathogens, insect, or plants. Investigating ligand-binding pockets and/or active sites in the proteins' structures is usually the first step in designing new green pesticides. Thus, molecular target structures are extremely important for the discovery and development of such pesticides. In this manuscript, we present a review of the molecular target structures, including those of antiviral, fungicidal, bactericidal, insecticidal, herbicidal, and plant growth-regulator targets, currently used in agrochemical research. The data will be helpful in pesticide design and the discovery of new green pesticides.

Analysis of Volatile Components in Different Ophiocordyceps sinensis and Insect Host Products.

The artificial production of Ophiocordyceps sinensis mycelia and fruiting bodies and the Chinese cordyceps has been established. However, the volatile components from these O. sinensis products are not fully identified. An efficient, convenient, and widely used approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography and quadrupole time-of-flight mass spectrometry (GC×GC-QTOFMS) was developed for the extraction and the analysis of volatile compounds from three categories of 16 products, including O. sinensis fungus, Thitarodes hosts of O. sinensis, and the Chinese cordyceps. A total of 120 volatile components including 36 alkanes, 25 terpenes, 17 aromatic hydrocarbons, 10 ketones, 5 olefines, 5 alcohols, 3 phenols, and 19 other compounds were identified. The contents of these components varied greatly among the products but alkanes, especially 2,5,6-trimethyldecane, 2,3-dimethylundecane and 2,2,4,4-tetramethyloctane, are the dominant compounds in general. Three categories of volatile compounds were confirmed by partial least squares-discriminant analysis (PLS-DA). This study provided an ideal method for characterizing and distinguishing different O. sinensis and insect hosts-based products.

Insects as human food; from farm to fork.

Over the course of the last few years, the consumption of insects, known as entomophagy, has sparked increasing interest amongst scientists and environmentalists as a potential solution to the inevitable global food security and sustainability issues humans will be facing in the coming years. Despite the fact that insects have been an integral part of over 2 billion people's diet worldwide, the concept of eating insects is still new to Western culture. As a result, there are many unknowns regarding insects as a food source, and this has led to a number of studies and investigations being done in recent years to create more knowledge and awareness around this new concept in the food industry. This review discusses some of the key topics and new developments published over recent years, such as the nutritional benefits, food safety concerns, functional properties, potential product concepts and the current ideas and attitudes towards insects as a food source in Western culture. © 2017 Society of Chemical Industry.