Substantial urbanization-driven declines of larval and adult moths in a subtropical environment

Recent work has shown the decline of insect abundance, diversity and biomass, with potential implications for ecosystem services. These declines are especially pronounced in regions with high human activity, and urbanization is emerging as a significant contributing factor. However, the scale of these declines and the traits that determine variation in species-specific responses remain less well understood, especially in subtropical and tropical regions, where insect diversity is high and urban footprints are rapidly expanding. Here, we surveyed moths across an entire year in protected forested sites across an urbanization gradient to test how caterpillar and adult life stages of subtropical moths (Lepidoptera) are impacted by urbanization. Specifically, we assess how urban development affects the total biomass of caterpillars, abundance of adult moths and quantify how richness and phylogenetic diversity of macro-moths are impacted by urban development. Additionally, we explore how life-history traits condition species' responses to urban development. At the community level, we find that urban development decreases caterpillar biomass and adult moth abundance. We also find sharp declines of adult macro-moths in response to urban development across the phylogeny, leading to a decrease in species richness and phylogenetic diversity in more urban sites. Finally, our study found that smaller macro-moths are less impacted by urban development than larger macro-moths in subtropical environments, perhaps highlighting the tradeoffs of metabolic costs of urban heat favoring smaller moths over the relative benefits of dispersal for larger moths. In summary, our research underscores the far-reaching consequences of urbanization on moths and provides compelling evidence that urban forests alone may not be sufficient to safeguard biodiversity in cities.

Transcriptome analysis and immune gene expression of channel catfish (Ictalurus punctatus) fed diets with inclusion of frass from black soldier fly larvae

The larval waste, exoskeleton shedding, and leftover feed components of the black soldier fly and its larvae make up the by-product known as frass. In this study, we subjected channel catfish (Ictalurus punctatus) to a 10-week feeding trial to assess how different dietary amounts of frass inclusion would affect both systemic and mucosal tissue gene expression, especially in regard to growth and immune-related genes. Fish were divided in quadruplicate aquaria, and five experimental diets comprising 0, 50, 100, 200, and 300 g of frass per kilogram of feed were fed twice daily. At the end of the trial, liver, head kidney, gill, and intestine samples were collected for gene expression analyses. First, liver and intestine samples from fish fed with a no frass inclusion diet (control), low-frass (50 g/kg) inclusion diet, or a high-frass (300 g/kg) inclusion diet were subjected to Illumina RNA sequencing to determine global differential gene expression among diet groups. Differentially expressed genes (DEGs) included the upregulation of growth-related genes such as glucose-6-phosphatase and myostatin, as well as innate immune receptors and effector molecules such as toll-like receptor 5, apolipoprotein A1, C-type lectin, and lysozyme. Based on the initial screenings of low/high frass using RNA sequencing, a more thorough evaluation of immune gene expression of all tissues sampled, and all levels of frass inclusion, was further conducted. Using targeted quantitative PCR panels for both innate and adaptive immune genes from channel catfish, differential expression of genes was identified, which included innate receptors (TLR1, TLR5, TLR9, and TLR20A), proinflammatory cytokines (IL-1β type a, IL-1β type b, IL-17, IFN-γ, and TNFα), chemokines (CFC3 and CFD), and hepcidin in both systemic (liver and head kidney) and mucosal (gill and intestine) tissues. Overall, frass from black soldier fly larvae inclusion in formulated diets was found to alter global gene expression and activate innate and adaptive immunity in channel catfish, which has the potential to support disease resistance in this species in addition to demonstrated growth benefits.

Puke or poop? Comparison of regurgitate and faecal samples to infer alpine grasshopper (Paprides nitidus Hutton) diet in experimental plant communities

Characterising plant-herbivore interactions is important to understanding the processes that influence community structure and ecosystem functioning. Traditional methods used to identify plant-herbivore interactions are being superseded by non-destructive molecular approaches that can infer interactions with greater resolution and accuracy from environmental DNA (e.g. faeces and regurgitate). However, few studies have compared the success of using different sample types and whether they provide similar or contrasting information about species' diet. Here we compared the success of DNA amplification and host plant species identification using restriction fragment length polymorphism (RFLP) applied to faecal and regurgitate samples collected from alpine grasshoppers Paprides nitidus Hutton during a grassland community mesocosm experiment. We found that DNA amplification success was 23% and 86% higher for faecal than regurgitate samples from female and male grasshoppers, respectively. In contrast, successful host plant identification using RFLP was 9% higher for regurgitate than faecal samples. The mean number of host plant species identified per sample (1.40) did not differ between sample types or grasshopper sexes. Of the 136 paired faecal-regurgitate samples, just 41% and 74% produced exactly or partially matching host plant identifications, respectively, indicating that different sample types provided complementary information about herbivore diet. Some plant species were more likely to be identified from faecal samples than expected by chance, and we found that this identification bias skewed towards plant species with higher investment in leaf tissue. We conclude that multiple sample types may be required to fully characterise an invertebrate herbivore species' diet.

Bioconversion of Different Waste Streams of Animal and Vegetal Origin and Manure by Black Soldier Fly Larvae Hermetia illucens L. (Diptera: Stratiomyidae)

Black soldier fly larvae (BSFL) are considered a commercially viable solution for global organic waste problems. The objective of this study was to assess the feasibility of rearing BSFL on a wide range of low-value waste streams and its potential to transform them into high-quality animal feed and fertilizer. Six waste streams of different origins were selected and each tested in triplicate. Several parameters were analysed: growth performance, waste reduction index (WRI), conversion efficiency (ECI) and larval composition. Frass composition was also analysed. Larvae reared on fast food waste (FFW) had the highest ECI and WRI and the lowest values when reared on pig manure slurry mixed with silage grass (PMLSG) and slaughter waste (SW). The highest protein content was found for larvae reared on mushroom stems (MS) although this substrate had the lowest protein content. Moreover, the frass nutritional profile was proportionally related to the substrate's nutritional profile: the protein-rich substrate (SW) resulted in protein-rich frass and the low-protein substrate (MS) resulted in protein-poor frass. The same was true for the lipid content. In conclusion, this study showed that BSFL can be successfully reared on a wide range of waste streams that can affect the larval and frass chemical compositions.

The Variety of Applications of Hermetia illucens in Industrial and Agricultural Areas-Review

Hermetia illucens (Diptera: Stratiomyidae, Linnaeus, 1978), commonly known as the black soldier fly (BSF), is a saprophytic insect, which in recent years has attracted significant attention from both the scientific community and industry. The unrestrained appetite of the larvae, the ability to forage on various organic waste, and the rapid growth and low environmental impact of its breeding has made it one of the insect species bred on an industrial scale, in the hope of producing fodder or other ingredients for various animals. The variety of research related to this insect has shown that feed production is not the only benefit of its use. H. illucens has many features and properties that could be of interest from the point of view of many other industries. Biomass utilization, chitin and chitosan source, biogas, and biodiesel production, entomoremediation, the antimicrobial properties of its peptides, and the fertilizer potential of its wastes, are just some of its potential uses. This review brings together the work of four years of study into H. illucens. It summarizes the current state of knowledge and introduces the characteristics of this insect that may be helpful in managing its breeding, as well as its use in agro-industrial fields. Knowledge gaps and under-studied areas were also highlighted, which could help identify future research directions.

The Effect of Mealworm Frass on the Chemical and Microbiological Properties of Horticultural Peat in an Incubation Experiment

Insect farming is growing in popularity, and in addition to insect meal, it generates waste products such as exuviae and frass, which can be recycled in agriculture. The aim of this incubation experiment was to evaluate the effect of Tenebrio molitor L. frass on selected chemical and biological properties of deacidified peat, which is widely used in horticulture. The optimal rate of frass fertilizer in peat for growing vegetables and ornamental plants was determined, with special emphasis on mineral nitrogen levels. Peat was fertilized with five nitrogen rates, 0, 50, 100, 200, and 400 mg dm^-3, and supplied with frass or urea. The study demonstrated that frass can be used as organic fertilizer. An increase in the nitrogen rate significantly increased mineral nitrogen content and electrical conductivity and decreased Ca content in peat. Both frass and urea increased the ammonification rate at the beginning of incubation and the nitrification rate from the second week of the experiment. Higher frass rates (5 and 10 g dm^-3) increased the content of plant-available nutrients (nitrogen, phosphorus, magnesium, potassium, and sodium) in peat as well as the abundance of microorganisms supporting organic matter mineralization. Unlike frass, urea increased the counts of nitrogen-fixing bacteria in peat.

Colorado potato beetle exploits frass-associated bacteria to suppress defense responses in potato plants

BACKGROUND

Colorado potato beetle (CPB; Leptinotarsa decemlineata) is a destructive quarantine pest that develops broad physiological adaptations to potato plants. During feeding, CPB deposits a copious amount of wet frass onto the surface of leaves and stems that remains in place for long periods. Insect behaviors such as feeding, crawling and oviposition are able to mediate plant defenses. However, the specific role of CPB defecation-associated cues in manipulating plant defenses remains unclear.

RESULTS

CPB larval frass significantly suppressed potato polyphenol oxidase activity and enhanced larval growth on treated potato plants. The incorporation of antibiotics into larval frass triggered higher jasmonic acid (JA)-regulated defense responses in potato plants compared with antibiotic-free frass. Four bacterial symbionts belonging to the genera Acinetobacter, Citrobacter, Enterobacter and Pantoea were isolated from larval frass and suppressed plant defenses. After reinoculation of these bacteria into axenic larvae, Acinetobacter and Citrobacter were found to be highly abundant in the frass, whereas Enterobacter and Pantoea were less abundant probably due to the negative effect of potato steroidal glycoalkaloids (SGA) such as α-solanine. Furthermore, direct application of Acinetobacter and Citrobacter to wounded potato plants significantly inhibited the expression of genes associated with the JA-mediated defense signaling pathway and SGA biosynthesis.

CONCLUSION

Our findings demonstrate that CPB exploits frass-associated bacteria as a deceptive strategy of plant defense suppression, adding an interesting dimension to our understanding of how CPB successfully specializes on potato plants. © 2022 Society of Chemical Industry.

Glasshouse Evaluation of the Black Soldier Fly Waste Product HexaFrass™ as an Organic Fertilizer

Simple Summary

In recent years farmers have relied on highly efficient synthetic nitrogen fertilizers to achieve increased yields. However, the extensive application of nitrogen-based fertilizers is now associated with several negative impacts on the environment, such as pollution of waterways and eutrophication of lakes and estuaries. To promote more sustainable food production, less environmentally damaging methods of adding nutrients and organic matter to soils are needed. One potential organic fertilizer has arisen recently as a by-product of insect farming. Mass production of the black soldier fly (BSF; Hermetia illucens L.) results in the production of waste or frass, which is high in organic matter and contains essential plant nutrients such as nitrogen, phosphorous and potassium. In this study, it was found that one such product, HexaFrass™, improved the shoot and root growth of several herb and vegetable plants when grown under glasshouse conditions, and had similar effects to other commonly-used organic fertilizers, such as chicken manure pellets. As HexaFrass™ is a waste by-product, and the BSF are themselves raised on other food or organic wastes, the use of BSF frass has good potential as a sustainable, more environmentally-friendly, organic soil amendment.

Abstract

The mass farming of the black soldier fly (BSF; Hermetia illucens L.), to produce insect-based feed for livestock and fish, results in considerable amounts of insect frass, which contains substantial amounts of organic matter and bioavailable nutrients. Insect frass has shown good potential as a soil amendment and organic fertilizer. This study examined the effects of HexaFrass™ on the growth of common vegetables and herbs under glasshouse conditions. In an organically-rich potting mix, HexaFrass™ increased shoot dry weight by an average of 25%, although this effect was variable among test plants. In other trials, application of HexaFrass™ caused an increase in plant growth similar to that obtained by applying chicken manure and a commercial organic fertilizer. Increases in shoot and root dry weight showed quadratic relationships with HexaFrass™ dose, indicating that application of excessive quantities could lead to plant inhibition. Shoot:root dry matter ratio tended to increase with HexaFrass™ dose suggesting there was no specific stimulation or enhancement of root growth. Overall, these results provide further evidence of the potential of insect frass as an effective organic fertilizer for vegetables and herbs.

The Rapid Identification of Anoplophora chinensis (Coleoptera: Cerambycidae) From Adult, Larval, and Frass Samples Using TaqMan Probe Assay

A molecular diagnostic method using TaqMan probe qPCR is presented for the identification of Anoplophora chinensis (Förster) (Coleoptera: Cerambycidae) from whole body insects (adults and larvae) and frass samples stored under different conditions. The results showed a perfect amplification of DNA from all samples; the repeatability and reproducibility of the protocol were very good, with standard deviations of inter-run and intra-run variability less than or equal to 0.5. The assay allowed to discern all A. chinensis samples from those of the other non-target wood-borer species, with 100% correspondence to the homologous sequences. No amplification or cross reactions were observed with A. glabripennis (Motschulsky) (Coleoptera: Cerambycidae), which is the most related species among those tested. The protocol was validated by an internal blind panel test which showed a good correspondence between the results obtained by different operators in the same lab. The analytical sensitivity for the lab frass with the Probe qPCR, namely the lowest amount of A. chinensis DNA that can be detected (LoD), was 0.64 pg/µl with a Cq of 34.87. The use of indirect evidence for the identification of a pest is an important feature of the method, which could be crucial to detect the presence of wood-boring insects. This diagnostic tool can help prevent the introduction of A. chinensis into new environments or delimit existing outbreak areas thanks to indirect frass diagnosis.

Mealworm (Tenebrio molitor): Potential and Challenges to Promote Circular Economy

Simple Summary

The main objective of this review is to analyse the potential of insects from the perspective of circular economy, focusing our attention on mealworm larvae. After pointing out the key concepts of circular economy and describing the use of insects in bioconversion processes, we discuss the most relevant uses of the mealworm in different industries, which show the great contribution this insect can make within circular productive systems. This topic has attracted a lot of attention due to its implications from an economic and environmental point of view. Recently, mealworm larvae were positively assessed by European Food Safety Authority (EFSA) as a safe novel food. As a matter of fact, the mealworm is the first edible insect to achieve this important milestone in the EU. Due to this new scientific opinion, considerable expectations arise on mealworms and their potential in different fields, which will surely lead to market developments in the following years.

Abstract

Over the last few years, the concept of Circular Economy (CE) has received a lot of attention due to its potential contribution to the Sustainable Development Goals (SDGs), especially by reconciling economic growth with the protection of the environment through its grow-make-use-restore approach. The use of insects in circular production systems has been a good example of this concept as insects can transform a wide range of organic waste and by-products into nutritious feedstuffs, which then go back into the production cycle. This paper explores the potential of mealworms (Tenebrio molitor) in circular production systems by reviewing their use and applicability in several industries such as pharmaceuticals, agriculture, food, etc. Despite the high versatility of this insect and its potential as a substitute source of nutrients and other valuable components, there are still many legislative and behavioural challenges that hinder its adoption and acceptance.

Method for Zero-Waste Circular Economy Using Worms for Plastic Agriculture: Augmenting Polystyrene Consumption and Plant Growth

Polystyrene (PS) is one of the major plastics contributing to environmental pollution with its durability and resistance to natural biodegradation. Recent research showed that mealworms (Tenebrio molitor) and superworms (Zophobas morio) are naturally able to consume PS as a carbon food source and degrade them without observable toxic effects. In this study, we explored the effects of possible food additives and use of worm frass as potential plant fertilizers. We found that small amounts of sucrose and bran increased PS consumption and that the worm frass alone could support dragon fruit cacti (Hylocereus undatus) growth, with superworm frass in particular, supporting better growth and rooting than mealworm frass and control media over a fortnight. As known fish and poultry feed, these findings present worms as a natural solution to simultaneously tackle both the global plastic problem and urban farming issue in a zero-waste sustainable bioremediation cycle.

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

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

Conversion of Spent Coffee and Donuts by Black Soldier Fly (Hermetia illucens) Larvae into Potential Resources for Animal and Plant Farming

Nutritionally unbalanced organic waste can be converted into potential resources for animal and plant farming by culturing black soldier fly (Hermetia illucens) larvae (BSFL) and prepupae (BSFP). BSFL and BSFP are rich sources of protein and lipids, while the leftover excrement called "frass" can be used as an organic fertilizer. Using readily available resources, BSFL were cultured on spent coffee, donut dough or an equal blend for 35 days. Survival, productivity, daily pupation and biochemical composition of BSFL and BSFP were measured along with the nitrogen-phosphorus-potassium values of the frass. Survival was highest in the blend compared (81%) to spent coffee (45%) or dough (24%); however, BSFL and BSFP were significantly longer and heavier from dough. Stage and food significantly influenced the protein, lipid and glycogen content of the BSFL and BSFP, which tended to be higher in the latter. While fatty acids were often significantly higher in BSFL fed spent coffee, the amino acid composition of BSFL was generally higher in dough. Frass from the blend had significantly highest nitrogen content, while potassium and phosphorus were significantly higher and lower from spent coffee, respectively. Although coffee and donut dough were suboptimal substrates for BSFL, a blend of these produced BSFL and frass that were nutritionally comparable to soybean meal and many organic fertilizers, respectively.

confusum

Primary pests such as Rhyzoperta dominica may increase the contents of dockage, dust, and frass in grain mass. Although it has been suggested that frass can affect the population growth of stored product pests and ecological interactions among primary and secondary pests in stored grain, this has not been validated experimentally. Therefore, this work experimentally tested the hypothesis that R. dominica wheat frass may support population increases in secondary pests such as Tribolium confusum, T. castaneum, and Oryzaephilus surinamensis for the first time. The effect of frass on secondary pest performance was compared with the effects of various physical qualities of wheat grain (i.e., intact grain kernels, grain fragments, flour, grain + frass) and an artificially enriched control diet (milled wheat kernels, oat flakes, and yeast). The results showed that the clean intact grain kernels did not support the population growth of any tested species, and the nutrient-rich control diet provided the best support. Frass was a significantly better food medium for O. surinamensis and T. castaneum than flour or cracked grain, while T. confusum performed equally well on flour and frass. Our results showed that in terms of food quality and suitability for the tested species, frass occupied an intermediate position between the optimized breeding diet and simple uniform cereal diets such as cracked grain or flour. The results suggest that (i) the wheat frass of primary pest R. dominica is a riskier food source for the development of the tested secondary pests than intact or cracked wheat grain or flour; (ii) frass has the potential to positively influence interspecific interactions between R. dominica and the tested secondary pests; and (iii) wheat grain should be cleaned if increases in R. dominica populations and/or accumulated frass are detected.

Occurrence of Antibiotic Resistance Genes in Hermetia illucens Larvae Fed Coffee Silverskin Enriched with Schizochytrium limacinum or Isochrysis galbana Microalgae

Hermetia illucens larvae are among the most promising insects for use as food or feed ingredients due to their ability to convert organic waste into biomass with high-quality proteins. In this novel food or feed source, the absence of antibiotic-resistant bacteria and their antibiotic resistance (AR) genes, which could be horizontally transferred to animal or human pathogens through the food chain, must be guaranteed. This study was conducted to enhance the extremely scarce knowledge on the occurrence of AR genes conferring resistance to the main classes of antibiotics in a rearing chain of H. illucens larvae and how they were affected by rearing substrates based on coffee silverskin supplemented with increasing percentages of Schizochytrium limacinum or Isochrysis galbana microalgae. Overall, the PCR and nested PCR assays showed a high prevalence of tetracycline resistance genes. No significant effect of rearing substrates on the distribution of the AR genes in the H. illucens larvae was observed. In contrast, the frass samples were characterized by a significant accumulation of AR genes, and this phenomenon was particularly evident for the samples collected after rearing H. illucens larvae on substrates supplemented with high percentages (>20%) of I. galbana. The latter finding indicates potential safety concerns in reusing frass in agriculture.

Ambrosia Beetle (Coleoptera: Curculionidae) Communities and Frass Production in 'Ōhi'a (Myrtales: Myrtaceae) Infected With Ceratocystis (Microascales: Ceratocystidaceae) Fungi Responsible for Rapid 'Ōhi'a Death

Rapid 'Ōhi'a Death (ROD) is a deadly disease that is threatening the native Hawaiian keystone tree species, 'ōhi'a lehua (Metrosideros polymorpha Gaudich). Ambrosia beetles (Curculionidae: Scolytinae) and their frass are hypothesized to play a major role in the spread of ROD, although their ecological niches and frass production within trees and across the landscape are not well understood. We characterized the beetle communities and associated frass production from bolts (tree stem sections) representative of entire individual 'ōhi'a trees from multiple locations across Hawai'i Island by rearing beetles and testing their frass for viable ROD-causing fungi. Additionally, we estimated frass production for three beetle species by weighing their frass over time. We found that Xyleborinus saxesenii (Ratzburg), Xyleborus affinis Eichhoff, Xyleborus ferrugineus (Fabricius), Xyleborus perforans (Wollaston), and Xyleborus simillimus Perkins were commonly found on ROD-infected 'ōhi'a and each produced frass containing viable Ceratocystis propagules. The Hawai'i Island endemic beetle and the only native ambrosia beetle associated with 'ōhi'a, X. simillimus, was limited to high elevations and appeared to utilize similar tree heights or niche dimensions as the invasive X. ferrugineus. Viable Ceratocystis propagules expelled in frass were found throughout entire tree bole sections as high as 13 m. Additionally, we found that X. ferrugineus produced over 4× more frass than X. simillimus. Our results indicate the ambrosia beetle community and their frass play an important role in the ROD pathosystem. This information may help with the development and implementation of management strategies to control the spread of the disease.

Molecular Identification of Anoplophora glabripennis (Coleoptera: Cerambycidae) From Frass by Loop-Mediated Isothermal Amplification

Anoplophora glabripennis (Motschulsky, 1853), native to eastern Asia, is a destructive woodborer of many ornamental species, leading to the decline and the death of the attacked trees. In outbreak areas as Europe or North America, this pest is usually identified using morphological or molecular analyses of adult or larval specimens. However, the procedures for collecting A. glabripennis specimens from infested plants are too expensive and time consuming for routine screening. A noninvasive diagnostic tool based on frass discrimination is therefore crucial for the rapid identification of A. glabripennis at different development stages in the host. This article describes a rapid diagnostic protocol based on loop-mediated isothermal amplification (LAMP). DNA extracted from A. glabripennis frass was amplified with both visual and real-time LAMP and compared with those of nontarget species. The results show that the method is reliable and accurate and therefore could be a promising diagnostic tool in phytosanitary surveys.

Identification of Bacteria in Two Food Waste Black Soldier Fly Larvae Rearing Residues

Significant economic, environmental, and social impacts are associated with the avoidable disposal of foods worldwide. Mass-rearing of black soldier fly (Hermetia illucens) larvae using organic wastes and food- and agro-industry side products is promising for recycling resources within the food system. One current challenge of this approach is ensuring a reliable and high conversion performance of larvae with inherently variable substrates. Research has been devoted to increasing rearing performance by optimizing substrate nutrient contents and ratios, while the potential of the substrate and larval gut microbiota to increase rearing performance remains untapped. Since previous research has focused on gut microbiota, here, we describe bacterial dynamics in the residue (i.e., the mixture of frass and substrate) of black soldier fly larvae reared on two food wastes (i.e., canteen and household waste). To identify members of the substrate and residue microbiota, potentially associated with rearing performance, bacterial dynamics were also studied in the canteen waste without larvae, and after inactivation by irradiation of the initial microbiota in canteen waste. The food waste substrates had similar microbiota; both were dominated by common lactic acid bacteria. Inactivation of the canteen waste microbiota, which was dominated by Leuconostoc, Bacillus, and Staphylococcus, decreased the levels of all rearing performance indicators by 31-46% relative to canteen waste with the native microbiota. In both food waste substrates, larval rearing decreased the bacterial richness and changed the physicochemical residue properties and composition over the rearing period of 12 days, and typical members of the larval intestinal microbiota (i.e., Providencia, Dysgonomonas, Morganella, and Proteus) became more abundant, suggesting their transfer into the residue through excretions. Future studies should isolate members of these taxa and elucidate their true potential to influence black soldier fly mass-rearing performance.

Development of a Loop-Mediated Isothermal Amplification Assay as an Early-Warning Tool for Detecting Emerald Ash Borer (Coleoptera: Buprestidae) Incursions

The emerald ash borer (EAB), Agrilus planipennis (Fairmaire), is the most destructive invasive insect species of ash (Fraxinus spp.) in North America. An accurate method for early detection of this noxious insect pest is indispensable to providing adequate warning of A. planipennis infestation. A loop-mediated isothermal amplification (LAMP) assay (EAB-LAMP) was developed based on mitochondrial cytochrome c oxidase subunit I (COI) gene. The EAB-LAMP required only 30 min at 65°C to amplify A. planipennis DNA from specimens collected from geographically distinct locations. There was no cross-reactivity with other Agrilus and insect species. The developed EAB-LAMP differentially detected traces of A. planipennis genome (COI) within frass from various Fraxinus species. EAB-LAMP was also able to distinguish among A. planipennis DNA and other Agrilus species and nontarget insect species in trap captures. By detecting A. planipennis DNA in two additional trap captures (in situ), the EAB-LAMP was more sensitive and reliable than visual inspection. We tested the quantitative nature of the assay by evaluating pooled trap samples and demonstrated that the EAB-LAMP was capable of functioning optimally using a pool size of at least five individual trap samples. This potentially circumvents the need to perform large-scale individual analysis for processing trap samples. Considering its performance, specificity, sensitivity, and repeatability, the developed EAB-LAMP could be a valuable tool to support strategy and operation of large-scale surveillance for A. planipennis and could profitably be used in routine monitoring programs for effective management of A. planipennis.

Almond by-product composition impacts the rearing of black soldier fly larvae and quality of the spent substrate as a soil amendment

BACKGROUND

Insect biomass is a sustainable alternative to traditional animal feeds, particularly when insects are produced on low-value high-volume agricultural by-products. Seven samples of almond by-product (hulls and shells) were obtained from processors in California and investigated for larvae production. Experiments were completed with and without larvae and spent substrate samples were assessed for their potential as soil amendments based on standard compost quality indicators.

RESULTS

On average, specific larvae growth and average larval harvest weight were 158% and 109% higher, respectively, when larvae were reared on Monterey and pollinator hulls compared to nonpareil hulls and mixed shells. Larvae methionine and cystine contents were highest when larvae were reared on Monterey hulls and mixed shells, respectively. Available phytonutrients in spent substrate were affected by feedstock sample and larvae rearing. Spent nonpareil substrate without larvae had the highest NH₄ -N levels and spent pollinator substrate incubated without larvae had the highest PO₄ -P levels. Spent mixed shell substrate had the lowest availability of phytonutrients.

CONCLUSION

The findings demonstrate that by-product composition has a significant impact on larvae growth and the properties of the spent substrate, and that spent substrate from larvae rearing requires further stabilization before application as a soil amendment. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Assessment of the N- and P-Fertilization Effect of Black Soldier Fly (Diptera: Stratiomyidae) By-Products on Maize

To meet the growing demand for an alternative animal protein source, the Black Soldier Fly (BSF) (Hermetia illucens) industry is expanding. Thus, the valuation of its byproducts, foremost BSF frass, is getting more economic and ecological weight. Three different residues, BSF frass, larval skins, and dead adult flies, were compared with a mineral and an organic commercial fertilizer in a pot trial with maize (Zea mays L., [Poales: Poaceae]). byproducts were applied in three nutrient-based application rates (180; 215 kg N/ha; 75 kg P2O5/ha), and plant nutrients, physiological and yield parameters were measured at harvest date. Ground flies had the highest N-fertilizing effect of all byproducts, similar to commercial mineral and organic fertilizers used as controls, whereas its proportion of the BSF production systems' output is low. Frass as the abundant byproduct showed comparably low N-fertilization effects. Its low N availability was attributed to volatilization losses, mainly driven by high pH and ammonium contents. BSF frass as the main byproduct output is more suited as a basic fertilizer or potting substrate amendment than as a short-term organic fertilizer. Postprocessing of frass seems reasonable. For a profound assessment of frass as fertilizer, several aspects (e.g., the overall impact of postprocessing, plant strengthening and plant protection potential, effects on microbial processes) must be clarified.

From feces to data: A metabarcoding method for analyzing consumed and available prey in a bird-insect food web

Diets play a key role in understanding trophic interactions. Knowing the actual structure of food webs contributes greatly to our understanding of biodiversity and ecosystem functioning. The research of prey preferences of different predators requires knowledge not only of the prey consumed, but also of what is available. In this study, we applied DNA metabarcoding to analyze the diet of 4 bird species (willow tits Poecile montanus, Siberian tits Poecile cinctus, great tits Parus major and blue tits Cyanistes caeruleus) by using the feces of nestlings. The availability of their assumed prey (Lepidoptera) was determined from feces of larvae (frass) collected from the main foraging habitat, birch (Betula spp.) canopy. We identified 53 prey species from the nestling feces, of which 11 (21%) were also detected from the frass samples (eight lepidopterans). Approximately 80% of identified prey species in the nestling feces represented lepidopterans, which is in line with the earlier studies on the parids' diet. A subsequent laboratory experiment showed a threshold for fecal sample size and the barcoding success, suggesting that the smallest frass samples do not contain enough larval DNA to be detected by high-throughput sequencing. To summarize, we apply metabarcoding for the first time in a combined approach to identify available prey (through frass) and consumed prey (via nestling feces), expanding the scope and precision for future dietary studies on insectivorous birds.

Testing the Insecticidal Activity of Nanostructured Alumina on Sitophilus oryzae (L.) (Coleoptera: Curculionidae) Under Laboratory Conditions Using Galvanized Steel Containers

Most stored-grain pest insects increase their population within a relatively short time, causing serious damage to stored products. Sitophilus oryzae (L.) is one of the world’s major stored-grain pest insects and was chosen as the model insect for our studies. This study compared the efficacy of three different dusts under laboratory conditions: aluminum dust (nanostructured alumina), DiatomiD^®, and Protect-It^® (commercial diatomaceous earth). Parental survival, grain damage, and progeny production were measured at 250 and 500 ppm in treated wheat. The tests were conducted in 400 mL galvanized steel jars, an experimental model used for the first time to measure the effectiveness of nanostructured alumina, since most studies have been typically performed in small petri dishes. Parental survival obtained was highest in the untreated controls, followed in decreasing order by DiatomiD^®, Protect-It^®, and nanostructured alumina (NSA). NSA caused the greatest mortality. All treatments significantly reduced grain weight loss and frass production in wheat infested by S. oryzae. The degree of progeny (F1) suppression was directly related to the product and treatment rate, progeny being significantly suppressed by NSA in wheat followed by Protect-It^® and DiatomiD^®. Therefore, NSA had a greater impact on insect population dynamics.

Impact of urbanization on abundance and phenology of caterpillars and consequences for breeding in an insectivorous bird

Urbanization can have marked effects on plant and animal populations' phenology, population size, predator-prey, interactions and reproductive success. These aspects are rarely studied simultaneously in a single system, and some are rarely investigated, e.g., how insect phenology responds to urban development. Here, we study a tri-trophic system of trees, phytophagous insects (caterpillars), and insectivorous birds (Great Tits) to assess how urbanization influences (1) the phenology of each component of this system, (2) insect abundance, and (3) avian reproductive success. We use data from two urban and two forest sites in Hungary, central Europe, collected over four consecutive years. Despite a trend of earlier leaf emergence in urban sites, there is no evidence for an earlier peak in caterpillar abundance. Thus, contrary to the frequently stated prediction in the literature, the earlier breeding of urban bird populations is not associated with an earlier peak in caterpillar availability. Despite this the seasonal dynamics of caterpillar biomass exhibited striking differences between habitat types with a single clear peak in forests, and several much smaller peaks in urban sites. Caterpillar biomass was higher in forests than urban areas across the entire sampling period, and between 8.5 and 24 times higher during the first brood's chick-rearing period. This higher biomass was not associated with taller trees in forest sites, or with tree species identity, and occurred despite most of our focal trees being native to the study area. Urban Great Tits laid smaller clutches, experienced more frequent nestling mortality from starvation, reared fewer offspring to fledging age, and their fledglings had lower body mass. Our study strongly indicates that food limitation is responsible for lower avian reproductive success in cities, which is driven by reduced availability of the preferred nestling diet, i.e., caterpillars, rather than phenological shifts in the timing of peak food availability.

Herbivore-mediated material fluxes in a northern deciduous forest under elevated carbon dioxide and ozone concentrations

Anthropogenic changes in atmospheric carbon dioxide (CO2 ) and ozone (O3 ) are known to alter tree physiology and growth, but the cascading effects on herbivore communities and herbivore-mediated nutrient cycling are poorly understood. We sampled herbivore frass, herbivore-mediated greenfall, and leaf-litter deposition in temperate forest stands under elevated CO2 (c. 560 ppm) and O3 (c. 1.5× ambient), analyzed substrate chemical composition, and compared the quality and quantity of fluxes under multiple atmospheric treatments. Leaf-chewing herbivores fluxed 6.2 g m(-2)  yr(-1) of frass and greenfall from the canopy to the forest floor, with a carbon : nitrogen (C : N) ratio 32% lower than that of leaf litter. Herbivore fluxes of dry matter, C, condensed tannins, and N increased under elevated CO2 (35, 32, 63 and 39%, respectively), while fluxes of N decreased (18%) under elevated O3 . Herbivore-mediated dry matter inputs scaled across atmospheric treatments as a constant proportion of leaf-litter inputs. Increased fluxes under elevated CO2 were consistent with increased herbivore consumption and abundance, and with increased plant growth and soil respiration, previously reported for this experimental site. Results suggest that insect herbivory will reinforce other factors, such as photosynthetic rate and fine-root production, impacting C sequestration by forests in future environments.

Caterpillar attack triggers accumulation of the toxic maize protein RIP2

Some plant-derived anti-herbivore defensive proteins are induced by insect feeding, resist digestion in the caterpillar gut and are eliminated in the frass. We have identified several maize proteins in fall armyworm (Spodoptera frugiperda) frass that potentially play a role in herbivore defense. Furthermore, the toxicity of one of these proteins, ribosome-inactivating protein 2 (RIP2), was assessed and factors regulating its accumulation were determined. To understand factors regulating RIP2 protein accumulation, maize (Zea mays) plants were infested with fall armyworm larvae or treated with exogenous hormones. The toxicity of recombinant RIP2 protein against fall armyworm was tested. The results show that RIP2 protein is synthesized as an inactive proenzyme that can be processed in the caterpillar gut. Also, caterpillar feeding, but not mechanical wounding, induced foliar RIP2 protein accumulation. Quantitative real-time PCR indicated that RIP2 transcripts were rapidly induced (1 h) and immunoblot analysis indicated that RIP2 protein accumulated soon after attack and was present in the leaf for up to 4 d after caterpillar removal. Several phytohormones, including methyl jasmonate, ethylene, and abscisic acid, regulated RIP2 protein expression. Furthermore, bioassays of purified recombinant RIP2 protein against fall armyworm significantly retarded caterpillar growth. We conclude that the toxic protein RIP2 is induced by caterpillar feeding and is one of a potential suite of proteins that defend maize against chewing herbivores.

Penicillium expansum volatiles reduce pine weevil attraction to host plants

The pine weevil Hylobius abietis (L.) is a severe pest of conifer seedlings in reforested areas of Europe and Asia. To identify minimally toxic and ecologically sustainable compounds for protecting newly planted seedlings, we evaluated the volatile metabolites produced by microbes isolated from H. abietis feces and frass. Female weevils deposit feces and chew bark at oviposition sites, presumably thus protecting eggs from feeding conspecifics. We hypothesize that microbes present in feces/frass are responsible for producing compounds that deter weevils. Here, we describe the isolation of a fungus from feces and frass of H. abietis and the biological activity of its volatile metabolites. The fungus was identified by morphological and molecular methods as Penicillium expansum Link ex. Thom. It was cultured on sterilized H. abietis frass medium in glass flasks, and volatiles were collected by SPME and analyzed by GC-MS. The major volatiles of the fungus were styrene and 3-methylanisole. The nutrient conditions for maximum production of styrene and 3-methylanisole were examined. Large quantities of styrene were produced when the fungus was cultured on grated pine bark with yeast extract. In a multi-choice arena test, styrene significantly reduced male and female pine weevils' attraction to cut pieces of Scots pine twigs, whereas 3-methylanisole only reduced male weevil attraction to pine twigs. These studies suggest that metabolites produced by microbes may be useful as compounds for controlling insects, and could serve as sustainable alternatives to synthetic insecticides.

Sex differences in frass production and weight change in Tenebrio molitor (Coleoptera) infected with cysticercoids of the tapeworm Hymenolepis diminuta (Cestoda)

In their intermediate host, parasites alter aspects of host physiology including waste production and body weight. Further, this alteration may differ between female and male hosts. To study this, a beetle (Tenebrio molitor)-tapeworm (Hymenolepis diminuta) system was used. Infected and uninfected male and female beetles were individually housed in vials without food. Each beetle's weight change and frass production were measured over 24 h periods at 3, 7, 12 and 16 days post-infection. Treatment (infection) had no effect on weight change, but males lost more weight than females. Further, infected females produced more frass than control females. Males on the day of infection had a higher food intake than females. These results suggest that males will be more exposed to infection than females and could explain why males had a higher median cysticercoid infection level.