Entire Insect Research Articles

Single-fly genome assemblies fill major phylogenomic gaps across the Drosophilidae Tree of Life.

Long-read sequencing is driving rapid progress in genome assembly across all major groups of life, including species of the family Drosophilidae, a longtime model system for genetics, genomics, and evolution. We previously developed a cost-effective hybrid Oxford Nanopore (ONT) long-read and Illumina short-read sequencing approach and used it to assemble 101 drosophilid genomes from laboratory cultures, greatly increasing the number of genome assemblies for this taxonomic group. The next major challenge is to address the laboratory culture bias in taxon sampling by sequencing genomes of species that cannot easily be reared in the lab. Here, we build upon our previous methods to perform amplification-free ONT sequencing of single wild flies obtained either directly from the field or from ethanol-preserved specimens in museum collections, greatly improving the representation of lesser studied drosophilid taxa in whole-genome data. Using Illumina Novaseq X Plus and ONT P2 sequencers with R10.4.1 chemistry, we set a new benchmark for inexpensive hybrid genome assembly at US $150 per genome while assembling genomes from as little as 35 ng of genomic DNA from a single fly. We present 183 new genome assemblies for 179 species as a resource for drosophilid systematics, phylogenetics, and comparative genomics. Of these genomes, 62 are from pooled lab strains and 121 from single adult flies. Despite the sample limitations of working with small insects, most single-fly diploid assemblies are comparable in contiguity (>1 Mb contig N50), completeness (>98% complete dipteran BUSCOs), and accuracy (>QV40 genome-wide with ONT R10.4.1) to assemblies from inbred lines. We present a well-resolved multi-locus phylogeny for 360 drosophilid and 4 outgroup species encompassing all publicly available (as of August 2023) genomes for this group. Finally, we present a Progressive Cactus whole-genome, reference-free alignment built from a subset of 298 suitably high-quality drosophilid genomes. The new assemblies and alignment, along with updated laboratory protocols and computational pipelines, are released as an open resource and as a tool for studying evolution at the scale of an entire insect family.

Intensive ground cover management and landscape simplification affect community-wide floral visitor-plant interactions in olive groves

Plant-pollinator interaction networks can provide insights about the impacts of agricultural practices on biodiversity. However, studies on the agricultural impact on these networks most often focus on specific pollinator guilds (i.e., wild bees), hindering our understanding of the effects at the entire insect visitor community level. Here, we evaluated the impact of intensive agriculture and the moderation effects of landscape context on the topology of community-wide plant-visitor interaction networks (381 insect species). We also compared the responses of wild bee-based networks and community-wide plant-floral visitor networks to agricultural intensification to examine whether the former can be a good proxy of the latter. To this aim, we sampled plant-pollinator interaction networks in 24 paired olive farms with contrasting herb cover management (low-intensity management, where ground herb cover is not removed during the flowering season, and intensive management, with herbs persistently removed by herbicides and/or recurrent tillage) across a gradient of landscape complexity in Andalusia (Spain). Results show that the topology of whole floral visitor interaction networks was affected by the herb cover management and the landscape simplification. Furthermore, we found that the effects of the herb cover management were often moderated through the interaction with the landscape context at both floral stand and landscape scale. However, the landscape scale at which these interaction effects occurred varied with the network metric. Non-bee floral visitors were fundamentally redundant for the network topology. We concluded that the implementation of low-intensity management of ground covers in olive groves, together with the enhancement of the flower stands at the local level (e.g., floral strips) and the maintenance and/or restoration of semi-natural habitats at the large landscape scale, would be beneficial to the preservation of healthy and robust floral visitor communities. Our study further supports that wild-bee based interaction networks may adequately reflect the response of the entire networks of plant-floral visitor, at least in this study system.

The enigmatic robber fly Choerades mouchai Hradský, 1985 redescribed and recorded from the Alps (Diptera, Asilidae)

Records of Choerades mouchai Hradský, 1985, are reported from Switzerland. These are the first records of the species published since its description and extend its known range to include the Alps. Previously, it was known only from parts of the Carpathian Mountain chain in Slovakia and Romania. A redescription of the male is provided, accompanied by photographs of diagnostic features, including the terminalia, and images of the entire insect. A table listing morphological differences between the males of Ch. mouchai, Ch. femorata and Ch. marginata is presented. The Choerades fauna of Switzerland is discussed, as is the information available about the ecology of Ch. mouchai.

Rate-dependent adhesion together with limb collaborations facilitate grasshoppers reliable attachment under highly dynamic conditions

Dynamic attachment is indispensable for animals to cope with unexpected disturbances. Minor attention has been paid to the dynamic performance of insects' adhesive pads. Through experiments pulling whole grasshoppers off a glass rod at varying speeds, surprising findings emerged. The feet did not always maintain contact but released and then reconnected to the substrate rapidly during leg extension, potentially reducing the shock damage to pads. As the pulling speeds increased from 1 to 400mm/s, the maximum forces of single front tarsus insects and entire tarsi insects were nearly proportional to the 1/3 power of pulling speeds by 0.11 and 0.29 times, respectively. The force of some individuals could be even 800 times greater than their weight, which is unexpectedly high for smooth insect pads. This work not only helps us to understand the attachment intelligence of animals but is also informative for artificial attachment in extreme situations.

Elm tree defences against a specialist herbivore are moderately primed by an infestation in the previous season.

The studies of the long-term effects of insect infestations on plant anti-herbivore defences tend to focus on feeding-induced damage. Infestations by an entire insect generation, including egg depositions as well as the feeding insects, are often neglected. Whilst there is increasing evidence that the presence of insect eggs can intensify plants' anti-herbivore defences against hatching larvae in the short term, little is known about how insect infestations, including insect egg depositions, affect plant defences in the long term. We addressed this knowledge gap by investigating long-term effects of insect infestation on elm's (Ulmus minor Mill. cv. 'Dahlem') defences against subsequent infestation. In greenhouse experiments, elms were exposed to elm leaf beetle (ELB, Xanthogaleruca luteola) infestation (adults, eggs and larvae). Thereafter, the trees cast their leaves under simulated winter conditions and were re-infested with ELB after the regrowth of their leaves under simulated summer conditions. Elm leaf beetles performed moderately worse on previously infested elms with respect to several developmental parameters. The concentrations of the phenylpropanoids kaempferol and quercetin, which are involved in egg-mediated, short-term effects on elm defences, were slightly higher in the ELB-challenged leaves of previously infested trees than in the challenged leaves of naïve trees. The expression of several genes involved in the phenylpropanoid pathway, jasmonic acid signalling, and DNA and histone modifications appeared to be affected by ELB infestation; however, prior infestation did not alter the expression intensities of these genes. The concentrations of several phytohormones were similarly affected in the currently challenged leaves of previously infested trees and naïve trees. Our study shows that prior infestation of elms by a specialised insect leads to moderately improved defences against subsequent infestation in the following growing season. Prior infestation adds a long-term effect to the short-term enhancer effect that plants show in response to egg depositions when defending against hatching larvae.

Multiple and contrasting pressures determine intraspecific phytochemical variation in a tropical shrub.

Intraspecific phytochemical variation across a landscape can cascade up trophic levels, potentially mediating the composition of entire insect communities. Surprisingly, we have little understanding of the processes that regulate and maintain phytochemical variation within species, likely because these processes are complex and operate simultaneously both temporally and spatially. To assess how phytochemistry varies within species, we tested the degree to which resource availability, contrasting soil type, and herbivory generate intraspecific chemical variation in growth and defense of the tropical shrub, Piper imperiale (Piperaceae). We quantified changes in both growth (e.g., nutritional protein, above- and below-ground biomass) and defense (e.g., imide chemicals) of individual plants using a well-replicated fully factorial shade-house experiment in Costa Rica. We found that plants grown in high light, nutrient- and richer old alluvial soil had increased biomass. High light was also important for increasing foliar protein. Thus, investment into growth was determined by resource availability and soil composition. Surprisingly, we found that chemical defenses decreased in response to herbivory. We also found that changes in plant protein were more plastic compared to plant defense, indicating that constitutive defenses may be relatively fixed, and thus an adaptation to chronic herbivory that is common in tropical forests. We demonstrate that intraspecific phytochemical variation of P. imperiale is shaped by resource availability from light and soil type. Because environmental heterogeneity occurs over small spatial scales (tens of meters), herbivores may be faced with a complex phytochemical landscape that may regulate how much damage any individual plant sustains.

The connectome of an insect brain.

Brains contain networks of interconnected neurons and so knowing the network architecture is essential for understanding brain function. We therefore mapped the synaptic-resolution connectome of an entire insect brain (Drosophila larva) with rich behavior, including learning, value computation, and action selection, comprising 3016 neurons and 548,000 synapses. We characterized neuron types, hubs, feedforward and feedback pathways, as well as cross-hemisphere and brain-nerve cord interactions. We found pervasive multisensory and interhemispheric integration, highly recurrent architecture, abundant feedback from descending neurons, and multiple novel circuit motifs. The brain's most recurrent circuits comprised the input and output neurons of the learning center. Some structural features, including multilayer shortcuts and nested recurrent loops, resembled state-of-the-art deep learning architectures. The identified brain architecture provides a basis for future experimental and theoretical studies of neural circuits.

Acoustic Physiology in Mosquitoes.

The acoustic physiology of mosquitoes is perhaps the most complex within the entire insect class. Past research has uncovered several of its-sometimes stunningly unconventional-principles, but many mysteries remain. Their solution necessitates a concerted transdisciplinary effort to successfully link the neuroanatomical and biophysical properties of mosquito flagellar ears to the behavioral ecology of entire mosquito populations. Neuroanatomically, mosquito ears can rival those of humans in both complexity and sheer size. The approximately 16,000 auditory hair cells within the human organ of Corti, for example, are matched by the approximately 16,000 auditory neurons in the Johnston's organ of a male Anopheles mosquito. Both human and mosquito ears receive very extensive efferent innervation, which modulates their function in ways that are as yet poorly understood. Different populations of neuronal and nonneuronal cell types divide the labor of the mosquito ear amongst themselves. Yet, what exactly this labor is, and how it is achieved, is at best vaguely known. For the majority of mosquitoes, biologically relevant sounds are inextricably linked to their flight tones. Either these flight tones are (directly) the sounds of interest or they contribute (indirectly) to the production of audible sound through a process called nonlinear distortion. Finally, male ears can generate tones themselves: The generation of an internal "phantom copy" of a female flight tone (or self-sustained oscillation) is believed to aid the male hearing process. Here, we introduce protocols that target the mosquitoes' auditory neuroanatomy, electrophysiology, and behavior to help shed light on some of these issues.

Production of Sustainable Proteins Through the Conversion of Insects to Proteins Using Beauveria bassiana Cultures

Various strategies are being suggested to solve the challenges in the food system, such as changing the source of nutrients, including the use of non-traditional food sources such as insects. Although insects are promoted as a cheap and sustainable source of protein, consumers are reluctant to eat them. The mycoproteins produced by fungi, on the other hand, are very well received and appreciated by consumers. Thus, in this work we have studied the use of the entomopathogenic fungi Beauveria bassiana (Ascomycota: Hypocreales) for the production of protein using insects as feed. B. bassiana was cultivated in culture medium containing entire insects from the species Eurysacca and Hypothenemus or single carbon sources such as glucose or laminarin from Laminaria digitata. The results showed that B. bassiana can produce up to 16-fold more biomass and 8-fold more protein when grown in insect-based medium than when grown in glucose. The results also indicated that the production of proteins continuously increased when B. bassiana was grown in medium containing insects, reaching its maximum at 9 days (up to 3 mg/mL). On the other hand, when cultivated in glucose-supplemented medium, the production of proteins was constantly low (~0.5 mg/mL). In conclusion, B. bassiana was a large biomass producer and exuded a large amount of protein when grown in medium containing insect powder, making it an ideal intermediate link between insects and protein. Furthermore, the proteins produced by fungi such as B. bassiana can be used in the food, health, and cosmetic industries.

Synthetic aperture interference light (SAIL) microscopy for high-throughput label-free imaging.

Quantitative phase imaging (QPI) is a valuable label-free modality that has gained significant interest due to its wide potentials, from basic biology to clinical applications. Most existing QPI systems measure microscopic objects via interferometry or nonlinear iterative phase reconstructions from intensity measurements. However, all imaging systems compromise spatial resolution for the field of view and vice versa, i.e., suffer from a limited space bandwidth product. Current solutions to this problem involve computational phase retrieval algorithms, which are time-consuming and often suffer from convergence problems. In this article, we presented synthetic aperture interference light (SAIL) microscopy as a solution for high-resolution, wide field of view QPI. The proposed approach employs low-coherence interferometry to directly measure the optical phase delay under different illumination angles and produces large space-bandwidth product label-free imaging. We validate the performance of SAIL on standard samples and illustrate the biomedical applications on various specimens: pathology slides, entire insects, and dynamic live cells in large cultures. The reconstructed images have a synthetic numeric aperture of 0.45 and a field of view of 2.6 × 2.6 mm2. Due to its direct measurement of the phase information, SAIL microscopy does not require long computational time, eliminates data redundancy, and always converges.

Structure and Dynamics of the Gut Bacterial Community Across the Developmental Stages of the Coffee Berry Borer, Hypothenemus hampei.

The coffee berry borer (CBB); Hypothenemus hampei (Coleoptera: Curculionidae), is widely recognized as the major insect pest of coffee crops. Like many other arthropods, CBB harbors numerous bacteria species that may have important physiological roles in host nutrition, detoxification, immunity and protection. To date, the structure and dynamics of the gut-associated bacterial community across the CBB life cycle is not yet well understood. A better understanding of the complex relationship between CBB and its bacterial companions may provide new opportunities for insect control. In the current investigation, we analyzed the diversity and abundance of gut microbiota across the CBB developmental stages under field conditions by using high-throughput Illumina sequencing of the 16S ribosomal RNA gene. Overall, 15 bacterial phyla, 38 classes, 61 orders, 101 families and 177 genera were identified across all life stages, including egg, larva 1, larva 2, pupa, and adults (female and male). Proteobacteria and Firmicutes phyla dominated the microbiota along the entire insect life cycle. Among the 177 genera, the 10 most abundant were members of Ochrobactrum (15.1%), Pantoea (6.6%), Erwinia (5.7%), Lactobacillus (4.3%), Acinetobacter (3.4%), Stenotrophomonas (3.1%), Akkermansia (3.0%), Agrobacterium (2.9%), Curtobacterium (2.7%), and Clostridium (2.7%). We found that the overall bacterial composition is diverse, variable within each life stage and appears to vary across development. About 20% of the identified OTUs were shared across all life stages, from which 28 OTUs were consistently found in all life stage replicates. Among these OTUs there are members of genera Pantoea, Erwinia, Agrobacterium, Ochrobactrum, Pseudomonas, Acinetobacter, Brachybacterium, Sphingomonas and Methylobacterium, which can be considered as the gut-associated core microbiota of H. hampei. Our findings bring additional data to enrich the understanding of gut microbiota in CBB and its possible use for development of insect control strategies.

Markerless tracking of an entire insect colony.

Markerless tracking of an entire insect colony.

Edible insects, what about the perceptions of Belgian youngsters?

PurposeEdible insects are considered as a novel food in western countries, with their introduction to cuisine having to overcome major barriers, such as disgust. The studies related to acceptance of entomophagy have exponentially grown since 2015. However, such studies generally focus on people older than 18 years old. The purpose of this study is to assess the perceptions of youngsters towards edible insects.Design/methodology/approachA survey associated with an optional tasting session was conducted to record opinion of 151 youngsters in Belgium (9–17-year-olds).FindingsMany respondents are acquainted with entomophagy and had already eaten insect-based food. Most youngsters associated insects as snacks and salty foods, and they agreed to consume processed insects (falafel) during the tasting session. Tasters had to evaluate the falafel, and higher ratings were recorded in male respondents, as highlighted in studies including adults. More negative evaluations would be expected among older respondents if unprocessed insects were served, as they were more willing to consume processed insects than entire insects. Finally, attitudes towards entomophagy evolved positively after the tasting session. Such events are consequently recommended to promote entomophagy across western youngsters.Originality/valueFew studies explored the attitude of western youngsters towards entomophagy. This paper aims to fill this gap by focusing on this young component of the Belgian population.

A Modified Standardized Method to Extract and Store Insect Hemolymph with Use of a Glass Capillary

Abstract Hemolymph is the “blood” circulating in the entire insect body. Analysis of this fluid gives information about the condition of the insect. The most precise analyses are conducted on insects’ hemolymph suspended in 0.6% physiological saline (NaCl). Most current hemolymph extraction methods are either difficult or do not provide pure material, the contamination of collected insect “blood” can change results. This study aimed to develop a technique for extract hemolymph, both easy and without risk of contaminating derived material. The presented method is a modification of available ways to extract, store and transport hemolymph with the use of a glass capillary. For the development of this technique, adult worker honey bees (Apis mellifera L.) were used. The method required such basic equipment as a glass capillary, sterile tweezer, Eppendorf tube and physiological saline. The collected hemolymph were frozen and hence sent in a glass capillary to another laboratory for analysis.

Effects of a tropical cyclone on salt marsh insect communities and post‐cyclone reassembly processes

Concepts regarding effects of recurrent natural disturbances and subsequent responses of communities are central to ecology and conservation biology. Tropical cyclones constitute major disturbances producing direct effects (damage, mortality) in many coastal communities worldwide. Subsequent reassembly involves changes in composition and abundance for which the underlying mechanisms (deterministic and stochastic processes) are still not clear, especially for mobile organisms. We examined tropical cyclone‐induced changes in composition and reassembly of entire insect communities in 16 Louisiana coastal salt marshes before and after Hurricane Isaac in 2012 and 2013. We used the Shannon index and multivariate permutational ANOVA to study insect resistance and resilience, β diversity partitioning to evaluate the importance of species replacement, and null models to disentangle the relative roles of different assembly processes over time after the tropical cyclone. The α diversity and species composition, overall and for different trophic levels, decreased immediately after the tropical cyclone; nonetheless, both then increased rapidly and returned to pre‐cyclone states within one year. Changes in species abundance, rather than species replacement, was the primary driver, accounting for most temporal dissimilarity among insect communities. Stochastic processes, which drove community composition immediately after the tropical cyclone, decreased in importance over time. Our study indicates that rapid reformation of insect communities involved sequential landscape‐level dynamics. Cyclone‐resistant life cycle stages apparently survived in some, perhaps random locations within the overall salt marsh landscape. Subsequently, stochastic patterns of immigration of mobile life cycle stages resulted in rapid reformation of local communities. Post‐cyclone direct regeneration of salt marsh insect communities resulted from low resistance, coupled with high landscape‐level resilience via re‐immigration. Our study suggests that the extent of direct regeneration of local salt marsh insect communities might change with the size of larger marsh landscapes within which they are imbedded.

The case for emulating insect brains using anatomical “wiring diagrams” equipped with biophysical models of neuronal activity

Developing whole-brain emulation (WBE) technology would provide immense benefits across neuroscience, biomedicine, artificial intelligence, and robotics. At this time, constructing a simulated human brain lacks feasibility due to limited experimental data and limited computational resources. However, I suggest that progress toward this goal might be accelerated by working toward an intermediate objective, namely insect brain emulation (IBE). More specifically, this would entail creating biologically realistic simulations of entire insect nervous systems along with more approximate simulations of non-neuronal insect physiology to make "virtual insects." I argue that this could be realistically achievable within the next 20years. I propose that developing emulations of insect brains will galvanize the global community of scientists, businesspeople, and policymakers toward pursuing the loftier goal of emulating the human brain. By demonstrating that WBE is possible via IBE, simulating mammalian brains and eventually the human brain may no longer be viewed as too radically ambitious to deserve substantial funding and resources. Furthermore, IBE will facilitate dramatic advances in cognitive neuroscience, artificial intelligence, and robotics through studies performed using virtual insects.

Declines and Resilience of Communities of Leaf Chewing Insects on Missouri Oaks Following Spring Frost and Summer Drought

Extreme weather events dramatically impact populations of individual insect species but the consequences of such events for entire insect communities are not well documented. We present evidence that late spring frosts and summer drought negatively affect the community of insects found on Missouri oaks (Quercus alba and Q. velutina), amounting to a 23-186 fold decrease depending on the oak species, insect size and feeding guild, and the specific weather event. Spring faunas required three years or more following spring frosts to reach pre-event levels, whereas summer faunas were more resilient, rebounding within 1-2 years. The impact of summer drought on leaf tying caterpillars, however, lasted longer than that of the spring frost; it was five years before numbers of leaf ties reached pre-drought levels. Smaller species of leaf tying Lepidoptera took longer to recover than larger species following the drought. Overall, we found no evidence for a general decline in abundance, even a modest one, during the 20 years of study of faunas on oak trees in southeastern Missouri. However, the effects of drought reported here are likely to increase with time as the climate in the Midwest U.S. is only expected to become warmer and drier during the summer months. Similarly, the risk of late season frost damage to trees is expected to increase with predicted earlier onset of spring. Understanding the impact of such weather events on insect communities influences our ability to predict how habitat and landscape management, or lack thereof, will influence future patterns of insect abundance and diversity.

Putting the genome in insect phylogenomics

Next-generation sequencing technologies provide a substantial increase in the size of molecular phylogenetic datasets that can be obtained for studies of insect systematics. Several new genome reduction approaches are leveraging these technologies to generate large phylogenomic datasets: targeted amplicon sequencing, target capture, and transcriptome sequencing. Although cost effective, these approaches provide limited data for questions outside of phylogenetics. For many groups of insects, sequencing the entire genome at modest coverage is feasible. Using these genomic reads, an automated Target Restricted Assembly Method (aTRAM) can use the results of blast searches to assemble thousands of single copy ortholog genes across a group of interest. These locally assembled genes can then be compiled into very large phylogenomic datasets. These genomic libraries have the advantage in that they also contain reads from the mitochondrial genome and symbiont genomes, as well the entire insect genome, and can be leveraged for additional studies beyond phylogenetics.

Detection and Quantification of Potato virus Y Genomes in Single Aphid Stylets.

Typically, the detection of a plant virus within its vector is carried out on the entire insect body. This process can be a possible source of confusion in the quantification of transmissible virus particles for styletborne viruses such as Potato virus Y (PVY), since the transmissible virus fraction is the one only retained in the aphid vector's mouthparts. The objective of this study was to develop and validate the quantitative PCR method for the detection and quantification of PVY in the vector's stylet. Using a specific method based on TaqMan chemistry with higher sensitivity than conventional reverse transcription PCR, this study reveals that a significant amount of the virus is enclosed within the dissected stylets of Myzus persicae. Because this quantification only concerns the portion of the virus attached to the stylets, uniformity was observed in the recorded numbers of virus targets. This novel assay is applicable to several PVY strains as a rapid and sensitive detection method for use in PVY research and offers a convenient tool for deciphering the mechanism of Potyvirus acquisition.

Trichoplusia ni (Lepidoptera: Noctuidae) Qualitative and Quantitative Sequestration of Host Plant Carotenoids.

Carotenoids are fundamental precursors for hormones and antioxidants, and insects must acquire carotenoids from their diet. Previous research has shown that insects can selectively absorb dietary carotenoids, often modifying them qualitatively or quantitatively, and quantities may be proportional to those found in the diet. Trichoplusia ni Hübner is a generalist herbivore with host plants varying greatly in carotenoid profiles and concentrations. Larvae sequester carotenoids in their hemolymph, and carotenoid sequestration contributes to their cryptic green coloration. Our objectives were to compare the types of carotenoids found in T. ni and their host plants to determine whether qualitative changes occurred, and compare the amounts of sequestered carotenoids in T. ni reared upon different host plants to determine whether quantitative variation influences sequestration. To fulfill these objectives, larvae were fed romaine lettuce (Lactuca sativa L. [Asterales: Asteraceae] var. longifolia) or kale (Brassica oleracea L. [Brassicales: Brassicaceae] var. sabellica) for a period of 5 d, and sequestered carotenoids from the entire insect were resolved with thin-layer chromatography and measured with spectrophotometer. All carotenoids resolved from plants were also resolved from larvae, and although the carotenoids of plants differed quantitatively, the sequestered carotenoids did not differ between host plants. Regardless of host plant species, T. ni sequestered carotenoids at concentrations up to 20 times higher than the concentrations found in the plants. Future research may be able to explicitly identify enzyme systems involved in the transport and modification of carotenoids in T. ni and other animals.