Hornworm Research Articles

Shedding light with harmonic radar: Unveiling the hidden impacts of streetlights on moth flight behavior

One of the most dramatic changes occurring on our planet is the ever-increasing extensive use of artificial light at night, which drastically altered the environment to which nocturnal animals are adapted. Such light pollution has been identified as a driver in the dramatic insect decline of the past years. One nocturnal species group experiencing marked declines are moths, which play a key role in food webs and ecosystem services such as plant pollination. Moths can be easily monitored within the illuminated area of a streetlight, where they typically exhibit disoriented behavior. Yet, little is known about their behavior beyond the illuminated area. Harmonic radar tracking enabled us to close this knowledge gap. We found a significant change in flight behavior beyond the illuminated area of a streetlight. A detailed analysis of the recorded trajectories revealed a barrier effect of streetlights on lappet moths whenever the moon was not available as a natural celestial cue. Furthermore, streetlights increased the tortuosity of flights for both hawk moths and lappet moths. Surprisingly, we had to reject our fundamental hypothesis that most individuals would fly toward a streetlight. Instead, this was true for only 4% of the tested individuals, indicating that the impact of light pollution might be more severe than assumed to date. Our results provide experimental evidence for the fragmentation of landscapes by streetlights and demonstrate that light pollution affects movement patterns of moths beyond what was previously assumed, potentially affecting their reproductive success and hampering a vital ecosystem service.

Trades-offs between pollinator attraction and florivore defense maximize reproductive success in the self-incompatible Rivea ornata (Convolvulaceae)

BackgroundRivea ornata, a rare species from the morning glory family, exhibits uncommon characteristics compared to other typical morning glories, including nocturnal flowers that fit the classic moth pollination syndrome. However, the accuracy of its predicted pollination syndrome and its mating system have never been assessed. Additionally, R. ornata flowers attract not only pollinators but also florivores, potentially reducing plant reproductive success. Therefore, this study examined two populations of R. ornata in Thailand and assessed traits related to pollinator attraction and reward, determined its mating system, identified floral visitors and effective pollinators, and investigated the effect of florivory on reproductive success.ResultsRivea ornata is highly fertile but self-incompatible and an obligate outcrosser, rendering it highly dependent on pollinators. Lepidopterans, particularly nocturnal hawk moths, were found to account for a significant proportion of all visits and were the sole effective pollinators of this plant species, in correspondence with its predicted pollination syndrome. Surprisingly, florivory did not significantly reduce reproductive success. This phenomenon may be explained by the strategies employed by R. ornata, which align with the optimal defense hypothesis and functional trade-offs. Specifically, R. ornata appears to invest resources in defending key floral structures while, simultaneously, guard ants are conspicuously absent from flowers, resulting in some florivore damage to non-vital floral organs but ensuring that pollinators are not deterred by ants and thus maintaining high pollinator visitation rates.ConclusionsOur findings indicate that reproduction-related traits in R. ornata, including those involved in pollinator attraction and reward and florivore defense, are highly effective and work in concert to maximize plant reproductive success. Therefore, a main risk that R. ornata faces is the decline or disappearance of hawk moths and other lepidopterans given its extreme specialization and high dependence on pollinators, and conservation efforts should include habitat protection for both R. ornata and its pollinators.

The hawkmoth proboscis: an insect model for sensorimotor control of reaching and exploration.

Reaching and inspecting objects is an intricate part of human life, which is shared by a diversity of animals across phyla. In addition to appendages like legs and antennae, some insects use their mouthparts to reach and inspect targets. Hawkmoths of the family Sphingidae (Lepidoptera) use their extremely long and straw-like proboscis to drink nectar from flowers. As they approach flowers, hawkmoths uncoil their proboscis and explore the floral surface while hovering to target the proboscis to the nectary hole. Several sensory modalities provide feedback to control and guide these extremely versatile proboscis movements. The control task faced by the hawkmoths' nervous system during such behaviors in not unlike that of an animal guiding limbs or a robotic agent guiding a manipulator to a target. Hawkmoths perform these reaching maneuvers while simultaneously hovering, and hence require rapid and continuous coordination between the proboscis, neck and and flight motor systems, thereby providing a unique invertebrate model for studying appendage guidance and reaching. Here, we review what is known about how hawkmoths use their proboscis for floral inspection and nectar discovery, as well as the role of various sensors in proboscis guidance. We give a brief overview of the morphology and muscular apparatus of the hawkmoth proboscis, and discuss how multimodal sensory feedback might be turned into motor action for appendage guidance.

Chromosome-level Genome Assembly of Theretra japonica (Lepidoptera: Sphingidae)

Theretra japonica is an important pollinator and agricultural pest in the family Sphingidae with a wide range of host plants. High-quality genomic resources facilitate investigations into behavioral ecology, morphological and physiological adaptations, and the evolution of genomic architecture. However, chromosome-level genome of T. japonica is still lacking. Here we sequenced and assembled the high-quality genome of T. japonica by combining PacBio long reads, Illumina short reads, and Hi-C data. The genome was contained in 95 scaffolds with an accumulated length of 409.55 Mb (BUSCO calculated a genome completeness of 99.2%). The 29 pseudochromosomes had a combined length of 403.77 Mb, with a mapping rate of 98.59%. The genomic characterisation of T. japonica will contribute to further studies for Sphingidae and Lepidoptera.

No evidence for the melanin desiccation hypothesis in a larval Lepidopteran

Water regulation is an important physiological challenge for insects due to their small body sizes and large surface area to volume ratios. Adaptations for decreasing cuticular water loss, the largest avenue of loss, are especially important. The melanin desiccation hypothesis states that melanin molecules in the cuticle may help prevent water loss, thus offering protection from desiccation. This hypothesis has much empirical support in Drosophila species, but remains mostly untested in other taxa, including Lepidoptera. Because melanin has many other important functions in insects, its potential role in desiccation prevention is not always clear. In this study we investigated the role of melanin in desiccation prevention in the white-lined Sphinx moth, Hyles lineata (Lepidoptera, Sphingidae), which shows high plasticity in the degree of melanin pigmentation during the late larval instars. We took advantage of this plasticity and used density treatments to induce a wide range of cuticular melanization; solitary conditions induced low melanin pigmentation while crowded conditions induced high melanin pigmentation. We tested whether more melanic larvae from the crowded treatment were better protected from desiccation in three relevant responses: i) total water loss over a desiccation period, ii) change in hemolymph osmolality over a desiccation period, and iii) evaporation rate of water through the cuticle. We did not find support for the melanin desiccation hypothesis in this species. Although treatment influenced total water loss, this effect did not occur via degree of melanization. Interestingly, this implies that crowding, which was used to induce high melanin phenotypes, may have other physiological effects that influence water regulation. There were no differences between treatments in cuticular evaporative water loss or change in hemolymph osmolality. However, we conclude that osmolality may not sufficiently reflect water loss in this case. This study emphasizes the context dependency of melanin’s role in desiccation prevention and the importance of considering how it may vary across taxa. In lepidopteran larvae that are constantly feeding phytophagous insects with soft cuticles, melanin may not be necessary for preventing cuticular water loss.

Feeding rate in adult Manduca sexta is unaffected by proboscis submersion depth.

Adult moths from framily Spingidae (i.e. hawkmoths or sphinx moths) commonly feed on flower nectar through an extended proboscis, often several centimeters in length and longer than the body of the moth. Feeding on a viscous liquid (nectar) through a long and narrow tube is a challenging fluid dynamic problem and the subject of long-running scientific investigation. Here we characterized the relationship between proboscis submergence depth and nectar drinking rate in Manduca sexta hawkmoths. Video recordings of moth feeding bouts were collected and neural networks were used to extract data by object localization, tracking the location of the nectar meniscus and moths' proboscis tips. We found that although feeding rates vary among bouts, the variation was not associated with proboscis submergence depth. These results show that despite the theoretical possibility of fluid uptake through the walls of the proboscis, such effects do not have a substantial effect on nectar uptake rate, and suggest that nectar must traverse the full length of the proboscis.

DNA barcoding elucidates ecological dynamics regulating the diversity of Theretra, Hübner 1819 (Lepidoptera: Sphingidae) from northernmost Western Ghats

The study investigates the distribution and diversity of the old-world moth genus Theretra from the family Sphingidae in the Indian subcontinent. Through extensive data collection and molecular analysis from the Northernmost Western Ghats (Nashik District), seven species of Theretra were identified: T. alecto, T. castanea, T. clotho, T. gnoma, T. nessus, T. oldenlandiae, and T. sumatrensis.Molecular clustering identifies genetically similar specimens, which further helps to recognise similar ecological niches and the associated ecological drivers regulating the distribution pattern of similar specimens. A dataset of 196 published records from Barcode of Life Data Systems (BOLD), including outgroup and the sequences generated in the present study for the Indian species of Theretra, were compiled in a dataset ‘THEREIND’. The crucial role of monsoon and elevation in the diversity and distribution of these moths was comprehended using DNA barcoding and sequence clustering on BOLD. The comparisons suggested a strong correlation with either monsoon or elevation or both.In the purview of the sixth mass extinction and the first true extinction of insects, adequate information on the diversity and the factors affecting it would provide fundamental information to insinuate conservation strategies required for coping with continuous climatic changes.

To seal a wound, caterpillars transform blood from a viscous to a viscoelastic fluid in a few seconds

In insects vulnerable to dehydration, the mechanistic reaction of blood after wounding is rapid. It allows insects to minimize blood loss by sealing the wound and forming primary clots that provide scaffolding for the formation of new tissue. Using nano-rheological magnetic rotational spectroscopy with nickel nanorods and extensional rheology, we studied the properties of blood dripping from the wound of caterpillars of the Carolina sphinx moth (Manduca sexta) with a high concentration of blood cells. We discovered that wound sealing followed a two-step scenario. First, in a few seconds, the Newtonian low-viscosity blood turns into a non-Newtonian viscoelastic fluid that minimizes blood loss by retracting the dripping blood back into the wound. Next, blood cells aggregate, starting from the interfaces and propagating inward. We studied these processes using optical phase-contrast and polarized microscopy, X-ray imaging, and modeling. Comparative analyses of the cell-rich and cell-poor blood of different insects revealed common features of blood behavior. These discoveries can help design fast-working thickeners for vertebrate blood, including human blood.

Caterpillar sonic defences: diversity of vocalisations in silk and hawk moth (Bombycoidea) larvae

ABSTRACT Several Bombycoidea caterpillars, renowned for their large size and diverse appearances, possess an intriguing hidden talent – the ability to ‘vocalise’. Vocalisation is a rare form of sound production in insects, whereby sounds emanate from the oral cavity by air being forced through the foregut. Here, we report on vocalisation in 10 Bombycoidea species that occur across three families. Sounds in all 10 species are evoked in response to simulated predator attacks. Species were identified as vocalisers based primarily on video evidence of mouthparts being open during sound production. Vocalisations, when considered collectively across all 10 species studied, sound like a train of ‘hisses’ (sound units) that occur following an attack. Each sound unit comprises a series of pulses (4–104 on average) and is broadband with high dominant frequency (24–49 kHz on average). Given that vocalising species occur in different families across this large superfamily, we asked whether related species shared similar sound features. We found considerable overlap between sound characteristics of different vocalising species, suggesting a shared mechanism overall. However, distinct differences were also noted between families, suggesting that vocalisation may have evolved multiple times within Bombycoidea. The evolutionary origins and specific functions of vocalisation in caterpillars are discussed.

Taxonomic Assessment and Distributional Records of Sphingidae Moths (Lepidoptera: Heterocera) from Nagaland

An updated checklist of 22 moth species under 14 genera belonging to Sphingidae has been catalogued with an aim to follow the current state of knowledge in moth diversity from the north-eastern state of Nagaland. Although, richly endowed with an array of biodiversity, the state seriously lacks attention regarding faunal status and distributions; ergo, the present work to ascertain the diversity of hawk moths of the state based on records from available literature to fill the void on the path of systematic research.

Checklist of the Moth (Lepidopteran) Fauna of District Buner Khyber Pakhtunkhwa, Pakistan

An annotated checklist of the Moth (Lepidopteran) fauna of District Buner, KP, Pakistan were presented. In the current study 563 specimens of Moth were collected. Throughout entomological investigation a total of 28 species belonging to 25 genera names asCyana hemata (Walker, 1854), Aloa lactinea (Cramer, 1777), Creatonotos transiens (Walker, 1855), Olene mendosa (Hubner, 1823), Cyana puella (Drury, 1773), Syntomoides imaon (Cramer, 1779),Spilosoma obliqua (Walker, 1855), Stigmatophora palmata (Moore, 1878),Marumba sperchius (Menetries, 1857), Psilogramma increta (Walker1865), Leucophlebia lineata (Westwood, 1847), Polyptychus dentatus (Cramer, 1777), Theretra alecto (Linnaeus, 1758),Theretra oldenlandiae (Fabricius, 1775), Biston suppressaria (Guenée, 1858), Declana atronivea (Walker, 1865), Dysgonia torrida (Guenee, 1852), Polytela gloriosae (Fabricius, 1781), Chasmina candida (Walker, 1865),Anua tirhaca (Cramer, 1777), Aegocera venulia (Cramer, 1777), Anua coronata (Fabricius, 1976), Bradina diagonalis (Guenee, 1852), Archernis capitalis (Fabricius, 1794), Dinara combusta (Walker, 1855), Phalera raya (Moore, 1849), Euthrix potatoria (Linnaeus, 1758) and Ocinara varians (Walker, 1855) were reported. The species recorded under 8 families. i.e.Family Erebidae, Family Sphingidae, Family Geometridae, Family Noctuidae, family Crambidae, Family Notodontidae, Family Lasiocampidae and Family Bombycidae. Among them the most abundant family was Family Erebidae.

New Distribution Record of Cechenena transpacifica (Clark, 1923) and Theretra acuta (Vaglia & Liyous, 2010) of Family Sphingidae in Mindanao, Philippines: Identification based on Morphology and CO1 DNA Barcode

Hawkmoths belonging to Family Sphingidae are distinguished by their narrow wings, streamlined bodies and varying length of proboscis making them one of the most important insects in our ecosystem. Two species collected in Mt. Balatukan and Mt. Melibengoy were identified based on morphological description and DNA barcoding (LepF and LepR primers) as Cechenena transpacifica (Clark, 1923) and Theretra acuta (Vaglia & Liyous, 2010). This species were only recorded to exist in Luzon and Visayas. In this study, we provide detailed morphological description and identification based on DNA barcoding of the two species as reported to be found in Mindanao for the first time. The phylogenetic tree inferred from Maximum-Likelihood Method showing monophyletic clade with Family Sphingidae for the two species.

Brain size scaling through development in the whitelined sphinx moth (Hyles lineata) shows mass and cell number comparable to flies, bees, and wasps

Factors regulating larval growth and determinants of adult body size are described for several holometabolous insects, but less is known about brain size scaling through development. Here we use the isotropic fractionation (“brain soup”) method to estimate the number of brain cells and cell density for the whitelined sphinx moth (Lepidoptera: Hyles lineata) from the first instar through the adult stage. We measure mass and brain cell number and find that, during the larval stages, body mass shows an exponential relationship with head width, while the total number of brain cells increases asymptotically. Larval brain cell number increases by a factor of ten from nearly 8000 in the first instar to over 80,000 in the fifth instar. Brain cell number increases by another factor of 10 during metamorphosis, with the adult brain containing more than 900,000 cells. This is similar to increases during development in the vinegar fly (Drosophila melanogaster) and the black soldier fly (Hermetia illucens). The adult brain falls slightly below the brain-to-body allometry for wasps and bees but is comparable in the number of cells per unit brain mass, indicating a general conservation of brain cell density across these divergent lineages.

The adaptive role of melanin plasticity in thermally variable environments.

Understanding the evolution of adaptive plasticity is fundamental to our knowledge of how organisms interact with their environments and cope with environmental change. Plasticity in melanin pigmentation is common in response to variable environments, especially thermal environments. Yet, the adaptive significance of melanin plasticity in thermally variable environments is often assumed, but rarely explicitly tested. Furthermore, understanding the role of plasticity when a trait is responsive to multiple environmental stimuli and plays many functional roles remains poorly understood. We test the hypothesis that melanin plasticity is an adaptation for thermally variable environments using Hyles lineata, the white-lined sphinx moth, which shows plasticity in melanin pigmentation during the larval stage. Melanin pigmentation influences thermal traits in H. lineata, as melanic individuals had higher heating rates and reached higher body temperatures than non-melanic individuals. Importantly, melanin pigmentation has temperature specific fitness consequences. While melanic individuals had an advantage in cold temperatures, neither phenotype had a clear fitness advantage at warm temperatures. Thus, the costs associated with melanin production may be unrelated to thermal context. Our results highlight the importance of explicitly testing the adaptive role of plasticity and considering all the factors that influence costs and benefits of plastic phenotypes across environments.

Critical re-examination of known purported fossil Bombycoidea (Lepidoptera)

We critically re-examine 17 records of fossils currently assigned to the lepidopteran superfamily Bombycoidea, which includes the silk moths, emperor moths and hawk moths. These records include subfossils, compression and impression fossils, permineralizations and ichnofossils. We assess whether observable morphological features warrant their confident assignment to the superfamily. None of the examined fossils displays characters that allow unequivocal identification as Sphingidae, but three fossils and a subfossil (Mioclanis shanwangiana Zhang, Sun and Zhang, 1994, two fossil larvae, and a proboscis in asphaltum) have combinations of diagnostic features that support placement in the family. The identification of a fossil pupa as Bunaeini (Saturniidae) is well supported. The other fossils that we evaluate lack definitive bombycoid and, in several cases, even lepidopteran characters. Some of these dubious fossils have been used as calibration points in earlier studies casting doubt on the resulting age estimates. All fossil specimens reliably assigned to Bombycoidea are relatively young, the earliest fossil evidence of the superfamily dating to the middle Miocene.

Ambulyx labuanensis sp. nov. from Flores Island, Indonesia (Lepidoptera: Sphingidae)

In this study, we describe Ambulyx labuanensis sp. nov., a new hawk moth species from Flores Island (East Nusa Tenggara, Indonesia). This species is morphologically similar to Ambulyx moorei Moore, 1858, A. amboynensis Rothschild, 1894, A. bakeri (Clark, 1929), A. celebensis (Jordan, 1919), A. dohertyi Rothschild, 1894, and A. semifervens (Walker, 1865). However, it clearly differs from these species by having two large saccular processes on the valva.

Climate Change as Dark Magic in <em>Miraculous: Tales of Ladybug & Cat Noir</em> Animation

Climate Change as Dark Magic in <em>Miraculous: Tales of Ladybug & Cat Noir</em> Animation

Implementation and Linearization of State-Space Free-Vortex Wake Models for Rotary- and Flapping-Wing Vehicles

This article describes the implementation and linearization of free-vortex wake models in state-variable form as applied to rotary- and flapping-wing vehicles. More specifically, the wake models are implemented and tested for a UH-60 rotor in forward flight and for a hovering insect representative of a hawk moth. A periodic solution to each wake model is found by time marching the coupled rotor/wing and vortex wake dynamics. Next, linearized harmonic decomposition models are obtained and validated against nonlinear simulations. Order reduction methods are explored to guide the development of linearized wake models that provide increased runtime performance compared to the nonlinear and linearized harmonic decomposition wake models while guaranteeing satisfactory prediction of the periodic response of the wake. This constitutes a first attempt to extend free-vortex wake methods in state-variable form, originally developed for rotary-wing applications, to flapping-wing flight.

TO THE BIOLOGY OF SOME SPECIES OF HAWK MOTHS (LIPIDOPTERA: SPHINGIDAE) IN KHABAROVSKY KRAI

New information about the features of the biology of three species of hawk moths (Sphecodina caudata, Callambulyx tatarinovii and Hyloicus morio) is presented, as well as the preimaginal stages based on materials from the Amur region are illustrated.

Chromosomal-level Genome Assembly of the Coffee Bee Hawk Moth Reveals the Evolution of Chromosomes and the Molecular Basis of Distinct Phenotypes.

Cephonodes hylas, the coffee bee hawk moth is a hawk moth species with unique characteristics, such as larvae feeding on gardenia, overcoming the toxicity of its iridoid glycosides, diurnal adults, and transparent wings. Although C. hylas is a fascinating model for molecular biological research, genome sequence analysis-based genetic approaches to elucidate these peculiarities have not yet been undertaken. We successfully achieved de novo genome assembly at the chromosome level of C. hylas comparable to the Lepidoptera model organism, silkworm. Additionally, 16,854 protein-coding genes were annotated, and the constructed genome sequence and annotated genes were of the highest quality BUSCO completion compared to closely related species. Comparative genome analysis revealed the process of chromosomal evolution from the Bombycoidea ancestral (n = 31) genome and changes in turnover at the chromosome level associated with chromosomal fusion events, such as the rate of repetitive sequence insertion. These analyses were only possible because the genome was constructed at the chromosome level. Additionally, increased the nonsynonymous/synonymous rate (dN/dS) ratios were observed in multiple photoreceptor-related genes that were strongly associated with the acquisition of diurnal activity. Furthermore, tandemly duplicated expanded genes containing many digestive and other enzymes and larval midgut-specific expression were also confirmed. These genes may be involved in the metabolism of genipin, a toxin found in gardenias. Using the genome sequence of C. hylas determined at the chromosome level, we have successfully identified new insights into the chromosomal evolution of Bombycoidea, as well as the relationship between the genome sequence and its characteristic traits.