Conspecific and heterospecific cueing in shelter choices of Blaptica dubia cockroaches.

Background: Like many cockroaches, Argentinian wood roaches, Blaptica dubia, prefer darker shelters over lighter shelters. In three experiments, we asked whether chemical cues from other roaches might influence shelter choice, a process known as conspecific or heterospecific cueing, depending on whether the cues come from an individual of the same or a different species, respectively. Methods: Each experiment involved trials with focal B. dubia cockroaches in testing arenas containing plastic shelters of varying levels of darkness, with filter paper under each shelter acting as a carrier for chemical cues. In Experiment 1, we tested female and male B. dubia cockroaches with two shelters matched for darkness but differing in cues (conspecific vs. none). The shelter with no cue contained a blank filter paper as a control. In Experiment 2 (conspecific cueing) and Experiment 3 (heterospecific cueing), we tested B. dubia cockroach choices for lighter or darker shelters with filter papers containing chemical cues of other roaches or no chemical cues. For the conspecific cueing study of Experiment 2, we used chemical cues from other B. dubia cockroaches. In contrast, for the heterospecific cueing study of Experiment 3, we used chemical cues from a different species, the death's head cockroach, Blaberus craniifer. Results: In Experiment 1, B. dubia cockroaches overwhelmingly preferred shelters with conspecific chemical cues over darkness-matched shelters without cues. In Experiments 2 and 3, they strongly preferred darker shelters, especially when chemical cues were present. Additionally, they were more likely to be under the lighter shelter when chemical cues were present there. These results reveal that the public information B. dubia cockroaches gain from chemical cues-including those from other species-can drive shelter choices in this species.

Anatomical organization of the cerebrum of the praying mantis Hierodula membranacea.

Many predatory animals, such as the praying mantis, use vision for prey detection and capture. Mantises are known in particular for their capability to estimate distances to prey by stereoscopic vision. While the initial visual processing centers have been extensively documented, we lack knowledge on the architecture of central brain regions, pivotal for sensory motor transformation and higher brain functions. To close this gap, we provide a three-dimensional (3D) reconstruction of the central brain of the Asian mantis, Hierodula membranacea. The atlas facilitates in-depth analysis of neuron ramification regions and aides in elucidating potential neuronal pathways. We integrated seven 3D-reconstructed visual interneurons into the atlas. In total, 42 distinct neuropils of the cerebrum were reconstructed based on synapsin-immunolabeled whole-mount brains. Backfills from the antenna and maxillary palps, as well as immunolabeling of γ-aminobutyric acid (GABA) and tyrosine hydroxylase (TH), further substantiate the identification and boundaries of brain areas. The composition and internal organization of the neuropils were compared to the anatomical organization of the brain of the fruit fly (Drosophila melanogaster) and the two available brain atlases of Polyneoptera-the desert locust (Schistocerca gregaria) and the Madeira cockroach (Rhyparobia maderae). This study paves the way for detailed analyses of neuronal circuitry and promotes cross-species brain comparisons. We discuss differences in brain organization between holometabolous and polyneopteran insects. Identification of ramification sites of the visual neurons integrated into the atlas supports previous claims about homologous structures in the optic lobes of flies and mantises.

A Taxonomic Revision of the South American Trilobite Cockroaches of Parahormetica Brunner von Wattenwyl 1865 (Blattodea: Blaberidae), with Description of Parahormetica museunacional sp. nov. from the Atlantic Forest.

The taxonomically intricate genus of trilobite cockroaches, Parahormetica Brunner von Wattenwyl, 1865, is revised based on a comparative morphological analysis. The goals of this study are to review the nomenclature, propose hypotheses about specific delimitation, and provide diagnoses to allow identification of the taxonomic units in the genus. Based on the revised status of Parahormetica, we transferred Parahormetica hylaeceps Miranda-Ribeiro, 1936, and Parahormetica punctata Saussure, 1873, to the genus Bionoblatta Rehn, 1940. Therefore, the genus includes now four species of giant cockroaches which are predominantly distributed on the Atlantic Forest: Parahormetica bilobata (Saussure, 1864), Parahormetica cicatricosa Saussure, 1869, Parahormetica monticollis (Burmeister, 1838), and Parahormetica museunacional sp. nov. (holotype male deposited in DZUP: Brazil, Paraná). Diagnoses, key, distribution maps, images of living, non-type, and type specimens are made available. Our results make clear that the status and limits among Brachycolini genera pending a full revision.

Defensive glands in Stylotermitidae (Blattodea, Isoptera).

The large abundance of termites is partially achieved by their defensive abilities. Stylotermitidae represented by a single extant genus, Stylotermes, is a member of a termite group Neoisoptera that encompasses 83% of termite species and 94% of termite genera and is characterized by the presence of the frontal gland. Within Neoisoptera, Stylotermitidae represents a species-poor sister lineage of all other groups. We studied the structure of the frontal, labral and labial glands in soldiers and workers of Stylotermes faveolus, and the composition of the frontal gland secretion in S. faveolus and Stylotermes halumicus. We show that the frontal gland is a small active secretory organ in soldiers and workers. It produces a cocktail of monoterpenes in soldiers, and some of these monoterpenes and unidentified proteins in workers. The labral and labial glands are developed similarly to other termite species and contribute to defensive activities (labral in both castes, labial in soldiers) or to the production of digestive enzymes (labial in workers). Our results support the importance of the frontal gland in the evolution of Neoisoptera. Toxic, irritating and detectable monoterpenes play defensive and pheromonal functions and are likely critical novelties contributing to the ecological success of these termites.

The destructive subterranean termite Reticulitermes flavipes (Blattodea: Rhinotermitidae) can colonize arid territories.

Reticulitermes flavipes, one of the most destructive subterranean termite species, has been detected for the first time in an arid territory: Lanzarote (Canary Islands, Spain). This invasive species was introduced into several countries but never such a dry region. Although there are places with presence of this termite at similar or even higher temperatures, none has annual rainfall (10.1 mm) as low as Lanzarote. On this island it is present in semi-desert, near an affected urban area. Distribution, genetic, climate and host-plant data are evaluated to track and understand its invasion process in the archipelago.

A comprehensive sampling of mitogenomes shows the utility to infer phylogeny of termites (Blattodea: Termitoidae).

The mitogenome sequence data have been widely used in inferring the phylogeny of insects. In this study, we determined the complete mitogenome for Macrotermes sp. (Termitidae, Macrotermitinae) using next-generation sequencing. Macrotermes sp. possesses a typical insect mitogenome, displaying an identical gene order and gene content to other existing termite mitogenomes. We present the first prediction of the secondary structure of ribosomal RNA genes in termites. The rRNA secondary structures of Macrotermes sp. exhibit similarities to closely related insects and also feature distinctive characteristics in their helical structures. Together with 321 published mitogenomes of termites as ingroups and 8 cockroach mitogenomes as outgroups, we compiled the most comprehensive mitogenome sequence matrix for Termitoidae to date. Phylogenetic analyses were conducted using datasets employing different data coding strategies and various inference methods. Robust relationships were recovered at the family or subfamily level, demonstrating the utility of comprehensive mitogenome sampling in resolving termite phylogenies. The results supported the monophyly of Termitoidae, and consistent relationships within this group were observed across different analyses. Mastotermitidae was consistently recovered as the sister group to all other termite families. The families Hodotermitidae, Stolotermitidae, and Archotermopsidae formed the second diverging clade, followed by the Kalotermitidae. The Neoisoptera was consistently supported with strong node support, with Stylotermitidae being sister to the remaining families. Rhinotermitidae was found to be non-monophyletic, and Serritermitidae nested within the basal clades of Rhinotermitidae and was sister to Psammotermitinae. Overall, our phylogenetic results are largely consistent with earlier mitogenome studies.

Cockroaches as carriers of human medically important parasites.

Cockroaches have been identified as mechanical carriers of pathogens capable of infesting humans. The primary objective of this research was to detect and separate medically significant parasites found within the collected cockroaches. A total of 185 cockroaches were captured. In the laboratory, cockroaches underwent a series of steps. Initially, they were washed in a saturated salt solution and rinsed with 70% alcohol, dried, and subsequently dissected to examine endoparasites. In this study, a transport rate of 29.729% was documented, and four types of helminths were identified, which included Ascaris lumbricoides (47.27%), Enterobius vermicularis (30.91%), Trichuris spp. (7.27%), and Hymenolepis nana (14.55%). The parasites were more frequently found on the external surface of cockroaches (38/69.09%), compared to the internal surface (17/30.91%). Cockroaches captured in toilets were found to carry a higher percentage of parasites (31/16.75%) compared to those from kitchens (11/5.94%) and houses (13/7.02%). These findings suggest that cockroaches can serve as carriers for intestinal parasites and potentially act as mechanical agents in the dissemination of these parasites.

Two transcriptional cascades orchestrate cockroach leg regeneration.

The mystery of appendage regeneration has fascinated humans for centuries, while the underlying regulatory mechanisms remain unclear. In this study, we establish a transcriptional landscape of regenerating leg in the American cockroach, Periplaneta americana, an ideal model in appendage regeneration studies showing remarkable regeneration capacity. Through a large-scale in vivo screening, we identify multiple signaling pathways and transcription factors controlling leg regeneration. Specifically, zfh-2 and bowl contribute to blastema cell proliferation and morphogenesis in two transcriptional cascades: bone morphogenetic protein (BMP)/JAK-STAT-zfh-2-B-H2 and Notch-drm/bowl-bab1. Notably, we find zfh-2 is working as a direct target of BMP signaling to promote cell proliferation in the blastema. These mechanisms might be conserved in the appendage regeneration of vertebrates from an evolutionary perspective. Overall, our findings reveal that two crucial transcriptional cascades orchestrate distinct cockroach leg regeneration processes, significantly advancing the comprehension of molecular mechanism in appendage regeneration.

Dynamics of dimorphic workers of Constrictotermes cyphergaster (Blattodea: Termitidae) during nest repair.

Termite nest repairs are considered a defensive conduct as they reduce the colony's exposure to the external environment. Repair activities are carried out by worker castes that can be polymorphic, representing a relationship between polymorphism and divisions of functions that can enhance task completion. Repairs are influenced by the extent of damage, nest volume, and the population dynamics of the building species, which regulate the recruitment of individuals for this activity. Our objective was to verify the performances (recruitment for repair) of dimorphic workers of Constrictotermes cyphergaster (Silvestri, 1901) during the damage repair activities performed on the external walls of termite nests of different sizes. We found a significant difference in the presence of dimorphic workers that performed repairs, with greater recruitment of the small morphotype, and observed an alternation of morphotypes between initial and final repair activities, with no influence of morphotype on the replacement pattern. Our results also showed that the total number of recruited workers decreased with increasing nest volume. These results help to better understand the social organization of a Nasutitermitinae termite species and the strategies adopted to protect its colonies.

Efficient three-dimensional (3D) human bone differentiation on quercetin-functionalized isotropic nano-architecture chitinous patterns of cockroach wings.

Developing cost-effective, biocompatible scaffolds with nano-structured surface that truthfully replicate the physico-(bio)chemical and structural properties of bone tissue's extracellular matrix (ECM) is still challenging. In this regard, surface functionalization of natural scaffolds to enhance capability of mimicking 3D niches of the bone tissue has been suggested as a solution. In the current study, we aimed to investigate the potential of chitin-based cockroach wings (CW) as a natural scaffold for bone tissue engineering. To raise the osteogenic differentiation capacity of such a scaffold, a quercetin coating was also applied (hereafter this scaffold is referred as QCW). Moreover, the QCW scaffold exhibited effective antibacterial properties against gram-positive S. aureus bacteria. With respect to bone regeneration, the QCW scaffold optimally induced the differentiation of adipose-derived human mesenchymal stem cells (AD-hMSCs) into osteoblasts, as validated by mineralization assays, alkaline phosphatase (ALP) activity measurements, expression of pre-osteocyte marker genes, and immunocytochemical staining. Confirmation of the potent biocompatibility and physicochemical characteristics of the QCW scaffold through a series of in vitro and in vivo analysis revealed that surface modification had significant effect on multi-purpose features of obtained scaffold. Altogether, surface modification of QCW made it as an affordable bioinspired scaffold for bone tissue engineering.

Behavioral responses of field-collected German cockroaches to pyrethroids and pyrethroid-formulated insecticides.

BACKGROUND: Pyrethroids are synthetic insecticides with low mammalian toxicity and broad-spectrum activity across insects. One major challenge with pyrethroids is their perceived repellency. This perception can influence decisions made by pest control operators, especially when insecticides are used to reduce insect entry into or movement within structures. One major indoor pest that has been repeatedly shown to be repelled by some pyrethroids is the German cockroach, Blattella germanica. However, most experiments evaluating pyrethroid repellency in the German cockroach have used end-point assays, which do not provide information on the movement that led to the final position. Therefore, we evaluated the kinetic behavioral response of field-collected German cockroaches to five pyrethroid-based products and their active ingredients (A.I.) in open behavioral arenas using advanced video tracking software. In addition, in an effort to compare our free-moving experiments with end-point assays, we evaluated sheltering behavior using two-choice harborage arrestment assays where German cockroaches were provided a choice between pyrethroid-treated and untreated shelters. RESULTS: All pyrethroid-formulated products and their respective A.I.'s failed to affect field-collected German cockroach movement behavior in free-moving assays, while positive controls (DEET, corn mint oil) resulted in reduced time spent by German cockroaches in treated areas. However, despite their willingness to move over pyrethroids-treated surfaces, field-collected German cockroaches displayed a reduced propensity to arrest on pyrethroids treated tents. CONCLUSION: While most pyrethroids/pyrethroid-formulated products affected German cockroach arrestment, pyrethroids and pyrethroid-formulated products failed to change German cockroach movement behavior in free-moving assays. These results indicate the pyrethroids tested act as contact irritants rather than true-spatial repellents on field-collected German cockroaches. This distinction is critical to refining pest management strategies involving pyrethroids. © 2023 Society of Chemical Industry.

Economic framework to assess the impact of banning pesticides, with application to sulfuryl fluoride for drywood termites (Blattodea: Kalotermitidae) in California.

Sulfuryl fluoride (SF) is a fumigant used to eliminate drywood termites (DWT: Kalotermitidae; Froggatt) and other structural pests. Because of its global warming potential, it has been suggested that SF be restricted as a greenhouse gas (GHG). We present an economic model to assess the net social cost of restricting SF. We consider 3 approaches to address DWT control- no treatment, allowing SF fumigation and localized treatments, and only local treatment. Each approach generates private and public benefits and costs. We estimate that the annual damage and home equity loss by DWT in California is US$4.5-16.8 billion without treatment. If fumigation is used on 20% of the houses and local treatments on the others, the combined social cost of treatment, damage, and GHG emissions are between US$1-US$2 billion annually. The annual cost of local treatments only would be between US$3.2 and US$4.9 billion. If the application of SF is severely restricted or banned, the social costs will increase between US$1.43 and US$4.31 billion annually. The implied cost per ton of CO2 eliminated is between US$624 and US$1,465, much above the price range of CO2 in other applications. The restriction/ban has significant equity and environmental effects, impacting low-income individuals living in rented properties and replacing damaged wood in housing will increase GHG emissions. We further recommend the continued use of SF until a comparable whole-structure alternative is developed that fits the parameters of our model.

Oral toxicity of an artificial sweetener sucralose on the German cockroach (Blattodea: Ectobiidae) and its impact on water balance and gut microbiome.

Artificial or non-nutritive sweeteners are indigestible by most animals. Some sweeteners are orally toxic to insects and have received recent interest as potential safe insecticides due to their low mammalian toxicity. In this study, we investigated the oral toxicity of sucralose on insecticide-susceptible and resistant German cockroaches, Blattella germanica (L.). In a nonchoice test, we evaluated 5, 10, and 20% sucralose solutions. Depending on the cockroach strains, mean mortality ranged from 62.5 to 92.5%, 15 to 55%, and 2.5 to 27.5% for 20, 10, and 5% sucralose, respectively. Next, we measured the impact of a 20% sucralose treatment on water loss rates in the cockroach strains. All strains lost 23.0-30.29% of body water by 6 d. Dehydrated cockroaches were more prone to be killed by sucralose than nondehydrated ones. Lastly, we evaluated the effect of 20% sucralose treatment on gut bacterial composition and found the diversity of gut bacteria in treated cockroaches was significantly reduced after 3 days, implicating a rapid change in the alimentary environment.

Mating- and oviposition-dependent changes of the spermatheca and colleterial glands in the pest termite Cryptotermes brevis (Blattaria, Isoptera, Kalotermitidae).

The spermatheca and colleterial glands of female insects are organs associated with the reproductive system, responsible for sperm storage and secretion of egg coverings, respectively. Here we compared the development, secretory activity, and chemical nature of the secretion in the spermatheca and colleterial glands of different-aged females of the drywood termite Cryptotermes brevis. We also provide the ultrastructure of these organs in alate females. These structures have been poorly investigated in termites when compared to other eusocial insects (Hymenoptera) and termite-related dictyopterans (mantises and cockroaches). The spermatheca of C. brevis comprises a cone-shaped structure, connected to the genital chamber by a short duct. The colleterial glands, in turn, are divided into anterior and posterior tubules, each showing a basal trunk, and join into a common duct. Histological and histochemical analyses showed that the secretion of proteins and polysaccharides by the spermatheca takes place before pairing, but increases as females mate and store sperm. Colleterial glands of alates showed non-synchronous secretory activity, but the synthesis of products increased in egg-laying queens, together with the epithelium height. Ultrastructure of the spermatheca and colleterial glands revealed epithelia composed of class III secretory cells. Richness of mitochondria and electron-dense secretion in the spermatheca indicates synthesis and transport of content. Presence and absence of colleterial gland secretion in different individuals may reflect variable maturation stages of the females and secretory cells. Assuming that termites are iteroparous, the development and secretion of the spermatheca and colleterial glands play a crucial role for C. brevis queens.

Transmission of antimicrobial resistance in the gut microbiome of gregarious cockroaches: the importance of interaction between antibiotic exposed and non-exposed populations.

Antimicrobial resistance (AMR) is a major global health concern, further complicated by its spread via the microbiome bacterial members. While mathematical models discuss AMR transmission through the symbiotic microbiome, experimental studies are scarce. Herein, we used a gregarious cockroach, Pycnoscelus surinamensis, as an in vivo animal model for AMR transmission investigations. We explored whether the effect of antimicrobial treatment is detectable with metagenomic sequencing, and whether AMR genes can be spread and established in unchallenged (not treated with antibiotics) individuals following contact with treated donors, and under various frequencies of interaction. Gut and soil substrate microbiomes were investigated by metagenomic sequencing for bacterial community composition and resistome profiling. We found that tetracycline treatment altered the treated gut microbiome by decreasing bacterial diversity and increasing the abundance of tetracycline resistance genes. Untreated cockroaches that interacted with treated donors also had elevated tetracycline resistance. The levels of resistance differed depending on the magnitude and frequency of donor transfer. Additionally, treated donors showed signs of microbiome recovery due to their interaction with the untreated ones. Similar patterns were also recorded in the soil substrate microbiomes. Our results shed light on how interacting microbiomes facilitate AMR gene transmission to previously unchallenged hosts, a dynamic influenced by the interaction frequencies, using an in vivo model to validate theoretical AMR transmission models.IMPORTANCEAntimicrobial resistance is a rising threat to human and animal health. The spread of resistance through the transmission of the symbiotic gut microbiome is of concern and has been explored in theoretical modeling studies. In this study, we employ gregarious insect populations to examine the emergence and transmission of antimicrobial resistance in vivo and validate modeling hypotheses. We find that antimicrobial treatment increases the levels of resistance in treated populations. Most importantly, we show that resistance increased in untreated populations after interacting with the treated ones. The level of resistance transmission was affected by the magnitude and frequency of population mixing. Our results highlight the importance of microbial transmission in the spread of antimicrobial resistance.

Octopamine is involved in TRP-induced thermopreference responses in American cockroach.

Insects' thermoregulatory processes depend on thermosensation and further processing of thermal information in the nervous system. It is commonly known that thermosensation involves thermoreceptors, including members of the TRP receptor family, but the involvement of neurotransmitters in thermoregulatory pathways remains unstudied. We conducted test to determine whether octopamine, a biogenic amine that acts as a neurotransmitter and neurohormone in insects, is involved in TRP-induced thermoregulatory responses in Periplaneta americana. We used capsaicin, an activator of the heat-sensitive TRP channel, Painless, to induce thermoregulatory response in cockroaches. Then, we evaluated the behavioural (thermal preferences and grooming), physiological (heart rate) and biochemical responses of insects to capsaicin, octopamine and phentolamine - octopaminergic receptor blocker. Capsaicin, similar to octopamine, increased cockroaches' grooming activity and heart rate. Moreover, octopamine level and protein kinase A (PKA) activity significantly increased after capsaicin treatment. Blocking octopaminergic receptors with phentolamine diminished cockroaches' response to capsaicin - thermoregulatory behaviour, grooming and heart rate were abolished. The results indicate that octopamine is a neurotransmitter secreted in insects after the activation of heat receptors.

Residual profiles and health risk of indoor allergens in China.

Exposure to indoor allergens is a principal risk factor for allergic diseases. However, most of the previous studies on indoor allergens focused on very limited kinds of allergens in China. Knowledge of the simultaneous exposure to multiple allergens is still lacking. In this study, the residual profiles of 8 allergens were investigated in 166 dust samples from 11 cities in China. The house dust mite allergens including Der p 1, Der f 1, and Der 2 were detected in the range of <0.02-283.83 µg/g dust. The concentrations of dog allergen Can f 1 and cat allergen Fel d 1 varied widely, from <0.84-22,896.46 µg/g dust for Can f 1 and from <0.02-6298.96 µg/g dust for Fel d 1. Cockroach allergen Bla g 2 was detected in 68% of the samples but at a low level with a maximum of 9.44 µg/g dust. Comparatively low detection frequencies were found for mouse allergen Mus m 1 as 37% and for fungi allergen Asp f 2 as 24%. The frequency of cleaning sheets/bedding was negatively correlated to the levels of house dust mite allergens. The presence of pets indoors was associated with higher levels of pet allergens and lower levels of house dust mite allergens and cockroach allergen. Risk evaluation reveals that at least 4 allergens were found in more than 80% of the rooms and more than 2 allergens with median/high risk were detected in 42% of the rooms, indicating that simultaneous exposure to multiple allergens is prevalent in China.

Rapid insecticide resistance bioassays for three major urban insects in Taiwan.

BACKGROUND: Taiwan's warm and humid climate and dense population provide a suitable environment for the breeding of pests. The three major urban insects in Taiwan are house flies, cockroaches, and mosquitoes. In cases where a disease outbreak or high pest density necessitates chemical control, selecting the most effective insecticide is crucial. The resistance of pests to the selected environmental insecticide must be rapidly assessed to achieve effective chemical control and reduce environmental pollution. METHODS: In this study, we evaluated the resistance of various pests, namely, house flies (Musca domestica L.), cockroaches (Blattella germanica L. and Periplaneta americana), and mosquitoes (Aedes aegypti and Ae. albopictus) against 10 commonly used insecticides. Rapid insecticide resistance bioassays were performed using discriminating doses or concentrations of the active ingredients of insecticides. RESULTS: Five field strains of M. domestica (L.) are resistant to all 10 commonly used insecticides and exhibit cross- and multiple resistance to four types of pyrethroids and three types of organophosphates, propoxur, fipronil, and imidacloprid. None of the five field strains of P. americana are resistant to any of the tested insecticides, and only one strain of B. germanica (L.) is resistant to permethrin. One strain of Ae. albopictus is resistant to pirimiphos-methyl, whereas five strains of Ae. aegypti exhibit multiple resistance to pyrethroids, organophosphates, and other insecticides. CONCLUSIONS: In the event of a disease outbreak or high pest density, rapid insecticide resistance bioassays may be performed using discriminating doses or concentrations to achieve precise and effective chemical control, reduce environmental pollution, and increase control efficacy.

The long-acting walking control of a cockroach bio-bot for vision-aided pipeline navigation.

Many small bionic crawling robots have been invented for search and rescue missions in narrow spaces. However, their locomotion capability is far from that of insects of the same size. Transforming a cockroach into a bio-bot has been a hot topic in the past decade. Herein, we modified this insect to perform surveillance work in dark confined environments. The synergistic electrical stimulation for turning control was proposed by alternating electrical stimulation of the cerci and antennae every 5 trials. The result showed that this method was able to control cockroaches turning steadily 117 times. An electronic backpack was designed, which was capable of transmitting images in real time, and a light emitting diode (LED) was installed on the backpack providing a light source for the camera. Thus, a vision-aided navigation system was formed for dark confined environments, e.g. pipelines. With a host computer software, the operator controlled the bio-bot to pass through a completely dark and closed pipeline. The electronic backpack and the host computer were connected via transmission control protocol (TCP), which allows the operator to manipulate the bio-robot remotely. This technology can be applied in pipeline surveillance in the future.

Investigation of euthanasia techniques in four species of cockroaches.

While cockroaches are commonly exhibited in zoos and museums, studied in research laboratories, and even kept as pets, scientifically based guidelines for their euthanasia are lacking. This study assessed euthanasia techniques in four species of cockroaches (Dubia (Blaptica dubia), red runner (Shelfordella lateralis), Madagascar hissing (Gromphadorhina portentosa), and giant cave (Blaberus giganteus)). In an initial pilot study, two hundred fifty adult Dubia cockroaches were exposed in groups of ten to a cotton ball soaked with 2 mL of isoflurane in a 1 L air-tight chamber. Thirty minutes beyond loss of any individual movement, groups were exposed to one of the following secondary treatments: freezing at -18 °C or -80 °C from 0.25 to 24 hours; immersion in 10% neutral buffered formalin, 70% isopropyl alcohol, or reverse osmosis water for 0.25 or 0.5 hours; or intracoelomic injection of potassium chloride (456 mEq/kg) or pentobarbital-based euthanasia solution (3.9 g/kg). A control group remained in the air-tight isoflurane chamber for 24 hours. Following all treatments, cockroaches were monitored for an additional 24 hours for spontaneous movement. Irreversible loss of movement was considered synonymous with irreversible loss of consciousness (death). Across all species, isoflurane anesthesia followed by either 70% isopropyl alcohol immersion for 0.25 or 0.5 hours or isoflurane exposure for 24 hours resulted in euthanasia in 100% of cockroaches. This study is the first evaluation of American Veterinary Medical Association-recommended euthanasia protocols in cockroaches.