Treponema Endosymbionts are the Dominant Bacterial Members with Ureolytic Potential in the Gut of the Wood-Feeding Termite, Reticulitermes Hesperus

Termites are remarkable for their ability to digest cellulose from wood as their main energy source, but the extremely low nitrogen (N) content of their diet presents a major challenge for N acquisition. Besides the activity of N 2 -fixing bacteria in the gut, the recycling of N from waste products by symbiotic microbes as a complementary N-provisioning mechanism in termites remains poorly understood. In this study, we used a combination of high-throughput amplicon sequencing, quantitative PCR, and cultivation to characterize the microbial community capable of degrading urea, a common waste product, into ammonia in the guts of termites ( Reticulitermes hesperus ) from a wild and laboratory-reared colony. Taxonomic analysis indicated that a majority of the urease ( ureC ) genes in the termite gut (53.0%) matched with a Treponema endosymbiont of gut protists previously found in several other termites, suggesting an important contribution to the nutrition of essential cellulolytic protists. Furthermore, analysis of both the 16S rRNA and ureC amplicons revealed that the laboratory colony had decreased diversity and altered community composition for both prokaryotic and ureolytic microbial communities in the termite gut. Estimation by quantitative PCR showed that microbial ureC genes decreased in abundance in the laboratory-reared colony compared to the wild colony. In addition, most of our cultivated isolates appeared to originate from non-gut environments. Together, our results underscore a more important role for ureolysis by endosymbionts within protists than by free-swimming bacteria in the gut lumen of R. hesperus .

Methods for estimating and modelling spruce budworm development rates at constant temperatures

We describe an experimental protocol for measuring the response of spruce budworm postdiapause larval development to temperature. This protocol is specifically designed to include measurements of development near their upper and lower thermal thresholds. The application of this protocol to a laboratory colony allowed for the first experimental evidence that spruce budworm larval development occurs at temperatures as low as 5 °C and as high as 35 °C, and it provides data to fit stage-specific development models. Our protocol is also designed to minimise mortality near the thermal development thresholds, thus allowing for multigenerational studies. We observed developmental plasticity in larvae reared at constant temperatures, particularly the occurrence of up to 42% of some individuals requiring only five instars to complete development compared to the expected six instars. The occurrence exhibited no clear relation to temperature. Although this protocol is specifically designed for spruce budworm, it provides a template for the study of other species’ developmental responses to temperature.

Acoustic and postural displays in a miniature and transparent teleost fish, Danionella dracula

Individuals can reveal their relative competitive ability or mate quality through acoustic communication, varying signals in form and frequency to mediate adaptive interactions including competitive aggression. We report robust acoustic displays during aggressive interactions for a laboratory colony of Danionella dracula, a recently discovered miniature and transparent species of teleost fish closely related to zebrafish (Danio rerio). Males produce bursts of pulsatile, click-like sounds and a distinct postural display, extension of a hypertrophied lower jaw, during resident-intruder dyad interactions. Females lack a hypertrophied lower jaw and show no evidence of sound production or jaw extension under such conditions. Novel pairs of size-matched or mismatched males were combined in resident-intruder assays where sound production and jaw extension could be linked to individuals. Resident males produce significantly more sound pulses than intruders in both dyad contexts; larger males are consistently more sonic in size-mismatched pairs. For both conditions, males show a similar pattern of increased jaw extension that frequently coincided with acoustic displays during periods of heightened sonic activity. These studies firmly establish D. dracula as a sound-producing species that modulates both acoustic and postural displays during social interactions based on either residency or body size, thus providing a foundation for investigating the role of these displays in a new model clade for neurogenomic studies of aggression, courtship and other social interactions.

Persistence of Dengue Virus (DENV-1, 2, 3,4) Transovarial-Transgenerational with Realtime Polymerase Chain Reaction (qPCR) in Ae. Aegypti and Ae. Albopictus (Diptera: Culicidae)

Ae. aegypti and Ae. albopictus have an important role in DHF transmission because they can simultaneously transmit the dengue virus vertically / transovarially or horizontally. This phenomenon indicates the persistence of the dengue virus by vectors. The aim of this research was to prove the persistence of the transovarial-transgenerational dengue virus (DENV-1,2,3,4) with real time polymerase chain reaction (qPCR) in Ae. aegypti and Ae. albopictus (Diptera: Culicidae). Quasi experimental design with intervention infects DENV 1-2-3-4 serotypes in Ae. aegypti and Ae. albopictus intratoracally. Research population Ae. aegypti and Ae. albopictus laboratory colony females. Dengue virus detection uses real-time polymerase chain reaction (qPCR). Transovarial detection by qPCR indicates detection of dengue virus in Ae. albopictus DENV-1 to progeny 1 (F1), DENV-2 and DENV-3 to F2, DENV-4 to F3. Next to Ae. aegypti DENV-1 to 1st progeny (F1), DENV-2 to F2, DENV-3 to F4 and DENV-4 to F3. there was no difference in MIR value (p value: 0.356) for the four serotypes in Ae. albopictus and Ae. aegypti. DENV-3 is the most persistent serotype in Ae. aegypti with 83.3% MIR and DENV-4 were the most persistent serotypes in Ae.albopictus with 100% MIR. The need to improve vector control models that focus not only on the main vector, but also other co-vectors.

Food as a factor of fertility, development duration, and changes in morphometric parameters in Henosepilachna vigintioctomaculata (Motschulsky)

Relevance.The physiology of insects nutrition and digestion reflects the diversity of their food specialization, aimed at the most effective use of feed. The choice of the object of nutrition is provided by attractants in it, as well as the presence of substances necessary for the insect to pass the stages of development and general nutrition. On the other hand, the “plant-phytophage” system has well-developed barriers that limit the choice of plants by insects for settling, feeding, and eggs laying. In the modern literature, there is very little information on the effect of food plants on fertility, development duration, and changes in morphometric parameters in 28-spotted potato ladybird Henosepilachna vigintioctomaculata (Motschulsky). However, they are important for understanding the ecology of the pest and developing effective control measures.Research methodology. The laboratory colony of Henosepilachna vigintioctomaculata (Motschulsky) was established in 2019. Adults were collected in various locations throughout Primorsky Territory, Russia. For an introduction into the culture of the insectarium, imagos, clutches, and larvae were collected in natural habitats. Standard methods of keeping and breeding insect cultures were used, aimed at optimizing the parameters of the environment, the density of the content, and the feed supply.Results. The uneven influence of crops on different aspects of the ontogenesis of the potato ladybird was revealed. The potato was the most favorable food in most experiments. When feeding with this crop, the smallest incubation period of eggs, the largest sizes of larvae of initial ages, the largest sizes of pupae, fertility, low mortality was observed, and as a result, the largest growth coefficient (3.22±0.22) and the shortest period of development from eggs to imago (21.3±0.81) were revealed. The remaining forage plants used in the study showed a less unambiguous result. The different influence of crops on both individual indicators and the ontogenetic periods of the phytophage was found. When eating tomato, cucumber, pumpkin, lime, high overall mortality was noted. At the same time, linden stimulated the development of eggs and the growth of young larvae but provoked low fertility and a general prolongation of the development period. According to the set of characteristics, pumpkin, cucumber, and linden were the least favorable for nutrition.

Transovarial Transmission of Borrelia hermsii by Its Tick Vector and Reservoir Host Ornithodoros hermsi

Transovarial passage of relapsing fever spirochetes (Borrelia species) by infected female argasid ticks to their progeny is a widespread phenomenon. Yet this form of vertical inheritance has been considered rare for the North American tick Ornithodoros hermsi infected with Borrelia hermsii. A laboratory colony of O. hermsi was established from a single infected female and two infected males that produced a population of ticks with a high prevalence of transovarial transmission based on infection assays of single and pooled ticks feeding on mice and immunofluorescence microscopy of eggs and larvae. Thirty-eight of forty-five (84.4%) larval cohorts (groups of larvae originating from the same egg clutch) transmitted B. hermsii to mice over four and a half years, and one hundred and three single and one hundred and fifty-three pooled nymphal and adult ticks transmitted spirochetes during two hundred and fourteen of two hundred and fifty-six (83.6%) feedings on mice over seven and a half years. The perpetuation of B. hermsii for many years by infected ticks only (without acquisition of spirochetes from vertebrate hosts) demonstrates the reservoir competence of O. hermsi. B. hermsii produced the variable tick protein in eggs and unfed larvae infected by transovarial transmission, leading to speculation of the possible steps in the evolution of borreliae from a tick-borne symbiont to a tick-transmitted parasite of vertebrates.

Ontogeny of audible squeaks in yellow steppe lemming Eolagurus luteus: trend towards shorter and low-frequency calls is reminiscent of those in ultrasonic vocalization

Background Rodents are thought to be produced their human-audible calls (AUDs, below 20 kHz) with phonation mechanism based on vibration of the vocal folds, whereas their ultrasonic vocalizations (USVs, over 20 kHz) are produced with aerodynamic whistle mechanism. Despite of different production mechanisms, the acoustic parameters (duration and fundamental frequency) of AUDs and USVs change in the same direction along ontogeny in collared lemming Dicrostonyx groenlandicus and fat-tailed gerbil Pachyuromys duprasi. We hypothesize that this unidirectional trend of AUDs and USVs is a common rule in rodents and test whether the AUDs of yellow steppe lemmings Eolagurus luteus would display the same ontogenetic trajectory (towards shorter and low-frequency calls) as their USVs, studied previously in the same laboratory colony. Results We examined for acoustic variables 1200 audible squeaks emitted during 480-s isolation-and-handling procedure by 120 individual yellow steppe lemmings (at 12 age classes from neonates to breeding adults, 10 individuals per age class, up to 10 calls per individual, each individual tested once). We found that the ontogenetic pathway of the audible squeaks, towards shorter and lower frequency calls, was the same as the pathway of USVs revealed during 120-s isolation procedure in a previous study in the same laboratory population. Developmental milestone for the appearance of mature patterns of the squeaks (coinciding with eyes opening at 9–12 days of age), was the same as previously documented for USVs. Similar with ontogeny of USVs, the chevron-like squeaks were prevalent in neonates whereas the squeaks with upward contour were prevalent after the eyes opening. Conclusion This study confirms a hypothesis of common ontogenetic trajectory of call duration and fundamental frequency for AUDs and USVs within species in rodents. This ontogenetic trajectory is not uniform across species.

Individual Ants Do Not Show Activity-Rest Rhythms in Nest Conditions

Circadian rhythms, which respond to the day-night cycle on the earth, arise from the endogenous timekeeping system within organisms, called the “biological clock.” For accurate circadian rhythms, daily fluctuations in light and temperature are considered one of the important time cues. In social insects, both abiotic and biotic factors (i.e., social interactions) play a significant role in activity-rest rhythm regulation. However, it is challenging to monitor individual activity-rest rhythms in a colony because of the large group size and small body size. Therefore, it is unclear whether individuals in a colony exhibit activity-rest rhythms and how social interactions regulate their activity-rest rhythms in the colony. This study developed an image-based tracking system using 2D barcodes for Diacamma cf. indicum from Japan (a monomorphic ant) and measured the locomotor activities of all colony members under laboratory colony conditions. We also investigated the effect of broods on activity-rest rhythms by removing all broods under colony conditions. Activity-rest rhythms appeared only in isolated ants, not under colony conditions. In addition, workers showed arrhythmic activities after brood removal. These results suggested that a mixture of social interactions, and not light and temperature, induces the loss of activity-rest rhythms. These results contribute to the knowledge of a diverse pattern of circadian activity rhythms in social insects.

Susceptibility of Ixodes scapularis (Acari: Ixodidae) to Permethrin Under a Long-Term 4-Poster Deer Treatment Area on Shelter Island, NY

Pesticide resistance in medically significant disease vectors can negatively impact the efficacy of control efforts. Resistance research on ticks has focused primarily on species of veterinary significance that experience relatively high degrees of control pressure. Resistance in tick vectors of medical significance has received little attention, in part because area-wide pesticide applications are not used to control these generalist tick species. One of the few effective methods currently used for area-wide control of medically important ticks, including Ixodes scapularis Say (Acari: Ixodidae), is deployment of 4-poster devices. Deer self-apply a topical acaricide (permethrin) while feeding on corn from the devices. A 4-poster program using permethrin has been deployed on Shelter Island, NY to control I. scapularis populations since 2008. We collected engorged female ticks from deer in this management area and a location in the Mid-Hudson River Valley, NY without area-wide tick control. Larvae were reared from egg masses and their susceptibility to permethrin was tested. Larvae originating from a long-term laboratory colony were used as a susceptible baseline for comparison. Compared against the laboratory colony, resistance ratios at LC-50 for Shelter Island and Hudson Valley I. scapularis were 1.87 and 1.51, respectively. The susceptibilities of the field populations to permethrin were significantly lower than that of the colony ticks. We provide the first data using the larval packet test to establish baseline susceptibility for I. scapularis to permethrin along with information relevant to understanding resistance emergence in tick populations under sustained control pressure from 4-poster devices.

Spiroplasma Isolated From Third-Generation Laboratory Colony Ixodes persulcatus Ticks

Spiroplasma are vertically-transmitted endosymbionts of ticks and other arthropods. Field-collected Ixodes persulcatus have been reported to harbour Spiroplasma, but nothing is known about their persistence during laboratory colonisation of this tick species. We successfully isolated Spiroplasma from internal organs of 6/10 unfed adult ticks, belonging to the third generation of an I. persulcatus laboratory colony, into tick cell culture. We screened a further 51 adult male and female ticks from the same colony for presence of Spiroplasma by genus-specific PCR amplification of fragments of the 16S rRNA and rpoB genes; 100% of these ticks were infected and the 16S rRNA sequence showed 99.8% similarity to that of a previously-published Spiroplasma isolated from field-collected I. persulcatus. Our study shows that Spiroplasma endosymbionts persist at high prevalence in colonised I. persulcatus through at least three generations, and confirms the usefulness of tick cell lines for isolation and cultivation of this bacterium.