The morphological diagnosis of 2 economically important subterranean termites in Western Indonesia, Coptotermes curvignathus and Coptotermes gestroi (Blattodea, Rhinotermitidae).

In Indonesia, the control of Coptotermes curvignathus populations as living tree termite pests has been carried out since the early 20th century. Recently, C. curvignathus has been considered the main termite pest and designated as the only species model for wood and wood products resistance tests against subterranean termite attack testing protocol in the Indonesian National Standard (SNI). However, the species distribution range of C. curvignathus has been long questioned as Coptotermes gestroi is commonly reported as a species found in urban areas of Southeast Asian region, particularly in Indonesia. One of the reasons for the species distribution discrepancies is the lack of morphological markers to distinguish both species in the field. Thus, limiting the field inspection effectiveness in termite pest management in Indonesia. This study reexamined and clarified the morphological differences between C. curvignathus and C. gestroi, based on soldier caste. The head shape, mandible shape, and distribution of genal setae on the ventro-anterior head part and pronotum marked the difference between the 2 species. These current results support previous findings of C. curvignathus as the forest dweller while clarifying C. gestroi as the common urban dweller in Indonesia. The putative benefit of morphological features related to the head, mandible, and setae distribution to the defensive adaptation in their common habitat was discussed. Ultimately, the inclusion of C. gestroi into the Indonesian National Standard (SNI) as an alternative species for efficacy tests against subterranean termites is highly recommended.

Caste-specific development of the dopaminergic system in bumble bees (Bombus ignitus).

The dopaminergic system is involved in caste-specific behaviors in eusocial bumble bees. However, little is known about how the caste differences in dopaminergic system are formed during pupal stages in the brains of bumble bees. Thus, we investigated the levels of dopamine-related substances and expression of genes encoding enzymes involved in dopamine synthesis and metabolism, dopamine receptors, and a dopamine transporter in the brain of female Bombus ignitus. The levels of dopamine and dopamine-related substances in the brain were significantly higher in gynes than in workers from the late pupal stage to emergence, but the dynamics were similar between the castes. The relative expression levels of genes encoding enzymes involved in dopamine synthesis (BigTh and BigDdc) and dopamine metabolism (BigNat) increased significantly from pupal stage to emergence, but there were no differences in the relative expression levels of these genes between castes. A similar pattern was seen in the relative expression levels of four dopamine receptor genes (BigDop1, BigDop2, BigDop3, and BigDopEcR) and a dopamine transporter gene (BigDat). Compared with the honey bee Apis mellifera, the caste-specific dopaminergic system in the bumble bee is less differentiated, which might reflect the degree of behavioral specialization in these two species.

Inter-clonal competition over queen succession imposes a cost of parthenogenesis on termite colonies.

In social insect colonies, selfish behaviour due to intracolonial conflict among members can result in colony-level costs despite close relatedness. In certain termite species, queens use asexual reproduction for within-colony queen succession but rely on sexual reproduction for worker and alate production, resulting in multiple half-clones of a single primary queen competing for personal reproduction. Our study demonstrates that competition over asexual queen succession among different clone types leads to the overproduction of parthenogenetic offspring, resulting in the production of dysfunctional parthenogenetic alates. By genotyping the queens of 23 field colonies of Reticulitermes speratus, we found that clone variation in the queen population reduces as colonies develop. Field sampling of alates and primary reproductives of incipient colonies showed that overproduced parthenogenetic offspring develop into alates that have significantly smaller body sizes and much lower survivorship than sexually produced alates. Our results indicate that while the production of earlier and more parthenogenetic eggs is advantageous for winning the competition for personal reproduction, it comes at a great cost to the colony. Thus, this study highlights the evolutionary interplay between individual-level and colony-level selection on parthenogenesis by queens.

The diverse roles of insulin signaling in insect behavior.

In insects and other animals, nutrition-mediated behaviors are modulated by communication between the brain and peripheral systems, a process that relies heavily on the insulin/insulin-like growth factor signaling pathway (IIS). Previous studies have focused on the mechanistic and physiological functions of insulin-like peptides (ILPs) in critical developmental and adult milestones like pupation or vitellogenesis. Less work has detailed the mechanisms connecting ILPs to adult nutrient-mediated behaviors related to survival and reproductive success. Here we briefly review the range of behaviors linked to IIS in insects, from conserved regulation of feeding behavior to evolutionarily derived polyphenisms. Where possible, we incorporate information from Drosophila melanogaster and other model species to describe molecular and neural mechanisms that connect nutritional status to behavioral expression via IIS. We identify knowledge gaps which include the diverse functional roles of peripheral ILPs, how ILPs modulate neural function and behavior across the lifespan, and the lack of detailed mechanistic research in a broad range of taxa. Addressing these gaps would enable a better understanding of the evolution of this conserved and widely deployed tool kit pathway.

Diversity and antimicrobial activity of the tropical ant-derived actinomycetes isolated from Thailand.

Antibiotic resistance is one of the most important global healthcare challenges and is responsible for the mortality of millions of people worldwide every year. It is a crisis attributed to misuse of antibiotics and a lack of new drug development. Actinomycetes constitute a group of Gram-positive bacteria known for their distinctive high guanine-cytosine (G+C) content in their genomic DNA. These microorganisms are widely recognized for their capability to generate a wide range of secondary metabolites with diverse biological activities. These versatile microorganisms are ubiquitous in diverse ecosystems, including soil, freshwater, marine sediments, and within the bodies of insects. A recent study has demonstrated that social insects, such as ants, host a diverse array of these bacteria. In this study, we involved the isolation and characterization of a total of 72 actinomycete strains obtained from 18 distinct ant species collected from various regions across Thailand. Utilizing 16S rRNA gene analysis, these isolated actinomycetes were classified into four distinct genera: Amycolatopsis (2 isolates), Micromonospora (1 isolate), Nocardia (8 isolates), and Streptomyces (61 isolates). Among the Streptomyces strains, 23 isolates exhibited antimicrobial activity against a panel of Gram-positive bacteria, including Bacillus subtilis ATCC 6633, Staphylococcus epidermidis ATCC 12228, Staphylococcus aureus ATCC 25923, Kocuria rhizophila ATCC 9341, and Methicillin-resistant Staphylococcus aureus (MRSA) DMST 20646. Additionally, two isolates displayed antifungal activity against Candida albicans TISTR 5554. Based on 16S rRNA gene sequence similarity studies, these two isolates, ODS25 and ODS28, were demonstrated to be closely related to Streptomyces lusitanus NBRC 13464T (98.07%) and Streptomyces haliclonae DSM 41970T (97.28%), respectively. The level of 16S rRNA gene sequence similarity below 98.65% cutoff indicates its potential as a novel actinomycete species. These findings underscore the potential of actinomycetes sourced from ants as a valuable reservoir of novel antimicrobials.

Immune response in paper wasp workers: Task matters more than age.

Workers of social hymenopterans (ants, bees and wasps) display specific tasks depending on whether they are younger or older. The relative importance of behavior and age in modulating immune function has seldom been addressed. We compared the strength of encapsulation-melanization immune response (hereafter melanotic encapsulation) in paper wasps displaying age polyethism or experimentally prevented from behavioral specialization. Foragers of Polybia paulista had higher melanotic encapsulation than guards, regardless of their age. Nevertheless, melanotic encapsulation decreased with age when wasps were prevented from behavioral specialization. Thus, in this species, worker melanotic encapsulation seems more sensitive to task than age. Foraging is considered one of the riskier behaviors in terms of pathogen exposure, so upregulating melanotic encapsulation in foragers can possibly improve both individual and colony-level resistance against infections.

The influence of climate oscillations and geological events on population differentiation of Camponotus japonicus in the Chinese mainland.

Camponotus japonicus (Hymenoptera: Formicidae) is an omnivorous social insect which builds sizable colonies in sparse woodlands or cropland and spreads across multiple climatic zones in the Chinese mainland. This study aims to reveal the role of climate changes and geological events in driving the genetic structure of social insect populations by investigating the phylogenetics and historical demography of C. japonicus in the Chinese mainland. Phylogenetic analyses were conducted based on the mitochondria DNA dataset using MrBayes and IQ-TREE. We constructed a haplotype network, calculated analyses of molecular variance, estimated the divergence time, and reconstructed the maximum clade credibility tree. Mismatch distribution and Bayesian skyline plots were used to infer historical population fluctuations. Additionally, ecological niche modeling was employed to predict the potential distribution of the species during the present, mid-holocene, and last glacial maximum periods in the Chinese mainland. The phylogenetic tree and median-joining network analyses support the presence of four distinct lineages in C. japonicus. These lineages exhibit significant genetic differentiation and limited gene flow. The divergence among the four lineages began in the early Pleistocene, approximately 1.41 million years ago (Ma). Subsequently, the central lineage diverged from both the northern and southern lineages around 1.16 Ma, while the northern and southern lineages diverged from each other at approximately 1.07 Ma. Population expansion was observed in the southern, central, and northern lineages prior to the last glacial maximum, while the Yunnan-Sichuan lineage experienced a slight increase in population size in more recent times. The predicted distribution of the species corresponds well with the actual distribution. Furthermore, the current suitable habitat areas in northern Xinjiang, southern Tibet, and the southeast coastal regions have significantly decreased compared to the last glacial maximum and the mid-holocene periods. Our results suggest that climate oscillations and geological events play an important role in driving genetic patterns and differentiation of C. japonicus. Mountain barriers isolate populations from each other, hinder the flow of genes, and effectively prevent the spread of this species. But at the same time, it also formed refugia at low altitudes areas such as Qinling-Bashan Mountains and Yanshan-Taihang Mountains and provide suitable habitats during glaciation. This study provides a good model for understanding how complex climate changes and geological events affect population genetic differentiation of social insects in the Chinese mainland.

Effect of Solenopsis invicta virus 3 on brood mortality and egg hatch in Solenopsis invicta.

Solenopsis invicta virus 3 (SINV-3) has been shown to cause significant mortality among all stages of its host, Solenopsis invicta. One impact of the virus is alteration of worker ant foraging behavior, which results in colony starvation and collapse over time. Additionally, it has been hypothesized that SINV-3 infection of S. invicta may disrupt worker ant brood care behavior. To investigate this possibility, various combinations of SINV-3-infected and -uninfected adult (worker) and immature (brood) stages were placed together and monitored using the response variables, mortality, egg hatch, and virus load. While significant differences in percent cumulative S. invicta worker ant mortality among six combinations of SINV-3-infected and -uninfected stages were observed, no significant differences in percent cumulative mortality of S. invicta larvae or pupae were observed. No significant differences in egg hatch were observed among SINV-3-uninfected, SINV-3-infected (colony-treated and queen-treated), and starved colonies. Eggs hatched normally in 10-12 days for all treatments indicating that egg care by worker ants was unaffected by SINV-3 infection status. The study further clarifies SINV-3 pathogenesis in its host, S. invicta. Larval mortality in SINV-3-infected colonies does not appear to be caused by worker ant neglect. S. invicta brood under the care of SINV-3-infected worker ants did not exhibit higher mortality rates compared with those tended by SINV-3-uninfected worker ants.

Reminiscences on the honeybee genome project and the rise of epigenetic concepts in insect science.

The sequencing of the honeybee genome in 2006 was an important technological and logistic achievement experience. But what benefits have flown from the honeybee genome project? What does the annotated genomic assembly mean for the study of behavioural complexity and organismal function in honeybees? Here, I discuss several lines of research that have arisen from this project and highlight the rapidly expanding studies on insect epigenomics, emergent properties of royal jelly, the mechanism of nutritional control of development and the contribution of epigenomic regulation to the evolution of sociality. I also argue that the term 'insect epigenetics' needs to be carefully redefined to reflect the diversity of epigenomic toolkits in insects and the impact of lineage-specific innovations on organismal outcomes. The honeybee genome project helped pioneer advances in social insect molecular biology, and fuelled breakthrough research into the role of flexible epigenomic control systems in linking genotype to phenotype.

Gustatory responsiveness in Vespula germanica workers: exploring the interplay between sensory perception and task specialization.

Workers' task specialization and division of labor are critical features of social insects' ecological success. It has been proposed that the division of labor relies on response threshold models: individuals varying their sensitivity (and responsiveness) to biologically relevant stimuli and performing a specific task when a stimulus exceeds an internal threshold. In this work, we study carbohydrate and protein responsiveness and their relation to worker task specialization in Vespula germanica, an invasive social wasp. The sucrose and peptone responsiveness of two different subcastes, preforagers and foragers, was determined by stimulating the antenna of the wasps with increasing concentrations of the solution and quantifying whether each concentration elicited a licking response. We studied responsiveness in five different ways: (1) response threshold, (2) concentration 50 (concentration to which at least 50% of wasps responded), (3) maximum response, (4) mean scores and (5) median scores. Our results suggest that V. germanica foragers are more sensitive to sucrose (lower thresholds) than preforager workers. However, we found no differences for peptone thresholds (i.e., a protein resource). Nonetheless, this is the first study to investigate response thresholds for protein resources. The intercaste variation in sucrose responsiveness shown in our work contributes to the existing knowledge about response threshold theory as a mechanism for task specialization observed in V. germanica.

British Columbia beekeeping revenues and costs: survey data and profit modeling.

British Columbia beekeepers, like many beekeepers around the world, are currently facing declines in honey bee health and high overwinter colony losses. To better understand the economics and the cycle of yearly colony loss and replacement of this critical agricultural industry, we collected and analyzed survey data on beekeeping costs and returns. Forty British Columbia beekeepers provided details about revenue sources, variable costs, capital costs, and investments. Ten surveyed beekeepers managed between 1 and 9 colonies, 10 managed between 10 and 39 colonies, 9 managed between 40 and 100 colonies, 5 managed between 101 and 299 colonies, 3 managed between 300 and 699 colonies, and 3 managed 700 colonies or more. The data was used to calculate beekeeping profit and to parameterize a model that explores the economic impact of colony loss rates and replacement strategies. Survey results show that when the data is aggregated, revenues exceed costs for beekeeping operations in British Columbia with a per colony profit of $56.92 or $0.87 per pound of honey produced. Surveyed operations with fewer than 100 colonies have negative profits, while operations with 100-299 colonies have positive profits. Surveyed operations in the Cariboo, North Coast, and Okanagan regions have the highest profits while surveyed operations in the Peace region have the lowest profits. Profit modeling shows that replacing losses with packages generates lower profit than replacing losses with split colonies. Our modeling shows that operations that diversify their revenue to include bee sales and commercial pollination accrue higher profits and can withstand higher winter loss rates.

Postural analysis reveals persistent changes in paper wasp foundress behavioral state after conspecific challenge.

Vigilant animals detect and respond to threats in the environment, often changing posture and movement patterns. Vigilance is modulated not only by predators but also by conspecific threats. In social animals, precisely how conspecific threats alter vigilance behavior over time is relevant to long-standing hypotheses about social plasticity. We report persistent effects of a simulated conspecific challenge on behavior of wild northern paper wasp foundresses, Polistes fuscatus. During the founding phase of the colony cycle, conspecific wasps can usurp nests from the resident foundress, representing a severe threat. We used automated tracking to monitor the movement and posture of P. fuscatus foundresses in response to simulated intrusions. Wasps displayed increased movement, greater bilateral wing extension, and reduced antennal separation after the threat was removed. These changes were not observed after presentation with a wooden dowel. By rapidly adjusting individual behavior after fending off an intruder, paper wasp foundresses might invest in surveillance of potential threats, even when such threats are no longer immediately present. The prolonged vigilance-like behavioral state observed here is relevant to plasticity of social recognition processes in paper wasps.

Cuticular Hydrocarbon Profiling by Fractionation and GC-MS in Socially Parasitic Ants.

Ants use cuticular hydrocarbon (CHC) as a semiochemical for recognizing their nestmates. For socially parasitic ants, deceiving the CHC is an important survival strategy. Profiling and quantifying CHC is a potent approach to understanding such nestmate discrimination behavior. Thus, a highly efficient, stable, and reproducible extraction method for CHC is essential for this purpose. This paper describes a method for socially parasitic ants to disguise the host species' CHC profile under laboratory conditions, as well as the extraction and measurement of CHC from ants (from a previous study). First, the artificial isotopic substance is applied to the host worker; then, the socially parasitic ant disguises the host-like CHC profile against the above host worker. Next, the CHC is extracted and fractionated from a socially parasitic ant using hexane and silica gel. After concentrating the fractionated product, this product is then used for measurement by gas chromatographymass spectrometry (GC-MS). The CHC extraction protocol described in this paper may be used for various ant species.

Sexual maturation and allometry of reproductive traits in large- and small-sized male honeybees.

The body size of male honeybees (Apis mellifera L.) is a cause of skewed reproductive success. Large males are usually produced in colonies and have advantages in competition for mating and fertilisation. However, distinct small-sized males were produced depending on the colony conditions, particularly under queen-less conditions. Understanding the reproductive traits of small-sized males is currently limited, but it may provide insight into the developmental patterns and reproductive strategies that maximise reproductive success depending on body size and colony conditions. This study evaluated the process of sexual maturation in large- and small-sized males and the allometry between reproductive traits and body size. Changes in reproductive traits, including reproductive organs, number of spermatozoa, and sperm density, occurred earlier in small-sized males than in large-sized males after emergence. These results suggest that small males are precocious. The relatively early development of small-sized males would reflect the low developmental cost, which is likely to allow the production of many males and ensure reproductive success under circumstances in which available resources are limited. Furthermore, reproductive traits were positively correlated with body size, but allometry was different for these traits. Hence, the findings suggest that there is a given investment pattern toward reproductive traits with increasing body size, which would be responsible for high mating and fertilisation success in large males.

The royal food of termites shows king and queen specificity.

Society in eusocial insects is based on the reproductive division of labor, with a small number of reproductive individuals supported by a large number of nonreproductive individuals. Because inclusive fitness of all colony members depends on the survival and fertility of reproductive members, sterile members provide royals with special treatment. Here, we show that termite kings and queens each receive special food of a different composition from workers. Sequential analysis of feeding processes demonstrated that workers exhibit discriminative trophallaxis, indicating their decision-making capacity in allocating food to the kings and queens. Liquid chromatography tandem-mass spectrometry analyses of the stomodeal food and midgut contents revealed king- and queen-specific compounds, including diacylglycerols and short-chain peptides. Desorption electrospray ionization mass spectrometry imaging analyses of 13C-labeled termites identified phosphatidylinositol and acetyl-l-carnitine in the royal food. Comparison of the digestive tract structure showed remarkable differences in the volume ratio of the midgut-to-hindgut among castes, indicating that digestive division of labor underlies reproductive division of labor. Our demonstration of king- and queen-specific foods in termites provides insight into the nutritional system that underpins the extraordinary reproduction and longevity of royals in eusocial insects.

Next-generation sequencing dataset of bacterial communities of Microcerotermes crassus workers associated with Ironwood trees (Casuarina equisetifolia) in Guam.

Ironwood trees (Casuarina equisetifolia) in Guam have been suffering from Ironwood Tree Decline (IWTD) since 2002. Putative plant pathogenic bacteria such as Ralstonia solanacearum and Klebsiella species were identified in the ooze of declining trees and considered to be linked to IWTD. In addition, termites were found to be significantly associated with IWTD. Microcerotermes crassus Snyder (Blattodea: Termitidae) was identified as a termite species that attacks ironwood trees in Guam. Since termites harbor a diverse community of symbiotic and environmental bacteria, we sequenced the microbiome of M. crassus workers attacking ironwood trees in Guam to assess the presence of IWTD-associated pathogens in termite bodies. This dataset contains 652,571 raw sequencing reads present in M. crassus worker samples collected from six ironwood trees in Guam obtained via sequencing the V4 region of the16S rRNA gene on the Illumina NovaSeq (2 × 250bp) platform. Sequences were taxonomically assigned in QIIME2 using SILVA 132 and NCBI GenBank as reference databases. Spirochaetes and Fibrobacteres were the most dominant phyla in M. crassus workers. No putative plant pathogens of the genera Ralstonia or Klebsiella were found in the M. crassus samples. The dataset has been made publicly available through NCBI GenBank under BioProject ID PRJNA883256. This dataset can be used to compare the bacterial taxa present in M. crassus workers in Guam to bacteria communities of related termite species from other geographical locations. In addition, this dataset can also be used to investigate the relationship between termite microbiomes and the microbiomes of ironwood trees they attack and of the surrounding soil.

Elevated expression of immune and DNA repair genes in mated queens and kings of the Reticulitermes chinensis termites.

Studies have identified that mating induces a series of physiological changes in animals. In this period, males tending to invest more energy, immune peptides, and other substances to reduce the cost of living for females. This results in lower survival rates in later life than females. Meanwhile, both males and females shorten lifespans due to reproduction. However, the reasons why termites' queens and kings are both extremely long-lived and highly fecund are unclear. Therefore, this study aimed to examine the effects of mating on the expression of immune and DNA repair genes for lifespan extension in termite queens and kings. Here, we reported that mated queens show relatively higher expression of immune genes (phenoloxidase, denfensin, termicin, transferrin), antioxidant genes (CAT, SOD), detoxification genes (GST, CYP450) than virgin queens in the Reticulitermes chinensis. In addition, mated kings also highly expressed these genes, except for termicin, transferrin, GST, and CYP450. After mating, both queens and kings significantly upregulated the expression of DNA repair genes (MLH1, BRCA1, XRCC3, RAD54-like). Mismatch repair genes (MMR) MSH2, MSH4, MSH6 were considerably increased in mated queens, while MSH4, MSH5, MSH6 were upregulated in mated kings. Our results suggest that mating increases the expression of immune and DNA repair genes in the termite queens and kings, and thus possibly improving their survival during reproductive span due to the omnipresent pathogens.

Meta-Analysis of Public RNA Sequencing Data Revealed Potential Key Genes Associated with Reproductive Division of Labor in Social Hymenoptera and Termites.

Eusociality in insects has evolved independently many times. One of the most notable characteristics of eusociality is the reproductive division of labor. In social insects, the reproductive division of labor is accomplished by queens and workers. Transcriptome analyses of queens and workers have been conducted for various eusocial species. However, the genes that regulate the reproductive division of labor across all or multiple eusocial species have not yet been fully elucidated. Therefore, we conducted a meta-analysis using publicly available RNA-sequencing data from four major groups of social insects. In this meta-analysis, we collected 258 pairs (queen vs. worker) of RNA-sequencing data from 34 eusocial species. The meta-analysis identified a total of 20 genes that were differentially expressed in queens or workers. Out of these, 12 genes have not previously been reported to be involved in the reproductive division of labor. Functional annotation of these 20 genes in other organisms revealed that they could be regulators of behaviors and physiological states related to the reproductive division of labor. These 20 genes, revealed using massive datasets of numerous eusocial insects, may be key regulators of the reproductive division of labor.

Colony-level aggression escalates with the value of food resources.

BACKGROUND: Theory predicts that the level of escalation in animal contests is associated with the value of the contested resource. This fundamental prediction has been empirically confirmed by studies of dyadic contests but has not been tested experimentally in the collective context of group-living animals. Here, we used the Australian meat ant Iridomyrmex purpureus as a model and employed a novel field experimental manipulation of the value of food that removes the potentially confounding effects of nutritional status of the competing individual workers. We draw on insights from the Geometric Framework for nutrition to investigate whether group contests between neighbouring colonies escalate according to the value to the colony of a contested food resource. RESULTS: First, we show that colonies of I. purpureus value protein according to their past nutritional intake, deploying more foragers to collect protein if their previous diet had been supplemented with carbohydrate rather than with protein. Using this insight, we show that colonies contesting more highly valued food escalated the contest, by deploying more workers and engaging in lethal 'grappling' behaviour. CONCLUSION: Our data confirm that a key prediction of contest theory, initially intended for dyadic contests, is similarly applicable to group contests. Specifically, we demonstrate, through a novel experimental procedure, that the contest behaviour of individual workers reflects the nutritional requirements of the colony, rather than that of individual workers.