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The Formosan subterranean termite, Coptotermes formosanus Shiraki, is both an economically impactful pest and a successful invader. One method of subterranean termite control is baiting. According to the label, baits are installed surrounding the structure at a uniform interval distance of ≈3 m. However, homeowners and pest control professionals are often concerned that termites may bypass bait stations and have access to the structure. To address this concern, we experimentally duplicated field conditions using a large planar arena (3.6 m × 1.1 m) to study the optimal distribution of bait stations based on colony-wide foraging activity. We installed 2 bait stations 3 m apart as per label instructions and introduced C. formosanus colonies to allow them to explore the arena by tunneling through the sand. In this real-scale arena, all termite colonies intercepted a bait station in an average of 21 (± 8 SD) days. We assumed that termites could find bait faster if there were more bait stations by overlaying additional hypothetical baits closer than per label instruction, but the improvement was incremental, requiring 4 times more stations (0.45 m interval) to obtain a significant difference. We also revealed the characteristic behavior after intercepting bait stations, termites created a burst of tunnels that radiated from the bait station. These branching tunnels averaged 16 cm in length, suggesting immediate interceptions of additional auxiliary stations placed within 16 cm of an active station. These findings contribute to our understanding on how subterranean termites intercept inground bait stations., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

In 1995, the launch of the first commercial chitin synthesis inhibitor (CSI) bait led to the transformation of the subterranean termite control industry around the world. Their slow mode of action, which relies on both their ability to be transferred among nestmates and termite molting biology, has made them cost-effective solutions for subterranean termite colony elimination while minimizing the introduction of pesticides into the soil toward an environmentally sustainable strategy. However, despite successful commercial implementations, the acceptance of their use varies within the pest control industry around the world. Notably, the nuanced complexity of how CSI baits lead to colony elimination upon feeding by termite foragers has, in part, remained elusive for the past 3 decades, allowing for long-lasting misconceptions to persist. A recent series of studies has since provided complementary elements of understanding how CSI baits utilize termites' inherent colony demography, behavior, and physiology to trigger colony elimination after a characteristic succession of events within the colony collapse process. I here provide a synthetic overview of subterranean termite colony characteristics when exposed to CSI baits using Coptotermes (Wasmann) (Blattodea: Heterotermitidae) as a primary model system. The changes in colony demography through the colony collapse reflect how the mode of action of CSI baits makes them a prime solution for sustainable subterranean termite pest management. Following decades of innovation, ongoing interactions among termite researchers, bait product manufacturers, and pest management providers must continue to bring solutions to existing and emerging termite pest problems around the world., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America.)

The use of nonrepellent liquid termiticides against subterranean termites has long relied on the assumption that foraging termites in soils could transfer toxicants to nestmates to achieve population control. However, their dose-dependent lethal time can lead to rapid termite mortality in proximity of the treatment, triggering secondary repellency. The current study characterizes the dynamic nature of the "death zone," i.e., the area adjacent to soil termiticides that termites would avoid owing the accumulation of cadavers. Using whole subterranean termite laboratory colonies of Coptotermes gestroi (Wasmann) with 3 × 15 m foraging distances, fipronil was implemented at 1.5 m, 7.5 m, or 12.5 m away from colony central nests, emulating a corrective action against an termite structural infestation. For treatments at 7.5 m and 12.5 m, the death zone stabilized at an average of ~2.56 m away from the treatment after 40 d post-treatment, and colonies suffered as little as 1.5% mortality by 200 d post-treatment. Colonies located 1.5 m away from the treatment minimized the death zone to ~1.1 m and suffered as little as 23.5% mortality. Mortality only occurred within the first few days of treatment from initial exposure, as the rapid emergence of the death zone negated further transfer effects among nestmates over time. In some cases, foraging termites were trapped within the infested structure. While technically nonrepellent, fipronil becomes functionally repellent from the rapid mortality onset near the treatment. Even if diligently implemented to successfully protect structures, surrounding termite colonies are minimally impacted by fipronil soil treatments., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America.)

The higher classification of termites requires substantial revision as the Neoisoptera, the most diverse termite lineage, comprise many paraphyletic and polyphyletic higher taxa. Here, we produce an updated termite classification using genomic-scale analyses. We reconstruct phylogenies under diverse substitution models with ultraconserved elements analyzed as concatenated matrices or within the multi-species coalescence framework. Our classification is further supported by analyses controlling for rogue loci and taxa, and topological tests. We show that the Neoisoptera are composed of seven family-level monophyletic lineages, including the Heterotermitidae Froggatt, Psammotermitidae Holmgren, and Termitogetonidae Holmgren, raised from subfamilial rank. The species-rich Termitidae are composed of 18 subfamily-level monophyletic lineages, including the new subfamilies Crepititermitinae, Cylindrotermitinae, Forficulitermitinae, Neocapritermitinae, Protohamitermitinae, and Promirotermitinae; and the revived Amitermitinae Kemner, Microcerotermitinae Holmgren, and Mirocapritermitinae Kemner. Building an updated taxonomic classification on the foundation of unambiguously supported monophyletic lineages makes it highly resilient to potential destabilization caused by the future availability of novel phylogenetic markers and methods. The taxonomic stability is further guaranteed by the modularity of the new termite classification, designed to accommodate as-yet undescribed species with uncertain affinities to the herein delimited monophyletic lineages in the form of new families or subfamilies., (© 2024. The Author(s).)

Hybridization between invasive pest species may lead to significant genetic and economic impacts that require close monitoring. The two most invasive and destructive termite species worldwide, Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann), have the potential for hybridization in the field. A three-year field survey conducted during the dispersal flight season of Coptotermes in Taiwan identified alates with atypical morphology, which were confirmed as hybrids of the two Coptotermes species using microsatellite and mitochondrial analyses. Out of 27,601 alates collected over three years, 4.4% were confirmed as hybrid alates, and some advanced hybrids (>F1 generations) were identified. The hybrid alates had a dispersal flight season that overlapped with the two parental species 13 out of 15 times. Most of the hybrid alates were females, implying that mating opportunities beyond F1 may primarily be possible through female hybrids. However, the incipient colony growth results from all potential mating combinations suggest that only backcross colonies with hybrid males could sometimes lead to brood development. The observed asymmetrical viability and fertility of hybrid alates may critically reduce the probability of advanced-hybrid colonies being established in the field., (© 2024. The Author(s), under exclusive licence to The Genetics Society.)

Background: To control subterranean termite pests, chitin synthesis inhibitor (CSI) baits have been widely applied. Despite CSI baits having low impacts on the environment, they require a lengthy time period to eliminate colonies. 20-hydroxyecdysone (20E) was proposed to speed up the baiting process as it showed faster mortality than CSI baits. However, the efficacy of 20E has previously not been tested at the colony level prior to applying in the field., Results: We compared the effect of 20E, 20E + noviflumuron, noviflumuron and untreated control using colonies of Coptotermes formosanus. Our result revealed that both 20E and 20E + noviflumuron did not accelerate colony elimination and termite activity remained relatively stable during the observation periods. To determine the limited effects of 20E, we further investigated feeding duration and consumption amount of 20E with different concentrations (control, 100 and 1000 ppm) for 10 days. Termites ceased feeding after 1 day in 100 and 1000 ppm treatment and 100% mortality was observed within 10 days in 1000 ppm 20E, while mortality in the 100 ppm 20E treated group was much lower than that in the 1000 ppm group. Furthermore, no termites molted in the control and termites died from hyperecdysonism in 1000 ppm 20E treatment, whereas about 20% of termites molted in 100 ppm 20E., Conclusion: This study demonstrated that 20E may not be suitable as a sole active ingredient to accelerate elimination of a subterranean termite colony, while CSI baits and lower concentrations of 20E may reduce the lengthy time period in colony elimination. © 2023 Society of Chemical Industry., (© 2023 Society of Chemical Industry.)

With recent evidence of hybridization events in the field, the phenotypic traits of F1 hybrid colonies of 2 destructive subterranean termite species, Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) remain to be investigated. In this study, laboratory colonies of 2 conspecific pairings and 2 heterospecific pairings (hybrid F = ♀C. formosanus × ♂C. gestroi, hybrid G = ♀C. gestroi × ♂C. formosanus) were examined in Florida, USA, and in Taiwan. Colony nest architecture for both hybrids displayed disorganized carton materials compared to the defined trabecular carton of both parental species. Soldier head measurements were not a reliable approach for diagnostic purposes, as soldier morphometric traits widely overlapped across all mating combinations, except for hybrid F soldiers displaying abnormally long mandibles. Hybrid F soldiers' mandibles also remained parallel when at rest. However, 4 qualitative morphological differences in soldiers were determined for diagnostic purposes. First, the fontanelle in both hybrids is horizontally ellipsoid whereas subcircular in C. gestroi and trianguliform in C. formosanus. Second, sclerotized striations along the postmental sulcus are present in C. gestroi, absent in C. formosanus, and intermediate in both hybrid soldier types. Third, each lateral margin of the fontanelle is flanked by 2 setae in C. formosanus and both hybrids, while a single seta resides on each side of the fontanelle in C. gestroi. Finally, C. gestroi and hybrid soldiers' heads are characterized by a bulging vertex that is lacking in C. formosanus. Therefore, a combination of these 4 characteristics now allows for soldier identification of hybrid Coptotermes., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America.)

The traditional stake survey and in-ground (IG) monitoring stations have been ineffective in aggregating the Asian subterranean termite, Coptotermes gestroi (Wasmann) in southeastern Florida. In this study, we used both IG and above-ground (AG) Sentricon stations to monitor and bait C. gestroi, and as expected, none of the 83 IG stations was intercepted. Despite this, AG bait stations with 0.5% noviflumuron were successfully used to eliminate C. gestroi colonies. From 2 field experiments, the mean colony elimination time (±SD) using AG baits were 6.4 ± 3.8 wk (n = 4) and 8.0 ± 2.1 wk (n = 12), respectively. Such results were compatible with baiting studies against field colonies of C. gestroi elsewhere, that is, 4-9 wk. The successful rates in monitoring and baiting of C. gestroi with IG stations in other regions also varied, which may be due to the variabilities in tunnel geometry of this species in different environments. In areas with established C. gestroi populations, routine inspection for signs of activity in structures and surrounding trees can be a critical component for pest control providers for early detection of infestation and colony elimination with AG bait stations., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Perfume making in male orchid bees is a unique behavior that has given rise to an entire pollination syndrome in the neotropics. 1 , 2 Male orchid bees concoct and store species-specific perfume mixtures in specialized hind-leg pockets 3 using volatiles acquired from multiple environmental sources, including orchid flowers. 4 , 5 However, the function and the ultimate causes of this behavior have remained elusive. 2 , 6 Although previous observations suggested that male perfumes serve as chemical signals, the attractiveness for females has not be shown. 7 , 8 Here, we demonstrate that the possession of perfume increases male mating success and paternity in Euglossa dilemma, a species of orchid bees recently naturalized in Florida. We supplemented males reared from trap-nests with perfume loads harvested from wild conspecifics. In dual-choice experiments, males supplemented with perfumes mated with more females, and sired more offspring, than untreated, equal-aged, control males. Although perfume supplementation had little effect on the intensity of male courtship display, it changed the dynamics of male-male interactions. Our results demonstrate that male-acquired perfumes are sexual signals that stimulate females for mating and suggest that sexual selection is key in shaping the evolution of perfume communication in orchid bees., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Coptotermes formosanus Shiraki and C. gestroi (Wasmann) are economically important structural pests in urban areas. Due to anthropogenic activity, both species have been introduced into the United States, with their respective invasive ranges now overlapping in Florida, and the two species have the capability to hybridize. The potential for structural damage from subterranean termite colonies primarily depends on colony size. However, long-term colony growth and wood consumption capabilities of hybrid Coptotermes colonies remain to be investigated, to determine the potential pest status of field-established hybrid colonies. In this study, we investigated long-term colony development over four years to determine if aging hybrid colonies display vigor in terms of colony growth. In addition, we compared wood consumption rate of hybrid colonies to compare their potential impact as structural pests with the two parental species. In aging colonies (four-year-old), both hybrid mating types displayed a colony growth equivalent to C. formosanus. However, the wood consumption rates of four-year-old colonies of the two parental Coptotermes species and their hybrids were similar, indicating equal damaging potential. We also found multiple secondary reproductives in hybrid colonies, even in the presence of primary reproductives, which may favor their potential establishment and spread. Although hybrid colonies or hybrid alates have yet to be detected in the field, our results suggest that such hybrid colonies would be an additional termite threat in the future if they were established in the field., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Wood-feeding termites have a nitrogen-poor diet and have therefore evolved nitrogen conservation strategies. However, termite workers molt periodically, and throughout the lifetime of a colony, millions of exuviae, a nitrogen-rich resource, are produced by the colony. In Coptotermes Wasmann, workers foraging at remote feeding sites must return to the central part of the nest to molt, where the queen, king, eggs, and larvae are located. It was hypothesized that this molting-site fidelity is an efficient way to recycle nitrogen for reproduction and colony growth, as nestmates involved in exuviae consumption can directly transfer such resources to individuals engaged in reproduction (the queen) or growth (larvae). This study investigates whether incipient colonies of C. gestroi (Wasmann) can gain additional biomass when they are fed supplementary exuviae. Incipient colonies were reared in nitrogen-poor or nitrogen-rich conditions, and 0, 1, 5, or 10 exuviae were added to 3-month-old colonies. After 6.5 months, colonies reared in nitrogen-poor environments gained significantly more biomass when exuviae were added than colonies with no added exuviae. However, the addition of exuviae had no effect on colony growth for colonies reared in nitrogen-rich environments. In a second experiment, queens from colonies in which exuviae were effectively removed laid fewer eggs than queens from colonies in which exuviae were not removed. Therefore, consumption of exuviae from molting individuals by nestmates is an important part of the nitrogen recycling strategy in Coptotermes colonies, as it facilitates queen oviposition and colony growth, especially when such colonies have limited access to nitrogen-rich soils., (Published by Oxford University Press on behalf of Entomological Society of America 2023.)

Nitrogen, a limiting growth factor in wood-feeding insects, was hypothesized to play a role in the recently discovered behavior of subterranean termites returning to the nest to molt. Coptotermes gestroi (Wasmann) exuviae is approximately 11% N by dry weight, and therefore a potentially rich source of recyclable nitrogen. Exuviae from a C. gestroi colony were marked with immunoglobulin G (IgG) and were fed to two-year-old C. gestroi colonies. IgG-marked exuviae were detected with an enzyme-linked immunosorbent assay. The IgG marker was later detected in every caste and life stage except first-instar larvae (L1). The proportion of individuals positive for the marker varied by caste, with the queens always being positive for the marker. The queens and second-or-higher-instar workers (W2+) had significantly higher concentrations of the marker than the eggs and L1. The trophic path of exuviae includes individuals that directly fed on marked exuviae (workers and possibly second-instar larvae) and individuals that secondarily received marked exuviae through trophallaxis (queens, kings, and soldiers). This study described the trophic path of consumed exuviae and demonstrated its role in the recycling of nitrogen in a subterranean termite. Molting at the central nest may be an efficient means to transfer nitrogen from shed exuviae to recipients and may be a nitrogen recycling behavior conserved from a termite ancestor., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America.)

Termites (Blattodea: Isoptera) have evolved specialized defensive strategies for colony protection. Alarm communication enables workers to escape threats while soldiers are recruited to the source of disturbance. Here, we study the vibroacoustic and chemical alarm communication in the wood roach Cryptocercus and in 20 termite species including seven of the nine termite families, all life-types, and all feeding and nesting habits. Our multidisciplinary approach shows that vibratory alarm signals represent an ethological synapomorphy of termites and Cryptocercus. In contrast, chemical alarms have evolved independently in several cockroach groups and at least twice in termites. Vibroacoustic alarm signaling patterns are the most complex in Neoisoptera, in which they are often combined with chemical signals. The alarm characters correlate to phylogenetic position, food type and hardness, foraging area size, and nesting habits. Overall, species of Neoisoptera have developed the most sophisticated communication system amongst termites, potentially contributing to their ecological success., (© 2023. The Author(s).)

Elaborate task allocation is key to the ecological success of eusocial insects. Termite colonies are known for exhibiting age polyethism, with older instars more likely to depart the reproductive center to access food. However, it remains unknown how termites retain this spatial structure against external disturbances. Here we show that a subterranean termite Coptotermes formosanus Shiraki combines age polyethism and behavioral flexibility to maintain a constant worker proportion at the food area. Since this termite inhabits multiple wood pieces by connecting them through underground tunnels, disastrous colony splitting events can result in the loss of colony members. We simulated this via weekly removal of all individuals at the food area. Our results showed that termites maintained a worker proportion of ~ 20% at the food area regardless of changes in total colony size and demographic composition, where younger workers replaced food acquisition functions to maintain a constant worker proportion at the food area. Food consumption analysis revealed that the per-capita food consumption rate decreased with younger workers, but the colony did not compensate for the deficiency by increasing the proportion of workers at the feeding site. These results suggest that termite colonies prioritize risk management of colony fragmentation while maintaining suitable food acquisition efficiency with the next available workers in the colony, highlighting the importance of task allocation for colony resiliency under fluctuating environments., (© 2022. The Author(s).)

Background: Foraging in group living animals such as social insects, is collectively performed by individuals. However, our understanding on foraging behavior of subterranean termites is extremely limited, as the process of foraging in the field is mostly concealed. Because of this limitation, foraging behaviors of subterranean termites were indirectly investigated in the laboratory through tunnel geometry analysis and observations on tunneling behaviors. In this study, we tracked subsets of foraging workers from juvenile colonies of Coptotermes formosanus (2-yr-old) to describe general foraging behavioral sequences and to find how foraging workers allocate time between the foraging site (food acquisition or processing) and non-foraging site (food transportation)., Results: Once workers entered into the foraging site, they spent, on average, a significantly longer time at the foraging site than the non-foraging site. Our clustering analysis revealed two different types of foraging workers in the subterranean termite based on the duration of time they spent at the foraging site and their foraging frequency. After entering the foraging site, some workers (cluster 1) immediately initiated masticating wood fragments, which they transferred as food boluses to recipient workers at the foraging site. Conversely, the recipient workers (cluster 2) moved around after entering the foraging site and received food from donating workers., Conclusions: This study provides evidence of task specialization within foraging cohorts in subterranean termites., (© 2021. The Author(s).)

Subterranean termite control methods using chitin synthesis inhibitors (CSIs) aim at eliminating colonies that feed upon a bait formulation. Several benzoylurea active ingredient formulations are currently commercially available as alternative termite management strategies to liquid termiticides. Individual workers need to molt on a regular basis and CSIs interfere with such molting process, allowing sufficient time for the acquisition of a colony-wide lethal dose prior to widespread mortality. As workers progressively die, the colony eventually collapses, leaving only soldiers and primary reproductives that starve to death. One common observation is that young workers often die early owing to their relatively short molting cycle. However, the absence of brood in dying colonies raises questions about the potential fate of eggs laid by the queen. This study aims to determine if CSI baits also terminate the ability of a colony to produce a new cohort of workers by disabling the ongoing brood development. Incipient termite colonies were used to test the impact of noviflumuron on the queen's ability to lay eggs and on the eggs' ability to hatch. Our results showed that queens in colonies exposed to CSI not only initially laid less eggs than the control queens, but eggs also did not develop and were progressively cannibalized, eventually leading to colony establishment failure. This result implies that queens of mature colonies exposed to CSI would lose the ability to lay viable eggs as the colony collapses, leading to an absence of worker replacement, aiding in colony elimination., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

AbstractCuticular hydrocarbons (CHCs) are waxy compounds on the surface of insects that prevent desiccation and frequently serve as chemical signals mediating social and mating behaviors. Although their function in eusocial species has been heavily investigated, little is known about the evolution of CHC-based communication in species with simpler forms of social organization lacking specialized castes. Here we investigate factors shaping CHC variation in the orchid bee Euglossa dilemma , which forms casteless social groups of two to three individuals. We first assess geographic variation, examining CHC profiles of males and females from three populations. We also consider CHC variation in the sister species, Euglossa viridissima , which occurs sympatrically with one population of E. dilemma . Next, we consider variation associated with female behavioral phases, to test the hypothesis that CHCs reflect ovary size and social dominance. We uncover a striking CHC polymorphism in E. dilemma spanning populations. In addition, we identify a separate set of CHCs that correlate with ovary size, social dominance, and expression of genes associated with social behavior, suggesting that CHCs convey reproductive and social information in E. dilemma . Together, our results reveal complex patterns of variation in which a subset of CHCs reflect the social and reproductive status of nestmates.

Intrinsic dinitrogen (N 2 ) fixation by diazotrophic bacteria in termite hindguts has been considered an important pathway for nitrogen acquisition in termites. However, studies that supported this claim focused on measuring instant N 2 fixation rates and failed to address their relationship with termite colony growth and reproduction over time. We here argue that not all wood-feeding termites rely on symbiotic diazotrophic bacteria for colony growth. The present study looks at dietary nitrogen acquisition in a subterranean termite (Rhinotermitidae, Coptotermes). Young termite colonies reared with wood and nitrogen-rich organic soil developed faster, compared to those reared on wood and inorganic sand. More critically, further colony development was arrested if access to organic soil was removed. In addition, no difference of relative nitrogenase expression rates was found when comparing the hindguts of termites reared between the two conditions. We therefore propose that subterranean termite (Rhinotermitidae) colony growth is no longer restricted to metabolically expensive intrinsic N 2 fixation, as the relationship between diazotrophic bacteria and subterranean termites may primarily be trophic rather than symbiotic. Such reliance of Rhinotermitidae on soil microbial decomposition activity for optimal colony growth may also have had a critical mechanistic role in the initial emergence of Termitidae., (© 2021. The Author(s).)

In collective animal motion, coordination is often achieved by feedback between leaders and followers. For stable coordination, a leader's signals and a follower's responses are hypothesized to be attuned to each other. However, their roles are difficult to disentangle in species with highly coordinated movements, hiding potential diversity of behavioural mechanisms for collective behaviour. Here, we show that two Coptotermes termite species achieve a similar level of coordination via distinct sets of complementary leader-follower interactions. Even though C. gestroi females produce less pheromone than C. formosanus , tandem runs of both species were stable. Heterospecific pairs with C. gestroi males were also stable, but not those with C. formosanus males. We attributed this to the males' adaptation to the conspecific females; C. gestroi males have a unique capacity to follow females with small amounts of pheromone, while C. formosanus males reject C. gestroi females as unsuitable but are competitive over females with large amounts of pheromone. An information-theoretic analysis supported this conclusion by detecting information flow from female to male only in stable tandems. Our study highlights cryptic interspecific variation in movement coordination, a source of novelty for the evolution of social interactions.

The development of baits for subterranean termite control over the past 25 yr has provided cost-effective alternatives to liquid termiticide treatments. Current bait products use one of the few available benzoylurea chitin synthesis inhibitors (CSIs) labeled for subterranean termites. These insecticides are used because of their nonrepellency, their slow-acting mode of action, and their dose-independent lethal time. Although many studies have provided ample evidence of the efficacy of CSI baits for subterranean termite colony elimination, most have focused on hexaflumuron and noviflumuron. However, bait products using alternative CSIs have not received the same level of scrutiny, limiting the amount of evidence proving their efficacy. One such compound is novaluron, the active ingredient currently used in the Trelona ATBS-Advance Termite Baiting System bait product. The current study independently tested the efficacy of this commercially available bait formulation against whole colonies of Coptotermes gestroi (Wamann) (~63,910 workers) in the laboratory, using an extended experimental setup to simulate a 15-m foraging distance from the central part of the nest to the bait, while having access to alternative food sources. Treated colonies progressively ceased to feed on wood items within 45 d after being provided access to the novaluron bait formulation, with a subsequent progressive collapse of the population, leading to colony elimination by 91 d. This study therefore confirms the efficacy of novaluron baits against subterranean termites, and currently remains one of the few CSIs that can be applied for the successful control of Coptotermes infestations., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Subterranean termites are hemimetabolous social insects where most of the individuals in a colony molt on a regular basis until they die. Nitrogen is a limiting growth factor in wood-feeding insects, such as termites. Because the exuviae of molting termites are consumed by nestmates, it is possible that exuviae represent a potential source of nitrogen that could be recycled and be part of the overall nitrogen conservation strategy of the colony. Although it was documented that cockroach exuviae can contain relatively high levels of nitrogen, the nitrogen content of subterranean termite exuviae has not been examined. This study determines the nitrogen content of Coptotermes gestroi (Wasmann) exuviae collected from four-year-old laboratory colonies using a carbon/nitrogen analyzer. Coptotermes gestroi exuviae contained 11.24 ± 0.64% N (Mean ± SD). The exuviae had a higher proportion of nitrogen than whole bodies of termites (~10.46%), wood (~0.12%), and organic soil (~2.49%). These results support the importance of exuviae consumption by nestmates during the ecdysis process as an aspect of nitrogen conservation strategies in Coptotermes colonies., Competing Interests: The authors declare no conflict of interest.

Termites are a clade of eusocial wood-feeding roaches with > 3000 described species. Eusociality emerged ~ 150 million years ago in the ancestor of modern termites, which, since then, have acquired and sometimes lost a series of adaptive traits defining of their evolution. Termites primarily feed on wood, and digest cellulose in association with their obligatory nutritional mutualistic gut microbes. Recent advances in our understanding of termite phylogenetic relationships have served to provide a tentative timeline for the emergence of innovative traits and their consequences on the ecological success of termites. While all "lower" termites rely on cellulolytic protists to digest wood, "higher" termites (Termitidae), which comprise ~ 70% of termite species, do not rely on protists for digestion. The loss of protists in Termitidae was a critical evolutionary step that fostered the emergence of novel traits, resulting in a diversification of morphology, diets, and niches to an extent unattained by "lower" termites. However, the mechanisms that led to the initial loss of protists and the succession of events that took place in the termite gut remain speculative. In this review, we provide an overview of the key innovative traits acquired by termites during their evolution, which ultimately set the stage for the emergence of "higher" termites. We then discuss two hypotheses concerning the loss of protists in Termitidae, either through an externalization of the digestion or a dietary transition. Finally, we argue that many aspects of termite evolution remain speculative, as most termite biological diversity and evolutionary trajectories have yet to be explored.

Native to eastern Asia, the Formosan subterranean termite Coptotermes formosanus (Shiraki) is recognized as one of the 100 worst invasive pests in the world, with established populations in Japan, Hawaii and the southeastern United States. Despite its importance, the native source(s) of C. formosanus introductions and their invasive pathway out of Asia remain elusive. Using ~22,000 SNPs, we retraced the invasion history of this species through approximate Bayesian computation and assessed the consequences of the invasion on its genetic patterns and demography. We show a complex invasion history, where an initial introduction to Hawaii resulted from two distinct introduction events from eastern Asia and the Hong Kong region. The admixed Hawaiian population subsequently served as the source, through a bridgehead, for one introduction to the southeastern US. A separate introduction event from southcentral China subsequently occurred in Florida showing admixture with the first introduction. Overall, these findings further reinforce the pivotal role of bridgeheads in shaping species distributions in the Anthropocene and illustrate that the global distribution of C. formosanus has been shaped by multiple introductions out of China, which may have prevented and possibly reversed the loss of genetic diversity within its invasive range.

Search theory predicts that animals evolve efficient movement patterns to enhance encounter rates with specific targets. The optimal movements vary with the surrounding environments, which may explain the observation that animals often switch their movement patterns depending on conditions. However, the effectiveness of behavioural change during search is rarely evaluated because it is difficult to examine the actual encounter dynamics. Here we studied how partner-seeking termites update their search strategies depending on the local densities of potential mates. After a dispersal flight, termites drop their wings and walk to search for a mate; when a female and a male meet, they form a female-led tandem pair and search for a favourable nesting site. If a pair is separated, they have two search options-reunite with their stray partner, or seek a new partner. We hypothesized that the density of individuals affects separation-reunion dynamics and thus the optimal search strategy. We observed the searching process across different densities and found that termite pairs were often separated but obtained a new partner quickly at high mate density. After separation, while females consistently slowed down, males increased their speed according to the density. Under high mate density, separated males obtained a partner earlier than females, who do not change movement with density. Our data-based simulations confirmed that the observed behavioural change by males contributes to enhancing encounters. Males at very low mate densities did best to move slowly and thereby reduce the risk of missing their stray partner, who is the only available mate. On the other hand, males that experienced high mate densities did better in mating encounters by moving fast because the risk of isolation is low, and they must compete with other males to find a partner. These results demonstrate that termite males adaptively update their search strategy depending on conditions. Understanding the encounter dynamics experienced by animals is key to connecting the empirical work to the idealized search processes of theoretical studies., (© 2020 British Ecological Society.)

Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) (Blattoidea: Rhinotermitidae) are invasive subterranean termite pest species with a major global economic impact. However, the descriptions of the mutualistic protist communities harbored in their respective hindguts remain fragmentary. The C. formosanus hindgut has long been considered to harbor three protist species, Pseudotrichonympha grassii (Trichonymphida), Holomastigotoides hartmanni, and Cononympha (Spirotrichonympha) leidyi (Spirotrichonymphida), but molecular data have suggested that the diversity may be higher. Meanwhile, the C. gestroi community remains undescribed except for Pseudotrichonympha leei. To complete the characterization of these communities, hindguts of workers from both termite species were investigated using single-cell PCR, microscopy, cell counts, and 18S rRNA amplicon sequencing. The two hosts were found to harbor intriguingly parallel protist communities, each consisting of one Pseudotrichonympha species, two Holomastigotoides species, and two Cononympha species. All protist species were unique to their respective hosts, which last shared a common ancestor ~18 MYA. The relative abundances of protist species in each hindgut differed remarkably between cell count data and 18S rRNA profiles, calling for caution in interpreting species abundances from amplicon data. This study will enable future research in C. formosanus and C. gestroi hybrids, which provide a unique opportunity to study protist community inheritance, compatibility, and potential contribution to hybrid vigor., (© 2020 International Society of Protistologists.)

Cuticular hydrocarbons (CHCs) have, in insects, important physiological and ecological functions, such as protection against desiccation and as semiochemicals in social taxa, including termites. CHCs are, in termites, known to vary qualitatively and/or quantitatively among species, populations, castes, or seasons. Changes to hydrocarbon profile composition have been linked to varying degrees of aggression between termite colonies, although the variability of results among studies suggests that additional factors might have been involved. One source of such variability may be colony age, as termite colony demographics significantly change over time, with different caste and instar compositions throughout the life of the colony. We here hypothesize that the intracolonial chemical profile heterogeneity would be high in incipient termite colonies but would homogenize over time as a colony ages and accumulates older workers in improved homeostatic conditions. We studied caste-specific patterns of CHC profiles in Coptotermes gestroi colonies of four different age classes (6, 18, 30, and 42 months). The CHC profiles were variable among castes in the youngest colonies, but progressively converged toward a colony-wide homogenized chemical profile. Young colonies had a less-defined CHC identity, which implies a potentially high acceptance threshold for non-nestmates conspecifics in young colonies. Our results also suggest that there was no selective pressure for an early-defined colony CHC profile to evolve in termites, potentially allowing an incipient colony to merge nonagonistically with another conspecific incipient colony, with both colonies indirectly and passively avoiding mutual destruction as a result., Competing Interests: None Declared., (© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

Congeneric species that live in sympatry may have evolved various mechanisms that maintain reproductive isolation among species. However, with the spread of invasive organisms owing to increased global human activity, some species that evolved in allopatry can now be found outside their native range and may have the opportunity to interact, in the absence of mechanisms for reproductive isolation. In South Florida, where the Asian subterranean termite, Coptotermes gestroi (Wamann), and the Formosan subterranean termite, Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae) are invasive, the two species can engage in heterospecific mating behavior as their distribution range and their dispersal flight season both overlap. Termites rely on semiochemicals for many of their activities, including finding a mate after a dispersal flight. In this study, we showed that females of both species produce (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol (DTE) from their tergal glands as a shared sex pheromone. We suggest that both species primarily rely on an inundative dispersal flight strategy to find a mate, and that DTE is used as a short distance pheromone or contact pheromone to initiate and maintain the tandem between males and females. The preference of C. gestroi males for C. formosanus females during tandem resulted from the relatively high amount of DTE produced by tergal glands of C. formosanus females, when compared with those of C. gestroi females. This results in confusion of mating in the field during simultaneous dispersal flights, with a potential for hybridization. Such observations imply that no prezygotic barriers emerged while the two species evolved in allopatry for ~18 Ma.

Termite colony size can influence its foraging activity, reproductive maturity, and, for pest species, potential for structural damage. Estimating colony size of subterranean termite species in field conditions has been challenging owing to their extensive foraging territory and their cryptic nesting habit and has primarily relied on mark-recapture methods. With laboratory-reared colonies in individual containers, determining colony size can be achieved by processing all termites from the nest material, which can be labor intensive and partially destructive. However, with the recent rise in the need of large laboratory colonies for use in colony-wide experimental protocols, there was an imperative to develop a procedure to estimate initial colony sizes without imposing a major stress on colonies before an experiment. In this study, the average daily wood consumption of whole colonies was used to infer the colony size of two Coptotermes, Wasmann (Blattodea: Rhinotermitidae) species and their hybrids in laboratory-rearing conditions. Correlations between the daily wood consumption and several demographic variables within colonies were established. Linear models varied across all species mating types with R2 values greater than 0.8 for all demographic variables. For colonies from all mating combinations, Pearson's correlation coefficient values were greater than 0.94 between their daily wood consumption and both the number of workers and total number of termites, and greater than 0.91 between daily wood consumption and colony mass. Therefore, in colonies with fixed laboratory conditions, their average daily wood consumption determination, which is nondestructive on colonies, can be used to infer colony size of subterranean termites., (Published by Oxford University Press on behalf of Entomological Society of America 2020.)

As a social insect, termites have different castes and division of labor in a colony. Investigating the social behavior of subterranean termites is a challenge due to the cryptic nature and large colony size. Planar arenas are commonly used to study these termites under laboratory conditions, and have provided several advantages. However, there is no means to designate areas such as a royal chamber or central nest from foraging sites because reproductives can move freely across arenas. In this study, we examined the minimum passing size of different castes of Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae), in order to develop a reproductive excluder and correlated minimum passing size with head widths and heights. We found that workers and soldiers of C. formosanus were able to pass through a gap greater than or equal to 0.7 mm. Our results showed that there are significant differences in the head width and height based on castes and head height was more critical than head width to determine passing size. We further confirmed feasibilities of the reproductive excluders using incipient colonies of C. formosanus. Confining reproductives using the excluder in laboratory experiments will provide more chances to study the royal chamber and central nest independently of foraging sites., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Temperature preference of two invasive subterranean termites, Coptotermes gestroi (Wasmann) and Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae), and their hybrids were determined in a horizontal thermal gradient. The activity of workers of four mating combinations: ♀C. gestroi × ♂C. gestroi (C. gestroi), ♀C. formosanus × ♂C. formosanus (C. formosanus), ♀C. gestroi × ♂C. formosanus (Hybrid G), and ♀C. formosanus × ♂C. gestroi (Hybrid F), when placed on the temperature gradients were videotaped and analyzed to determine the mean temperature preference values (mTPV). The temperature ranges for active termites were 21.9-39.5°C for C. gestroi, 11.1-39.5°C for C. formosanus, 25.3-38.2°C for Hybrid G, and 24.9-39.3°C for Hybrid F. There was no significant difference in the mTPV of C. gestroi and both hybrid mating combinations. The mTPV of both Hybrid G and Hybrid F was significantly higher than the parental species C. formosanus. Our results indicate that hybrid populations of C. formosanus and C. gestroi might be more active in tropical than temperate regions, and if established in temperate regions, they will be more active in summer months when the mean temperature exceeds 25°C., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Laboratory studies of Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae) often employ the use of field-collected foraging populations of individuals as defined colonies. The biological relevance of this practice is often called into question, because these colonies lack a full composition of reproductive castes and brood, which may have physiological and behavioral consequences. Rearing intact laboratory colonies can be done; however, it is time-consuming and labor-intensive. The artificial fusion of field-collected foraging populations with a young, laboratory-reared incipient colony may provide whole, intact colonies for laboratory research. The current study measures survivorship of fused colonies using laboratory-reared complete incipient colonies ranging in age from 0 to 5 mo, fused with 100 workers and 10 soldiers from field-collected populations of different colonial origin. Results indicate that 60% of colony fusion was successful when the incipient colony introduced is 5 mo of age. This method of colony fusion will provide researchers with intact colonies using minimal resources., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)