Genetic analysis reveals the putative native range and widespread double-clonal reproduction in the invasive longhorn crazy ant.

Clonal reproduction can provide an advantage for invasive species to establish as it can circumvent inbreeding depression which often plagues introduced populations. The world's most widespread invasive ant, Paratrechina longicornis, was previously found to display a double-clonal reproduction system, whereby both males and queens are produced clonally, resulting in separate male and queen lineages, while workers are produced sexually. Under this unusual reproduction mode, inbreeding is avoided in workers as they carry hybrid interlineage genomes. Despite the ubiquitous distribution of P. longicornis, the significance of this reproductive system for the ant's remarkable success remains unclear, as its prevalence is still unknown. Further investigation into the controversial native origin of P. longicornis is also required to reconstruct the evolutionary histories of double-clonal lineages. Here, we examine genetic variation and characterize the reproduction mode of P. longicornis populations sampled worldwide using microsatellites and mitochondrial DNA sequences to infer the ant's putative native range and the distribution of the double-clonal reproductive system. Analyses of global genetic variations indicate that the Indian subcontinent is a genetic diversity hotspot of this species, suggesting that P. longicornis probably originates from this geographical area. Our analyses revealed that both the inferred native and introduced populations exhibit double-clonal reproduction, with queens and males around the globe belonging to two separate, nonrecombining clonal lineages. By contrast, workers are highly heterozygous because they are first-generation interlineage hybrids. Overall, these data indicate a worldwide prevalence of double clonality in P. longicornis and support the prediction that the unusual genetic system may have pre-adapted this ant for global colonization by maintaining heterozygosity in the worker force and alleviating genetic bottlenecks.

Ultrastructure and distribution of sensory receptors on the nonolfactory organs of the soldier caste in subterranean termite (Coptotermes spp.).

The soldier caste of termites uses sensilla to sense pheromonal, tactile, and vibrational cues to communicate inside and outside their nest. Although sensilla with many modalities on the antennae of subterranean termites have been well explored, there remains a lack of information regarding sensillum characteristics and distribution of the nonolfactory organs of the soldier caste in the Coptotermes genus. In this study, the ultrastructure of sensilla from the soldier caste of three Coptotermes spp. (Coptotermes formosanus, Coptotermes curvignathus, and Coptotermes gestroi) was observed by scanning and transmission electron microscopy, and the putative function of each type was deduced. Six total sensillum types were observed, with two mechanoreceptive sensillum types (hair and plate). The long flexible-peg mechanoreceptive sensilla may work as contact-chemoreceptive sensilla due to their elongated dendritic outer segments and uniporous characteristics. There was a significant depletion of mechano-chemoreceptive sensillum numbers in C. gestroi, which was compensated by a high density of short-peg mechanoreceptive sensilla on the pronotum. Finally, cuticular and innervation characteristics of thermo-/hygrosensitive sensilla were observed for the first time on the labrum of the soldier caste of Coptotermes.

Improving invasive species management using predictive phenology models: an example from brown marmorated stink bug (Halyomorpha halys) in Japan.

BACKGROUND: In order to better understand the population dynamics of invasive species in their native range, we developed two predictive phenological models using the ubiquitous invasive insect pest, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), as the model organism. Our work establishes a zero-inflated negative binomial regression (ZINB) model, and a general additive mixed model (GAMM) based on 11 years of black light trap monitoring of H. halys at three locations in Japan. RESULTS: The ZINB model indicated that degree days (DD) have a significant effect on the trap catch of adult H. halys, and that precipitation has no effect. A dataset generated by 1000 simulations from the ZINB suggested that higher predicted trap catches equated to a lower probability of encountering a zero-count. The GAMM produced a cubic regression smooth curve which forecasts the seasonal phenology of H. halys as following a bell-shaped trend in Japan. Critical DD points during the field season in Japan included 261 DD for first H. halys adult detection and 1091 DD for peak activity. CONCLUSIONS: This study establishes the first models capable of forecasting native H. halys population dynamics based on DD. These robust models practically improve population forecasting of H. halys in the future and help fill gaps in knowledge pertaining to its native phenology, thus ultimately contributing to the progression of efficient management of this globally invasive species. © 2021 Society of Chemical Industry.

Morphometric Analysis of Coptotermes spp. Soldier Caste (Blattodea: Rhinotermitidae) in Indonesia and Evidence of Coptotermes gestroi Extreme Head-Capsule Shapes.

Linear and geometric morphometrics approaches were conducted to analyze the head capsule (HC) shape of collected soldier caste specimens of Coptotermes from various locations in Indonesia. The soldiers' morphology was observed and measured. The results of the principal component analysis of the group of all species showed two important groups of variables, i.e., the body size and setae characteristics of the pronotum and head. The multicollinearity of the morphometric variables showed the importance of body measurements as well as important alternative characteristics such as the pronotum setae (PrS) and HC setae. Four trends of HC shape were observed across the species. Interestingly, three extreme shapes were depicted by geometric morphometrics of the C. gestroi HC. The phylogenetic tree inferred from 12S and 16S mitochondrial gene fragments showed high confidence for C. gestroi populations. The lateral expansion of the posterior part of the HC across the species was in accordance with the increasing of the number of hairlike setae on the pronotum and HC. These differences among species might be associated with mandible-force-related defensive labor and sensitivity to environmental stressors.

Termite Assemblage and Damage on Tree Trunks in Fast-Growing Teak Plantations of Different Age: A Case Study in West Java, Indonesia.

We conducted surveys of termite assemblages and tree trunks damaged by termites in teakwood (Tectona grandis L.f.) plantations. The surveys were conducted in five-, six-, and nine-year-old plantations. We used a standardized belt-transect to collect termites and build tree inventories. Data of collected termites at the genus and functional-group levels and termites' diversity between plantations were compared with their attack rate. The results showed that four genera of soil recycler termites belonging to groups IIf and III were present across the plantations. Distribution analysis suggested that termite communities might develop from a stochastic distribution to a nonrandom co-occurrence distribution over time. Diversity analysis showed an increased nestedness-resultant diversity contribution to the total dissimilarity over time. Observed attacks on tree trunks were superficial and limited to the outer bark, with group IIf as the main contributor. Furthermore, the level of damage done by termites to tree trunks was positively correlated with increases in the group IIf occupancy area and overgrown understory vegetation. Plantation management by maintaining an adequate understory might suppress termite attacks on fast-growing teakwood, although in the case of our study, termite attacks are inevitable when termites from group IIf were already present.

Influence of Age and Mating Status on Pheromone Production in a Powderpost Beetle Lyctus africanus (Coleoptera: Lyctinae).

Powderpost beetles such as Lyctus africanus are a common pest group for dried cured wood, causing significant harm to wood and wood products. We examined the life span and effects of aging and mating status on pheromone production in the powderpost beetle L. africanus (Coleoptera: Lyctinae). Experiments compared starved and unstarved male groups, and chemical analysis was used to determine factors affecting pheromone production. Regarding lifespan, male beetles provided food survived up to 14 weeks, while starved beetles died before the fifth week. Thus, an adult L. africanus male may require food throughout its lifespan, and food availability may affect pheromone production. There was no significant difference in the quantity of two major pheromone compounds, compound 2 (3-pentyl dodecanoate) and 3 (3-pentyl tetradecanoate) between mated and un-mated males. On the other hand, a minor compound, compound 1 (2-propyl dodecanoate) showed increased quantity after mating. The two major compounds were produced in low amounts by young L. africanus beetles, increasing until the fifth week, and beginning to decrease at the ninth week. The minor compound was produced steadily without significant change up to 9 weeks. Our results represent a step forward in the knowledge of the chemical communication of this important pest.

Evidence for Common Horizontal Transmission of Wolbachia among Ants and Ant Crickets: Kleptoparasitism Added to the List.

While Wolbachia, an intracellular bacterial symbiont, is primarily transmitted maternally in arthropods, horizontal transmission between species has been commonly documented. We examined kleptoparasitism as a potential mechanism for Wolbachia horizontal transmission, using ant crickets and their host ants as the model system. We compared prevalence and diversity of Wolbachia across multiple ant cricket species with different degrees of host specificity/integration level. Our analyses revealed at least three cases of inter-ordinal Wolbachia transfer among ant and ant crickets, and also showed that ant cricket species with high host-integration and host-specificity tend to harbor a higher Wolbachia prevalence and diversity than other types of ant crickets. This study provides empirical evidence that distribution of Wolbachia across ant crickets is largely attributable to horizontal transmission, but also elucidates the role of intimate ecological association in successful Wolbachia horizontal transmission.

Antibacterial and antifungal two phenolic sesquiterpenes from Dysoxylum densiflorum.

A new phenolic sesquiterpene, dysoxyphenol (1), and the known sesquiterpene, 7R,10S-2-hydroxycalamenene (2), were isolated from the acetone extract of Dysoxylum densiflorum seeds. The structures of these compounds were determined based on physical, Nuclear Magnetic Resonance, and mass spectral data. Both compounds were evaluated for their antibacterial and antifungal properties against seven pathogenic bacteria and two wood-rotting fungi, respectively. The results showed that both compounds have significant antibacterial properties only against Bacillus subtilis (Minimum Inhibitory Concentration 28 µM), while in the antifungal evaluation compound 1 was found to be more active than compound 2. Therefore, compound 1 has promising antifungal properties that can be developed further for finding new antifungal agents.

Genetic Diversity and Wolbachia Infection Patterns in a Globally Distributed Invasive Ant.

Understanding the phylogeographic history of an invasive species may facilitate reconstructing the history and routes of its invasion. The longhorn crazy ant, Paratrechina longicornis, is a ubiquitous agricultural and household pest throughout much of the tropics and subtropics, but little is known about the history of its spread. Here, we examine worldwide genetic variation in P. longicornis and its associated Wolbachia bacterial symbionts. Analyses of mtDNA sequences of 248 P. longicornis workers (one per colony) from 13 geographic regions reveal two highly diverged mtDNA clades that co-occur in most of the geographic regions. These two mtDNA clades are associated with different Wolbachia infection patterns, but are not congruent with patterns of nDNA (microsatellite) variation. Multilocus sequence typing reveals two distinct Wolbachia strains in P. longicornis, namely, wLonA and wLonF. The evolutionary histories of these two strains differ; wLonA appears to be primarily transmitted maternally, and patterns of mtDNA and nDNA variation and wLonA infection status are consistent with a relatively recent Wolbachia-induced selective sweep. In contrast, the observed patterns of mtDNA variation and wLonF infections suggest frequent horizontal transfer and losses of wLonF infections. The lack of nDNA structure among sampled geographic regions coupled with the finding that numerous mtDNA haplotypes are shared among regions implies that inadvertent long-distance movement through human commerce is common in P. longicornis and has shaped the genetic structure of this invasive ant worldwide.

Comparison of Water Relation in Two Powderpost Beetles Relative to Body Size and Ontogenetic and Behavioral Traits.

Heterobostrychus aequalis (Waterhouse) (Coleoptera: Bostrychidae) and Lyctus africanus Lesne (Coleoptera: Lyctidae) are distributed mainly in tropical regions. The primary mechanism allowing these beetles to survive in cold and arid habitats beyond the native tropical region is a reduced water loss rate. This study investigated the water relations of these two beetles in relation to their size, ontogenetic traits, and behavioral characteristics to determine how they can survive in desiccated wood. H. aequalis and L. africanus share similar water characteristic with beetles living in desert and woodlands. They have high percentage total body water (%TBW) content (58.38 ± 1.86% to 63.20 ± 1.38%), but low %TBW loss (4.28 ± 1.02% to 48.26 ± 8.28%) due to their impermeable cuticle (cuticular permeability [CP] value: 0-15.57 ± 4.90 µg cm-2 h-1 mmHg-1) at all life stages. Although the larvae of L. africanus exhibited relatively high %TBW loss, they had relatively shorter development times that minimized prolonged exposure to dry conditions inside the wood. The aggregative behavior of the adult could be responsible for maintaining a low water loss rate to compensate for their small body size. In contrast, the larvae of H. aequalis had larger body size and significantly lower CP values, allowing them to survive in the desiccated wood for a longer period of time. These results demonstrate the remarkably sophisticated strategies that insects employ as a trade-off between body size, ontogenetic development, and insect sociality (aggregative and non-aggregative behavior) to maintain their water balance in xeric environments.

NMR studies on lignocellulose deconstructions in the digestive system of the lower termite Coptotermes formosanus Shiraki.

Termites represent one of the most efficient lignocellulose decomposers on earth. The mechanism by which termites overcome the recalcitrant lignin barrier to gain access to embedded polysaccharides for assimilation and energy remains largely unknown. In the present study, softwood, hardwood, and grass lignocellulose diets were fed to Coptotermes formosanus workers, and structural differences between the original lignocellulose diets and the resulting feces were examined by solution-state multidimensional nuclear magnetic resonance (NMR) techniques as well as by complementary wet-chemical methods. Overall, our data support the view that lignin polymers are partially decomposed during their passage through the termite gut digestive system, although polysaccharide decomposition clearly dominates the overall lignocellulose deconstruction process and the majority of lignin polymers remain intact in the digestive residues. High-resolution NMR structural data suggested preferential removal of syringyl aromatic units in hardwood lignins, but non-acylated guaiacyl units as well as tricin end-units in grass lignins. In addition, our data suggest that termites and/or their gut symbionts may favor degradation of C-C-bonded ß-5 and resinol-type ß-ß lignin inter-monomeric units over degradation of ether-bonded ß-O-4 units, which is in contrast to what has been observed in typical lignin biodegradation undertaken by wood-decaying fungi.

Effects of lignins as diet components on the physiological activities of a lower termite, Coptotermes formosanus Shiraki.

We investigated the effects of lignins as diet components on the physiological activities of a lower termite, Coptotermes formosanus Shiraki. Artificial diets composed of polysaccharides with and without purified lignins (milled-wood lignins) from Japanese cedar (softwood), Japanese beech (hardwood), and rice (grass), were fed to C. formosanus workers. The survival and body mass of the workers as well as the presence of three symbiotic protists in the hindguts of the workers were then periodically examined. The survival rates of workers fed on diets containing lignins were, regardless of the lignocellulose diet sources, significantly higher than those of workers fed on only polysaccharides. In addition, it was clearly observed that all the tested lignins have positive effects on the maintenance of two major protists in the hindguts of C. formosanus workers, i.e., Pseudotrichonympha grassii and Holomastigotoides hartmanni. Overall, our data suggest that the presence of lignin is crucial to maintaining the physiological activities of C. formosanus workers during their lignocellulose decomposition. Our data also suggested that some components, possibly minerals and/or non-structural carbohydrates, in grass lignocellulose negatively affect the survival of C. formosanus workers as well as the present rate of the symbiotic protists in their hindguts.

The effect of remnant forest on insect successional response in tropical fire-impacted peatland: A bi-taxa comparison.

Fire has become a common feature in tropical drained peatlands, and it may have detrimental impacts on the overall biodiversity of the forest ecosystem. We investigated the effect of fire on termite and ant assemblages and the importance of remnant forest in restoring species diversity in fire-impacted tropical peat swamp forests. The species loss of both termites and ants was as high as 50% in some fire-impacted peats compared to remnant forests, but in most cases the species richness for termites and ants was statistically equal along the land uses surveyed. However, a pronounced difference in functional group composition of termites was detected. In particular, sites close to remnant forests contained two additional termite feeding groups so that they shared a similar composition structure with remnant forests but were significantly different from sites distant from remnant forests. In general, ants were resilient to fire, and the similarity index showed a high degree of similarity among ant communities in all land uses surveyed. The Shannon diversity index for termites and ants decreased with increasing distance from the remnant forests and level of ecological degradation. Peat vegetation variables and ecological degradation were important in shaping termite and ant communities in the tropical peatlands, but their relative importance was not significant in fire-impacted peats regardless of distance from the remnant forests. This study highlights the importance of remnant forests as a biodiversity repository and natural buffer that can enhance species diversity and recolonization of forest-adapted species.

A case of falciparum malaria: Acute hearing loss as the initial symptom.

A 49-year-old healthy woman, who returned from Burkina Faso, visited an ear, nose, and throat clinic with complaints of left hearing loss, tinnitus, and dizziness. Pure tone audiometry demonstrated bilateral mild sensorineural hearing loss. Three days later, she was transported in an ambulance to a general hospital due to high fever and disturbance of consciousness. Plasmodium falciparum was found in the peripheral blood smear. After diagnosing severe falciparum malaria with cerebral involvement, quinine hydrochloride, clindamycin, and artemether/lumefantrine were administered. After recovery of consciousness, she was followed up at our department with bilateral hearing loss. After taking prednisolone for 10 days, there was improvement to normal hearing level. Furthermore, no neurologic sequelae were observed. In this case, acute sensorineural hearing loss occurred before administration of the antimalarial drug. Therefore, hearing loss was not drug-induced, but was caused by the malaria itself. In patients with acute hearing loss and who have history of travel to tropical regions, physicians should include malaria and other causes of acute deafness in the differential diagnoses.

Evidence of Subterranean Termite Feeding Deterrent Produced by Brown Rot Fungus Fibroporia radiculosa (Peck) Parmasto 1968 (Polyporales, Fomitopsidaceae).

We found that decayed wood stakes with no termite damage collected from a termite-infested field exhibited a deterrent effect against the termite Reticulitermes speratus, Kolbe, 1885. The effect was observed to be lost or reduced by drying. After identification, it was found that the decayed stakes were infected by brown rot fungus Fibroporia radiculosa (Peck) Parmasto, 1968. In a no-choice feeding test, wood blocks decayed by this fungus under laboratory condition deterred R. speratus feeding and n-hexane extract from the decayed stake and blocks induced termite mortality. These data provided an insight into the interaction between wood-rot fungi and wood-feeding termites.

The Impact of Tropical Peat Fire on Termite Assemblage in Sumatra, Indonesia: Reduced Complexity of Community Structure and Survival Strategies.

Tropical peat swamp forests in Southeast Asia account for approximately 72% of global peatland. However, extensive forest exploitation following peat drainage for agricultural expansion has been leading to catastrophic peat fires. In this study, we compared the termite assemblage in burnt and unburnt peats in Sumatra, Indonesia. We also identified which taxonomic group is particularly resistant to fire disturbance and the traits that correlate with its persistence in fire-impacted peatlands. Overall, the termite species richness in fire-impacted peats was up to 40% lower than that of the total species found in peat swamp forests. Although the estimated species richness values in fire-impacted peats and peat swamp forests were not significantly different, fire changed termite community structure significantly. Only termites of the family Rhinotermitidae survived in the fire event, whereas members of the Termitidae that were reportedly resilient to fire and open habitats elsewhere disappeared during the fire events. The rhinotermitids found in the burnt sites were exclusively wood nesters. This suggests that the desiccation tolerance of termites in open habitat is not the simple underlying survival strategy, but tree branches and barks might have provided a refuge from heat during fire. The result also suggests that the high similarity in species composition in recently burnt peats and long burnt peats implies low species turnover. Thus, regardless of how much time had passed since the fire-impacted peats were abandoned or cultivated, the increase in habitat complexity did not favor colonization by the forest-dependent group.

Nest-Gallery Development and Caste Composition of Isolated Foraging Groups of the Drywood Termite, Incisitermes minor (Isoptera: Kalotermitidae).

An X-ray computed-tomographic examination of nest-gallery development from timbers naturally infested by foraging groups of Incisitermes minor colonies was conducted. This study documents the colonization process of I. minor to new timbers and how the isolated groups maintain their nest-gallery system. The results suggested that development of a nest-gallery within a suitable wood item is not random, but shows selection for softer substrate and other adaptations to the different timber environments. Stigmergic coordinations were expressed in dynamic changes of the nest-gallery system; indicated by fortification behavior in sealing and re-opening a tunnel approaching the outer edge of the timber, and accumulating fecal pellets in particular chambers located beneath the timber surface. The study also examines the caste composition of isolated groups to discover how I. minor sustains colonies with and without primary reproductives.

Effects of Decompression Treatment for Controlling the Powderpost Beetle, Lyctus africanus Lesne, (Coleoptera: Lyctinae).

The efficacy of decompression treatment as a non-destructive method to control larvae of the powderpost beetle, Lyctus africanus Lesne, was evaluated in the laboratory using various combinations of two pressure levels, 1.1 kPa and 40 kPa, and three temperature levels, 20, 25, and 40 °C. Larval mortality generally depended on weight reduction while decreases in the oxygen level had relatively little effect. The lower pressure, 1.1 kPa, significantly affected mortality, and no larvae survived after 12 h of this pressure treatment, at 25 °C. The average body weight was reduced with treatment time and temperature, and the reduction rate at 25 °C was higher than that at the lower temperature, 20 °C. Effects on larvae of the higher pressure treatment, 40 kPa, with a CO2 gas purge, were tested to determine the feasibility of decompression treatment in the manufacturing process. Although higher pressure resulted in low mortality, the body weight was dramatically decreased using the CO2 purge. These results present important information on the possibility of using decompression treatment for wood products.

Effects of Induced High Carbon Dioxide and Desiccated Atmospheres on the Water Loss and Survival of Subterranean and Invading Drywood Termites.

Termites have evolved a variety of morphological, physiological, and behavioral adaptations that together increase the chances of survival in unfavorable environments. Morphological advantages (i.e., a relatively large body size, a large mass of reserves that are metabolized by reducing body water mass, a mass of cuticular lipids, and cuticular hydrocarbons) increase the cuticular resistance to water loss under desiccating conditions. However, termites are incapacitated when exposed to high levels of CO2 and can be eradicated at sufficiently high levels. Based on the results of this study, in an artificially induced high CO2 atmosphere, the loss of body water from drywood termites increased, which generally led to increased rates of mortality. Although the mechanism for the increased loss of body water under high CO2 conditions was not determined, for practical application, the time required for fumigation can be reduced because of the increase in the rate of body water loss from drywood termites in high CO2 conditions.