Evaluation of hexaflumuron for controlling the subterranean termite Coptotermes curvignathus (Isoptera: Rhinotermitidae) in Malaysia

Cellulosic bait matrices containing 0.5% hexaflumuron were tested against field colonies of the subterranean termite Coptotermes curvignathus Holmgren in Malaysia. Foraging activities of the termites were first monitored for several months by using survey stakes and wood bundles placed in underground monitoring traps. Infested stakes were replaced with bait devices. Termite workers to act as recruits were collected from infested stakes and placed in the bait devices. Subsequent activities of the termites were monitored by examining and weighing the wood in the monitoring traps. Data show that the four colonies had populations of 166,288-709,052 foragers and mean wood consumption rates of 305.9-508.2 g/mo per trap. These colonies ceased their activities at all monitoring devices 25-44 d after baiting had commenced. Colonies consumed approximately 27-79 g of bait matrix or 137.5-395 mg of hexaflumuron. Thus, C. curvignathus colonies could be monitored, characterized, baited, and foraging eliminated by using a bait matrix containing hexaflumuron.     

台湾乳白蚁与赭黄乳白蚁的异名关系---基于形态与分子特征的分析(等翅目：鼻白蚁科）

乳白蚁属Coptotermes是鼻白蚁科Rhinotermitidae最具经济意义的属之一,其中的台湾乳白蚁Coptotermes formosanus Shriaki分布广、适应性强,个体在不同种群以及不同巢龄间外部形态存在明显变异,已报道多个同物异名。本研究发现在模式产地重新采集到经形态学鉴定为赭黄乳白蚁Coptotermes ochraceus Ping et Xu的标本,其形态特征与台湾乳白蚁相似度较高,又以线粒体16S rRNA和CO II基因作为分子标记,将两者进行了序列比对,并与美国国立生物技术信息中心(NCBI)中台湾乳白蚁以及其他一些乳白蚁种类的相应序列一起进行了遗传差异比较和同源性分析。结果表明,台湾乳白蚁与赭黄乳白蚁16S rRNA和CO II序列的遗传差异均明显小于台湾乳白蚁与属内其它种之间的差异;在基于两种分子标记构建的支序图中,台湾乳白蚁和赭黄乳白蚁均聚为一支,并得到了很高的自展支持率。综合分子和形态两方面的证据,本研究建议赭黄乳白蚁为台湾乳白蚁的次异名。     

Genetic relationship between Coptotermes gestroi and Coptotermes vastator (Isoptera: Rhinotermitidae)

The phylogenetic relationship of Coptotermes gestroi (Wasmann) and Coptotermes vastator Light (Isoptera: Rhinotermitidae) was determined using DNA sequence comparisons of mitochondrial genes. Partial sequences of the ribosomal RNA small subunit 12S, ribosomal RNA large subunit 16S, and mitochondrial COII were obtained from nine populations of C. gestroi from South East Asia (Malaysia, Singapore, Thailand, and Indonesia) and four populations of C. vastator from the Philippines and Hawaii. In addition, four populations of Coptotermes formosanus Shiraki and Globitermes sulphureus (Haviland) were used as the outgroups. Consensus sequences were obtained and aligned. C. vastator and C. gestroi are synonymous, based on high sequence homology across the 12S, 16S, and COII genes. The interspecific pairwise sequence divergence, based on Kimura 2-parameter model between C. gestroi and C. vastator, varied only up to 0.80%. Morphometric measurements of 16 characteristics revealed numerous overlaps between the examined individuals of both species. Based on the molecular phylogenetics and morphometric data, it is proposed that C. vastator is a junior synonym of C. gestroi.     

Response of Reticulitermes spp. (Isoptera: Rhinotermitidae) in northern California to baiting with hexaflumuron with sentricon termite colony elimination system

Colonies of Reticulitermes spp. were baited with prototype and commercial Sentricon stations (Dow AgroSciences LLC, Indianapolis, IN) to test the efficacy of hexaflumuron in different concentrations and bait matrices and to document reinvasion of the foraging territories vacated by eliminated colonies. Seven colonies of Reticuliternes spp. from two sites were characterized with cuticular hydrocarbon analyses and mark-release-recapture and agonistic behavioral studies. Three colonies were observed as controls and four colonies were baited. When a connection between the bait station and the monitoring station could not be confirmed by mark-release-recapture studies, the results of the baiting were equivocal. The monitoring stations of a colony at our wildland site were devoid of termites 406 d after baiting with one Sentricon station, but became reoccupied with the same species of termites approximately 6 mo after baiting. A colony at the residential site was baited with 0.5% hexaflumuron in the Recurit II bait matrix; 60 d later termites were absent from all monitoring stations. These monitoring stations remained unoccupied for > or = 18 mo. Foraging Reticulitermes spp. appeared in three of the seven monitoring stations 18, 24, and 36 mo after baiting, respectively. Using cuticular hydrocarbon analyses and agonistic behavior studies, we determined that the Reticulitermes spp. occupying these monitoring stations were from three different colonies; none were members of the original colony destroyed by baiting. Another colony at the residential site was baited using a noncommercial, experimental bait; 52 d later termites were absent from all monitoring stations. The monitoring stations remained unoccupied for > or = 9 mo. A different Reticulitermes sp. colony invaded one monitoring station 9 mo after baiting.     

Hermetically sealed baits for subterranean termites (Isoptera: Rhinotermitidae)

Cellulose baits containing 0.5% hexaflumuron were hermetically sealed in a closed cell polyethylene sheet envelope and placed in soil to test their durability and efficacy against field colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki, or the eastern subterranean termite, Reticulitermes flavipes (Kollar). The closed cell polyethylene sheet was readily tunneled through by termites, yet it was impervious to water and protected the cellulose baits and hexaflumuron from the environment. Only in a few incidents did the polyethylene envelope become infiltrated by plant roots, resulting in water intrusion and apparent degradation of cellulose baits. After consuming one to three sealed baits, three colonies each of both termite species were eliminated. The sealed baits may be placed in soil for months or years without the need of monitoring, and they are readily penetrated and fed upon by termites when they are present. Application of baits hermetically sealed in a protective sheet may save labor costs by bypassing the monitoring phase, circumvent the station avoidance by some termite species, and enable the use of baiting technologies in large areas such as agricultural fields in which the manual monitoring is impractical.     

Elimination and reinvasion studies with Coptotermes formosanus (Isoptera: Rhinotermitidae) in Louisiana

Three Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), colonies located inside the 12.75-ha Louis Armstrong Park, New Orleans, were selected for elimination by using the chitin synthesis inhibitor hexaflumuron. Once eliminated, each vacated foraging territory was monitored for reinvasion by neighboring C. formosanus colonies, Reticulitermnes flavipes (Kollar) (Isoptera: Rhinotermitidae) colonies, or both. Each selected colony was eliminated in approximately 3 mo by using baits containing hexaflumuron. Overall activity of each untreated colony in the park remained unchanged during the same period. New C. formosanus and R. flavipes activity was detected in two of the three vacated territories, and in both areas, within days of selected colony elimination. The third vacated territory was completely reoccupied by a new C. formosanus colony approximately 7 mo later. Mark-recapture studies and DNA fingerprinting confirmed the distinctness of the reinvaders from eliminated and neighboring colonies.     

Interspecific competition and territory defense mechanisms of Coptotermes formosanus and Coptotermes gestroi (Isoptera: Rhinotermitidae)

Coptotermes formosanus Shiraki and C. gestroi (Wasmann) are the most widely distributed species of the genus and occur sympatrically in the subtropics. Results of two bioassays in the current study showed that C. gestroi was more aggressive than C. formosanus. In the petri-dish bioassays, C. gestroi won most of the agonistic encounters over C. formosanus. In the two-dimensional foraging arena bioassays, over 73% tunnel interceptions observed in the 18 replications were caused by progressing tunnels of C. gestroi encountering the tunnels of C. formosanus. Tunnel interception of the two species resulted in minor agonistic interactions. Both species quickly buried the connected tunnel at multiple locations. Termite cadavers resulting from agonistic behavior appeared to have induced sand deposition that resulted in tunnel blockages and deterred reopening of these blockages. Sealing individual tunnels in response to encounters with other species acts to prevent further agonism and mortality, and on a broad scale, the aggregate of such blocked tunnels may come to define the borders between adjacent colonies.     

Phylogeography illuminates maternal origins of exotic Coptotermes gestroi (Isoptera: Rhinotermitidae)

Coptotermes gestroi, the Asian subterranean termite (AST), is an economically important structural and agricultural pest that has become established in many areas of the world. For the first time, phylogeography was used to illuminate the origins of new found C. gestroi in the US Commonwealth of Puerto Rico; Ohio, USA; Florida, USA; and Brisbane, Australia. Phylogenetic relationships of C. gestroi collected in indigenous locations within Malaysia, Thailand, and Singapore as well as from the four areas of introduction were investigated using three genes (16S rRNA, COII, and ITS) under three optimality criteria encompassing phenetic and cladistic assumptions (maximum parsimony, maximum likelihood, and neighbor-joining). All three genes showed consistent support for a close genetic relationship between C. gestroi samples from Singapore and Ohio, whereas termite samples from Australia, Puerto Rico, and Key West, FL were more closely related to those from Malaysia. Shipping records further substantiated that Singapore and Malaysia were the likely origin of the Ohio and Australia C. gestroi, respectively. These data provide support for using phylogeography to understand the dispersal history of exotic termites. Serendipitously, we also gained insights into concerted evolution in an ITS cluster from rhinotermitid species in two genera.     

Cuticular permeability of two species of Coptotermes Wasmann (Isoptera: Rhinotermitidae)

Cuticular permeability (CP) values of worker and soldier castes of Coptotermes formosanus Shiraki and Coptotermes vastator Light were determined using gravimetric techniques. Comparisons were made between castes, species, and between colonies of C. formosanus and C. vastator. CP values did not differ among either species or colony, however they did differ between castes. Data reported here and that of established data in the literature for C. formosanus are inconsistent, with the current report having values as small as half that of previously published data. Examining mean CP data by colony indicated that there is a range for Coptotermes spp. termites, from 6.84+/-1.2 to 25.61+/-1.49 microg H(2)Ocm(-2)mmHg(-1)h(-1) dependent upon caste. A novel method of examining intercaste CP variability is the use of worker:soldier CP ratios. Ratios for C. formosanus were consistent between the current study and previous reports. Mean percentage total body water (%TBW) lost at the time of death was 33.75+/-1.15% (soldiers) and 54.24+/-1.43% (workers) for C. formosanus, and 37.69+/-3.31% (soldiers) and 52.87+/-3.65% (workers) for C. vastator. Consistently, %TBW (and fresh mass) was greater in worker than in soldier castes. These data suggest the use of water storage mechanisms in worker termites, as shown for other rhinotermitids.     

Panic escape polyethism in worker and soldier Coptotermes formosanus (Isoptera: Rhinotermitidae)

Termites were the first animal to form societies. Two hundred million years of evolution provide for a multitude of innate social behaviors that can be experimentally dissected. These fine‐tuned patterns of behavior are especially interesting when observing group decision making in the panic mode. In this study, we examined behavioral patterns of termites under panic conditions to gain insight into how an escape flow self‐organizes. One hundred worker and 10 soldier Coptotermes formosanus were released into agar plates. After a disturbance was created most workers followed each other and ran along the wall of dishes, thus forming a unidirectional escape flow, whereas soldiers showed a significantly higher frequency of moving to the center of the arena or on periphery of the escape flow as compared to workers. Agonistic behavior was usually observed as soldiers moved to center or periphery. This is the first report on the behavioral repertoire of termites when panicked, with details on the behavioral polymorphism of workers and soldiers during an escape.     

Areawide field study on effect of three chitin synthesis inhibitor baits on populations of Coptotermes formosanus and Reticulitermes flavipes (Isoptera: Rhinotermitidae)

Periodic sampling of 43 independent monitors, initially active with Formosan subterranean termite, Coptotermes formosanus Shiraki, or the eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), was conducted to evaluate the effects of cellulose baits containing one of three chitin synthesis inhibitors (CSIs)-diflubenzuron, hexaflumuron, or chlorfluazuron-on termite populations. Diflubenzuron at 0.1% active ingredient (AI, wt:wt) had no noticeable effect on termite populations. Chlorfluazuron (0.25% [AI]) significantly reduced termite populations in approximately 3 yr. Chlorfluazuron used after > 2-yr diflubenzuron treatment significantly reduced termite populations within months. This suggests diflubenzuron exposure increased the termite's sensitivity to chlorfluazuron accelerating population collapse. Hexaflumuron (0.5% [AI]) also reduced termite populations in approximately 2 yr. The process of removing most detectable termite populations from the approximately 160,000-m2 campus of the Southern Regional Research Center, New Orleans, LA, with CSIs baits required approximately 3 yr. Adjustments in the specific bait formulations and application procedures might reduce time to suppression. Establishment of new independent termite populations provides a mechanism to minimize the effects of baits. Remedial control measures around and under structures should be considered when implementing an area wide management strategy.     

Toxic effects of 2-deoxy-D-galactose on Coptotermes formosanus (Isoptera: Rhinotermitidae) and symbionts

In the interest of developing interventions to infestations by Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), several rare sugars were tested for effects on the termites and symbionts. Among these, the D-galactose analog, 2-deoxy-D-galactose (2deoxyGal) showed promise as a potential control chemical. At a test concentration of 2deoxyGal (320.4 microg/mm3) in water applied to 5-cm filter paper, in bioassays with 20 termite workers, we found that worker termite mortality was significantly affected over a 2-wk period. Subsequent dose-mortality feeding studies confirmed these findings. In addition, consumption of the sugar-treated filter paper by termites caused a significant decrease in hindgut protozoan populations. 2deoxyGal caused dose-dependent termite mortality, taking on average 1 wk to begin killing workers, indicating that it may have promise as a delayed action toxin, which, if added to baits, could allow time after bait discovery for an entire colony to be affected.     

Reinvasion and colony expansion of Coptotermes formosanus (Isoptera: Rhinotermitidae) after areawide elimination

The population recovery of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) colonies were monitored after an areawide elimination of all detectable colonies from September 2003 to August 2005 in Louis Armstrong Park, New Orleans, LA. Six colonies reinvaded the vacant niche created by the full elimination. These colonies expanded their territories throughout the study period. This represented 43% of the original number of colonies present in the park before the elimination. To determine the mode of the reinvasion, nuptial pair establishment was monitored during the C. formosanus dispersal flight seasons. Nuptial pairs were discovered up to 1 yr after the elimination. Morphological and genetic data were collected from field colonies before the full elimination in 2002 and again in 2005 after the reinvasion of these territories by new colonies. These data were used to estimate the relative age of reinvading colonies as compared with their predecessors. It is proposed that the first three reinvading colonies detected were smaller colonies that were undetectable before the full elimination, or were older, established colonies present outside of the park, that expanded their foraging territories into the park in the absence of competition from the eliminated populations. The subsequent three colonies to reinvade seemed to be small colonies founded during or just before the study period by an imago pair after a dispersal flight into the park from outlying areas. The implications of this study on subterranean termite areawide integrated pest management strategies are discussed.     

乳白蚁属Coptotermes(Isoptera: Rhinotermitidae)检疫分子鉴定研究进展

白蚁是一类受到世界广泛关注的重要社会性昆虫,对人类生活、经济以及生态环境等有很大的影响,特别是乳白蚁属Coptotermes众多种类危害尤为严重。乳白蚁常随木质包装或原木远距离传播异地建群,其为害隐蔽、潜伏期长,一旦爆发则为害严重且难防治,因其种类多、形态趋同,同一巢群中有龄期不一的虫态和多种生物型,可用分类特征少,造成形态分类困难、人为分类现象普遍。近年来分子生物学技术的日益发展,使得白蚁的分类鉴定更加快速、灵敏和可靠,系统发育分析研究更为深入全面,遗传进化方面取得大量研究成果。本文对基于生物信息学的乳白蚁属检疫分类鉴定和系统发育研究方法进行了介绍和评述,并对DNA技术在乳白蚁属分类和进化研究中的应用进行了讨论。     

Insecticide susceptibility in Coptotermes formosanus and Reticulitermes virginicus (Isoptera: Rhinotermitidae).

Lethal time to mortality responses were established for eight insecticides against workers and soldiers of the Formosan subterranean termite, Coptotermes formosanus Shiraki, and workers of Reticulitermes virginicus (Banks). There were significant differences in the tolerance ratios between workers of C. formosanus colonies to all toxicants tested except fipronil. One colony was 16 times more tolerant than another to deltamethin. C. formosanus soldiers had significant differences in tolerance ratios among colonies exposed to all toxicants except chlorpyrifos. Methoxychlor, permethrin, deltamethrin, and fipronil did not kill soldiers from two, one, one, and three colonies, respectively, within 8 h. Seventy-five percent of R. virginicus colonies were significantly less susceptible than the most susceptible colony to chlordane, methoxychlor, chlorpyrifos, cypermethrin, and fipronil, with 50% of the colonies less susceptible to permethrin and bendiocarb. In 50% of C. formosanus colonies the worker lethal time curves displayed substantial flattening in response to permethrin, and deltamethrin. Lethal time curses for C. formosanus soldiers exposed to chlordane, chlorpyrifos, permethrin, cypermethrin, deltamethrin, and bendiocarb showed substantial flattening. R. virginicus workers demonstrated substantial curve flattening when exposed to chlordane, methoxychlor, chlorpyrifos, deltamethrin, and fipronil. These findings indicate substantial intercolony and intra-colony differences in susceptibility to insecticides.     

Phylogeny of Australian Coptotermes (Isoptera: Rhinotermitidae) species inferred from mitochondrial COII sequences

Six Australian species of Coptotermes are traditionally recognized, but recent cuticular hydrocarbon studies suggest that some of these may represent more than one species. An understanding of the phylogenetic diversity of Australian Coptotermes, particularly the pest species, is likely to be important for the improvement of termite management strategies. A study of phylogenetic relationships among species of this genus was performed, based on the mitochondrial cytochrome oxidase (COII) gene, comparing the data with recent data from Asian species. Representatives of the species C. lacteus (Froggatt), C. frenchi Hill and C. michaelseni Silvestri were each found to form closely related monophyletic groups, however representatives of C. acinaciformis (Froggatt) were not. For C. acinaciformis, representatives from northern mound-building populations were found to form a distinct group to southern, tree-nesting forms. Among southern C. acinaciformis, two Western Australian representatives were found to be divergent from other populations. The results suggest that C. acinaciformis probably represents a complex of species rather than one, as has been suggested previously. One unidentified Coptotermes sp. taxon from Melbourne was found to be divergent from other taxa. Notably, some Australian species were more closely related to Asian species than other Australian species.     

台湾乳白蚁肠道鞭毛虫群落结构及三种研究方法的比较

大量鞭毛虫栖息在低等白蚁肠道内, 是白蚁赖以生存的共生微生物。不同种类的鞭毛虫共同作用形成了一套降解食物的系统, 为宿主提供营养和能量。研究鞭毛虫群落结构是揭示其各组成种类生理功能的基础。利用形态特征进行物种鉴定受鞭毛虫生长发育阶段、 样品制备方法等多种因素的影响, 而基于分子标记的分子生物学方法能不受这些因素的制约来研究复杂的微生物群落。本研究结合形态特征鉴定和分子生物学方法研究台湾乳白蚁Coptotermes formosanus肠道鞭毛虫群落结构, 并对这些方法进行了比较。通过光学显微镜和扫描电子显微镜进行形态观察鉴定, 确定了台湾乳白蚁肠道内的3种鞭毛虫, 分别为伪披发虫Pseudotrichonympha grassii、 全鞭毛虫Holomastigotoides mirabile和旋披发虫Spirotrichonympha leidyi。18S rDNA文库限制性片段长度多态性分析较形态鉴定能够反映群落更复杂的物种多样性。利用光学显微镜进行细胞计数较18S rDNA文库克隆数能更准确地反映各种鞭毛虫数量, 每头工蚁肠道内平均含伪披发虫780±179头, 全鞭毛虫1 630±391头, 旋披发虫2 950±1 003头。本研究建立了光学显微镜形态鉴定和18S rDNA分子标记相结合调查鞭毛虫多样性和数量的方法, 为进一步研究白蚁肠道共生生物的功能奠定了基础。     

Dimensionally stable sensors for a continuous monitoring program to detect subterranean termite (Isoptera: Rhinotermitidae) activity

A dimensionally stable sensor composed of a closed-cell polyethylene sheet on which a silver particle circuit was painted and sandwiched between two spruce stakes was tested for use in a monitoring program to detect subterranean termites. Sensors were connected to a datalogger for continuous monitoring of sensor circuit breakages over 12 mo, and were manually inspected monthly to assess sensor performance. The mean monthly sensor accuracy for three field test sites was 98.7%, with most false responses caused by early timing of the monthly inspection when termites entered the station before damaging the sensor circuits. Mean sensor longevity (the time for a sensor circuit to break in the absence of termites) of the dimensionally stable sensors was 11.7 mo; a substantial improvement over the 4.4-mo longevity recorded previously for wooden sensors.     

木腐菌对台湾乳白蚁取食偏好性的影响

本文测定了经红芝、紫芝、茯苓、黄孢原毛平革菌和密褐褶孔菌5种木腐菌腐蚀的马尾松木屑对台湾乳白蚁行为和取食反应的影响.在双重选择性试验中,与未经木腐菌腐蚀的马尾松木屑相比,台湾乳白蚁嗜好聚集和取食木腐菌腐蚀过的马尾松木屑.在多重选择性试验中,结果显示台湾乳白蚁偏好取食经茯苓、红芝或密褐褶孔菌腐蚀过的马尾松木屑.