Allelochemical resistance of bald cypress,Taxodium distichum,heartwood to the subterranean termite,Coptotermes formosanus

The heartwood of bald cypress,Taxodium distichum (L.) Rich., resisted feeding attack by the Formosan subterranean termite,Coptotermes formosanus Shiraki. Hexane-extracted heartwood, however, was consumed at > 12 times the amount of sound heartwood eaten. A bioassay usingT. distichum sapwood as a feeding substrate was employed to assess the antitermitic activity of successive hexane, acetone, and methanol extracts of heartwood shavings and isolates derived from the active hexane extract. Two fractions, eluted from the crude hexane extract by liquid chromatography, significantly reduced termite feeding compared to the parent extract, while a third fraction was less active than the original hexane extract. Each fraction contained one major component. All three components were structurally related diterpenes. The two most active heartwood constituents were identified by GC-MS and NMR as ferruginol and manool, while the third and least active, but most prevalent, compound in heartwood was identified as nezukol. Results of bioassays suggest that these allelochemicals act principally as feeding deterrents with accompanying termite mortality due to starvation.     

Defensive sesquiterpenoids from a dipterocarp (Dipterocarpus kerrii)

Four sesquiterpenoids (2, 4, 7, and9) have been isolated and characterized from the termiticidal fraction ofDipterocarpus kerrii resin. The major constituent of this resin is -gurjunene (1).Presented at the Third Annual Meeting of the International Society of Chemical Ecology, June 21–24, 1986, University of California, Berkeley.     

DIET-MEDIATED INTER-COLONIAL AGGRESSION IN THE FORMOSAN SUBTERRANEAN TERMITE <Emphasis Type="Italic">Coptotermes formosanus</Emphasis>

In most social insects, intercolonial and interspecific aggression are expressions of territoriality. In termites, cuticular hydrocarbons (CHCs) have been extensively studied for their role in nestmate recognition and aggressive discrimination of nonnest-mates. More recently, molecular genetic techniques have made it possible to determine relatedness between colonies and to investigate the influence of genetics on aggression. In the Formosan subterranean termite, Coptotermes formosanus, however, the role of CHCs and genetic relatedness in inter-colony aggression has been ambiguous, suggesting the involvement of additional factors in nest-mate recognition. In this study we assess the range of aggression in this termite species and characterize the influence of genetic relatedness, CHC profiles and diet on aggression levels. We collected four colonies of C. formosanus, feeding either on bald cypress or birch, from three locations in Louisiana. Inter-colony aggression ranged from low to high. Differences in CHC profiles, as well as genetic distances between colonies determined by using microsatellite DNA markers, showed no significant correlation with aggression. However, termite diet (host tree) played a significant role in determining the level of aggression. Thus, two distantly related colonies, each feeding on different diets, showed high aggression that significantly diminished if they were fed on the same wood in the laboratory (spruce). Using headspace solid phase microextraction, we found three compounds from workers fed on birch that were absent in workers fed on spruce. Such diet-derived chemicals may be involved in the complex determination of nest-mate recognition in C. formosanus.     

Termite Resistance of MDF Panels Treated with Various Boron Compounds

In this study, the effects of various boron compounds on the termite resistance of MDF panels were evaluated. Either borax (BX), boric acid (BA), zinc borate (ZB), or sodium perborate tetrahydrate (SPT) were added to urea-formaldehyde (UF) resin at target contents of 1%, 1.5%, 2% and 2.5% based on dry fiber weight. The panels were then manufactured using 12% urea-formaldehyde resin and 1% NH₄Cl. MDF samples from the panels were tested against the subterranean termites, Coptotermes formosanus Shiraki. Laboratory termite resistance tests showed that all samples containing boron compounds had greater resistance against termite attack compared to untreated MDF samples. At the second and third weeks of exposure, nearly 100% termite mortalities were recorded in all boron compound treated samples. The highest termite mortalities were determined in the samples with either BA or BX. Also, it was found that SPT showed notable performance on the termite mortality. As chemical loadings increased, termite mortalities increased, and at the same time the weight losses of the samples decreased.     

优秀历史建筑白蚁防治技术探讨

上海市优秀历史建筑白蚁危害严重,而通常的白蚁防治方法与优秀历史建筑保护原则存在不协调的地方。从优秀历史建筑保护原则出发,通过对优秀历史建筑白蚁高危害率的分析,提出了适合于上海市优秀历史建筑的白蚁防治方法,为上海市优秀历史建筑的保护提供新的依据。     

房屋蚁患分析及预防

从白蚁的危害性、白蚁群体的发展规律等方面进行了调研,分析了上海地区近几年白蚁危害率呈逐年上升原因针对上海地区的蚁患状况和地理环境,介绍了国内外常用的几种白蚁预防方法,并提出适合于上海地区白蚁预防的技术。     

广西水库大坝白蚁防治浅析

广西地理和气候特点,很适合白蚁繁殖,白蚁在广西各地非常常见,水库大坝普遍有白蚁存在。结合广西水库大坝管理工作经验,指出水库大坝白蚁防治现状及存在的问题,分析水库大坝白蚁的危害性和严重性,探讨水库大坝白蚁治理的方法,提出广西水库大坝白蚁治理的对策和建议。     

模拟现场试验测定氟虫腈粉剂对散白蚁的毒性传递性

采用模拟现场试验测定了氟虫腈粉剂对散白蚁的毒性传递性,结果表明,喷粉处理白蚁的数量占群体的比例≥4％,且氟虫腈粉剂浓度在0．10％～0．50％之间时,毒性能有效传递到2m外的个体。     

无毒无害的防白蚁电缆

论述了白蚁对电缆的危害、电缆防白蚁研究现状和技术动向 ,对化学防蚁法和物理防蚁法作了技术比较 ,根据电缆线路易受白蚁侵害的情况和人类对环保的要求 ,提出了应该大力发展无毒无害的物理法防白蚁电缆的观点。     

Interspecific variation of diterpene composition ofCubitermes soldier defense secretions

Soldiers of the humivorous termite generaCubitermes andCrenetermes (Isoptera: Termitidae: Termitinae) secrete a mixture of unusual diterpene hydrocarbons from the fontanellar opening of the frontal gland. The defense secretions of sixCubitermes species and oneCrenetermes species show species-specific distributions of the five chemically identified major components and 12 unidentified minor components. The secretion is also present with its characteric terpene distribution in white presoldiers and newly molted soldiers, but is completely absent in workers.Fellow of the Alfred P. Sloan Foundation (1981–85) and Camille and Henry Dreyfus Teacher-Scholar (1981–86).