[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to evaluate survival and wood consumption of the Formosan subterranean termite, Coptotermes formosanus Shiraki, on ten different species of wood used as commercial lumber. Six of the wood species had natural resistance to termites and caused an average of >75% mortality. Southern yellow pine and spruce were the most palatable and teak was the most resistant of the wood tested. A test was also conducted to compare survival of termites on resistant wood with survival under starvation conditions after three and six weeks. After six weeks, survival of termites on teak was significantly lower than in the starvation control, suggesting that at least some of the termite mortality on teak may have been due to toxicity. Toxic chemical components of teak hold the most promise as wood preservatives.
[Show abstract][Hide abstract] ABSTRACT: This field study investigated the colony effect of a fipronil spot treatment applied to active infestations of Formosan subterranean termite, Coptotermes formosanus Shiraki. Spot treatments were applied to a single active independent monitor from each of four colonies in which multiple independent monitors were established. All treated monitors were abandoned, and the contents of the treated monitors were replaced with untreated wood at the approximately 30-d posttreatment inspection. All colonies survived treatment and only one colony exhibited long-term effects, which included significant reductions in termite collections and increased worker size. The affected colony was treated within 1 m of its primary nest. Two colonies exhibited a correlation between monitor termite production and distance from treatment. Distance appears to be a factor limiting fipronil's colony effects. The Formosan subterranean termite may not be a good candidate for the exterior perimeter and localized interior treatment label option because of the large range and size of the colony.
[Show abstract][Hide abstract] ABSTRACT: Podophyllotoxin is currently in high demand as the lead chemical precursor for the anti-cancer drugs etoposide and teniposide. We conducted a two-phase study: (i) screening of Juniperus and other related species and identified Juniperus virginiana as the species with the highest podophyllotoxin concentration and (ii) established the limits of variations of podophyllotoxin and essential oil content and composition in J. virginiana in the United States. In the second phase of the study. J. virginiana trees at 49 locations in Mississippi. Alabama, Tennessee, and North Dakota were sampled and analyzed for both podophyllotoxin and essential oil. Both the essential oil and podophyllotoxin had similar concentration ranges as percent of dry J. virginiana leaves. Hence the following qualitative grouping with respect to concentration of natural products in the leaves was assigned: very high (>0.3%), high (0.2-0.3%), medium (0.1-0.2%), and low (<0.1%). Based on the above qualitative grouping, the J. virginiana accession were divided into 10 different groups (chemotypes). The J. virginiana accessions also differed in essential oil composition, with wide variation of individual constituents. Based on the essential oil composition, the J. virginiana accessions were divided into the following groups (chemotypes): (1) safrole-limonene-linalool; (2) safrole-beta-pinene-limonene-linalool; (3) beta-pinene-limonene; (4) limonene; (5) limonene-linalool; (6) limonene-safrole; (7) limonene-safrole-beta-pinene; (8) beta-pinene-limonene-bornyl acetate; (9) beta-pinene-limonene-linalool-bornyl acetate; and (10) myrcene-limonene chemotype. The essential oil of two of the J. virginiana chemotypes showed differential antioxidant activity. J. virginiana leaves, a by-product from the timber industry could be used as a sustainable source for both podophyllotoxin and essential oil. The availability of various chemotypes offers an opportunity for the development of cultivars for commercial production of podophyllotoxin and essential oil with specific compositional profile to meet the market requirements.
[Show abstract][Hide abstract] ABSTRACT: Nine years of periodic acoustical monitoring of 93 trees active with Formosan subterranean termite, Coptotermes formosanus Shiraki, were evaluated for imidacloprid tree foam and noviflumuron bait to reduce termite activity in trees. Long term, imidacloprid suppressed but did not eliminate termite activity in treated trees. Noviflumuron bait did not significantly reduce the proportion of trees with high termite activity but significantly increased the number of trees with no termite activity. Noviflumuron changed termite distribution by possibly eliminating only some fraction of numerous colonies whereby surviving colonies avoided trees containing dead termites.
[Show abstract][Hide abstract] ABSTRACT: Two new polyacetylene thiophenes, echinopsacetylenes A and B (1 and 2), were isolated from the roots of Echinops transiliensis. The structures of 1 and 2 were elucidated on the basis of spectroscopic analyses and chemical transformations. Echinopsacetylenes A (1) is the first natural product possessing an α-terthienyl moiety covalently linked with another thiophene moiety. Echinopsacetylenes B (2) is the first natural thiophene conjugated with a fatty acid moiety. Echinopsacetylene A (1) showed toxicity against the Formosoan subterranean termite (Coptotermes formosanus).
[Show abstract][Hide abstract] ABSTRACT: Among the termite infestations in the United States, the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), is considered to be the most devastating termite pest. This pest most likely invaded North America as a result of the disembarkation of wooden military cargo at the port of New Orleans that arrived from Asia during and after World War II. It has now spread over other states, including Texas, Florida, South Carolina and California. Devastation caused by C. formosanus in North America has been estimated to cost $ US 1 billion a year. Over the past decades, organochlorines and organophosphates, the two prominent classes of termite control agents, have been banned owing to environmental and human health concerns. At the present time, phenylpyrazoles, pyrethroids, chloronicotinyls and pyrroles are being used as termite control agents. Mammalian toxicity and seeping of these compounds into groundwater are some of the drawbacks associated with these treatments. The instruction for the application of these termiticides indicate ground water advisory. Hence, with the increasing spread of termite infestation there is an increased need to discover effective, environmentally friendly and safe termite control agents with minimal mammalian toxicity.
Chromene analogs derived from a natural-product-based chromene amide isolated from Amyris texana were tested in a collaborative discovery program for effective, environmentally friendly termite control agents. Several chromene derivatives were synthesized and characterized as a novel class of potential termiticides, followed by bioassays. These compounds exhibited significantly higher mortalities compared with untreated controls in laboratory bioassays.
Chromene derivatives have been shown to be a potential novel class of termiticides against Formosan subterranean termites.
Pest Management Science 11/2011; 67(11):1446-50. DOI:10.1002/ps.2196 · 2.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three-chambered apparatus were compared between treatments with dry soil in the center container and treatments where the soil in the center container was moist. When a wood block was located in the release container, termites fed significantly more on that block, regardless of treatment or soil type. In the treatment with dry clay, none of the termites tunneled through the dry clay barrier to reach the distal container. When termites had to tunnel through a barrier of dry sand, topsoil, or clay to reach the sole wood block, there was no effect on wood consumption for the sand treatment, but there was significantly less feeding on wood in the treatments with dry topsoil or clay. When foraging arenas had a section of dry sand in the center, the dry sand significantly reduced tunneling in the distal section after 3 days, but not after 10 days. There was a highly significant effect on the ability of termites to colonize food located in dry sand. Only one feeding station located in dry sand was colonized by termites, compared with 11 feeding stations located in moist sand.
[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to determine how seasonal changes affect the foraging activity and wood consumption of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in New Orleans, LA. There was a significant correlation between wood consumption and air temperature, soil temperature, and soil moisture, but not precipitation or number of rainy days. In the first year of the study, wood consumption was the lowest in December, February, and March. Wood consumption in January was not significantly different from consumption during the rest of the year. There were no seasonal changes in the number of underground monitoring stations occupied by termites. In the second year of the study, wood consumption was lowest from January to March. There was a significant decrease in the number of monitoring stations occupied by termites during the winter. This study determined that C. formosanus will remain in monitoring stations and resume feeding during warmer periods of a mild winter if average soil temperatures remain above 15 degrees C. Only prolonged periods of cold weather, with average soil temperatures below 15 degrees C, caused a significant number of termites to abandon underground monitoring stations. Seasonal changes in foraging activity would probably only disrupt baiting programs during severe winters in New Orleans, LA.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Phytotoxic microbial metabolites produced by certain phytopathogenic fungi and bacteria, and a group of phytotoxic plant metabolites including Amaryllidacea alkaloids and some derivatives of these compounds were evaluated for algicide, bactericide, insecticide, fungicide, and herbicide activities in order to discover natural compounds for potential use in the management and control of several important agricultural and household structural pests. Among the various compounds evaluated: i) ophiobolin A was found to be the most promising for potential use as a selective algicide; ii) ungeremine was discovered to be bactericidal against certain species of fish pathogenic bacteria; iii) cycasin caused significant mortality in termites; iv) cavoxin, ophiobolin A, and sphaeropsidin A were most active towards species of plant pathogenic fungi; and v) lycorine and some of its analogues (1-O-acetyllycorine and lycorine chlorohydrate) were highly phytotoxic in the herbicide bioassay. Our results further demonstrated that plants and microbes can provide a diverse and natural source of compounds with potential use as pesticides.
[Show abstract][Hide abstract] ABSTRACT: This study examined the influence of soil type and moisture availability on termite foraging behavior. Physical properties of the soil affected both tunneling behavior and shelter tube construction. Termites tunneled through sand faster than top soil and clay. In containers with top soil and clay, termites built shelter tubes on the sides of the containers. In containers with sand, termites built shelter tubes directly into the air and covered the sides of the container with a layer of sand. The interaction of soil type and moisture availability affected termite movement, feeding, and survival. In assays with moist soils, termites were more likely to aggregate in top soil over potting soil and peat moss. However, termites were more likely to move into containers with dry peat moss and potting soil than containers with dry sand and clay. Termites were also significantly more likely to move into containers with dry potting soil than dry top soil. In the assay with dry soils, termite mortality was high even though termites were able to travel freely between moist sand and dry soil, possibly due to desiccation caused by contact with dry soil. Evaporation from potting soil and peat moss resulted in significant mortality, whereas termites were able to retain enough moisture in top soil, sand, and clay to survive for 25 d. The interaction of soil type and moisture availability influences the distribution of foraging termites in microhabitats.
[Show abstract][Hide abstract] ABSTRACT: Underground monitoring stations were active with Formosan subterranean termites, Coptotermes formosanus Shiraki, less than a month after City Park, an urban park in New Orleans, Louisiana, was inundated with 0.5 to 2.5 meters of flood water. This study examines whether C. formosanus are able to survive inundation by finding air pockets in either wood or their gallery system in the soil and whether termites move up from the substrate to higher ground in response to rising water. We found no evidence that termites are able to survive in their gallery system or within wood after submersion, and no evidence that termites attempt to move up from the substrate in order to escape rising water. However, significant numbers of termites located within the hollowed-out core of a wood block at the time of the flooding were able to escape slowly rising water. Formosan subterranean termite colonies most likely survived the flooding of City Park because these colonies were living within trees at the time of the flood. The construction of carton nests within the hollowed-out trunks of living trees may be a behavioral adaptation to survive flooding.
[Show abstract][Hide abstract] ABSTRACT: This study examined the effect of diet, experimental design, and length of time in the laboratory on intercolonial agonism among Formosan subterranean termite, Coptotermes formosanus Shiraki, colonies. In pairings of 12 C. formosanus Shiraki colonies collected in an urban forest, there was no significant reduction in survival of termites in 30 out of 59 colony pairs compared to colony controls, but there was <50% survival in 18 colony pairs and <10% survival in six colony pairs. There was no correlation between the level of aggressive behavior and the laboratory diet of the termites. Effect of bioassay design and length of time in the laboratory was evaluated in three colony pairs where tests were first conducted on the day of field collection, then colony pairs were retested every 7 days. Aggressive behavior decreased over time in both bioassays, but it tended to decrease more rapidly in the Petri dish tests. The rapid loss of agonism in groups of termites kept in the laboratory demonstrates that changes in environmental factors affect intercolonial agonism.
[Show abstract][Hide abstract] ABSTRACT: Mature colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki, like most other termite species, produce a reproductive caste in the form of nymphs that subsequently give rise to alates. Temporal production of nymphs in C. formosanus was monitored in monthly collections from four field traps in New Orleans, LA. Nymphs were present throughout the year with peak numbers observed during October/November and May. Large nymphs first occurred in December and peaked in March. Fewer than 1.5% workers formed nymphs within 3 months after collection from the field and after removal of the preexisting nymphs. Collections from other colonies, kept in the laboratory for >2 yr, did not produce any nymphs. It is speculated that a nymph induction factor (NIF), possibly coming from a mature physogastric queen, elicits nymph formation. The same or a similar factor may also be responsible for further development of nymphs and their transformation to alates. In the absence of this latter factor, the nymphs, except those in the most advanced stage of development, are either cannibalized or transform into brachypteroid neotenics. A scheme for the formation and transformation of various developmental stages within each caste of C. formosanus is presented.
Annals of the Entomological Society of America 01/2009; 97(Jul 2004):757-764. DOI:10.1603/0013-8746(2004)097[0757:NOTFST]2.0.CO;2 · 1.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Termite activity had been continuously monitored in four sections of City Park since 2002. Between 2002 and 2005, 12 distinct Formosan subterranean termite, Coptotermes formosanus Shiraki, colonies had been delineated using mark-release-recapture techniques. This study examines how the distribution of subterranean termites has changed in City Park three years after Hurricane Katrina by using mark-release-recapture techniques to delineate distinct C. formosanus colonies post-Katrina.
Entomological Society of America Annual Meeting 2008; 11/2008
[Show abstract][Hide abstract] ABSTRACT: Hurricane Katrina (2005) resulted in extensive flooding in the city of New Orleans, LA. Periodic sampling of monitors before the flood, and of different monitors in the same areas after the flood, was used to evaluate the effects of long-term flooding on populations of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Monitors were located adjacent to buildings and in urban forests. Significant population reductions occurred in areas that flooded 2-3 wk with brackish water, with termite populations associated with pine (Pinus spp.) trees and buildings slower to recover than populations associated with oak trees. Alate production in flooded areas showed no reduction from previous years.
[Show abstract][Hide abstract] ABSTRACT: A large number of naturally occurring and synthetic benzoquinones were evaluated for activity against the Formosan subterranean termite, Coptotermes formosanus, with potential use in termite control. Among these bioactive naturally occurring benzoquinones are 2-methyl-5-isopropyl-1,4-benzoquinone, 2-methoxy-6-pentyl-1,4-benzoquinone, 2,3-dimethoxy-5-methyl-6-(3-methyl-2-butenyl)-1,4-benzoquinone, 2,3-dimethoxy-5,6-dimethyl-1,4-benzoquinone, and 2,3-dichloro-5,6-dimethyl-1,4-benzoquinone. All five of these compounds demonstrated 100% mortality against C. formosanus by day 11 at a concentration of 1% (wt/wt) or less. In general, benzoquinones with one or two hydrophobic groups on the 5 and/or 6 positions of the quinone ring along with one or two group(s) on the opposite side of the ring, at the 2 and/or 3 position, led to high rates of mortality against C. formosanus. Quantitative structure-activity relationship (QSAR) studies showed no correlation between lipophilicity (calculated log P) and mortality for the entire group of nonhalogenated benzoquinones. A correlation was observed between C-6 chain length and day 3 percent mortality for 2,3-dimethoxy-5-methyl-6-substituted aliphatic benzoquinones where short chain lengths resulted in higher mortality.
Journal of Agricultural and Food Chemistry 07/2008; 56(11):4021-6. DOI:10.1021/jf800331r · 2.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Systematic bioassay-guided fractionation of the methylene chloride extract of the roots from Ligularia macrophylla was performed to identify both phytotoxic and antifungal compounds. Four phytotoxic eremophilanes (furanoeremophilan-14beta,6alpha-olide, 6beta-angeloyloxy-10beta-hydroxyfuranoeremophilane, eremophil-7(11)-ene-12,8alpha;14beta,6alpha-diolide, and 3alpha-angeloyloxybakkenolide A) and two antifungal fatty acids (linoleic acid and alpha-linolenic acid) were isolated. The X-ray crystal structure determination of 6beta-angeloyloxy-10beta-hydroxyfuranoeremophilane is reported here for the first time. All four eremophilanes substantially inhibited growth of the monocot Agrostis stolonifera (bentgrass) while demonstrating little activity against the dicot Lactuca sativa (lettuce) at 1000 microM. In a dose-response screening of all compounds for growth inhibitory activity against Lemna paucicostata, 6beta-angeloyloxy-10beta-hydroxyfuranoeremophilane was the most active with an IC50 of 2.94+/-0.16 microM. This compound also caused the greatest reduction of photosynthetic electron flow; however, its mode of action remains to be determined. Evaluation of isolated compounds for activity against the Formosan subterranean termite, Coptotermes formosanus, is also reported. At a concentration of 0.5% (wt/wt), 6beta-angeloyloxy-10beta-hydroxyfuranoeremophilane significantly reduced the consumption of filter paper by C. formosanus.
Journal of Agricultural and Food Chemistry 01/2008; 55(26):10656-63. DOI:10.1021/jf072548w · 2.91 Impact Factor