Structural requirements for repellency: norsesquiterpenes and sesquiterpenoid derivatives of nootkatone against the Formosan subterranean termite (Isoptera: Rhinotermitidae)

BACKGROUND: Research has shown that the family of grapefruit flavors called nootkatones have significant repellant and toxic effects to Formosan subterranean termites (Coptotermes formosanus Shiraki). RESULTS: Nineteen synthetic nootkatone derivatives, along with three commercially available nootkatone derivatives, were tested for repellent activity against C. formosanus by a choice assay in a petri dish with a two‐step triage procedure. Based on the repellency threshold value, the relationships between structure and activity are discussed. CONCLUSION: Four derivatives of nootkatone have very high repellency and toxicity to C. formosanus, 9 times the potency of the primary compound nootkatone. Four other compounds have between 2 and 3 times the repellency of nootkatones, and three compounds are equal in their repellency to nootkatone. Copyright © 2010 Society of Chemical Industry     

Response of the subterranean termite Coptotermes formosanus (Isoptera: Rhinotermitidae) to soil treated with microencapsulated fenobucarb

BACKGROUND: Treating soil with insecticides is thought to be an effective method for termite control. Speed of action and repellency of insecticides are important factors for discussing their barrier effects as soil-treatment termiticides. The chemical barrier effect of microencapsulated fenobucarb against Coptotermes formosanus Shiraki was examined in the laboratory.RESULTS: Fenobucarb had a significantly faster lethal effect when applied to the mouthparts than to the tergites of worker termites. Soil that had been treated with > or = 50 mg kg(-1) of microencapsulated fenobucarb had a barrier effect within a single day, and could stop or retard the penetration of termites for 7 days. Microencapsulated fenobucarb did not act as a repellent, as indicated by a gradual increase in mortality at > or = 50 mg kg(-1) with slight penetration into the treated soil during the 7 day test.CONCLUSION: The results suggest that microencapsulated fenobucarb is a fast-acting termiticide, with a good barrier effect as a soil treatment, that also acts as a reduced repellent, retarding entry of termites into treated soil.     

Identification of two haplotypes of cytochrome oxidase subunit II (COII) gene of the Formosan subterranean termite,Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in southern Mississippi

BACKGROUND: Coptotermes formosanus Shiraki was accidentally introduced into the United States from Asia. The introduction of the pest has brought significant economic consequences. During the past decade, Mississippi has become a significantly infested state, partly due to the proximity to coastal port cities such as New Orleans. This study was initiated to investigate the origin and infestation route of C. formosanus in southern Mississippi. RESULTS: Twenty‐eight colonies (21 colonies from Mississippi, six from Louisiana, one from China) were collected. Sequencing and analysis of 112 sequences revealed 15 haplotypes of cytochrome oxidase subunit II (COII) gene in the world. Two haplotypes of COII were identified in Mississippi. In addition, specific primers were designed and tested differentially to amplify characteristic fragments for verifying and surveying different genotypes of C. formosanus in the future. CONCLUSION: Of the two haplotypes identified in Mississippi, the GA group was identical to those reported previously in Georgia, Louisiana, Alabama and other infested states. The second haplotype, the AT group, was identified for the first time in southeastern United States. Sequence identity of the AT‐group C. formosanus with those reported mainly in southeastern Asian countries provided evidence of at least two introductions of C. formosanus into the United States. Copyright © 2010 Society of Chemical Industry     

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。     

Survivorship, tunneling and feeding behaviors of Coptotermes formosanus (Isoptera: Rhinotermitidae) in response to 2'-acetonaphthone-treated sand

In laboratory tests, 2'-acetonaphthone was incorporated into sand at different concentrations (4.16-200 mg kg(-1)) and evaluated for survivorship, feeding and tunneling effects on the Formosan subterranean termite, Coptotermes formosanus Shiraki. 2'-Acetonaphthone at 8.33 mg kg(-1) sand significantly reduced survivorship (89-94%), tunnel area (68-91%) and food consumption (84-100%) compared with the control. Most of the dead workers were found at the release point and a few had traveled to the surface of the treated sand. Malformed workers (< or =27%) with an unexpected symptom of molting failure were observed, particularly at the lowest concentration tested (4.16 mg kg(-1)). In choice assays, threshold concentration for significant reduction in survivorship, tunnel construction in treated sand and food consumption in the treated-sand side was 8.33mg kg(-1) with termites collected from New Orleans, LA and 35.0 mg kg(-1) for those from Lake Charles, LA. Termites actively fed and tunneled in the untreated sand, whereas 2'-acetonaphthone at 140mg kg(-1) completely inhibited consumption of food placed on the treated sand.     

Plant-derived natural products exhibiting activity against formosan subterranean termites (Coptotermes formosanus)

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is among the most devastating termite pests. Natural products derived from plant extracts were tested in a discovery programme for effective, environmentally friendly termite control agents. Among the natural products tested, vulgarone B (isolated from Artemisia douglasiana Besser), apiol (isolated from Ligusticum hultenii (Fern.) Calder & Taylor) and cnicin (isolated from Centaurea maculosa Lam.) exhibited significantly higher mortalities than in untreated controls in laboratory bioassay. These compounds are present at high levels in their respective plant sources and also possess other biological activities such as phytotoxic and antifungal properties.     

Transfer of indoxacarb among workers of Coptotermes formosanus (Isoptera: Rhinotermitidae): effects of dose, donor:recipient ratio and post-exposure time

Horizontal transfer of indoxacarb among workers of the Formosan subterranean termite, Coptotermes formosanus Shiraki, was examined under laboratory conditions. The effects of dose (0, 10, 20, 50, 100 or 200 ng AI per donor), donor:recipient ratio (1:1, 1:4 or 1:9) and post-exposure time (2, 4, 8, 16, 20 and 24 days) on lethal transfer of indoxacarb were investigated using a donor/recipient model in groups of 100 workers. Transfer of lethal doses from donors to recipients was evidenced by significant recipient mortality in 13 out of 15 treatments within 24 days post-exposure. Dosage significantly affected indoxacarb transfer. Higher doses resulted in greater recipient mortality than lower doses. The highest dose tested resulted in 100% death of recipients and donors within 20 days. A dose of 100 ng resulted in recipient mortalities ranging from 68 to 100%, whereas doses < or =50 ng killed <60% of recipients within 24 days. Donor:recipient ratio also had considerable effect on indoxacarb transfer. At 24 days post-exposure, greater recipient mortalities were observed at ratios > or =1:4 at doses > or =20 ng, but only at a ratio 1:1 at dose 10 ng. Recipient mortality increased significantly as post-exposure time increased. The higher the doses applied on donors, the shorter were the times required for the onset of recipient mortality to occur and for recipients to reach maximum mortality. Significantly greater recipient mortalities were not observed at doses 20 and 50 ng until more than 20 days post-exposure, indicating a delayed activity of indoxacarb. Possible transfer mechanisms are discussed.     

二氧化碳对台湾乳白蚁的引诱作用

台湾乳白蚁Coptotermes formosanus Shiraki是华南地区农林树木、木质构件的重要钻蛀性害虫。本文测定分析了二氧化碳(CO2)对台湾乳白蚁的引诱效果。分析结果显示,二氧化碳对台湾乳白蚁具有显著的引诱活性,其中浓度1.5%的二氧化碳对台湾乳白蚁的引诱作用较强,但引诱作用随着二氧化碳浓度的升高而减小。为了便于应用,进一步利用发酵产生的二氧化碳分析,结果显示二氧化碳较常规引诱物松木具有更显著的引诱效果。本研究将为台湾乳白蚁新型引诱剂开发提供参考,有助于提高台湾乳白蚁饵剂的防治效果。     

Group effects on insecticide toxicity in workers of the Formosan subterranean termite,Coptotermes formosanus Shiraki

Coptotermes formosanus workers were treated topically with insecticide and subsequently held individually or in groups to examine possible effects on insecticide toxicity. Chlorpyrifos, cypermethrin and chlordane toxicities were 1.4-, 1.5-, and 1.3-fold greater, respectively, among workers held in groups compared with those held individually after insecticide treatment. Experiments were conducted to examine how enhanced toxicity occurred among termites held in groups after topical insecticide treatment. When workers were treated topically with chlordane and immediately placed with untreated workers, significantly greater numbers of untreated workers were killed compared with controls at all ratios examined (insecticide-treated:untreated). These data indicated that workers treated topically with insecticide were capable of somehow transferring a lethal dose of insecticide to untreated workers confined in the vial. Chlordane was recovered from untreated workers which had been confined with chlordane-treated workers; significantly higher quantities of chlordane were recovered from dead workers exposed to chlordane-treated workers compared with surviving workers exposed to chlordane-treated workers. Possible mechanisms of insecticide transfer from insecticide-treated to untreated termites are discussed.     

Transfer of five commercial termite bait formulations containing benzoylphenyl urea chitin synthesis inhibitors within groups of the subterranean termite Reticulitermes flavipes (Blattodea: Rhinotermitidae)

ABSTRACT

Eastern subterranean termite, Reticulitermes flavipes (Kollar), workers were exposed for 7 days to one of five chitin synthesis inhibitors (CSIs): diflubenzuron, hexaflumuron, lufenuron, noviflumuron, and novaluron in commercially available bait matrices. Following a 7 day exposure period, termite donors (D) were combined with naïve (not exposed) termite recipients (R) at five D:R ratios (20:0, 15:5, 10:10, 5:15, and 1:19) and mortality determined daily for up to 68 days. Lethal time and percent mortality data suggest efficient transfer at all D:R ratios for all CSIs tested, except diflubenzuron at 1:19. Despite the data indicating transfer of lufenuron in bioassay, this material may not be effective in field use based on behavioral observations that include limited movement by donors. We also report frequency of visible evidence of CSI intoxication, including the previously described “jackknife” pose and an additional physical deformity, we term “curled-body”. The implications these data and observations have for laboratory evaluation and field population management using commercial termite baiting systems is discussed.     

United States Department of Agriculture-Agriculture Research Service research on targeted management of the Formosan subterranean termite Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae)

The Formosan subterranean termite, Coptotermes formosanus Shiraki is currently one of the most destructive pests in the USA. It is estimated to cost consumers over US dollars 1 billion annually for preventative and remedial treatment and to repair damage caused by this insect. The mission of the Formosan Subterranean Termite Research Unit of the Agricultural Research Service is to demonstrate the most effective existing termite management technologies, integrate them into effective management systems, and provide fundamental problem-solving research for long-term, safe, effective and environmentally friendly new technologies. This article describes the epidemiology of the pest and highlights the research accomplished by the Agricultural Research Service on area-wide management of the termite and fundamental research on its biology that might provide the basis for future management technologies. Fundamental areas that are receiving attention are termite detection, termite colony development, nutrition and foraging, and the search for biological control agents. Other fertile areas include understanding termite symbionts that may provide an additional target for control. Area-wide management of the termite by using population suppression rather than protection of individual structures has been successful; however, much remains to be done to provide long-term sustainable population control. An educational component of the program has provided reliable information to homeowners and pest-control operators that should help slow the spread of this organism and allow rapid intervention in those areas which it infests.     

Effect of hexaflumuron on mortality of the Western subterranean termite (Isoptera: Rhinotermitidae) during and following exposure and movement of hexaflumuron in termite groups

The effects of hexaflumuron consumption on the mortality of workers of the Western subterranean termite, Reticulitermes hesperus Banks, were observed following various exposures to a substrate treated with 14C-labeled hexaflumuron at 5 g kg(-1). Uptake of hexaflumuron by workers was rapid, peaking at approximately 280 ng hexaflumuron per termite 12 days after exposure. The onset of mortality began at day 8, with cumulative mortality reaching approximately 96% by day 45. Excretion of hexaflumuron from worker termites was rapid following various exposure periods, half-lives ranging from 2.1 to 4.7 days. Trophallaxis among worker termites was efficient, hexaflumuron levels in recipient termites approaching two-thirds of levels present in donor termites feeding continuously on hexaflumuron-treated filter paper. The effect of donor-to-recipient group ratios was negligible on the amounts of hexaflumuron transferred from donors to recipients. In laboratory tests, hexaflumuron diffused from a feeding source within 7 days. The presence of additional food sources appeared to inhibit movement of hexaflumuron. Movement of hexaflumuron by cannibalism and coprophagy occurred, but was significant only when termites were starved. Hexaflumuron also appeared to adversely affect egg development by preventing hatch. Hexaflumuron was readily transferred through termite groups, effectively suppressing laboratory populations of R hesperus. Variable efficacy in field situations employing baiting with hexaflumuron in southern California may be a consequence of sporadic feeding at bait stations, the rapid clearance of hexaflumuron from individual termites, and the difficulties in bait presentation (low foraging activity, poor bait station foraging fidelity) inherent in the foraging characteristics of the Western subterranean termite.     

Effects of non-repellent termiticides on the tunneling and walking ability of the eastern subterranean termite (Isoptera: Rhinotermitidae)

BACKGROUND: Non-repellent insecticides, including fipronil and indoxacarb, are becoming increasingly important for soil treatments to manage the eastern subterranean termite, Reticulitermes flavipes (Kollar). The effects of these insecticides on termite walking and tunneling behavior could significantly reduce their efficacy against colonies. RESULTS: Groups of R. flavipes were exposed to several concentrations of commercial formulations of fipronil and indoxacarb, and the ability of treated termites to tunnel in soil and walk was assessed. Increasing insecticide concentration resulted in a reduction in the ability of R. flavipes to walk, tunnel and form tunnel branches; the importance of these effects on the use of non-repellent insecticides is discussed. CONCLUSION: Exposure of R. flavipes to 1, 10 or 50 mg L⁻¹ of fipronil or 50, 100 or 200 mg L⁻¹ of indoxacarb significantly reduced termite walking and tunneling and the number of tunnel branches. Distance walked (ca 73 mm) by untreated control termites did not change over time for at least 16 h after treatment; control termites formed ca 150 cm of tunnels with ca 40 branches. Copyright © 2012 Society of Chemical Industry     

Acute and sublethal toxicity of novaluron, a novel chitin synthesis inhibitor, to Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

The acute and sublethal toxicities of novaluron, a novel chitin synthesis inhibitor, to a laboratory-reared insecticide-susceptible strain of Colorado potato beetle, Leptinotarsa decemlineata (Say), were determined. Novaluron exhibited excellent residual (120 h LC(50) = 0.42 mg litre(-1)) and good direct contact (120 h LC(50) = 27 mg litre(-1)) activity against second-instar larvae (L2). Hatch of eggs exposed by direct contact to novaluron solutions > or =100 mg litre(-1) was significantly reduced, as was the ability of emerged first-instar larvae to moult. L2 from eggs exposed to > or =100 mg litre(-1) novaluron weighed significantly less (P < 0.0001) than those from untreated eggs. However, L2 from eggs treated with 1 mg litre(-1) novaluron weighed significantly more (P < or = 0.05) than those from untreated eggs, suggesting novaluron can have a hormetic effect on L decemlineata larval development. Leptinotarsa decemlineata mating pairs fed foliage treated with novaluron at 25 or 75 g AI ha(-1) produced approximately 25% fewer egg masses and eggs per mass. Hatch of eggs on treated foliage was almost completely suppressed, and longevity of male beetles was reduced by approximately 50% when fed foliage treated with novaluron at 75 g AI ha(-1).     

Distribution of a juvenogen and its metabolites in a laboratory system during juvenogen-induced caste differentiation in a termite, Reticulitermes santonensis (Isoptera: Rhinotermitidae)

BACKGROUND: Juvenoids and juvenogens have been for many years considered promising candidates for control of pest insect species including termites. Their use as termite pest management agents requires the generation of knowledge concerning their degradation and distribution in time and space. Groups of 40 Reticulitermes santonensis de Feytaud workers were provided with wood impregnated with a juvenogen, ethyl cis-N-{2-[4-(2-butyryloxycyclohexylmethyl)phenoxy]ethyl}carbamate, labelled with tritium in the benzene ring (305 GBq mmol(-1)). After 14 days the radioactivity was determined in all elements of the experimental system. RESULTS: The majority of the input activity was detected in the wood, only about 1% in the bodies of surviving termites and 1% in the substrate. A considerable part of the input activity was probably lost as gaseous termite metabolites. The activity in workers was significantly higher than in presoldiers, which had differentiated under the influence of the labelled juvenogen. A stable value of radioactivity was detected on the body surfaces. CONCLUSIONS: The results suggest good stability of the compound in the wooden carrier and low contamination of the environment with non-gaseous residuals, together with the desired biological impact on termite caste differentiation.     

Catching Ips duplicatus (Sahlberg) (Coleoptera: Scolytidae) with pheromone‐baited traps: optimal trap type,colour, height and distance to infestation

BACKGROUND: Field trapping experiments were carried out to evaluate effective trap characteristics for maximising Ips duplicatus (Sahlberg) catches in pheromone‐baited traps in China. RESULTS: Window‐slot and cross‐barrier traps had significantly higher catches than multiple‐funnel traps. The colour of window‐slot traps showed a significant effect on catches, with dark colours (black and red) being more effective than light colours, especially white and yellow. Window‐slot traps at a 1.5–2.0 m level caught more beetles than those at either ground level (0–0.5 m) or at 3.5–4.0 m. Ips duplicatus can be attracted to pheromone‐baited traps over a distance of > 100 m from the forest edge in an open grassy field. There was a strong diurnal pattern of flight activity, with catches on window‐slot traps occurring during the daytime with one broad peak at mid‐ to late afternoon. The seasonal flight activity of I. duplicatus as monitored by pheromone‐baited window‐slot traps during 2007–2008 indicated that three major flight peaks occurred in early June, late June–early July and late July respectively, suggesting the existence of a potential second generation. CONCLUSION: The optimal trap characteristics will improve the performance of pheromone‐baited traps as a critical monitoring or mass‐trapping tool to combat outbreaks of this pest species. Copyright © 2009 Society of Chemical Industry