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.     

拟除虫菊酯的杀虫活性和温度的关系

除了戊酸醚酯对苜蓿蚜呈弱的正温度系数外,杀灭菊酯、二氯苯醚菊酯、氯氰菊酯、溴氰菊酯、氟氰菊酯及百树菊酯,都呈负温度系数。杀灭菊酯、戊酸醚酯、二氯苯醚菊酯、氯氰菊酯、溴氰菊酯和氟氰菊酯,对梨网蝽全部呈正温度系数。氯氰菊酯对粘虫呈负温度系数,杀灭菊酯、戊酸醚酯、二氯苯醚菊酯和溴氰菊酯都呈正温度系数。杀灭菊酯和溴氰菊酯对粘虫卵也呈正温度系数。杀灭菊酯对小菜蛾的杀虫活性,受温度的影响不明显,而戊酸醚酯则呈负温度系数。杀灭菊酯和戊酸醚酯对蚊幼呈正温度系数,而二氯苯醚菊酯则呈负温度系数。     

Extended selections for pyrethroid resistance in the German cockroach (Dictyoptera: Blattellidae).

Selection experiments with a pyrethrins-susceptible and a pyrethrins-resistant strain of German cockroaches, Blattella germanica (L.), were conducted for 17 generations with either permethrin or fenvalerate as the selecting agent. Large nymphs were left on treated glass surfaces for extended periods of time each generation. Mortality was assessed at 24 h. The level of resistance was determined periodically by time-mortality testing. The VPI-susceptible strain served as the basis for comparison. The pyrethrins-susceptible strain developed resistance to pyrethrins early in the selection process; this strain ultimately became resistant to allethrin, phenothrin, permethrin, fenvalerate, cyfluthrin, and cypermethrin. Fenvalerate caused faster development of resistance than did permethrin. The pyrethrins-resistant strain, selected with fenvalerate, quickly became resistant to allethrin, permethrin, phenothrin, and fenvalerate. Ultimately, it developed resistance to all nine pyrethroids tested.     

Isolation of broad-specificity domain antibody from phage library for development of pyrethroid immunoassay

An antibody to phenoxybenzoic acid (PBA), the conserved chemical region of pyrethroids, was developed using a domain antibody (DAB) library to enable pyrethroid detection in agricultural products. The DAB library, constructed without animal immunization and based on a human VH framework, displayed repertoires on filamentous bacteriophage. After four rounds of panning, we obtained five domain antibodies that are capable of binding to PBA. Antibody A3 has strong identification capability to cypermethrin, β-cypermethrin, and fenvalerate. The antibody A3 was used to develop an enzyme-linked immunosorbent assay (ELISA). The IC₅₀ values were 2.586, 1.814, and 2.251 μg/ml for cypermethrin, β-cypermethrin, and fenvalerate, respectively. The assay shows weak competition with flucythrinate but shows no competition with fenpropathrin, deltamethrin, and permethrin. The developed ELISA process was successfully applied to fortified Chinese cabbage samples, with the recoveries of cypermethrin, β-cypermethrin, and fenvalerate ranging from 84.4 to 112.3%. We developed an immunoassay to detect pyrethroids depending on the domain antibody library, which overcomes the limitation of requiring protein antigen to immunize animals raising antibody.     

Effects of pyrethroid insecticides on gap junctional intercellular communications in Balb/c3T3 cells by dye-transfer assay

The effects of fenvalerate, esfenvalerate, permethrin, cypermethrin, deltamethrin, p-chlorophenylisovaleric acid (CPIA, major metabolite of fenvalerate) and DDT, a liver tumor promoter, on gap junctional intercellular communication (GJIC) were examined in Balb/c3T3 cells by dye-transfer assay. Separate groups of Balb/c3T3 cells were exposed to the chemicals for 1 day. On the following day, GJIC was measured by counting the number of dye-transferring cells per injection of Lucifer Yellow under a fluorescent microscope. Fenvalerate, esfenvalerate, permethrin, cypermethrin, deltamethrin and DDT inhibited GJIC at noncytotoxic concentrations, while CPIA did not inhibit GJIC even, at a cytotoxic concentration. It is concluded that the examined pyrethroid insecticides, but not a metabolite, have inhibitory effects on GJIC in Balb/c3T3 cells.Abbreviations DDT 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane - DMSO dimethyl sulfoxide     

Effects of several insecticide formulations on oothecal drop and hatchability in German cockroaches (Dictyoptera: Blattellidae)

Formulations used for control of German cockroaches, Blattella germanica (L.), were investigated. The insecticides tested on gravid females were bendiocarb, chlorpyrifos, cyfluthrin, cypermethrin, fenvalerate, hydramethylnon, malathion, propetamphos, propoxur, and pyrethrins. Exposure to each insecticide increased the frequency of oothecal drop and reduced the percentage oothecal hatch. The percentage of oothecae that were dropped increased as a curvilinear function of insecticide concentration. An LD50 of propoxur to female German cockroaches resulted in the greatest oothecal drop (83.50%); fenvalerate caused the least drop (22.60%). LD50's of cypermethrin, propetamphos, and propoxur resulted in 29.60, 31.807, and 37.30% hatch from dropped oothecae, respectively. The smallest percentage hatch from retained oothecae was caused by LD50's of propoxur (1.5%) and cyfluthrin (7.70%). Retained oothecae from females treated with an LD50 of fenvalerate (68.70%) or pyrethrins (68.70%) had the greatest percentage hatch. Total percentage hatch (dropped and retained oothecae) declined exponentially as the insecticide concentration increased. An LD50 of cypermethrin limited total oothecal hatch to 24.50%, whereas LD50's of fenvalerate, malathion, and pyrethrins resulted in 53.60, 52.20, and 58.90% hatch, respectively. Mean time to oothecal hatch increased linearly with increasing insecticide concentration for all insecticides tested.     

Termite Diversity along an Amazon–Andes Elevation Gradient,Peru

Through their role as ‘ecosystem engineers’, termites provide a range of ecosystem services including decomposition, and carbon and nitrogen cycling. Although termite diversity levels differ between regions as a result of variation in regional species pool size, in general, termite diversity is thought to decline with elevation. This study (1) investigated how termite species density, abundance, functional group diversity and termite attack on dead wood vary with altitude along an Amazon–Andes altitudinal gradient in Peru; (2) identified likely environmental causes of this pattern; and (3) explored the implications of termite presence for ecosystem functioning (notably for decomposition). Termites were sampled with a standardized 100 × 2 m straight‐belt transect at five undisturbed forest sites along a gradient 190 to 3025 m, as were environmental variables and termite and fungus attack on dead wood. Termite diversity was similar to that found at comparable sites in South America, and there was little turnover of assemblage composition with elevation suggesting that montane specialists are not present. Termite diversity declined with increased elevation, though the upper distribution limit for termites was at a lower elevation than anticipated. We suggest that key drivers of this elevation pattern are reduced temperature with altitude and mid‐elevation peaks in soil water content. Also, attack on dead wood diminished with decreasing termite indirect absolute abundance, while the depth of the soil humic layer increased. We hypothesize that termite abundance is a major accelerant of decomposition rates (and associated mineralization) in Amazonian forests.     

Effect of insecticides on the emergence ofTrichogramma Brasiliensis [Hymenoptera: Trichogrammatidae] from parasitized host eggs

The effect of 9 insecticides recommended for the control of cotton bollworms was studied, under laboratory conditions, on the emergence ofTrichogramma brasiliensis Ashmead from the parasitized eggs ofCorcyra cephalonica (Stainton) of different age groups. The insecticide concentrations tested were equivalent to those recommended for field application viz. phenthoate 0.14%, phosalone 0.15%, endosulfan 0.25%, permethrin 0.014%, monocrotophos 0.13%, fenvalerate 0.014%, cypermethrin 0.014%, fenitrothion 0.30% and quinalphos 0.14%, quinalphos and fenitrothion caused complete inhibition of emergence of the parasitoid from parasitized host eggs of all ages (1 to 7 days); but in general, adverse effect of insecticides on the disruption of emergence decreased with the advancement in the age of the parasitized eggs. For 1 day old parasitized host eggs, emergence ofT. brasiliensis adults varied from 33 to 57% for the remaining 7 treatments. For the 7 days old parasitized host eggs, emergence of parasitoids from the treatments with endosulfan, phosalone and phenthoate was similar to that from control. However, 46 to 59% inhibition of emergence was observed for permethrin, monocrotophos and cypermethrin. Fenvalerate treatment also significantly inhibited the emergence but at a comparatively lower level (40%). Out of 9 insecticides tested, phosalone and fenvalerate were considered to be relatively safe toT. brasiliensis.      

Pyrethroid resistance and synergism in a field strain of the German cockroach (Dictyoptera: Blattellidae).

A field-collected strain of the German cockroach, Blattella germanica (L.), was highly resistant to 10 pyrethroid insecticides (cyfluthrin, cyhalothrin, cypermethrin, fenvalerate, esfenvalerate, fluvalinate, permethrin, resmethrin, sumithrin, tralomethrin) based on topical applications and comparison with a known susceptible strain. Resistance ratios ranged from 29 to 337. In general, pyrethroid compounds with an alpha-cyano functional group were more toxic than those lacking this moiety, but resistance ratios were similar for both classes of compound. The metabolic inhibitors DEF and PBO were tested for synergism in conjunction with cypermethrin (alpha-cyano) and permethrin (non alpha-cyano). Application of synergists resulted in partial elimination of resistance, suggesting that the basis of resistance involves enhanced metabolism as well as target site insensitivity. These results suggest that pyrethroid insecticides may have a very short functional life in German cockroach control unless they are used judiciously.     

Pyrethroids and the striatal dopaminergic system in vivo

1. Type I (permethrin and allethrin) or type II (cypermethrin and fenvalerate) pyrethroids caused 23-37% increases in the striatal content of the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC). 2. Toxicity symptoms and increases in DOPAC were associated with higher brain concentrations for type I (2.6-5.8 micrograms/gm) than type II pyrethroids (0.4-0.6 micrograms/gm). 3. No specific difference in the interaction between type I and II pyrethroids and the striatal dopaminergic system were recognized.     

Carbon-based quantitation of pyrethrins by supercritical-fluid chromatography

All six insecticide active ingredients in pyrethrum extract were quantified by supercritical fluid chromatography and carbon calibration. Allethrin is a suitable reference compound for carbon calibration and pyrethrins calibrations. Carbon quantification in SFC is also applied to pyrethroids (phenothrin, permethrin, cypermethrin, fenvalerate and deltamethrin) and alkanes. Halogen substitution on pyrethroids requires halogens on the reference calibration compound. The method was applied to commercial extracts.     

Toxicity, repellency, and transfer of chlorfenapyr against western subterranean termites (Isoptera: Rhinotermitidae)

Chlorfenapyr is a slow-acting insecticide against western subterranean termite, Reticulitermes hesperus Banks, when applied to sand. The LD50 at day 7 for workers is 29.98 ng per termite and considerably higher than that of chlorpyrifos (14.01), cypermethrin (3.21), and fipronil (0.16). Brief exposures to sand treated with chlorfenapyr resulted in dose-dependent mortality over a broad range of concentrations. Brief 1-h exposures to > or =75 ppm provided >88% kill of termites at day 7. Chlorfenapyr deposits did not repel termites, even at 300 ppm. Termites tunneled from 0.1 to 1.8 cm into sand treated with 10- to 300-ppm chlorfenapyr deposits, resulting in > or =70% mortality. Within 1 h after being exposed to 50 ppm chlorfenapyr, approximately 17% of the termites exhibited impaired responses to synthetic trail pheromone. By 4 h, nearly 60% of the workers were not able to follow a 10 fg/cm pheromone trail. There was a direct linear relationship of the uptake of [14C]chlorfenapyr as concentration and duration of exposure increased. The percentage of chlorfenapyr transferred to recipients varied from 13.3 to 38.4%. Donors exposed for 1 h transferred a greater percentage of chlorfenapyr than did donors exposed for 4 h. A 1-h exposure on 100-ppm deposits provided sufficient uptake to kill 100% of the donors and sufficient transfer to kill 96% of the recipients. There was not enough transfer for recipients to serve as secondary donors and kill other termites. Horizontal transfer is limited to contact with the original donor and by the decreased mobility of workers within 4-8 h after exposure to treated sand. The effectiveness of chlorfenapyr barrier treatments is primarily due to its nonrepellency and delayed toxicity.     

Lack of mutagenicity of synthetic pyrethroids in Salmonella typhimurium strains and in V79 Chinese hamster cells

Seven pyrethroids, i.e., cypermethrin, permethrin, deltamethrin, bioresmethrin, resmethrin, cismethrin and fenvalerate, were not found to be mutagenic in (a) Salmonella typhimurium strains TA100 or TA98 in the presence or absence of a rat liver activation system using the plate incorporation assay and fluctuation tests, or (b) V79 Chinese hamster cells in the presence or absence of hepatocytes.     

Rapid degradation of termiticides under field conditions

Abstract  Soil testing is used by regulatory agencies to determine the adequacy of termiticide application by pest controllers. Because tests may be carried out years after treatment, an accurate knowledge of termiticide degradation rates is crucial if determinations are to be valid. Degradation of exposed residues of bifenthrin, chlorfenapyr, chlorpyrifos, fipronil and imidacloprid was investigated in a field trial conducted near Narrandera (inland New South Wales) and in Sydney. Samples of soil 75 mm deep were collected immediately after treatment and after 12 months from plots treated with termiticides to a minimum depth of 350 mm and analysed for termiticide residues. Bifenthrin and chlorfenapyr were the most persistent termiticides. Losses of chlorpyrifos exceeded 99% at both locations. Losses of fipronil and imidacloprid were 96% and 94%, respectively, at Narrandera and 67% and 50%, respectively, in Sydney. To explore the fate of chlorpyrifos, fipronil and imidacloprid in the soil profile at Narrandera, samples were collected 15 months after treatment to a depth of 450 mm, in 150 mm increments, from plots treated to a depth of 700 mm. In soil below 150 mm, chlorpyrifos and fipronil content was little changed from time of application whereas major losses of imidacloprid had occurred at all depths. These findings have implications for termite treatment regulation in Australia. Regulatory agencies have relied upon degradation rates observed in laboratory experiments to determine in situ treatment adequacy. Results of this field study suggest that termiticides can degrade more rapidly in situ than indicated by laboratory experiments.     

Effect of temperature on the toxicities of ten pyrethroids to German cockroach (Dictyoptera: Blattellidae).

Of 10 pyrethroids tested by topical application of male German cockroaches, Blattella germanica (L.), d-phenothrin was the least toxic at 19, 26, or 31 degrees C. lambda-cyhalothrin was most toxic. Pyrethroids with the alpha-cyano moiety (fluvalinate, fenvalerate, cypermethrin, esfenvalerate, tralomethrin, cyfluthrin, and lambda-cyhalothrin) were more toxic than those without this functional group (d-phenothrin, resmethrin, and permethrin). At LC50, toxicity was negatively related to temperature. Temperature-toxicity responses of five of seven alpha-cyano pyrethroids were parallel, possibly indicating qualitatively identical but quantitatively different levels of detoxification enzymes.     

Effect of tolerance to insecticides on substrate penetration by Formosan subterranean termites (Isoptera: Rhinotermitidae)

Seven selected insecticides were applied to three substrates and bioassayed for barrier efficacy and toxicity against the Formosan subterranean termite, Coptotermes formosanus Shiraki, originating from colonies that differed in their tolerance to the insecticides. A profound substrate effect was seen with all insecticides tested. Sand was the most difficult substrate to penetrate and caused faster and greater mortality of C. formosanus. Increased tolerance in C. formosanus was accompanied by a decrease in penetration of treated substrata with chlordane, methoxychlor, chlorpyrifos, and deltamethrin. The opposite was true in the case of permethrin and bendiocarb. More tolerance C. formosanus displayed decreased mortality in the presence of chlorpyrifos, deltamethrin, bendiocarb, and fipronil. The opposite was true for permethrin.     

Describing termite assemblage structure in a Peruvian lowland tropical rain forest: a comparison of two alternative methods

Termites are frequently dominant invertebrate decomposers and bioturbators in lowland tropical forests and therefore strongly influence ecosystem processes favouring soil stability, porosity and nutrient retention. In this study, we provide the first spatially replicated dataset on termite assemblage composition, abundance and biomass in a Peruvian rainforest by sampling six separate plots. In addition, two alternative sampling methods (transect method-TM and quadrat method-QM), providing termite species density data, were compared among the plots. The relationships between a range of environmental and spatial variables and species composition were examined using canonical correspondence analysis variation partitioning. We found that the TM captured a higher proportion of the known species in the site (82 %) compared with the QM (66 %). In addition, 56 % of the species sampled by TM were common between the plots while only 18 % of species overlapped using the QM. The QM may therefore potentially have undersampled the species pool. Environmental variables were shown to explain a larger proportion of the species patterns than the spatial variables with elevation, soil temperature and distance to the river being the most important. We discuss the impacts of the environmental and spatial variables on termite species composition.     

棉铃虫抗药性监测方法——浸叶法敏感毒力基线的建立及其应用

通过室内饲养的2个棉铃虫敏感品系,用浸叶法建立了11种常用药剂 (氯氰菊酯、溴氰菊酯、功夫菊酯、氰戊菊酯、久效磷、辛硫磷、甲基对硫磷、毒死蜱、灭多威、硫双灭多威、硫丹) 的敏感毒力基线,确定了它们的LC₅₀值和区分剂量。并用浸叶法监测了江苏、山东、河南、安徽4省棉田2代棉铃虫对氯氰菊酯、久效磷、灭多威和辛硫磷的抗性,结果表明用区分剂量监测抗性个体频率既快速简便,又适宜于进行早期抗性检测,因此这4种药剂的区分剂量可以推广应用于棉铃虫田间抗药性监测。     

Persistence and efficacy of termiticides used in preconstruction treatments to soil in Mississippi

Laboratory and field studies were conducted to determine the persistence and efficacy of termiticides used as preconstruction treatments against subterranean termites. Bifenthrin (0.067%), chlorpyrifos (0.75%), and imidacloprid (0.05%) ([AI]; wt:wt) were applied to soil beneath a monolithic concrete slab at their minimum labeled rates. Soil samples were taken from three depths (0-2.5, 2.6-7.6, and 7.7-15.2 cm) at six sampling times (0, 3, 6, 9, 12 and 48 mo) from sites in Harrison and Oktibbeha counties in Mississippi. Residue analyses were conducted on the 0-2.5- and 2.6-7.5-cm depths, and bioassays were conducted using all three depths. In field studies, significant termiticide degradation occurred between sampling times 0 and 48 mo for all termiticides. At all sampling times, the top 2.5 cm of soil contained more termiticide than the other depths. Time to 50% dissipation of termiticide in the 0-2.5-cm depth was 9, 6, and 2 mo for bifenthrin, chlorpyrifos, and imidacloprid, respectively. Termite mortalities in contact bioassays remained high for bifenthrin and chlorpyrifos throughout the 48-mo sampling period; however, mortality of termites exposed to imidacloprid-treated soil dropped after the initial sampling. Termites readily penetrated all termiticide-treated soil in bioassays of 52-mm soil cores at 48 mo. Percentage of mortality in these bioassays was 15, 43, and 13 for bifenthrin, chlorpyrifos, and imidacloprid respectively.     

Nestmate recognition mediated by intestinal bacteria in a termite, Reticulitermes speratus

Discrimination and aggressive responses toward non-nestmates have been observed in a number of termite species, but the mechanism is poorly understood. Here I present the novel hypothesis that differential intestinal bacteria composition leads to production of colony-specific chemical cues that enable nestmate recognition.
The intestinal microflora of a lower termite, Reticulitermes speratus , consisted of many bacteria species. The composition of the intestinal bacteria was exclusively colony-specific. Termites that had adsorbed an unfamiliar odor of bacteria sampled from another colony were fiercely attacked by nestmates. Experimental manipulation of the composition of bacteria by antibiotics successfully changed the recognition behavior toward nestmates. These results indicate that intestinal bacteria play an important role in nestmate recognition.