Benzoylphenyl Urea Insect Growth Regulator Research Articles

Prevalence of sheep lice and trends in control practices across Australia - Australian sheep parasite control surveys from 2003 to 2019.

The sheep body louse (Bovicola ovis) is a parasite of major economic concern in Australia. This article reports lice incidence and control practices on Australian sheep farms as determined by three cross-sectional surveys of the years 2003, 2011 and 2018. The incidence of live lice detected within a flock was similar across the survey years with a slight decline in 2018 (2003: 20%, 2011: 18.6% and 2018: 13.9%). In an average year, most farmers did not see any direct or indirect evidence of lice infestation (2011: 59.3% and 2018: 69.5%), however, over a five-year period 38.9% (2003), 66.3% (in 2011) and 55.8% (in 2018) reported seeing evidence of lice infestation at least once with significant variation between sheep producing regions in 2011. In an average year, nearly three quarters of respondents treated for lice (2011:73.5% and 2018: 73.3%) with the majority treating immediately following shearing and very few treating sheep with long wool. Even higher percentages treated for lice at least once in the preceding five-year period (2011: 86.2% and 2018: 87.5%). Backliner was the most popular method of chemical application for lice control in sheep off-shears or with short wool (2003: 77%, 2011: 73% and 2018: 74.3%). For long wool treatments, hand jetting declined in popularity from 2003 (64%) to 2011 (54%) and 2018 (8.6%) as backliners became more popular (2003: 36%, 2011: 51% and 2018: 60%). The use of benzoylphenyl urea insect growth regulators (IGR) for off-shears/short wool treatment declined from 2003 (92.8%) to 2011 (51%) and 2018 (2.9%) and were largely replaced by neonicotinoids and spinosad for backliner/spray-on products. The use of organophosphates declined for plunge dipping (2003: 83.8%, 2011: 83% and 2018: 7.7%). Spinosad use for plunge dipping off-shears/short wool increased over the survey years (2003, 0%, 2011: 9% and 2018:46.2%). The use of IGRs declined for backliner application on long wool and were mainly replaced by spinosad in 2011 and 2018. Fewer respondents reported suspected resistance to lice control products in 2018 (8%) compared with 2003 (26%) and 2011 (13%) with most reporting suspected resistance to IGR and synthetic pyrethroids and emerging suspicions of resistance to neonicotinoids in 2018. Resistance to lice control products also reduced in importance as a reason for recurring lice infestations between 2011 (ranked 2nd) and 2018 (ranked 6th). Biosecurity was important to sheep producers with the highest ranked reason for recurring lice infestations being from stray or purchased sheep.

Study of the photodegradation kinetics and pathways of hexaflumuron in liquid media.

Hexaflumuron, one of the benzoylphenylurea insect growth regulators, can be leached into surface water and thus having a potential impact on aquatic organisms. In this study, the photodegradation processes of hexaflumuron under high-pressure mercury lamp irradiation were assessed. The photodegradation kinetics were studied, as were the effects of pH, different light sources, organic solvents and environmental substances, including nitrate ions (NO3(-)), nitrite ions (NO2(-)), ferrous ions (Fe(2+)), ferric ions (Fe(3+)), humic acid, sodium dodecyl sulfate (SDS) and hydrogen peroxide (H2O2). Three photodegradation products in methanol were identified by gas chromatography-mass spectrometry (GC-MS). In general, the degradation of hexaflumuron followed first-order kinetics. In the four media studied, the photodegradation rate order was n-hexane > methanol > ultrapure water > acetone. Faster degradation was observed under high-pressure mercury lamp irradiation than under xenon lamp irradiation. The pH had a considerable effect, with the most rapid degradation occurring at pH 5.0. The photodegradation rate of hexaflumuron was promoted in the presence of NO3(-), NO2(-), Fe(2+), humic acid, SDS and H2O2, but inhibited by Fe(3+). Moreover, the presumed photodegradation pathway was proposed to be the cleavage of the urea linkage.

Susceptibility of the sheep body louse [Bovicola ovis (Schrank), Phthiraptera: Trichodectidae] to temephos and concentration stability during sheep dipping with a commercial temephos product

Laboratory bioassays were used to measure the susceptibility of sheep lice [Bovicola ovis (Schrank)] strains that were resistant to pyrethroid or benzoylphenyl urea insect growth regulator insecticides to the organophosphate temephos, the most commonly used wet dipping insecticide. Compared with the reference susceptible strain, only the pyrethroid-resistant ‘Rowena’ strain displayed low level (2.2×) tolerance of temephos. Lice exposed to the minimum lethal concentration of temephos began to be affected within 6–7 h and all had responded to the insecticide within 24 h. In a dipping trial with sheep, the working concentration of temephos in a 5000-L plunge dip operating according to constant replenishment principles remained close to the nominal application rate of 350 mg/L. The ease with which temephos dip concentration was maintained simplified the dipping process. If typical of similar field populations, the absence, or low level of cross-resistance to temephos reported here for insect growth regulator-resistant and pyrethroid-resistant lice, respectively, should make wool producers confident that thorough dipping with temephos according to product label directions should be effective in controlling lice on their sheep.

Stimulatory and Suppressive Effects of Novaluron on the Colorado Potato Beetle Reproduction

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is one of the most damaging insect pests of potato, Solanum tuberosum L. Novaluron is a relatively new benzoylphenyl urea insect growth regulator with good activity against this pest. Earlier studies revealed that feeding on potato foliage treated with novaluron induces reversible egg hatch inhibition in adult Colorado potato beetles. We investigated whether novaluron effects depend on physiological state of the beetles at the time of exposure. The following four treatments were created: young beetles unmated at the beginning of the experiment and feeding on potato foliage treated with novaluron, young beetles unmated at the beginning of the experiment and feeding on untreated foliage, older beetles mated at the beginning of the experiment and feeding on foliage treated with novaluron, and older beetles mated at the beginning of the experiment and feeding on untreated foliage. The beetles were exposed to the respective treatments for 5 d. After that, both young and older beetles feeding on novaluron-treated leaves were switched onto untreated leaves and monitored for another 5 d to test their ability to recover. Young beetles unmated at the beginning of the experiment produced more eggs after feeding on the treated foliage, possibly indicating the presence of a pesticide-induced homeostatic modulation. No such effect was observed in the older beetles. Regardless of beetle physiological state at the beginning of the experiment, eggs produced on treated foliage did not hatch. The beetles eventually resumed laying viable eggs after being switched onto untreated foliage, with the recovery being delayed by approximately 24 h in young beetles compared with older beetles. Our results corroborate that novaluron reduces fertility of treated adults.

Influence of biotic-abiotic factors on the degradation of novaluron in tropical soil

In this study, the degradation of novaluron (benzoylphenyl urea insect growth regulator) was investigated under controlled laboratory conditions in clay loam alluvial and coastal saline soils of West Bengal, India. The application rates were field rate (FR); 2FR and 10FR. The incubation study was carried out at 30 °C and 60% of maximum water holding capacity of both the soils. Degradation of novaluron in both the soils followed first order reaction kinetics at all application rates under non-sterile and sterile conditions. The half-lives of novaluron in non-sterilized soils ranged from 17.0–17.8 days (alluvial soil) and 11.4–12.7 days (coastal saline soil), while the values in case of the sterilized soils were 53.7–59.0 days (alluvial soil) and 28.9–29.8 days (coastal saline soil) respectively. The novaluron degradation patterns were found to be highly influenced by soil types, application rates, and biotic abiotic factors. Abiotic factors strongly influenced novaluron degradation in both the soils. Biotic degradation was higher in alluvial soil compared to the coastal saline soil.

Synergistic effect of a fungicide containing polyoxin B with insect growth regulators (IGRs) in the killing of common cutworm, Spodoptera litura (Lepidoptera: Noctuidae)

Polyoxin AL water-soluble powder (Polyoxin AL), a fungicide that inhibits chitin synthase, showed a synergistic effect with benzoylphenyl urea insect growth regulators (BPU-IGRs) in killing Spodoptera litura larvae. First, eight different commercially available insecticides were examined for a synergistic effect with Polyoxin AL in killing S. litura. Only Cascade, one of the BPU-IGRs, showed a synergistic effect. Next, eight BPU chemicals (six BPU-IGRs including Cascade and two reagents) were used. All eight chemicals showed a synergistic effect except for Dimilin. Finally, six fungicides, including Polyoxin AL, were examined for a synergistic effect with Cascade. Only Polyoxin AL showed a synergistic effect. These results suggest that the synergistic effect was specific for the combination of BPU chemicals and Polyoxin AL.

Residual Activity and Population Effects of Noviflumuron for German Cockroach (Dictyoptera: Blattellidae) Control

A benzoylphenyl urea insect growth regulator with the common name noviflumuron was evaluated for efficacy and residual activity on the German cockroach, Blattella germanica (L.). In laboratory studies evaluating residual activity, 0.05% noviflumuron suspension concentrate produced 100% nymphal mortality 120 d after application to steel and masonite substrates. Residual activity of noviflumuron was more variable on painted plywood substrates compared with stainless steel and masonite. In bioassay arenas, population reductions caused by noviflumuron were significantly greater than Archer and the untreated populations. After 16 wk, populations exposed to 0.05, 0.1, and 0.2% noviflumuron were reduced by 51.9 +/- 19.8, 62.2 +/- 6.5, and 62.6 +/- 18.4%, respectively. Control cockroach populations and populations exposed to 1.3% pyriproxyfen at labeled rate (Archer, 0.61 g/m2) increased by 1286.3 +/- 125.1 and 937.2 +/- 137.1%, respectively, at the end of 16 wk. A field study in multifamily housing complexes showed noviflumuron (0.2 and 0.5%) to provide 73.3 +/- 8.0 and 90.6 +/- 3.6% trap catch reduction at 4 wk posttreatment, respectively. There were no significant differences in the performance of noviflumuron, Maxforce FC Roach Bait Stations (0.05% [AI] fipronil), and Avert dust bait (0.05% [AI] abamectin B1). Noviflumuron shows excellent potential for use in cockroach management programs.

Laboratory Performance and Pharmacokinetics of the Benzoylphenylurea Noviflumuron in Eastern Subterranean Termites (Isoptera: Rhinotermitidae)

A benzoylphenylurea insect growth regulator with the common name noviflumuron was evaluated for use as a baiting toxicant against the eastern subterranean termite, Reticulitermes flavipes (Kollar). Noviflumuron demonstrated significantly greater potency and faster speed of action compared with the commercial standard hexaflumuron. In addition, noviflumuron was not a feeding deterrent on filter paper at concentrations of up to 10,000 ppm. The rates of uptake, clearance, and insect-to-insect transfer of [14C]noviflumuron were measured in R. flavipes in laboratory assays and compared with those previously reported for [14C]hexaflumuron. Under a continuous exposure regime, the uptake profile for noviflumuron was similar to that for hexaflumuron, although the time period of maximal uptake was shorter for noviflumuron. Noviflumuron was cleared from termites in a first order process with a half-life of ≈29 d, whereas the half-life of hexaflumuron was much shorter (8–9 d). Noviflumuron was efficiently transferred from treated to untreated termites by trophallaxis via kinetics similar to those reported for hexaflumuron; however, the systemic dose of noviflumuron required to result in toxicity of R. flavipes was found to be at least two- to three-fold less than that of hexaflumuron. The faster activity of noviflumuron compared with hexaflumuron in R. flavipes can be at least partially explained by the combination of slower clearance and greater intrinsic activity.

Development of biodegradable aluminium carboxymethylcellulose matrices for mosquito larvicides

The use of ecofriendly biodegradable controlled-release formulations of mosquito larvicides could reduce the frequency of application and losses due to degradation of the insecticide compared with conventional formulations. Among the 20 matrices developed by entrapping the organophosphorus mosquito larvicide, fenthion, in carboxymethylcellulose ionotropically cross-linked with aluminium ions which were studied for release profiles, two matrices, CRF3b and CRF5b, were found to be stable for 16 and 14 weeks under simulated field conditions. The average concentration of fenthion released per week ranged from 0.06 to 3.5 mg litre(-1) for CRF3b and 0.09 to 2.72 mg litre(-1) for CRF5b. Of these two formulations, CRF3b was the more stable, maintaining the concentration of the active ingredient at the level required to effect mosquito control. The cumulative release of fenthion per pellet was 80% from CRF3b and 72% from CRF5b. Based on the study with fenthion, two similar matrices for triflumuron, a benzoylphenylurea insect growth regulator, STAR3b and STAR5b were developed. These matrices were stable up to 16 weeks with the average concentration of triflumuron released per week ranging from 0.05 to 3.44 mg litre(-1) for STAR3b and 0.07 to 2.71 mg litre(-1) for STARSb. The cumulative release of triflumuron per pellet was 75% from STAR3b and 76% from STAR5b. From the results of this study under simulated conditions, it is estimated that the application of four pellets of either fenthion or triflumuron per square metre of the breeding surface may play a useful role in controlling Culex quinquefasciatus Say in larval habitats for about 4 months.

Development of a compound-specific ELISA for flufenoxuron and an improved class-specific assay for benzoylphenylurea insect growth regulators.

This study describes immunochemical approaches for the compound-specific detection of flufenoxuron and class-specific detection of benzoylphenylurea (BPU) insecticides. With the aim of developing a highly specific immunoassay for flufenoxuron, a hapten was synthesized by introducing a spacer arm at the 2,6-difluoro substituent aromatic ring of a flufenoxuron derivative. An IC(50) value of 2.4 ppb was obtained for flufenoxuron, with detection of the other four BPUs being more than 4000-fold less sensitive. For the development of class-specific ELISA for five BPUs, a new approach was used for the hapten preparation in which a butanoic acid linkage was introduced into the 3,5-dichloro-substituted aniline ring of chlorfluazuron analogue. Although the resultant ELISA still exhibited slightly differing cross-reactions for these five BPUs, this method had broader specificity than the previously reported polyclonal antibody-based ELISA. Spike and recovery studies for five BPUs in soil and water indicated that both the compound- and class-specific ELISAs were able to quantitatively detect BPU residues in soil and water. This study also provided additional insights into the influence of the immunizing hapten structure on the specificities of the antibodies obtained.

Ultrastructural and autoradiographic investigations of the interference of chlorfluazuron with cuticle differentiation in the spruce budworm, Choristoneura fumiferana

A time course study of the ultrastructural and autoradiographic effects of a sublethal dose of chlorfluazuron (a benzoylphenyl urea-insect growth regulator) on sixth-instar spruce budworm, Choristoneura fumiferana, which has a stadial length of about 8 days, was conducted to understand the mode of action of benzoylphenyl ureas. The effect of the compound was evident at 48 hr but reached a dramatic level at 60 hr, and at 72 hr the larvae showed signs of recovery. Accumulation of large numbers of vesicles and loss of microvilli together with the plasma membrane plaque were characteristic effects. Vesicle accumulation could indicate blockage of material being transported outside the epidermal cell, during some stage of post-translational processing, but the exact location of the blockage was not evident. Autoradiographic studies confirmed most of the ultrastructural observations.

Field studies on the impact of a new benzoylphenylurea insect growth regulator (UC-84572) on selected aquatic nontarget invertebrates.

Field studies on the impact of a new benzoylphenylurea insect growth regulator (UC-84572) on selected aquatic nontarget invertebrates.

Comparison of coating and immunizing antigen structure on the sensitivity and specificity of immunoassays for benzoylphenyl urea insecticides

Several sensitive enzyme-linked immunosorbent assays (ELISAs) were developed for the benzoylphenylurea insect growth regulators diflubenzuron, BAY SIR 8514, and penfluron. The sensitivities and specificities of the assays have been investigated by using several different benzoylphenylurea derivatives as the immunogens as well as coating antigens. The following approach was used to solve the problem of bridge recognition: (a) homologous site systems, to use the same coupling site on the benzoylphenylurea molecule in the immunogen and coating antigen but to vary the bridge structure, and (b) heterologous site systems, coupling the immunogen and coating antigen from different positions on the benzoylphenylurea molecule. The heterologous systems yielded more sensitive assays, but antisera obtained from all the immunogens were used successfully in developing ELISA's for benzoylphenylureas. With these sensitive ELISA's, diflubenzuron was detected in milk at a level of 2 ppb without any sample extraction procedure, and sample cleanup led to still more sensitive assays. The reproducibility and sensitivity of the method are adequate for practical residue analysis. This work illustrates that a limited collection of antisera and coating antigens can yield a powerful library of assays capable of specifically detecting single compounds or a variety of members of a compound class.

Some Parameters of Benzoylphenyl Urea Toxicity to Beet Army worms (Lepidoptera: Noctuidae)

Five benzoylphenyl urea insect growth regulators, diflubenzuron, penfluron (2,6-difluoro-N-[[[4-[trifluoromethoxy]phenyl]amino]carbonyl]benzamide)BAY SIR 8514 (2-chloro-N-[[[4-[trifluoromethoxyl]phenyl]amino]carbonyl]benzamide), EL 1215 (2,6-dimethoxy-N-[5[4[pentatluoroethoxy]phenyl]1,3,4-thiadiazo1-2yl] benzamide), and UC 62644 (2,6-difluoro-N-[[[4-[3-chloro-5-trifluoromethy1-2-pyridiny1-oxy]-3,5-dichlorophenyl]amino]carbonyl]benzamide) were tested against Spodoptera exigua (Hubner) in laboratory bioassays. The order of LC50 values was UC 62644 > penfluron > EL 1215 > diflubenzuron > BAY SIR 8514 with a 35 ✕ difference between the most and least toxic chemicals. Small differences in toxicity were observe between WP and T formulations. Treatments at the first 2 in stars and the 4th-instar indicated that these age classes were nearly equally susceptible. Diflubenzuron, penfluron, and BAY SIR 8514 were tested in 4th-instar topical biossays. Penfluron showed the highest toxicity in the topical bioassays.

Synergism of Two Benzoylphenyl Urea Insect Growth Regulators

An omnivorous leafroller, Platynota stultana Walsingham, and the beet armyworm, Spodoptera exigua (Hubner), are respectively tolerant and susceptible to the benzoylphenyl ureas diflubenzuron and Bay Sir 8514 (2-chloro- N -(((4-(trifluoromethoxy)phenyl)amino)carbonyl)benzamide). LC50 values for diflubenzuron and Bay Sir 8514 in artificial diet for 1st in stars were, respectively, 6938 and 173 ppm with P. stultana and 1.10 and 8.06 ppm with S. exigua . DEF® (S,S,S-tributylphosphorotrithioate), an esterase inhibitor, synergized diflubenzuron and Bay Sir 8514 3,319- and 45-fold, respectively, in P. stultana , but was not synergistic in S. exigua . Piperonyl butoxide, an oxidase inhibitor, did not synergize either benzoylphenyl urea in either insect.