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( S )-Methoprene has been widely applied as a powerful biochemical pesticide to control disease vectors and other pestiferous arthropods of economic importance. As a juvenile hormone analogue, many products based on ( S )-methoprene are developed and commercialized in the USA, Europe, and elsewhere. However, the agricultural use of ( S )-methoprene and its analogues remains underexplored. Here, based on an intermediate derivatization strategy and structural modification, a series of enantiopure ( S )-methoprene derivatives were designed for their expected bioactivity against two crop-threatening pests. Six compounds showed more than 2-fold stronger inhibition of emergence against Plutella xylostella than ( S )-methoprene, among which one that was designated as B2 showed even superior activity to the conventional chemical pesticide and biopesticide with IE 50 of 0.02 mg/L. Nine compounds exhibited over 2-fold higher bioactivity against Aphis craccivora growth than ( S )-methoprene. The physicochemical property evaluation and toxicological test showed that the potent ( S )-methoprene derivatives were low toxic to the nontarget organism and the environment. Molecular docking studies further demonstrated that the high bioactivity of B2 may be partially attributed to its great affinity for binding to juvenile hormone receptors of P. xylostella . The current study suggests that B2 is a biochemical pesticide candidate with potency to be developed as a new agrochemical for lepidopteran control.

Insect growth regulators (IGRs) have been playing a major role in the effective management of a range of stored product insect pests including species that have developed resistance to major groups of insecticides, such as organophosphates (OPs) and synthetic pyrethroids (SPs). In the present study, we evaluated the efficacy of S-methoprene alone and in combination with piperonyl butoxide (PBO), an adjuvant component of insecticides for synergy, against two strains, Lab-S (susceptible) and Met-R (Methoprene resistant) of an economically important pest species, the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae). Adults of both Lab-S and Met-R strains were exposed to wheat treated with multiple concentrations of S-methoprene ranging from 0.001 to 0.01 and 10 to 60 mg/kg, respectively, alone and in combination with PBO. A variety of concentrations, including 0.27, 0.53, 0.80, and 1.07 g/kg, were evaluated for PBO. Mortality of adults and percent reduction in progeny were assessed after 14 and 65 days of treatment, respectively. As anticipated, the adult mortality rates of both strains were not significantly affected by S-methoprene alone. However, the number of progeny produced confirmed that the Met-R strain exhibited a high level of resistance to S-methoprene alone, with over 50 F1 progeny adults surviving in wheat treated with the maximal rate, 10 mg/kg. In contrast, the toxicity of S-methoprene was increased against the same resistant strain (Met-R), by 0.80 or 1.07 g/kg of PBO in combination treatment, resulting in a significant reduction in progeny numbers (25 adults per container). Although the tested concentrations of S-methoprene and PBO were well above the currently registered rate globally, our results highlight the fact that PBO enhances the toxicity of S-methoprene to some extent, reaffirming that the mode of action of the latter involves the inhibition of mixed-function oxidases (MFOs) and highlights the need for further research into developing potential binary or triplet formulations containing these two active ingredients (AIs)., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: To cohouse cats experimentally infected with Bartonella clarridgeiae (Bc) with naive cats in a flea-free environment or with Ctenocephalides felis, Bartonella henselae (Bh), Mycoplasma haemofelis, and Candidatus Mycoplasma haemominutum to determine which flea could be a vector and to assess whether transmission of the infectious agents could be blocked by fipronil and (S)-methoprene., Animals: Specific pathogen-free cats (n = 34)., Methods: In experiment 1, Bc was inoculated in 1 cat that was housed with 9 naive cats without C felis. In experiment 2, the 2 cats inoculated with Bc were housed with 6 other cats (2 inoculated with Bh, 2 inoculated with M haemofelis, and 2 inoculated with Candidatus M haemominutum) in the center (enclosure 2) of 3 housing enclosures separated by mesh walls that allow passage of fleas but precludes fighting. C felis were placed only on cats in enclosure 2 (5 times). Cats in enclosures 1 (n = 8) and 2 (8) were untreated, and cats in enclosure 3 (8) were administered fipronil and (S)-methoprene. Blood was collected from all cats for PCR assays for the pathogens., Results: None of the cats housed with the cat inoculated with Bc became PCR positive in the absence of C felis. All cats in enclosure 2 became Bc DNA positive. While 2 of 8 cats in enclosure 1 became Bc PCR positive, none of the treated cats in enclosure 3 became infected., Clinical Relevance: The study demonstrated that C felis can be a vector for Bc. The results support the recommendation that flea control products can reduce the risk of transmission of flea-borne pathogens.

Insect growth regulators, like S-methoprene, are heavily relied upon worldwide for larval mosquito chemical control due to their target specificity and long-lasting effects. In this study, susceptibility to S-methoprene was evaluated in Culex pipiens, a globally important vector species. Populations from 14 sites throughout the Chicago area with a long history of S-methoprene use and two sites with minimal use in Wisconsin were examined. Using a bioassay methodology and probit analyses, LC 50 and LC 90 values were calculated and compared to a susceptible laboratory strain to develop resistance ratios, then categorized for resistance intensity. The resistance ratios observed required the addition of another category, termed 'extreme' resistance, indicating resistance ratios greater than 100. 'Low' to 'extreme' levels of resistance to S-methoprene were detected throughout Illinois populations, with resistance ratios ranging from 2.33 to 1010.52. Resistance was not detected in populations where S-methoprene pressure has been very limited. These 'extreme' resistance ratios observed have never been documented in a wild vector species mosquito population. The relationships between historical S-methoprene use, resistance detected with laboratory bioassays, and the potential for field product failure remain unclear. However, the profound resistance detected here demonstrates a potential critical threat to protecting public health from mosquito-borne diseases., (© 2024. The Author(s).)

The juvenile hormone analog S-methoprene is the only synthetic biopesticide that is registered with the United States Environmental Protection Agency to control arthropods of economic importance in public health, livestock, pets, urban, and stored products. The high activity, relative target specificity, and benign environmental profile of S-methoprene have been well documented. While the risk of resistance in mosquitoes to S-methoprene is generally low, there is a lack of information regarding cross resistance in S-methoprene-resistant mosquitoes to other pesticides. In this paper, a population of the southern house mosquito Culex quinquefasciatus Say from southern California acquired low levels of resistance to S-methoprene in the field, where the resistance ratios ranged 7.0- to 8.8-fold as compared with a laboratory reference colony. After 30 generations of laboratory selections by S-methoprene when resistance was elevated to 57.4- to 168.3-fold relative to an unselected population, various levels of cross resistance to other commonly used pesticides were revealed in the selected population. Cross resistance to the microbial mosquito larvicide Lysinibacillus sphaericus (Meyer & Neide) (Bacillales: Bacillaceae) was the most profound, amounting to 77.50- to 220.50-fold. The mechanism and potential management tactics toward cross resistance are discussed to preserve the unique value of this synthetic biopesticide., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

This work evaluated tick and flea burdens and the efficacy of a single topical application of 10% fipronil + 9% (S)-methoprene spot-on against experimental infestations of Rhipicephalus sanguineus sensu lato and Ctenocephalides felis felis on dogs that were submitted to regular baths for 56-days post-treatment. Four treatments (n = 24) were evaluated: no chemical treatment and no bathing (T01); no chemical treatment + bathing (T02); chemical treatment and no bathing (T03) and chemical treatment + bathing (T04). Dogs were infested with adult ticks and fleas seven days pre-treatment (-7). The ectoparasites were then counted and removed on day -5, followed by a new infestation on day -2 and treatment on day 0. Ticks and fleas were then counted without removal on day 1 and counted with removal on day 2. The dogs were then repeatedly infested with both ectoparasites on days 5, 12, 19, 26, 33, 40, 47 and 54 post-treatment. Baths and ectoparasite counts with removal were performed every 48 h before and after experimental infestation, respectively. Animals of T04 had lower (P ≤ 0.05) tick burden than animals from T01 and T02 from day 2 to day 28. For fleas, the counts varied among days of the study. Dogs from T03 presented lower (P ≤ 0.05) flea burden than dogs from T01 from day 1 until day 56. The same was true for T04 when compared to T01 from day 1 to day 42. Animals of T02 greater (P ≤ 0.05) flea burden than animals of T04 in all dates post treatment. In addition, dogs from T02 presented higher (P ≤ 0.05) flea burden than T01 from day 7 to day 28 and from day 49 to day 56. In sum, the efficacy of the spot-on formulation used declined over the time against both ectoparasites. The efficacy for ticks ranged from 0.0 to 96.5% and 0.0 to 98.52% for T03 and T04, respectively. While for fleas, the efficacy of the formulation ranged from 67.41 to 100% for T03 and 40.18 to 100% for T04. So, bathing dogs that were not treated increased C. f. felis burden but not R. sanguineus s. l. burden. The residual efficacy of the product had a shorter duration against these ectoparasites for dogs that received subsequent bathing., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Floating emergence traps were used in 15 road gullies to determine the effectiveness and longevity of S-methoprene briquets over 124 days. Samples were taken monthly from October 2014 to March 2015. Two treatment methods were assessed: application of briquet using a float, and application without a float. These methods were compared with untreated control gullies. Mosquito emergence peaked in early November, and decreased by February. Effectiveness of the briquet was not impacted significantly by the presence or absence of a float (P = 0.329). Gullies yielded a mean of 108 mosquitoes per day per gully over the season. Culex quinquefasciatus and Aedes notoscriptus were the most abundant species. The maximum number of Cx. quinquefasciatus emerging could exceed 1,600 per day per gully. Aedes notoscriptus numbers could exceed 70 adults per day per gully. Treatment with S-methoprene was highly effective against both species for at least 70 days and partially effective for up to 120 days. Treatment provided no control by day 124. S-methoprene provided 90% control over 124 days. Road gullies have been confirmed as a significant larval habitat and are likely to be increasing the potential for Ross River virus transmission in the area.

Cats are host to dipylidiid cestodes of the genera Diplopylidium, Dipylidium and Joyeuxiella. Broadline(®), a topical broad-spectrum combination parasiticide containing fipronil (8.3 % w/v), (S)-methoprene (10 % w/v), eprinomectin (0.4 % w/v) and the cestocide praziquantel (8.3 % w/v), has previously been shown to be efficacious against Dipylidium caninum and Diplopylidium spp. in cats. To evaluate its efficacy against Joyeuxiella species, a blinded clinical efficacy study was conducted according to GCP. All cats had evidence for naturally acquired dipylidiid cestode infection as confirmed by pre-treatment examination. Cats were allocated randomly to two groups of 13 cats each based on bodyweight: Control (untreated) and Broadline(®) at 0.12 mL/kg bodyweight administered once topically. Based on the comparison of helminth counts in the treated and untreated cats seven days post treatment, Broadline(®) demonstrated >99 % efficacy (p < 0.01) against mature J. fuhrmanni and J. pasqualei, with 11 and 13 of the untreated cats harbouring 1 to 102 or 2 to 95 cestodes, respectively. In addition, parasite counts indicated 95.9 % efficacy (p = 0.006) against the rictularoid nematode Pterygodermatites cahirensis.

Background: Efficacy of FRONTLINE TRITAK For Dogs (fipronil/(S)-methoprene/cyphenothrin, Merial, Inc., Duluth, GA) against Ixodes scapularis was evaluated in two separate, but concurrent laboratory studies., Methods: One day after topical treatment with placebo or active, dogs (n = 24) were infested with 50 unfed adult Ixodes scapularis ticks, with repeat infestations on Days 7, 14, 21 and 28. The number of live ticks was counted at 6 hours post-infestation in the first study (n = 12) and at 24 hours post-infestation in the second study (n = 12)., Results: Observed efficacies in study 1 were 93-99% at 6 hour assessments on Day 1 through Day 28 and in the second study, 98-100% at 24 hour assessments, occurring on Day 2 through Day 29., Conclusions: A single dose of FRONTLINE TRITAK For Dogs (fipronil/(S)-methoprene/cyphenothrin) (0.67 ml or 1.34 ml) prevented the establishment of a new infestation following treatment, as well as the repeated weekly re-infestations with Ixodes scapularis ticks, for 4 weeks.

Background: The efficacy of methoprene can vary with surface substrates, application methods and environmental conditions. The objectives of the present study were to examine the effects of temperature and grain type on the long-term persistence and efficacy of methoprene in controlling Rhyzopertha dominica from Guangzhou, China., Results: Methoprene applied at 1 mg kg(-1) caused >90% suppression of F1 adult progeny of R. dominica for 150-270 days. Temperature and grain type both influenced the long-term persistence of methoprene. Overall multivariate analysis of variance showed that the order of progeny reduction at different temperatures (°C) was: 24 > 28 > 32 > 36; the order of the progeny reduction on the different grains was: paddy > wheat and maize., Conclusion: The results of our experiments show the maximum effect of methoprene for R. dominica control at 24 °C on paddy., (© 2013 Society of Chemical Industry.)

A novel topical combination product (BROADLINE(®), Merial) composed of fipronil, (S)-methoprene, eprinomectin and praziquantel was evaluated for safety and efficacy against nematode and cestode infections in domestic cats. The study comprised a multi-centre, positive control, blinded, field study, using a randomized block design based on order of presentation for allocation. In total 196 client-owned cats, confirmed as positive for naturally acquired infections of nematodes and/or cestodes by pre-treatment faecal examination, were studied in seven countries in Europe. Pre-treatment faecal examination revealed the presence of Toxocara, hookworm, Capillaria and/or spirurid nematode infections in 129, 73, 33 or 1 cat(s), respectively; infections with taeniid and Dipylidium cestodes were demonstrated in 39 and 17 cats, respectively. Cats were allocated randomly to one of two treatments in a ratio of 2, topical fipronil (8.3%, w/v), (S)-methoprene (10%, w/v), eprinomectin (0.4%, w/v) and praziquantel (8.3%, w/v) (BROADLINE(®), Merial; 130 cats); and 1, topical PROFENDER(®) Spot-On (Bayer; 66 cats) and treated once on Day 0. For evaluation of efficacy, two faecal samples were collected, one prior to treatment (Day -4 ± 4 days) and one at the end of the study (Day 14 ± 5 days). These were examined for fecal forms of nematode and cestode parasites. For evaluation of safety, cats were examined by a veterinarian before treatment and at the end of the study, and cat owners recorded the health status of their cats daily until the end of the study. For cats treated with Broadline(®), the efficacy was >99.9%, 100%, and 99.6% for Toxocara, hookworms, and Capillaria, respectively; and the efficacy was >99.9%, >99.9%, and 98.5%, respectively, for the cats treated with Profender(®) (p<0.001 for all nematodes and both treatments). Efficacy was 100% for both cestodes for both treatments (p<0.001). No treatment related adverse experiences were observed throughout the study. For both treatments, every cat that completed the study was given a safety score of 'excellent' for both local and systemic evaluations. The topical combination product of fipronil, (S)-methoprene, eprinomectin and praziquantel was shown to have an excellent safety profile and demonstrated high levels of efficacy when administered once as topical solution to cats infected with nematodes and cestodes under field conditions., (Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.)

Four studies were conducted to determine the pharmacokinetic characteristics and in vitro metabolism of eprinomectin, a semi-synthetic avermectin, in cats. Pharmacokinetic parameters including bioavailability of eprinomectin were determined in a parallel study design comprised of one group of eight cats which were treated once topically at 0.12 mL/kg bodyweight with BROADLINE(®), a novel combination product (fipronil 8.3% (w/v), (S)-methoprene 10% (w/v), eprinomectin 0.4% (w/v) and praziquantel 8.3% (w/v)), delivering a dose of 0.5mg eprinomectin per kg body weight, and a group of six cats which received 0.4% (w/v) eprinomectin at 0.4 mg/kg bodyweight once by intravenous injection. For cats treated by topical application, the average eprinomectin (B1a component) maximum plasma concentration (Cmax) was 20 ng/mL. The maximum concentrations were reached 24h after dosing in the majority of the animals (six of eight cats). The average terminal half-life was 114 h due to slow absorption ('flip-flop' kinetics). Following intravenous administration the average Cmax was 503 ng/mL at 5 min post-dose, and the mean elimination half-life was 23 h. Eprinomectin was widely distributed with a mean volume of distribution of 2,390 mL/kg, and the clearance rate was 81 mL/h/kg. Mean areas under the plasma concentration versus time curves extrapolated to infinity were 2,100 ngh/mL and 5,160 ngh/mL for the topical and intravenous doses, respectively. Topical eprinomectin was absorbed with an average absolute bioavailability of 31%. In a second parallel design study, the dose proportionality of eprinomectin after single topical administration of BROADLINE(®) was studied. Four groups of eight cats each were treated once topically with 0.5, 1, 2 or 5 times the minimum recommended dose of the combination, 0.12 mL/kg bodyweight. Based on comparison of areas under the plasma concentration versus time curves from the time of dosing to the last time point at which eprinomectin B1a was quantified, and Cmax, dose proportionality was established. In addition, the metabolic pathway of eprinomectin using cat liver microsomes, and plasma protein binding using cat, rat, and dog plasma were studied in vitro. Results of the analyses of eprinomectin B1a described here showed that it is metabolically stable and highly protein bound (>99%), and thus likely to be, as with other species, excreted mainly as unchanged parent drug in the feces of cats., (Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: A recently launched topical ectoparasiticide containing fipronil, amitraz and S-methoprene has been associated with the development of an acantholytic pustular dermatitis similar to that of Promeris-triggered pemphigus foliaceus (PF)., Hypothesis/objectives: Our objectives were to describe the clinical, histological and immunological features of this PF-like cutaneous adverse drug reaction., Animals: Twenty-one dogs with a probable or definitive diagnosis of PF-like cutaneous adverse drug reaction were identified between May 2012 and February 2013., Material and Methods: Histology, direct and indirect immunofluorescence were employed to address the study objectives., Results: Most dogs were middle-aged or older (median, 9 years) and of large size (median, 23 kg). In six dogs (29%), the PF-like lesions remained confined to the site of application, while 15 dogs (71%) exhibited lesions at distant sites. One or two applications of the ectoparasiticide were sufficient to trigger PF-like lesions in seven (33%) and six (29%) dogs, respectively. Systemic signs were reported in nine dogs (43%), all with lesions extending to sites distant from application areas. Tissue-bound antikeratinocyte IgG was detected in the lesional epidermis of eight of 19 (42%) cases by direct immunofluorescence, while serum antikeratinocyte IgG was detected in 10 of 14 (71%) cases by indirect immunofluorescence. Autoantibodies were found to target canine desmocollin-1 in 11 of 14 dogs (79%), but not canine desmoglein-1, by indirect immunofluorescence on transfected cells. These immunological findings were similar in cases with localized and distant disease., Conclusions and Clinical Importance: This new topical ectoparasiticide containing fipronil, amitraz and S-methoprene is capable of triggering the development of an acantholytic pustular dermatosis that is a clinical, histological and immunological close match for Promeris-triggered PF and naturally occurring autoimmune PF in dogs., (© 2014 ESVD and ACVD.)

Benzophenanthridine alkaloids (chelerythrine and sanguinarine) inhibited binding of [(3)H]SR141716A to mouse brain membranes (IC50s: <1µM). Piperonyl butoxide and (S)-methoprene were less potent (IC50s: 21 and 63µM respectively). Benzophenanthridines and piperonyl butoxide were more selective towards brain CB1 receptors versus spleen CB2 receptors. All compounds reduced Bmax of [(3)H]SR141716A binding to CB1 receptors, but only methoprene and piperonyl butoxide increased Kd (3-5-fold). Benzophenanthridines increased the Kd of [(3)H]CP55940 binding (6-fold), but did not alter Bmax. (S)-methoprene increased the Kd of [(3)H]CP55940 binding (by almost 4-fold) and reduced Bmax by 60%. Piperonyl butoxide lowered the Bmax of [(3)H]CP55940 binding by 50%, but did not influence Kd. All compounds reduced [(3)H]SR141716A and [(3)H]CP55940 association with CB1 receptors. Combined with a saturating concentration of SR141716A, only piperonyl butoxide and (S)-methoprene increased dissociation of [(3)H]SR141716A above that of SR141716A alone. Only piperonyl butoxide increased dissociation of [(3)H]CP55940 to a level greater than CP55940 alone. Binding results indicate predominantly allosteric components to the study compounds action. 4-Aminopyridine-(4-AP-) evoked release of l-glutamate from synaptosomes was partially inhibited by WIN55212-2, an effect completely neutralized by AM251, (S)-methoprene and piperonyl butoxide. With WIN55212-2 present, benzophenanthridines enhanced 4-AP-evoked l-glutamate release above 4-AP alone. Modulatory patterns of l-glutamate release (with WIN-55212-2 present) align with previous antagonist/inverse agonist profiling based on [(35)S]GTPγS binding. Although these compounds exhibit lower potencies compared to many classical CB1 receptor inhibitors, they may have potential to modify CB1-receptor-dependent behavioral/physiological outcomes in the whole animal., (© 2013 Published by Elsevier B.V.)

A study based on naturally infested cats was designed to evaluate the effectiveness of a single treatment with a topical formulation containing fipronil, (S)-methoprene, eprinomectin and praziquantel, for the prevention of Otodectes cynotis infestation in cats. Six treated cats and six untreated cats were housed with three chronically Otodectes cynotis-infested cats, respectively. The cats of each group were kept together in a 20-m(2) room for 1 month. Both clinical examination and ear mite counts were conducted on Day 28. All donor cats were confirmed to be chronically infested with Otodectes cynotis on Day -1 and Day 28. From untreated control cats, 129 live mites were recovered on Day 28 and all cats were found to be infested. In the treated group, three cats were found to be infested, with a total of five live mites recovered, the difference between the two groups being significant (p = 0.003). One treatment corresponded to 96% preventive efficacy at Day 28 based on ear mite counts. With regard to cerumen, the clinical score increased significantly for untreated cats between Day -1 and Day 28 (p = 0.00026) and not for treated cats (p = 0.30). The difference in cerumen abundance was significant between untreated and treated cats on Day 28 (p = 0.0035). Concerning the pruritic reflex in at least one ear, all cats were negative at inclusion. All six untreated cats became positive and showed a reflex on Day 28, whereas no treated cat showed ear pruritus (p = 0.00026)., (© F. Beugnet et al., published by EDP Sciences, 2014.)

Background: A study was conducted to evaluate and compare the effectiveness of two different spot-on topical flea products to control flea infestations on naturally infested dogs and cats in Tampa, FL USA., Methods: Thirty-two dogs and 3 cats with natural flea infestations living in 18 homes were treated topically with a 19.53% w/w spot-on formulation of indoxacarb. Another thirty dogs and 2 cats living in 19 different homes were treated topically with either fipronil (9.8% w/w)/(s)-methoprene (8.89% w/w) or fipronil (9.8% w/w)/(s)-methoprene (11.8% w/w), respectively. All products were applied according to label directions by study investigators on day 0 and again between days 28 and 30. Flea populations on pets were assessed using visual area counts and premise flea infestations were assessed using intermittent-light flea traps on days 0, 7, 14, 21, 28-30, 40-45, and 54-60., Results: A single application of the indoxacarb or fipronil (s)-methoprene formulations reduced flea populations on pets by 97.8% and 85.5%, respectively within 7 days. One month (28-30 days) after treatment the indoxacarb and fipronil (s)-methoprene formulations reduced on-animal flea burdens by 95.0% and 49.5%, respectively. Following two monthly applications of either the indoxacarb or fipronil (s)-methoprene formulations, pet flea burdens were reduced by 99.1% and 54.8%, respectively, by days 54-60. At the end of the two month study, 77.1% and 15.6% of the dogs and cats in the indoxacarb and fipronil (s)-methoprene treatment groups, respectively were flea free. Flea numbers in the indoor-premises were markedly reduced in both treatment groups by days 54-60, with 97.7% and 84.6% reductions in intermittent-light flea trap counts in the indoxacarb and fipronil (s)-methoprene treatment groups, respectively., Conclusions: This in-home investigation conducted during the summer of 2013 in subtropical Tampa, FL, is the first published U.S field investigation of the indoxacarb topical formulation. The indoxacarb formulation was able to effectively control flea populations in heavily flea infested pets and homes. The efficacy achieved by the fipronil (s)-methoprene formulation against flea infestations on these pets was lower than in previous investigations using the same study design.

The ability of CERTIFECT(®) (a combination of fipronil, amitraz and (S)-methoprene) to prevent transmission of Ehrlichia canis was studied in two groups of eight dogs. One group was treated with CERTIFECT while the other group remained untreated. All dogs were exposed to E. canis-infected Rhipicephalus sanguineus ticks on Days 7, 14, 21 and again on day 28 post-treatment by releasing ticks into the kennels of the dogs to simulate the natural way of infestation. Animals were examined in situ for ticks on Days 9, 16 and 23 and any ticks present were counted and removed on Day 30. The efficacy of CERTIFECT against R. sanguineus was 100%, since no ticks were found on the treated dogs at any time. Clinical examinations (including monitoring body temperature and blood collections for PCR analysis and serology) were performed at intervals throughout the study until Day 56. Five out of 8 untreated control dogs (62.5%) became infected with E. canis, as demonstrated by detection of specific E. canis antibodies and the presence of E. canis DNA in blood samples by PCR. These dogs displayed fever and thrombocytopenia and were rescue-treated with doxycline. None of the 8 dogs treated with CERTIFECT became infected with E. canis, in comparison to the 5/8 control dogs, as confirmed by the lack of specific antibodies and absence of any ehrlichial DNA in blood samples by PCR. CERTIFECT prevented transmission of E. canis and effectively provided protection against monocytic ehrlichiose for at least 4 weeks post treatment., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Monitoring of the performance of flea control products under conditions of natural challenge is valuable in assessing continued effectiveness and determining the ongoing relevance of laboratory studies. A multi-clinic, investigator-blinded study was undertaken in client-owned dogs to investigate and compare the flea control provided by 3 consecutive monthly treatments of oral spinosad (SPN) or fipronil/(S)-methoprene topical (FSM) spot-on. The first household dog meeting enrollment criteria and with at least 10 fleas (whole-body flea count) served as the index dog in a household against which primary objectives were set. Stratification was based on pruritus scores at the enrollment visit and on single or multiple pet household. Index pets were randomized to treatment with either SPN or FSM, dispensed on day 0 for at-home administration by owners. All other household dogs and cats, maximum 4 pets per household, were dispensed the same treatment as the index dog (spinetoram was dispensed for cats in SPN households). Subsequent treatments were dispensed when index dogs were returned for whole-body flea counts and pruritus-scoring at visits on days 30 and 60, with final assessments on day 90 (±5 days on each occasion). Primary endpoints were the number of flea-free index dogs in each group one month after the final treatment, the reduction in owner-reported pruritus, and the reduction from baseline mean flea counts. One hundred twenty eight index dogs were enrolled (65 in the SPN arm; 63 in the FSM arm) at 10 clinics in FL (6), NC (2), LA (1), and TX (1). On day 0, geometric mean flea counts were 57.7 (range: 10-1469) and 44.8 (10-717) for the SPN and FSM groups, respectively. On Day 90, 55 of 58 (95%) and 21 of 55 (38%) index dogs completing the study were flea-free in SPN and FSM groups, respectively; mean SPN pruritus scores declined to 0.92 (6.67 on day 0), and to 3.83 (6.33 on day 0) for FSM; geometric mean flea counts (% control) were 0.08 (99.9%) and 5.19 (88.4%), for SPN and FSM groups, respectively. Between-treatment differences were highly statistically significant (p<0.0001). In conclusion, SPN provided reliable flea control in client-owned dogs, regardless of challenge level., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Flea infestations of pets continue to persist due to the lack of knowledge of flea biology and ecology. It is not unusual that pet owners believe regular hygiene, such as shampooing their dogs can replace regular insecticidal treatment. The objective of this study was to compare in a flea simulated environment, modelling exposure similar to that found in a home, that the use of regular physiological shampoo does not control fleas adequately when compared to a long acting topical formulation. Three groups of six dogs were formed: one untreated control group, one group treated monthly with the topical formulation of fipronil/(S)-methoprene, and a third group treated weekly with a hygiene shampoo. All dogs were infested with adult unfed Ctenocephalides felis fleas (200±5) on Days -28 and -21. Each animal's sleeping box was fitted with a plastic cup mounted to the inside roof of the box. The sleeping bench of each animal was covered with a carpet to accommodate flea development. The dogs were maintained in their kennels throughout the study. In order to maintain the environmental flea challenge, C. felis pupae (100±5) were placed in the plastic cup in each animal's sleeping box on Days -14, -7, 0, 7, 14, 21, 28, 35 and 42. The dogs were combed and fleas counted weekly on Days -1, 3, 10, 17, 24, 31, 38, 45, and 51. The fleas were placed immediately back on the dogs. On Day 60, fleas were counted and removed. Flea infestations in the untreated control group at each count averaged between 46.2 and 74.2 fleas throughout the study. The average number of fleas infesting dogs was significantly different (p<0.05) between the untreated and the two treatment groups and between the two treatment groups at all counts throughout the two months study (Days 3, 10, 17, 24, 31, 38, 45, 51 and 60). The efficacy was never below 99.1% in the fipronil/(S)-methoprene group, and efficacy in the shampoo group was never above 79.2%. Weekly shampooing in treatment group 3 was intentionally delayed after Day 42, to evaluate wether missing a weekly bath would affect the flea population. The Day 48 data indicate that forgetting or delaying a single weekly shampooing resulted in a clear increase in flea numbers and a significant decrease in efficacy from 68.2% to 34.8%. The fipronil(S)/methoprene treatment allowed a continuous control as demonstrated by the high efficacy against fleas, and also the number of flea-free dogs on seven of the nine weekly assessments, in spite of what was essentially a continuous flea challenge model.

This investigation focused primarily on the interaction of two benzophenanthridine alkaloids (chelerythrine and sanguinarine), piperonyl butoxide and (S)-methoprene with G-protein-coupled cannabinoid CB(1) receptors of mouse brain in vitro. Chelerythrine and sanguinarine inhibited the binding of the CB(1) receptor agonist [(3)H]CP-55940 to mouse whole brain membranes at low micromolar concentrations (IC(50)s: chelerythrine 2.20 μM; sanguinarine 1.10 μM). The structurally related isoquinoline alkaloids (berberine and papaverine) and the phthalide isoquinoline ((-)-β-hydrastine) were either inactive or considerably below IC(50) at 30 μM. Chelerythrine and sanguinarine antagonized CP-55940-stimulated binding of [(35)S] GTPγS to the G-protein (IC(50)s: chelerythrine 2.09 μM; sanguinarine 1.22 μM). In contrast to AM251, both compounds strongly inhibited basal binding of [(35)S]GTPγS (IC(50)s: chelerythrine 10.06 μM; sanguinarine 5.19μM). Piperonyl butoxide and S-methoprene inhibited the binding of [(3)H]CP-55940 (IC(50)s: piperonyl butoxide 8.2 μM; methoprene 16.4 μM), and also inhibited agonist-stimulated (but not basal) binding of [(35)S]GTPγS to brain membranes (IC(50)s: piperonyl butoxide 22.5 μM; (S)-methoprene 19.31 μM). PMSF did not modify the inhibitory effect of (S)-methoprene on [(3)H]CP-55940 binding. Our data suggest that chelerythrine and sanguinarine are efficacious antagonists of G-protein-coupled CB(1) receptors. They exhibit lower potencies compared to many conventional CB(1) receptor blockers but act differently to AM251. Reverse modulation of CB(1) receptor agonist binding resulting from benzophenanthridines engaging with the G-protein component may explain this difference. Piperonyl butoxide and (S)-methoprene are efficacious, low potency, neutral antagonists of CB(1) receptors. Certain of the study compounds may represent useful starting structures for development of novel/more potent G-protein-coupled CB(1) receptor blocking drugs., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Despite the increasing number of ectoparasiticides for pets and their use, flea infestations of cats and dogs are still widespread in Europe. It is therefore important to assess the maintenance of efficacy of the ectoparasiticides for cats and dogs. The present studies aimed to evaluate the efficacy of monthly treatments using a fipronil/(S)-methoprene combination spot-on (Frontline Combo) on dogs and cats from private veterinary clinics located in seven European countries. The survey was conducted for three months during the flea season 2009. A total of 233 dogs and 180 cats were included. Each animal was treated at Days 0 (Day 0), 30 (D30) and 60 (D60) at the vet clinics. For each animal, at least three flea counts were performed at D0, D30 and/or D60 and/or day 90 (Day 90) in order to evaluate the prevalence of flea infestation and the efficacy of control. At the beginning of the study the prevalence of infested animals was 41.63% (97/233) in dogs and 47.22% (85/180) in cats. At D90, the number of dogs remaining infested fell to 8/211 therefore 91.75% became flea-free. The number of infested cats fell from 85 to 9/173 at D90 therefore 89.41% were cured. All animals still infested at Day 90 were living under epidemiological conditions that favour heavy flea burdens. These results are similar or better to previous studies, indicating the continuous high level of efficacy for fipronil 10 years after launch.

The acaricidal efficacy against Dermacentor reticulatus in dogs of the commercial topical combinations fipronil/(S)-methoprene (FRONTLINE Combo spot-on dog), imidacloprid/permethrin (Advantix) and metaflumizone/amitraz (ProMeris Duo) was evaluated and compared. Three treatment groups and one untreated control group of six adult Beagle dogs each were randomly formed. Each treatment was administered topically once on Day-0, according to the recommended label dose and instructions for use. All dogs were infested weekly with approximately 50 adult unfed D. reticulatus over a period of seven weeks. Ticks were removed and counted approximately 48 hours after each infestation. The percent reduction in numbers of ticks for fipronil/(S)-methoprene was > or = 97% compared to untreated controls for all seven weekly infestations. The percent reductions for imidacloprid/permethrin and metaflumizone/amitraz were satisfactory initially but fell and stayed below 90 % after three weeks. From the third week onwards, fipronil/(S)-methoprene treated dogs had significantly fewer ticks than imidacloprid/permethrin or metaflumizone/amitraz treated dogs (p < 0.05).

To control West Nile Virus in the greater Toronto area of Ontario, Canada, S-methoprene (Altosid XRbriquets 2.1% AI) is applied each year to storm water catch basins. Because the efficacy of the XRbriquets to reduce adult mosquito populations had not been evaluated locally and was influenced by organic debris in a pilot study, we compared the efficacy of the briquets in 17 sediment and debris-filled catch basins versus 20 catch basins that were vacuumed free of debris. Emergence rates approached 100% in the 5 untreated control catch basins. Emergence rates were significantly lower, and S-methoprene was detected more often and at higher levels, in debris-filled basins versus cleaned catch basins. Overall, 20% of pupae emerged from clean catch basins versus only 3% from debris-filled ones, the difference between treatments becoming significant after 26 days. S-methoprene and total organic carbon concentrations in the catch basins were positively correlated (P < 0.001). We hypothesize that S-methoprene is binding to the organic fraction in the water and sediment in the debris-filled basins, prolonging S-methoprene doses, which are reflected in lower mosquito emergence rates.

This field trial was designed to test the efficacy, in terms of treatment and prevention, of the fipronil 10%+(S)-methoprene 9% combination against immature and adult stages of Rhipicephalus sanguineus in naturally infested dogs, and to assess the effect of a single plain water exposure. Twenty-four dogs of various age, sex, weight and coat length were divided into two homogeneous groups, treated (T) and control (C), and housed into twin outdoor kennels. Trial baseline was designed as day 0, when dogs from group T were treated with a commercial spot-on formulation of fipronil 10%+(S)-methoprene 9%, while subjects from group C were left untreated and served as control. After treatment, tick load for each included dog was estimated, for both adult and immature ticks, using the localization and count over the entire body surface at the following time-points: day 2, to evaluate the speed of kill and at days 7, 14, 21 and 28 to assess the persistence of efficacy. The effect of water exposure on the product efficacy was tested at day 14 of the study, when six dogs, homogenously selected from group T, were soaked through with plain water. The overall tick load in dogs from group C was high throughout the entire study period, ranging from 103.2 (day 28) to 161.3 (day 0), and confirmed the high tick pressure. Speed of kill calculated at 48 h post-treatment was slightly higher for adult ticks (96.2%) than for immature stages (91.6%). Compared to the control, dogs treated with the fipronil+(S)-methoprene maintained a significantly lower mean tick load for both adult and immature stages in the four weeks of observation. Persistence of efficacy against immature stages ranged from 97.1% the first week, 99.6% second week, 99.7 third week and 93.1% in the last week. In the same way, efficacy against adult ticks was constantly high, shifting from 94.5% to 92.5%. Overall efficacy (adults+immatures) was the strongest in the first two weeks (i.e., 96.1% and 96.6%) and lowered in the two remaining weeks (i.e., 94.2% and 93.4%). Results showed that water exposure did not affect the activity and persistence of the tested combination. On the basis of this field trial, the fipronil+(S)-methoprene combination represents a highly efficacious product to control all stages of R. sanguineus ticks on dogs., ((c) 2010 Elsevier B.V. All rights reserved.)

This study investigated the use of two commercial products, a deltamethrin-impregnated collar and a fipronil-(S)-methoprene spot-on formulation, in combination to protect dogs against sandflies and fleas when they live in or travel to leishmaniasis-enzootic areas. Interactions, tolerance, and efficacy were evaluated. The combination was well tolerated by the six treated dogs. The antifeeding effect on Phlebotomus perniciosus ranged from 89.6% (day 1) to 99.51% (day 21) and exceeded 95% from day 7 through the end of the study; the mortality effect against P. perniciosus ranged from 87.52% (day 22) to 96.82% (day 15). The combination was 100% effective in controlling Ctenocephalides felis felis infestations for 36 days after treatment. These results suggest that it is feasible and advantageous to combine these two commercial products to protect dogs against sandflies and fleas in leishmaniasis-enzootic areas.

Three field trials were conducted at Guana River State Park, Florida to evaluate the effectiveness of the granule formulation of methoprene, Altosid XR-G, against salt-marsh mosquitoes. Three applications of Altosid XR-G (1.5% s-methoprene) were made at application rates of 9.0, 4.5, and 2.3 kg/ha. Pupae were collected from control and treated sites after inundation. Under field conditions, Altosid XR-G gave 44.6% control at 67 days posttreatment at Site 1 (9.0 kg/ha), 43.7% control at 67 days posttreatment at Site 2 (4.5 kg/ha), and 38% control at 53 days posttreatment at Site 3 (2.3 kg/ha). All treatments taken together achieved an adjusted 10-wk cumulative mosquito emergence inhibition of 69%. Collections were composed of Ochlerotatus sollicitans 68%, Oc. taeniorhynchus 27%, and Psorophora columbiae 5%.

The red imported fire ant, Solenopsis invicta (Buren), is a major pest in the United States because of its painful sting. Toxic bait has been an important management tool against fire ants, but site registrations prohibit applications of most baits on grazed pastures. Extinguish, containing the insect growth regulator methoprene, was selected for this study because it has a broad site registration that includes grazed pastures. The primary objective of this research was to evaluate the efficacy for control of red imported fire ants by using broadcast applications of methoprene bait at a label rate of 1,121 g/ha versus applications around the perimeter of a target area at the reduced rate of 280 g/ha. Grazed pastures in Lee County, Alabama, and Chambers County, Alabama, were selected for this study, with broadcast treatments, perimeter treatments, and controls replicated three times at each site. All mounds were counted and rated using the USDA population index before applications and then at 8 and 16 wk posttreatment. Perimeter applications did not significantly reduce S. invicta mound abundance, but bait treatments significantly reduced mound abundance at 16 wk posttreatment at site 1 where applications were conducted in early evening. However, broadcast applications were not effective at site 2 where treatments were conducted in early morning with warmer temperatures. Emergence of winged alates was observed at 12 wk posttreatment, followed by a high density of incipient mounds that may have masked the full treatment effect of methoprene applications at site 2. Methoprene bait was effective in reducing abundance of S. invicta only when full label rates were applied.

Preventing tick bites is a fundamental step towards reducing the impact of tick-borne protozoal, bacterial and viral diseases (TBDs) in humans and animals. The aim of this study was to evaluate the efficacy of a combination of imidacloprid 10%/permethrin 50% and of fipronil 10%/S-methoprene 12% against ticks in naturally infected dogs and to assess methodological parameters to calculate drug efficacy on tick immature stages. From July to August 2004, 45 privately owned dogs of various sexes, ages, breeds, coat length and habits were enrolled in a trial carried out in an area (radius approximately 50km) in Southern Italy. Three homogeneous groups (both for dog population and tick population) were formed: 15 dogs treated with imidacloprid 10% and permethrin 50% spot-on (group A), 15 dogs treated with fipronil 10% and methoprene 12% spot-on (group B) and 15 untreated dogs (group C). The dogs in each group were then sub-grouped according to their age and weight. Two different treatments were administered (time 0 and +28 days) to groups A and B, and the dogs were checked weekly for tick infestation until day +56 post-treatment (p.t.). Twenty-four areas distributed on the whole body surface were examined for ticks at each follow-up, while only at time 0 and at day +56 p.t., ticks were collected from the dogs and identified. For the immature stages a semi-quantitative method was adopted and the load of immature stages was evaluated and grouped into four classes up to day +56 p.t. when the mean number of immature ticks (MIT) for each infection class was evaluated. All the adult ticks collected were identified as brown dog ticks (Rhipicephalus sanguineus). Immature stages were first compared at day +28 p.t.. The efficacy of both products used in groups A and B on adult ticks was high and generally very similar. Conversely, the efficacy of imidacloprid 10% and permethrin 50% against immatures was higher than that of fipronil 10% and methoprene 12% throughout the observation period with statistically significant differences (p<0.05) at day +28 p.t. (i.e. group A=98.52%, group B=72.40%). On the whole, in analysing the efficacy of both products against adult plus immature ticks, it was found that the combination of imidacloprid 10% and permethrin 50% was more effective than fipronil 10% and methoprene 12%, with the differences being statistically significant at day +28 p.t. (group A=98.43%, group B=77.56%).

The inhibitory activities of fipronil (10% (w/v) solution), (S)-methoprene (9% (w/v) solution), and fipronil/(S)-methoprene (10 and 9% (w/v) solution, respectively) combination against eggs and emerging adult cat fleas (Ctenocephalides felis) and adulticidal activity were tested on experimentally infested dogs. Thirty-two Beagle dogs were selected for this study and eight replicates of four animals were formed based on body weight within sex. One dog in each replicate was randomly allocated to treatment with: (1) untreated control; (2) fipronil 10% (w/v) solution, (3) (S)-methoprene 9% (w/v) solution, and (4) fipronil 10% (w/v) and (S)-methoprene 9% (w/v) combination solution. Treatments were applied once topically on Day 0 at the rate of 0.067 ml/kg. On Days -12, -1, 21, and weekly to Day 84 each dog was infested with approximately 200 fleas and comb counted approximately 24h later, or 2 days (our 48 h) after in the case of Day -1 infestation. On Days -11, 1, 22, and weekly to Day 85 each dog was again infested with approximately 200 fleas. Flea eggs were collected over approximately 24 h beginning 3 days after infestation. Fleas were combed off of the dogs and counted at the end of the egg collection period (approximately 96 h count). One aliquot of up to about 100 eggs, if available, from each animal at each infestation time was incubated for approximately 72 h to determine larval hatch and the other for 35 days to determine the number of adults that developed. The 10% (w/v) fipronil spot-on provided excellent control (>95%) of adult fleas on dogs for 5 weeks. Similarly, the combination spot-on of 10% (w/v) fipronil and 9% (w/v) (S)-methoprene provided excellent control of adult fleas, i.e., >95% for 5 weeks. From week 6 post-treatment onward, the relatively low inhibition of adult flea emergence substantiated the lack of significant ovicidal/larvicidal activity in the fipronil (10%, w/v) treatment group. However, the combination product provided excellent (>90%) ovicidal activity for 8 weeks and high (91.4%) inhibition of adult flea emergence for 12 weeks. In addition, a synergistic effect of the two compounds in combination was demonstrated with fipronil enhancing the ovicidal and inhibition of adult flea emergence activity of (S)-methoprene against cat flea eggs. When all stages of the life cycle of the cat flea are considered, the combination spot-on product provided a high level of total flea control yielding a curative effect against adult fleas and inhibition of flea development stages with little to no potential reinfestation pressure on the animal or in the environment for 12 weeks.

We conducted a field study to test if the addition of a pellet of S-methoprene (Altosid pellets) to an ovitrap would affect oviposition by Aedes aegypti or Ochlerotatus notoscriptus. In 2 trials conducted near Cairns, Queensland, Australia, no significant difference (P > 0.05) was found in the number of eggs of Ae. aegypti or Oc. notoscriptus laid in ovitraps with or without a methoprene pellet. These results suggest the addition of an S-methoprene pellet to ovitraps or sentinel tires could be employed to eliminate the risk of mosquito production by ovitrap surveys.

An isocratic reversed-phase high-performance liquid chromatographic (RP-HPLC) method development for the simultaneous determination of five active ingredients (S)-methoprene, MGK264, PBO, sumithrin and permethrin in a new complex pesticide formulation is described. These active ingredients have similar polarities and contain isomers. The RP-HPLC method development approach began with the selection of a column based on the component structure information, bonded phase, and particle physical characteristics. Second, the mobile phase composition was changed to improve peak resolution and peak sensitivity, especially with analytes containing isomers. Choosing the match between the stationary phase and mobile phase composition, the developed RP-HPLC method not only can simplify the procedure appreciably but also significantly decrease total analysis time and increase peak height. The developed isocratic RP-HPLC method for the analysis of this new formulation was then validated for specificity, linearity, precision, and accuracy. The chromatographic peak identification was identified by LC-MS using the electrospray ionisation in the positive-ion mode.

Effectiveness and residual activity tests of granular formulations of 2 insect growth regulators (IGRs), s-methoprene and pyriproxyfen, against laboratory-reared larvae of 5 colonized mosquitoes, Aedes aegypti, Aedes albopictus, Aedes taeniorhynchus, Anopheles quadrimaculatus, and Culex nigripalpus, were conducted in the laboratory and outdoors in plastic tubs. Culex quinquefasciatus was exposed to these two IGRs in the laboratory only. Each IGR formulation was applied at 0.02 and 0.05 ppm active ingredient (Al) against 5 of the 6 mosquito species both in the laboratory and the outdoor evaluations, whereas Cx. quinquefasciatus was exposed to 0.2 and 0.4 ppm AI of s-methoprene, and 0.1 and 0.2 ppm AI of pyriproxyfen in the laboratory. s-Methoprene at 0.02 and 0.05 ppm AI resulted in variable levels (<39-100%) of inhibition of adult emergence in the 5 species monitored for 6 weeks after treatment under both test conditions. Aedes taeniorhynchus was the most susceptible to s-methoprene in terms of initial and residual activity. Culex quinquefasciatus and Ae. albopictus were the most tolerant to s-methopene, with maximum emergence inhibitions amounting to 84% in Cx. quinquefasciatus at 0.4 ppm and 44.3% in Ae. albopictus at 0.05 ppm during the 1st week in the laboratory. Pyriproxyfen at comparable treatment rates to s-methoprene caused very high levels (>80-100% in most cases) of initial and residual emergence inhibitions of the tested species in the laboratory as well as outdoors. In several species, pyriproxyfen induced complete inhibition of adult emergence for several weeks after treatment, even at the lower rate of 0.02 ppm. The World Health Organization has recently recommended the use of pyriproxyfen for the control of some mosquito species at specified rates in certain habitats.

Evidence that amphibian deformities are on the rise has prompted a number of researchers to question a variety of natural and man-made substances, including chemicals such as s-methoprene (trademark Altosid), an insect growth regulator applied to water bodies for mosquito control. Despite conclusions reached by the U.S. Environmental Protection Agency and a considerable body of scientific evidence demonstrating that it is unlikely that s-methoprene or any of its degradation products are causing the high rates of deformities found in Minnesota and other states, concerns persist about potential negative impacts of s-methoprene on nontarget species, specifically anurans. Water analyses in field and laboratory conditions and a comparison of reported Altosid use with reported frog deformities in Minnesota demonstrate that a connection between frog deformities and Altosid use is unlikely. These results indicate that factors other than s-methoprene and its degradation products are contributing to the recent outbreak of frog deformities.

Laboratory bioassays were used to determine the efficacy of (S)-methoprene against 7 species of Australian mosquitoes. The 90% lethal concentration (LC90) ranged from 0.17 ppb for Aedes vigilax to 6.54 ppb for Culex sitiens. The survival of adults exposed as larvae to 2 sublethal dosages of (S)-methoprene was compared to a control group. Little effect was noted for Cx. sitiens and Culex annulirostris. However, survival of male and female Ae. vigilax was significantly reduced and appeared to be dose related. Bloodfeeding success of female Ae. vigilax was also significantly reduced.

Exposure of spring Aedes larvae to Altosid Liquid Larvicide formulated on the granular carrier Biodac under field conditions was evaluated. Both aerial and hand-applied treatments were monitored. Mosquitoes collected from aerially treated sites (9 kg/ha) showed an average 80% mortality. In hand-treated sites excellent control was achieved at label rates of 11.3-14.7 kg/ha (10-13 lb/acre); at dosages less than recommended rates, control was unsatisfactory.

Mosquito larval control by biorational larvicides plays a crucial role in mosquito and mosquito-borne disease management. However, the availability of larvicides that meet the criteria of efficacy, safety, and quality is limited and conventional pesticides are no longer preferred for larval control. Although efforts are made to research new active ingredients (AIs), it is equally important to innovate new formulations based on currently available AIs such as microbial agents and insect growth regulators. Studies were therefore conducted to compare the laboratory activity and semi-field efficacy of OmniPrene® G and Altosid® Pellets with DR-tech, both containing 4.25% S-methoprene, at 2.8 kg/ha and 11.2 kg/ha against the yellow fever mosquito Aedes aegypti (L.) in outdoor microcosms. Both products performed equally in bioassays against the test species with comparable inhibition of emergence activities. In the semi-field study, the lower dose of Altosid Pellets at 2.8 kg/ha, showed lower efficacy than OmniPrene G during the initial 6 weeks; this difference became negligible on week 7, followed by higher efficacy in Altosid Pellets on weeks 8 and 9. More uniform efficacy was observed at the higher dose of 11.2 kg/ha. Equal performance was revealed during weeks 2 to 6, with the OmniPrene G outperforming the Altosid Pellets in week 1, but the opposite during weeks 7 to 9. Mortality patterns were similar in both products, i.e., majority of mortality occurred before emergence, although more incomplete emergence was noted in lower doses, particularly in Altosid Pellets. Overall, newly available OmniPrene G provided comparable activity and efficacy with Altosid Pellets against the test species, with the advantages of fast initial AI release and even coverage, particularly when applied at low doses., (Copyright © 2024 by The American Mosquito Control Association, Inc.)

A single topical application of a combination of fipronil, (S)-methoprene, pyriproxyfen (Frontline® Gold, Merial, now part of Boehringer Ingelheim) on cats significantly prevented flea egg development (Ctenocephalides felis) in a simulated home environment for 15 weeks. Six healthy male cats were treated and then split in two groups of 3, and each group was housed in separate, identical rooms. For the duration of the study, the cats had free access to three sites in rooms that were covered by a carpet to allow contact with the animals' fur during resting. A portion of the original carpet was retained for use as control carpet. In order to assess the prevention of flea egg development, carpet discs of 48 mm in diameter were sampled on a weekly basis from each carpet, i.e., 6 discs/week, for 15 weeks, and placed into vials with 60 C. felis eggs and flea growth medium and were then incubated for 35 to 37 days. In parallel, six identical discs of carpets without any contact with treated cats were used as untreated controls. During the 15 weeks of the study, an average of 41.0 newly emerged adult fleas (36.5 - 45.3) were recovered weekly from the control carpets, and an average of 2.6 fleas (0.7 - 5.7) were recovered from the carpets in contact with the treated cats. Significantly fewer adults fleas were recovered from the carpets in contact with FRONTLINE Gold treated cats than the control carpets at all time-points (p<0.005). A single administration of FRONTLINE Gold administered topically to cats reduced flea egg development by an average of 93.6% for 15 weeks in this simulated environment. [ABSTRACT FROM AUTHOR]

Background: This controlled laboratory study was designed to evaluate the efficacy of the 10 % imidacloprid/4.5 % flumethrin collar (Seresto®, Bayer Animal Health) against fleas (Ctenocephalides f. felis) on cats, when compared to fipronil (9.8 %w/w)/(s)-methoprene (11.8 % w/w) topical spot-on formulation (Frontline® Plus for Cats and Kittens, Merial). Methods: Thirty cats were randomized into three groups of ten animals based on pre-treatment flea counts: Group 1: imidacloprid/flumethrin collar; Group 2: fipronil/(s)-methoprene topical spot-on and Group 3: non-treated controls. The imidacloprid/flumethrin collars were applied one time on Day 0, while the fipronil/(s)-methoprene spot-on was administered every 30 days from Day 0 through Day 210. Cats were infested with 100 fleas on study days 0, 7, 14, 29, 59, 89, 119, 149, 179, 209 and 239. All flea counts were conducted by combing to remove fleas on post-treatment days 2, 8, 15, 30, 60, 90, 120, 150, 180, 210 and 240. Results: The efficacy of the imidacloprid/flumethrin collar ranged from 98.2 to 100 % for eight months. The efficacy of fipronil/(s)-methoprene spot-on ranged from 68.2 to 99.9 %. Efficacy was < 85 % for fipronil/(s)-methoprene on Days 90, 150 and 210. The flea counts in both treatment groups were significantly fewer than those in the nontreated control group at every post-treatment study day (P < 0.0001). In addition, there were significantly fewer fleas in the imidacloprid/flumethrin collar group when compared to the fipronil/(s)-methoprene group on Days 90, 150 and 210 (P < 0.0001). Conclusions: This study demonstrated that the imidacloprid/flumethrin collar (Seresto®, Bayer Animal Health) maintained excellent ( > 98.2 %) efficacy against fleas on cats for the entire 8 month study. Monthly applications of fipronil/(s)-methoprene (Frontline® Plus for Cats and Kittens, Merial) generally had high, but variable (68.2 to 99.9 %) efficacy over the course of the eight month study. Based on the very high residual efficacy achieved by the imidacloprid/flumethrin collar in this study, veterinarians should expect that this collar will control and eliminate existing flea infestations on cats and in their in-home premises as long as every flea infested host is treated. [ABSTRACT FROM AUTHOR]

Aedes albopictus (Skuse) is a globally significant vector that complexifies management programs already contending with Aedes aegypti (L.). The Ae. albopictus mosquito is a daytime biting, container breeding, anthropophilic mosquito that is generally considered unresponsive to operational larviciding that does not also incorporate source reduction. S-methoprene is a readily available juvenile hormone mimic common to pest management. This 14-week study examines direct and indirect treatment efficacy using s-methoprene as an ultra-low volume (ULV) truck spray in area-wide operations against Ae. albopictus in the southeastern United States. An overall 63.3% reduction of Ae. albopictus adults and 47.8% reduction of deposited eggs in treatment areas were observed compared with control. Indirect plots saw reduction in Ae. albopictus adults by 32.7% and eggs by 32.3%. Using insect growth regulator bioassays, truck-mounted ULV application of s-methoprene was effective to an inhibition of emergence (IE) of ≥92% within directly treated (sprayed) areas and >65% IE among containers placed up to 90 m away. S-methoprene could still benefit urban vector management programs when applied at an operational scale. [ABSTRACT FROM AUTHOR]

Abstract Background Two studies evaluating the efficacy of an imidacloprid/flumethrin collar (Seresto®, Bayer Animal Health, IVP), a deltamethrin collar (Scalibor®, MSD, CP1), a fipronil/(s)-methoprene spot-on (Frontline Combo®, Merial, CP2), a dinotefuran/pyriproxyfen/permethrin spot-on (Vectra 3D®, Ceva, CP3) and an amitraz/fipronil/(s)-methoprene spot-on (Certifect®, Merial, CP4/CP5) against repeated infestations with Rhipicephalus sanguineus and Ctenocephalides felis felis on dogs were conducted over periods of 226 days and 71 days respectively. Methods The first study comprised 4 groups of treated dogs and one untreated control group, and the second 3 groups of treated dogs and one control group. Each group consisted of 8 dogs. All dogs were infested with ticks and fleas at regular intervals. Ticks were counted 6 h, 18 h or 48 h after infestations and fleas 24 h after infestations. Efficacies of the treatments were calculated by comparison with the untreated control groups using standard descriptive statistics. Results The protective 48 h tick efficacy was 97.8% to 100% for the IVP (226 days), 69.3% to 97.4% for CP1 (170 days), 99.6% to 43.4% for CP2 (35 days) and 98% to 61.4% for CP3 (35 days). The protective 18 h tick efficacy was 98% to 99.6% for the IVP (71 days), 100% to 86.5% for CP4 (29 days), 100% to 72.8% for CP4 after re-treatment (35 days) and 98.8% to 54.3% for CP5 (35 days). The protective 6 h tick efficacy was 85.6% at Day 7 and 90.1% to 97.1% from Day 14 onwards for the IVP (70 days), 92.3% to 70.7% for CP4 (35 days), 97.5% to 65.2% for CP4 after re-treatment (35 days) and 95.1% to 51.8% for CP5 (35 days). The protective 24 h flea efficacy was 99.5/90.9% to 100% for the IVP (71/226 days), 66.7% to 83% for CP1 (170 days), 100% to 88.5% for CP2 (35 days), 100% to 73.3% for CP3 (35 days), 100% to 98.7% for CP4 (35 days), 100% to 87.5% for CP4 after re-treatment (35 days) and 100% to 79.5% for CP5 (35 days). Conclusions These data suggest that the long-term efficacy provided by a medicated collar that is effective, is a means to overcome the fluctuating efficacy of spot-on treatments resulting from a lack of pet owner re-treatment compliance, and consequently protect animals successfully against ectoparasites and probably vector-borne diseases.