Sex- and caste-specific developmental responses to juvenile hormone in an ant with maternal caste determination.

Juvenile hormone is considered to be a master regulator of polyphenism in social insects. In the ant Cardiocondyla obscurior, whether a female egg develops into a queen or a worker is determined maternally and caste-specific differentiation occurs in embryos, so that queens and workers can be distinguished in a non-invasive manner from late embryogenesis onwards. This ant also exhibits two male morphs - winged and wingless males. Here, we used topical treatment with juvenile hormone III and its synthetic analogue methoprene, a method that influences caste determination and differentiation in some ant species, to investigate whether hormone manipulation affects the development and growth of male, queen- and worker-destined embryos and larvae. We found no effect of hormone treatment on female caste ratios or body sizes in any of the treated stages, even though individuals reacted to heightened hormone availability with increased expression of krüppel-homolog 1, a conserved JH first-response gene. In contrast, hormone treatment resulted in the emergence of significantly larger males, although male morph fate was not affected. These results show that in C. obscurior, maternal caste determination leads to irreversible and highly canalized caste-specific development and growth.

Regulation of soldier caste differentiation by microRNAs in Formosan subterranean termite (Coptotermes formosanus Shiraki).

The soldier caste is one of the most distinguished castes inside the termite colony. The mechanism of soldier caste differentiation has mainly been studied at the transcriptional level, but the function of microRNAs (miRNAs) in soldier caste differentiation is seldom studied. In this study, the workers of Coptotermes formosanus Shiraki were treated with methoprene, a juvenile hormone analog which can induce workers to transform into soldiers. The miRNomes of the methoprene-treated workers and the controls were sequenced. Then, the differentially expressed miRNAs (DEmiRs) were corrected with the differentially expressed genes DEGs to construct the DEmiR-DEG regulatory network. Afterwards, the DEmiR-regulated DEGs were subjected to GO enrichment and KEGG enrichment analysis. A total of 1,324 miRNAs were identified, among which 116 miRNAs were screened as DEmiRs between the methoprene-treated group and the control group. A total of 4,433 DEmiR-DEG pairs were obtained. No GO term was recognized as significant in the cellular component, molecular function, or biological process categories. The KEGG enrichment analysis of the DEmiR-regulated DEGs showed that the ribosome biogenesis in eukaryotes and circadian rhythm-fly pathways were enriched. This study demonstrates that DEmiRs and DEGs form a complex network regulating soldier caste differentiation in termites.

Investigating the role of the ROS/CncC signaling pathway in the response to xenobiotics in Spodoptera frugiperda using Sf9 cells.

Spodoptera frugiperda (fall armyworm, FAW) is an invasive polyphagous lepidopteran pest that has developed sophisticated resistance mechanisms involving detoxification enzymes to eliminate toxic compounds it encounters in its diet including insecticides. Although its inventory of detoxification enzymes is known, the mechanisms that enable an adapted response depending on the toxic compound remain largely unexplored. Sf9 cells were used to investigate the role of the transcription factors, Cap n' collar isoform C (CncC) and musculoaponeurotic fibrosarcoma (Maf) in the regulation of the detoxification response. We overexpressed CncC, Maf or both genes, and knocked out (KO) CncC or its repressor Kelch-like ECH associated protein 1 (Keap1). Joint overexpression of CncC and Maf is required to confer increased tolerance to indole 3-carbinol (I3C), a plant secondary metabolite, and to methoprene, an insecticide. Both molecules induce reactive oxygen species (ROS) pulses in the different cell lines. The use of an antioxidant reversed ROS pulses and restored the tolerance to I3C and methoprene. The activity of detoxification enzymes varied according to the cell line. Suppression of Keap1 significantly increased the activity of cytochrome P450s, carboxylesterases and glutathione S-transferases. RNAseq experiments showed that CncC mainly regulates the expression of detoxification genes but is also at the crossroads of several signaling pathways (reproduction and immunity) maintaining homeostasis. We present new data in Sf9 cell lines suggesting that the CncC:Maf pathway plays a central role in FAW response to natural and synthetic xenobiotics. This knowledge helps to better understand detoxification gene expression and may help to design next-generation pest insect control measures.

Unique peptidic agonists of a juvenile hormone receptor with species-specific effects on insect development and reproduction.

Juvenile hormones (JHs) control insect metamorphosis and reproduction. JHs act through a receptor complex consisting of methoprene-tolerant (Met) and taiman (Tai) proteins to induce transcription of specific genes. Among chemically diverse synthetic JH mimics (juvenoids), some of which serve as insecticides, unique peptidic juvenoids stand out as being highly potent yet exquisitely selective to a specific family of true bugs. Their mode of action is unknown. Here we demonstrate that, like established JH receptor agonists, peptidic juvenoids act upon the JHR Met to halt metamorphosis in larvae of the linden bug, Pyrrhocoris apterus. Peptidic juvenoids induced ligand-dependent dimerization between Met and Tai proteins from P. apterus but, consistent with their selectivity, not from other insects. A cell-based split-luciferase system revealed that the Met-Tai complex assembled within minutes of agonist presence. To explore the potential of juvenoid peptides, we synthesized 120 new derivatives and tested them in Met-Tai interaction assays. While many substituents led to loss of activity, improved derivatives active at sub-nanomolar range outperformed hitherto existing peptidic and classical juvenoids including fenoxycarb. Their potency in inducing Met-Tai interaction corresponded with the capacity to block metamorphosis in P. apterus larvae and to stimulate oogenesis in reproductively arrested adult females. Molecular modeling demonstrated that the high potency correlates with high affinity. This is a result of malleability of the ligand-binding pocket of P. apterus Met that allows larger peptidic ligands to maximize their contact surface. Our data establish peptidic juvenoids as highly potent and species-selective novel JHR agonists.

Efficacy of two endectoparasiticide products combining fipronil and (S)-methoprene or esafoxolaner with eprinomectin and praziquantel against fleas and intestinal helminths in cats naturally infested in Brazil.

Eprinomectin and praziquantel, nematodicide and cestodicide compounds, are both combined with the insecticide and acaricide compounds fipronil and (S)-methoprene in Frontline® Protect/Broadline®, or esafoxolaner in NexGard® Combo. These topical feline endectoparasiticide products were tested for efficacy against fleas and intestinal helminths in a field trial in Brazil. Flea- and/or helminth-infested domestic cats were treated twice at a monthly interval following label instructions: 160 cats with Frontline® Protect/Broadline® and 165 cats with NexGard® Combo. The flea and intestinal helminth infestations were evaluated using comb counts and copromicroscopy, respectively before first treatment for baseline value, then 9 and 30 days after each treatment for fleas, and 9 days after each treatment for helminths. Multiparasitism was very frequent at baseline, as amongst the 325 included cats, 295, 280, 86 and 93 cats were at least infested with Ctenocephalides fleas, Ancylostoma, Toxocara and Dipylidium caninum, respectively. Efficacies were calculated by comparing the geometric means at baseline and at post-treatment timepoints for each parasite genus/species. Inclusive of both products and of all evaluation timepoints, the Ctenocephalides, Ancylostoma, Toxocara and D. caninum efficacies were at least 98.3%, 99.8%, 99.8% and 96.3%, respectively. No adverse reactions were observed, except for a few instances of mild, transient, and self-resolving hypersalivation occurring on the day of treatment in both groups. This field trial demonstrated high-level efficacy of Frontline® Protect/Broadline® and NexGard® Combo against major parasites of cats in Brazil.

TITLE: Efficacité de deux produits endectoparasiticides associant fipronil et (S)-méthoprène ou esafoxolaner à l'éprinomectine et au praziquantel contre les puces et les helminthes intestinaux chez les chats naturellement infestés au Brésil. ABSTRACT: L'éprinomectine et le praziquantel, composés nématodicides et cestodicides, sont tous les deux associés aux composés insecticides et acaricides fipronil et (S)-méthoprène dans Frontline® Protect/Broadline®, ou esafoxolaner dans NexGard® Combo. Ces produits endectoparasiticides félins topiques ont été testés pour leur efficacité contre les puces et les helminthes intestinaux lors d'un essai sur le terrain au Brésil. Des chats domestiques infestés de puces et/ou d'helminthes ont été traités deux fois à intervalle d'un mois en suivant les instructions d'utilisation, 160 chats avec Frontline® Protect/Broadline® et 165 chats avec NexGard® Combo. Les infestations par les puces et les helminthes intestinaux ont été évaluées en utilisant respectivement par comptage au peigne et par copromicroscopie, avant le premier traitement pour la valeur de base, puis 9 et 30 jours après chaque traitement pour les puces, et 9 jours après chaque traitement pour les helminthes. Le multiparasitisme était très fréquent à l'inclusion puisque parmi les 325 chats inclus, 295, 280, 86 et 93 chats étaient au moins infestés respectivement par les puces Ctenocephalides, ou Ancylostoma, Toxocara et Dipylidium caninum. Les efficacités ont été calculées en comparant les moyennes géométriques au départ et aux points d'évaluation post-traitement pour chaque genre/espèce de parasite. En incluant les deux produits et tous les points temporels d'évaluation, les efficacités contre Ctenocephalides, Ancylostoma, Toxocara et D. caninum étaient respectivement d'au moins 98,3 %, 99,8 %, 99,8 % et 96,3 %. Aucun effet indésirable n'a été observé à l'exception de quelques cas d'hypersalivation légère, transitoire et auto-résolvante survenant le jour d'un traitement dans les deux groupes. Cet essai sur le terrain a démontré une efficacité de haut niveau de Frontline® Protect / Broadline® et NexGard® Combo contre les principaux parasites des chats au Brésil.

Efficacy of fipronil/(S)-methoprene/eprinomectin/praziquantel (Broadline®) against Thelazia callipaeda in naturally infected cats.

BACKGROUND: The present clinical field trial was conducted to assess the efficacy of a broad-spectrum parasiticide spot-on formulation containing eprinomectin (Broadline®) against Thelazia callipaeda eyeworm in naturally infected cats. METHODS: Fifteen privately owned cats harboring at least one live adult T. callipaeda were included in the study. Cats were randomly allocated to an untreated control group of seven cats or to a Broadline®-treated group of eight cats. Cats were treated on Day 0; ocular examinations were performed at inclusion and on Days 7 and 14; eyeworms were recovered and counted on Day 14. The primary efficacy assessment was based on group comparison of number of T. callipaeda on Day 14. RESULTS: Seven days after treatment, six of eight treated cats were negative for eyeworm infection per visual examination, and on Day 14 no eyeworms were found in the treated cats while the seven untreated cats were still infected (geometric mean: 1.97). All cats had inflammatory ocular signs at inclusion; on Day 14, five of eight treated cats had recovered while all untreated control cats were still symptomatic. All collected parasites were confirmed to be T. callipaeda by morphology and molecular characterization. CONCLUSIONS: A single treatment with Broadline® provided 100% efficacy against feline thelaziosis and improved related ocular inflammation signs.

Pharmacokinetics of a novel endectoparasiticide topical formulation for cats, combining esafoxolaner, eprinomectin and praziquantel.

Esafoxolaner, a purified enantiomer of afoxolaner with insecticidal and acaricidal properties, is combined with eprinomectin and praziquantel in NexGard® Combo, a novel topical endectoparasiticide formulation for cats. The parasiticide potencies of topical esafoxolaner, eprinomectin and praziquantel, are based on transcutaneous absorption, systemic distribution, and exposure of respective target parasites. For each compound, the pharmacokinetic profile, non-interference, dose linearity/proportionality after one administration, and the accumulation and time to reach a steady state after repeated monthly administrations of the novel formulation, were investigated. After one topical application of NexGard® Combo at the minimum recommended dose, the mean plasma concentration of esafoxolaner immediately reached (and remained at) a level supporting rapid onset and sustained efficacy against ectoparasites for at least 1 month. The mean Cmax, Tmax, T1/2, and the topical bioavailability of esafoxolaner were 130 ng/mL, 7.1 days, 21.7 days and 47.2%, respectively, and the plasma profiles of eprinomectin and praziquantel supported their known endoparasiticide properties. No relevant interference between the three compounds was observed. Dose proportionality was demonstrated for the three compounds over a range of 0.5× to 2× the minimum recommended dose. Steady state after repeated monthly administrations was reached by the second dose for praziquantel and by the fifth dose for esafoxolaner and eprinomectin. Accumulation was limited and drug plasma concentrations were maintained within a safe level.

TITLE: Pharmacocinétique d'une nouvelle formulation topique d'endectoparasiticide pour chats, combinant esafoxolaner, éprinomectine et praziquantel. ABSTRACT: L'esafoxolaner, un énantiomère purifié d'afoxolaner aux propriétés insecticides et acaricides, est combiné à l'éprinomectine et au praziquantel dans NexGard® Combo, une nouvelle formulation endectoparasiticide topique pour chats. Les pouvoirs parasiticides de l'esafoxolaner topique, de l'éprinomectine et du praziquantel sont basés sur l'absorption transcutanée, la distribution systémique et l'exposition des parasites cibles respectifs. Pour chaque composé, le profil pharmacocinétique, la non-interférence, la linéarité/proportionnalité de dose après une administration, ainsi que l'accumulation et le temps nécessaire pour atteindre un état d'équilibre après des administrations mensuelles répétées de la nouvelle formulation, ont été étudiés. Après une application topique de NexGard® Combo à la dose minimale recommandée, la concentration plasmatique moyenne d'esafoxolaner a immédiatement atteint et est restée à un niveau soutenant une apparition rapide et soutenue de l'efficacité contre les ectoparasites pendant au moins un mois. La Cmax moyenne, la Tmax, la T1/2, et la biodisponibilité topique de l'esafoxolaner était respectivement de 130 ng/mL, 7,1 jours, 21,7 jours et 47,2 %, et les profils plasmatiques de l'éprinomectine et du praziquantel ont confirmé leurs propriétés endoparasiticides connues. Aucune interférence significative entre les trois composés n'a été observée. La proportionnalité de la dose a été démontrée pour les trois composés sur une plage de 0,5 × à 2 × la dose minimale recommandée. L'état d'équilibre après des administrations mensuelles répétées a été atteint par la deuxième dose de praziquantel et par la cinquième dose d'esafoxolaner et d'éprinomectine. L'accumulation était limitée et les concentrations plasmatiques du médicament étaient maintenues à un niveau sûr.

Safety evaluation of a novel topical combination of esafoxolaner, eprinomectin and praziquantel, in reproducing female cats.

NexGard® Combo, a novel topical endectoparasiticide product for cats, is a combination of esafoxolaner, eprinomectin and praziquantel. The safety of this novel combination administered to females during reproduction and lactation was evaluated per analysis of breeding parameters and adverse reactions observed on females and offspring. Females with successful breeding history were randomized to three groups, a placebo group and groups treated with the novel formulation at 1× or 3× multiples of the maximum exposure dose. Females were dosed at 28-day intervals, at least twice before mating, then during a period including mating, pregnancy, whelping and 56 days of lactation. In the placebo, 1× and 3× groups, 10, 9 and 10 females, respectively completed the study (nine, seven and nine females achieved pregnancy), and were dosed 7.1 times on average. Breeding parameters included success of mating, success of gestation, length of gestation, abortion rate, number of live, dead and stillborn kittens at birth, number of kittens with abnormalities, weight of kittens after birth and at weaning, growth of kittens, proportion of male and female kittens, and proportion of kittens born alive and weaned. No significant adverse reactions related to the novel combination were observed on females and on kittens; no significant and adverse effects on breeding parameters were observed.

TITLE: Évaluation de l'innocuité d'une nouvelle combinaison topique d'esafoxolaner, d'éprinomectine et de praziquantel chez les chattes reproductrices. ABSTRACT: NexGard® Combo, un nouvel endectoparasiticide topique pour chats, est une combinaison d'esafoxolaner, d'éprinomectine et de praziquantel. La sécurité de cette nouvelle association administrée aux chattes pendant la reproduction et la lactation a été évaluée par analyse des paramètres d'élevage et des effets indésirables observés sur les femelles et les descendants. Les chattes ayant des antécédents de reproduction réussie ont été randomisées en trois groupes, un groupe placebo et des groupes traités avec la nouvelle formulation à des multiples de 1× ou 3× la dose d'exposition maximale. Les femelles ont reçu des doses à 28 jours d'intervalle, au moins deux fois avant l'accouplement, puis pendant une période comprenant l'accouplement, la gestation, la mise bas et 56 jours de lactation. Dans les groupes placebo, 1× et 3×, repectivement dix, neuf et dix chattes ont terminé l'étude (neuf, sept et neuf chattes ont été gestantes) et ont été traitées 7,1 fois en moyenne. Les paramètres d'élevage comprenaient le succès de l'accouplement, le succès de la gestation, la durée de la gestation, le taux d'avortement, le nombre de chatons vivants, morts et mort-nés à la naissance, le nombre de chatons présentant des anomalies, le poids des chatons après la naissance et au sevrage, la croissance des chatons, la proportion de chatons mâles et femelles et la proportion de chatons nés vivants et sevrés. Aucun effet indésirable significatif lié à la nouvelle association n'a été observé chez les femelles et les chatons et aucun effet indésirable significatif sur les paramètres d'élevage n'a été observé.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel in cats against Toxocara cati and Dipylidium caninum.

NexGard® Combo, a novel topical antiparasitic product for cats, combines the insecticide/acaricide esafoxolaner with the nematocide eprinomectin and cestodicide praziquantel. The efficacy of this combination product was evaluated against two common endoparasites of global occurrence in cats, the nematode Toxocara cati and the cestode Dipylidium caninum, in five controlled studies using naturally or experimentally infected cats with parasites of North American, South African or European origin. Cats evaluated in these studies harbored patent infection of the target parasite confirmed through a pre-treatment fecal examination. In each study, cats were allocated randomly to two groups of equal size (8 or 10 cats per group per study), one group treated with a placebo (mineral oil) and the other with NexGard® Combo. Both treatments were administered once as a spot-on at 0.12 mL per kg body weight to deliver the minimum label dosage (1.44 mg/kg esafoxolaner, 0.48 mg/kg eprinomectin, and 10.0 mg/kg praziquantel) to the NexGard® Combo-treated cats. To determine efficacy, geometric mean parasite counts seven to 12 days after treatment of placebo-treated (control) cats and NexGard® Combo-treated cats were compared. The efficacy of NexGard® Combo was 98.8% and 100% against adult T. cati in two studies; and 98.0%, 98.3% and 93.2% against D. caninum in three studies. No adverse events related to treatment were observed throughout the studies. These studies demonstrate high efficacy against these major feline endoparasites and excellent acceptability of the novel topical antiparasitic combination of esafoxolaner, eprinomectin and praziquantel.

TITLE: Efficacité d'une nouvelle association topique d'esafoxolaner, d'éprinomectine et de praziquantel chez le chat contre Toxocara cati et Dipylidium caninum. ABSTRACT: NexGard® Combo, un nouveau produit antiparasitaire topique pour chats combine l'insecticide/acaricide esafoxolaner avec le nématocide éprinomectine et le cestodicide praziquantel. L'efficacité de ce produit d'association a été évaluée contre deux endoparasites communs d'occurrence mondiale chez le chat, le nématode Toxocara cati et le cestode Dipylidium caninum, dans cinq études contrôlées utilisant des chats naturellement ou expérimentalement infectés par des parasites d'origine nord-américaine, sud-africaine ou européenne. Les chats évalués dans ces études présentaient une infection patente du parasite cible confirmée par un examen fécal avant le traitement. Dans chaque étude, les chats ont été répartis au hasard en deux groupes de taille égale (8 ou 10 chats par groupe et par étude), un groupe traité avec un placebo (huile minérale) et l'autre avec NexGard® Combo. Les deux traitements ont été administrés une fois par spot-on à 0,12 mL par kg de poids corporel pour délivrer la dose minimale indiquée sur l'étiquette (1,44 mg/kg d'esafoxolaner, 0,48 mg/kg d'éprinomectine et 10,0 mg/kg de praziquantel) pour les chats du groupe traité par NexGard® Combo. Pour déterminer l'efficacité, les nombres moyens géométriques de parasites sept à 12 jours après le traitement des chats traités par placebo (témoins) et des chats traités par NexGard® Combo ont été comparés. L'efficacité de NexGard® Combo était de 98,8 % et de 100 % contre T. cati adulte dans deux études, et de 98,0 %, 98,3 % et 93,2 % contre D. caninum dans trois études. Aucun événement indésirable lié au traitement n'a été observé tout au long des études. Ces études démontrent la grande efficacité contre ces principaux endoparasites félins et l'excellente acceptabilité de la nouvelle combinaison antiparasitaire topique d'esafoxolaner, d'éprinomectine et de praziquantel.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel against Notoedres cati mange in cats.

The therapeutic efficacy against notoedric mange of a topical combination of esafoxolaner, eprinomectin and praziquantel (Nexgard® Combo, Boehringer Ingelheim) was evaluated in a masked, controlled clinical study including 14 cats with natural or induced Notoedres cati infestation. Cats were allocated randomly to two groups of seven cats each, to be administered either mineral oil (placebo control) or NexGard® Combo. Each treatment was administered once as spot-on at 0.12 mL per kg body weight (representing the minimum label dosage of NexGard® Combo, i.e. 1.44 mg esafoxolaner, 0.48 mg eprinomectin, and 10.0 mg praziquantel per kg body weight). Live mites were counted in skin scrapings collected within seven days prior to and 14, 27/28, 42 and 56 days after treatment to calculate the percentage efficacy of NexGard® Combo based on the comparison of mean live mite counts of the two groups. Concurrently, mange lesions and clinical signs were scored to establish a clinical success valuation. No live mites were recovered from any NexGard® Combo-treated cats post-treatment, indicating 100% therapeutic efficacy following a single spot-on administration of the novel antiparasitic combination. The clinical success valuations in the NexGard® Combo-treated cats were 14.3%, 42.8%, 100% and 100% at 14, 27/28, 42 and 56 days after treatment, respectively. No health problems were observed throughout the study.

TITLE: Efficacité d'une nouvelle association topique d'esafoxolaner, d'éprinomectine et de praziquantel contre la gale à Notoedres cati chez le chat. ABSTRACT: L'efficacité thérapeutique contre la gale notoédrique d'une association topique d'esafoxolaner, d'éprinomectine et de praziquantel (Nexgard® Combo, Boehringer Ingelheim) a été évaluée dans une étude clinique contrôlée et masquée portant sur 14 chats atteints d'une infestation naturelle ou induite par Notoedres cati. Les chats ont été répartis au hasard en deux groupes de sept chats chacun, traités soit avec de l'huile minérale (contrôle placebo), soit avec NexGard® Combo. Chaque traitement a été administré en une seule fois à raison de 0,12 mL par kg de poids corporel (représentant la posologie minimale indiquée sur l'étiquette de NexGard® Combo, c'est-à-dire 1,44 mg d'esafoxolaner plus 0,48 mg d'éprinomectine plus 10,0 mg de praziquantel par kg de poids corporel). Les acariens vivants ont été comptés par grattage de peau et recueillis dans les sept jours précédant le traitement et 14, 27/28, 42 et 56 jours après le traitement pour calculer le pourcentage d'efficacité de NexGard® Combo basé sur la comparaison du nombre moyen d'acariens vivants des deux groupes. Parallèlement, les lésions de la gale et les signes cliniques ont été mesurés pour établir une évaluation du succès clinique. Aucun acarien vivant n'a été retrouvé chez les chats traités par NexGard® Combo après le traitement, ce qui indique une efficacité thérapeutique de 100% après une administration ponctuelle unique de la nouvelle association antiparasitaire. L'évaluation du succès clinique chez les chats traités par NexGard® Combo était de 14,3 %, 42,8 %, 100 % et 100 %, respectivement 14, 27/28, 42 et 56 jours après le traitement. Aucun problème de santé n'a été observé tout au long de l'étude.

Juvenile hormone suppresses aggregation behavior through influencing antennal gene expression in locusts.

Animals often exhibit dramatically behavioral plasticity depending on their internal physiological state, yet little is known about the underlying molecular mechanisms. The migratory locust, Locusta migratoria, provides an excellent model for addressing these questions because of their famous phase polyphenism involving remarkably behavioral plasticity between gregarious and solitarious phases. Here, we report that a major insect hormone, juvenile hormone, is involved in the regulation of this behavioral plasticity related to phase change by influencing the expression levels of olfactory-related genes in the migratory locust. We found that the treatment of juvenile hormone analog, methoprene, can significantly shift the olfactory responses of gregarious nymphs from attraction to repulsion to the volatiles released by gregarious nymphs. In contrast, the repulsion behavior of solitarious nymphs significantly decreased when they were treated with precocene or injected with double-stranded RNA of JHAMT, a juvenile hormone acid O-methyltransferase. Further, JH receptor Met or JH-response gene Kr-h1 knockdown phenocopied the JH-deprivation effects on olfactory behavior. RNA-seq analysis identified 122 differentially expressed genes in antennae after methoprene application on gregarious nymphs. Interestingly, several olfactory-related genes were especially enriched, including takeout (TO) and chemosensory protein (CSP) which have key roles in behavioral phase change of locusts. Furthermore, methoprene application and Met or Kr-h1 knockdown resulted in simultaneous changes of both TO1 and CSP3 expression to reverse pattern, which mediated the transition between repulsion and attraction responses to gregarious volatiles. Our results suggest the regulatory roles of a pleiotropic hormone in locust behavioral plasticity through modulating gene expression in the peripheral olfactory system.

Involvement of methoprene-tolerant (Met) in the determination of the final body size in Leptinotarsa decemlineata (Say) larvae.

In the tobacco hornworm Manduca sexta, juvenile hormone (JH) is critical for the control of species-specific size. However, whether the basic helix-loop-helix/Per-Arnt-Sim domain receptor methoprene-tolerant (Met) is involved remains unconfirmed. In the present paper, we found that RNA interference (RNAi)-aided knockdown of Met gene (LdMet) lowered the larval and pupal fresh weights and shortened the larval development period in the Colorado potato beetle Leptinotarsa decemlineata. Dietary introduction of JH into the LdMet RNAi larvae rescued neither the decreased weights nor the reduced development phase, even though JH ingestion by control larvae extended developmental time and caused large pupae. Moreover, the transcript levels of five genes involved in prothoracicotropic hormone and cap 'n' collar isoform C/Kelch-like ECH associated protein 1 pathways were upregulated in the LdMet silenced larvae. Ecdysteroidogenesis was thereby activated; 20-hydroxyecdysone (20E) titer was increased; and 20E signaling pathway was elicited in the LdMet RNAi larvae. Therefore, JH, acting through its receptor Met, inhibits PTTH production and release before the attainment of critical weight. Once the critical weight is reached, JH production and release are averted; and the hemolymph JH is removed. The elimination of JH allows the brain to release PTTH. PTTH subsequently stimulates ecdysteroid biosynthesis and release to start larval-pupal transition in L. decemlineata.

Juvenile hormone signaling in short germ-band hemimetabolan embryos.

The role of juvenile hormone (JH) in insect embryos is far from understood, especially in short germ-band hemimetabolan species. To shed light on this issue, we depleted the mRNA levels of Krüppel homolog 1, Methoprene-tolerant and JH acid O-methyltransferase, key elements of JH signaling, in embryos of the short germ-band hemimetabolan species Blattella germanica This precluded the formation of the germ-band anlage in a group of embryos. Hatchability was also reduced, which might have been caused by premature upregulation of laccase 2, a promoter of cuticle tanning. In other cases, development was interrupted in mid embryogenesis, involving defects related to dorsal closure and appendage formation. These phenotypes possibly result from the low levels of Broad-complex (BR-C) produced under JH-depleted conditions. This contrasts with holometabolan species, in which JH does not promote BR-C expression, which remains low during embryo development. Possibly, the stimulatory role of JH on BR-C expression and the morphogenetic functions of BR-C in hemimetabolan embryos were lost in holometabolan species. If so, this might have been a key driver for the evolution of holometabolan metamorphosis.

Modulation of gene expression by nutritional state and hormones in Bombyx larvae in relation to its growth period.

Insect growth and development are mainly regulated via synchronization of many extrinsic and intrinsic factors such as nutrition and hormones. Previously we have demonstrated that larval growth period influences the effect of insulin on the accumulation of glycogen in the fat body of Bombyx larvae. In the present study we demonstrate that Bombyx larvae at the terminal growth period (TGP, after critical weight) had a significantly greater increase in the expression level of Akt in the fat body than at the active growth period (AGP, before critical weight). The larvae at TGP also showed an increase in the expression level of ecdysone receptors (EcRB1 and USP1) and ecdysone-induced early genes (E75A and broad). The treatment of bovine insulin and methoprene to larvae at AGP induced the transcript levels of Akt, irrespective of the nutritional status of the larvae. However, in larvae at TGP, insulin repressed the transcript level of Akt. On contrary, 20-hydroxyecdysone (20E) induced the expression level of Akt in TGP larvae, but at feeding only. Insulin and 20E thus showed an antagonistic action on the Akt expression level in TGP larvae under feeding. The studies thus showed that larval growth period influences the expression level of Akt and ecdysone receptors in Bombyx. Further, the growth period and nutrition modulate the effect of exogenous hormones on Akt expression.

Fipronil/(S)-methoprene spot-on to control fleas on cats in a field trial in Spain

The study was conducted in order to evaluate the effect of a fipronil/(S)-methoprene formulation against fleas on naturally infested cats. The study involved a population of 89 cats distributed among 24 veterinary practices in 9 regions of Spain. The product was applied according to label instructions on days 0, 30 and 60. Animals underwent parasitological and clinical assessments on day 0 and thereafter in monthly intervals (every 30 days) until day 90. Ctenocephalides felis was the most abundant species (98.9% of all fleas collected), and flea abundance on Day 0 was associated with the hair type, the location of the household, and the time elapsed from the last anti-flea treatment. Fipronil/(S)-methoprene demonstrated high efficacy and induced the reduction of clinical signs related to the presence of fleas. Clinical signs and flea abundance decreased significantly throughout time (P=0.001) with an efficacy rate of 72.6% at Day 30, 88.4% at Day 60 and 93.9% at Day 90. A high level of flea control and a remission of the clinical signs related to presence of fleas were observed on cats following 3 monthly applications a fipronil/(S)-methoprene formulation.(AU)

The FOXO transcription factor controls insect growth and development by regulating juvenile hormone degradation in the silkworm, Bombyx mori.

Forkhead box O (FOXO) functions as the terminal transcription factor of the insulin signaling pathway and regulates multiple physiological processes in many organisms, including lifespan in insects. However, how FOXO interacts with hormone signaling to modulate insect growth and development is largely unknown. Here, using the transgene-based CRISPR/Cas9 system, we generated and characterized mutants of the silkworm Bombyx mori FOXO (BmFOXO) to elucidate its physiological functions during development of this lepidopteran insect. The BmFOXO mutant (FOXO-M) exhibited growth delays from the first larval stage and showed precocious metamorphosis, pupating at the end of the fourth instar (trimolter) rather than at the end of the fifth instar as in the wild-type (WT) animals. However, different from previous reports on precocious metamorphosis caused by juvenile hormone (JH) deficiency in silkworm mutants, the total developmental time of the larval period in the FOXO-M was comparable with that of the WT. Exogenous application of 20-hydroxyecdysone (20E) or of the JH analog rescued the trimolter phenotype. RNA-seq and gene expression analyses indicated that genes involved in JH degradation but not in JH biosynthesis were up-regulated in the FOXO-M compared with the WT animals. Moreover, we identified several FOXO-binding sites in the promoter of genes coding for JH-degradation enzymes. These results suggest that FOXO regulates JH degradation rather than its biosynthesis, which further modulates hormone homeostasis to control growth and development in B. mori In conclusion, we have uncovered a pivotal role for FOXO in regulating JH signaling to control insect development.

Environmental safety review of methoprene and bacterially-derived pesticides commonly used for sustained mosquito control.

Some pesticides are applied directly to aquatic systems to reduce numbers of mosquito larvae (larvicides) and thereby reduce transmission of pathogens that mosquitoes vector to humans and wildlife. Sustained, environmentally-safe control of larval mosquitoes is particularly needed for highly productive waters (e.g., catchment basins, water treatment facilities, septic systems), but also for other habitats to maintain control and reduce inspection costs. Common biorational pesticides include the insect juvenile hormone mimic methoprene and pesticides derived from the bacteria Bacillus thuringiensis israelensis, Lysinibacillus sphaericus and Saccharopolyspora spinosa (spinosad). Health agencies, the public and environmental groups have especially debated the use of methoprene because some studies have shown toxic effects on non-target organisms. However, many studies have demonstrated its apparent environmental safety. This review critically evaluates studies pertinent to the environmental safety of using methoprene to control mosquito larvae, and provides concise assessments of the bacterial larvicides that provide sustained control of mosquitoes. The review first outlines the ecological and health effects of mosquitoes, and distinguishes between laboratory toxicity and environmental effects. The article then interprets non-target toxicity findings in light of measured environmental concentrations of methoprene (as used in mosquito control) and field studies of its non-target effects. The final section evaluates information on newer formulations of bacterially-derived pesticides for sustained mosquito control. Results show that realized environmental concentrations of methoprene were usually 2-5µg/kg (range 2-45µg/kg) and that its motility is limited. These levels were not toxic to the vast majority of vertebrates and invertebrates tested in laboratories, except for a few species of zooplankton, larval stages of some other crustaceans, and small Diptera. Studies in natural habitats have not documented population reductions except in small Diptera. Bacterial larvicides showed good results for sustained control with similarly limited environmental effects, except for spinosad, which had broader effects on insects in mesocosms and temporary pools. These findings should be useful to a variety of stakeholders in informing decisions on larvicide use to protect public and environmental health in a 'One Health' framework.

Efficacy of a topical combination of fipronil, (S)-methoprene, eprinomectin and praziquantel (Broadline(®)) against naturally acquired infections with cestodes of the genus Joyeuxiella in cats.

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.

Comparative Speed of Kill, Repellent (anti-feeding) and Acaricidal Efficacy of an Imidacloprid/Flumethrin Collar (Seresto®) and a Fipronil/(S)-Methoprene/Eprinomectin/Praziquantel Spot-on (Broadline®) against Ixodes ricinus (Linné, 1758) on Cats.

Speed of kill, repellent (anti-feeding) and acaricidal efficacy of an imidacloprid 10 % (w/w) /flumethrin 4.5 % (w/w) collar (Seresto(®), Bayer) and a spot-on formulation of fipronil 8.3 % (w/v) /(S)-methoprene 10 % (w/v) /eprinomectin 0.4 % (w/v) /praziquantel 8.3 % (w/v) (Broadline(®), Merial) against artificiallyinduced infestations with Ixodes ricinus on cats, were assessed in a parallel group design, randomised, controlled study. Twenty-four cats were included and randomly allocated to treatment groups or a non-treated control group. Starting on Day (D) 7 after treatment until D28, cats were each infested with 50 I. ricinus at weekly intervals. Ticks were counted in situ on the cats at 6, 12 and 24 h and upon removal 48 h after each infestation. Based on arithmetic means, Seresto(®) proved to be 100 % effective against adult I. ricinus at all assessment times (6, 12, 24 and 48 h after infestation) throughout the month-long study. Broadline(®) was 0 % to 16.7 % effective at 6 h, 26.8 % to 50.0 % effective at 12 h, while at 24 h after infestation efficacy peaked at 81.5 % on D15 declining to 31.5 % on D29. Based on the 48 h tick counts, the efficacy of Broadline(®) peaked at 100 % on D16 after treatment and decreased to 83.2 % by D30. The Seresto(®) collar provided significantly faster speed of kill and better persistent acaricidal effectiveness against Ixodes ricinus on cats compared to Broadline(®) spot-on. The additional repellent (anti-feeding) effect of Seresto(®) prevents parasites from taking a blood meal and thereby reduces the risk of vector-borne disease pathogen transmission.

Efficacy of Broadline® spot-on against Aelurostrongylus abstrusus and Troglostrongylus brevior lungworms in naturally infected cats from Italy.

The increasing reports of Aelurostrongylus abstrusus infection and the new information on Troglostrongylus brevior have spurred the interest of the scientific community towards the research of pharmaceutical compounds effective against both pathogens. A novel topical combination of fipronil, (S)-methoprene, eprinomectin and praziquantel (Broadline®, Merial) has been released for the treatment of a variety of feline parasitic infections. The present study reports the efficacy of this spot-on in treating cats naturally infected by feline lungworms. Client owned cats (n=191) were enrolled from three geographical areas of Italy and faecal samples were examined by floatation and Baermann techniques. Twenty-three individuals were positive for L1 of A. abstrusus (n=18) or T. brevior (n=3) or for both species (n=2) and they were topically treated with Broadline®. Seventeen of them were also concomitantly infected by other parasites. Four weeks after treatment, faecal samples were collected and examined to assess the efficacy of a single administration of the product. Based on lungworm larvae counts, the efficacy of the treatment was 90.5% or 100% for A. abstrusus or T. brevior, respectively. Cats released significantly lower amounts of lungworm larvae after treatment compared to pre-treatment (p<0.0001). All but three cats were negative for other nematodes after treatment and all cats recovered from respiratory signs. Results of this study indicate that a single administration of the topical combination fipronil, (S)-methoprene, eprinomectin and praziquantel is effective and safe for the treatment of A. abstrusus and/or T. brevior infections in cats living under field conditions.