Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Nymph”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources
PubMed1985

Systemic activity of a benzimidazoline compound in cattle against ticks and biting flies.

A benzimidazoline compound [4-nitro-2-(1,1,2,2-tetrafluoroethyl)-6 -(trifluoromethyl)-1H-benzimidazol-2-, 01, sodium salt] referred to as EL-979 showed systemic acaricidal and insecticidal activity in cattle against 2 tick species, Amblyomma maculatum (Gulf Coast tick) and Dermacentor variabilis (American Dog tick) and adult Stomoxys calcitrans (stable flies). Larvae of black blow fly (Phormia regina) were fed serum collected from treated calves. A complete kill of larvae was obtained with a serum level of 3 parts per million (p.p.m.) of EL-979. Intravenous infusion at the rate of 0.25 mg kg-1 per day for 12 days provided a concentration of EL-979 in the blood of approximately 5 p.p.m. In A. maculatum this blood level prevented feeding in larvae and molting in nymphs, reduced numbers of females successfully feeding and prevented larvae production. D. variabilis adults were not as susceptible to a blood level of 5 p.p.m., but the number of feeding larvae and molting nymphs were reduced. Complete mortality of adult S. calcitrans occurred with repeated feedings of a 5 p.p.m. blood level. Fly control of 80% was found with 2.3 p.p.m. multiple feeds. Calf sera with a concentration range of 16--20 p.p.m. killed all flies which took a single feeding.

Animals↗
PubMed1986

Transmission of a Trypanosoma sp. to cattle by the tick Hyalomma anatolicum anatolicum.

Hyalomma anatolicum anatolicum engorged nymphs and flat adults were collected from two areas in northern Sudan. Various developing stages of Trypanosoma theileri-like flagellates were observed in the engorged nymphs, freshly moulted adults and mature adults partially engorged on rabbits. When these ticks were applied to two calves, one calf became infected with the trypanosome. The parasites were observed for one day in the enlarged lymph node nearest to the tick-feeding site 5 days after the tick application. Subsequently the trypanosomes were re-isolated in vitro from the infected calf. Inoculation of a ground-up tick supernatant suspension from the infected batch of ticks containing 10(4) trypanosomes into a calf did not produce a patent infection.

Animals↗
PubMed1989

The carrier status of sheep, cattle and African buffalo recovered from heartwater.

Sheep, cattle and the African buffalo (Syncerus caffer) were shown to remain carriers of heart-water (caused by Cowdria ruminantium) for long periods after recovery; 223, 246 and 161 days, respectively. Transmission was achieved using adults of the southern African bont tick (Amblyomma hebraeum) that had fed as nymphs on recovered animals. Our findings differ from those of other workers who attempted transmission using nymphs that had fed as larvae on recovered animals or with blood from recovered animals.

Animals↗
PubMed1995

The efficacy of Diflubenzuron against the body louse (Damalinia limbata) of Angora goats.

The efficacy of an insect growth regulator, Diflubenzuron, to control biting lice (Damalinia limbata) on Angora goats was investigated. Lice on goats which were dipped in a concentration of 625 g Diflubenzuron to 1,000 1 water and then kept in quarantine was eradicated after a single treatment. Nymphs remained present on these goats up to 4 weeks and adult lice up to 8 weeks post-treatment. A single treatment provided greater than 90% reduction in nymphal stages from Week 6 to Week 16 post-treatment in treated goats continuously exposed to reinfestation. The treatment reduced adult louse infestations on these goats by 78-94% through Weeks 6-16 post-treatment. At the end of the trial (24 weeks post-treatment), these goats had 88% fewer nymphs and 84% fewer adult lice compared with untreated control goats.

Animals↗
PubMed1994

Seasonal variation of ticks (Ixodidae) in Bos taurus x Bos indicus cattle under rotational grazing in forested and deforested habitats in northwestern Argentina.

The seasonal occurrence of ticks infesting cattle was monitored in a Bos taurus x Bos indicus commercial herd fed on a combination of native grasses and annual pastures in northwestern Argentina. The number of female ticks (Boophilus and Amblyomma) and the proportion of cattle infested with larvae and nymphs of Amblyomma ticks were recorded from a sample of 15 cows in 24 visits at intervals of 21-50 days from 5 December 1986 to 24 November 1988. The cattle were maintained on native grasses in forested habitats for 341 days, on native grasses in deforested habitats for 116 days and finally for 264 days on annual pastures. On 15 visits Boophilus microplus females were found, Amblyomma cajennense were detected on 11 counts, seven counts were positive for Amblyomma neumanni and two counts for Amblyomma parvum females. The peak of abundance of Boophilus microplus was found to be at the end of March 1987 with a mean of 36 females per side of cow. The peak numbers of A. cajennense (20 ticks), A. neumanni (12 ticks) and A. parvum (nine ticks) were found in December 1987, July 1987 and November 1988, respectively. The peak of Boophilus microplus was detected while cattle were on natural grasses in deforested habitats, peaks of other tick species were found when cattle were on natural grasses in forested habitats. The maximum cattle infestations with Amblyomma larvae (34% of cattle, May 1987) and nymphs (100%, August 1987) were detected while cattle were on natural grasses in forested habitats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

The acute toxicity of endosulfan to fresh-water organisms.

A static bioassay is performed for measuring the short-term (96 h) toxicity of endosulfan to juvenile catfish Clarias batrachus, insect nymph Enallagma sp. and frog tadpoles of Rana tigrina. Median Tolerance Limit, Slope Function, Confidence Limit, and Presumable Harmless Concentration were computed. The results showed that frog tadpoles are more susceptible to endosulfan than insect nymph and catfish. Morphological changes and behavioural alterations were evaluated as symptoms of endosulfan toxicity.

Animals↗
PubMed1986

Effect of benserazid and 6-hydroxydopamine on the development of the last larval instar of the house cricket, Acheta domestica L.

The effect of benserazid and 6-OHDA on the duration of the last larval instar and development of wings with intact corpora allata and following allatectomy on Acheta domestica L. was studied. 6-OHDA failed to alter the duration of the last larval instar in the nymphs with intact corpora allata but prolonged it in the allatectomized crickets. Introduction of 6-OHDA in the second phase of the last larval instar caused a deformation of the wings both in allatectomized and intact crickets. Injection of benserazid to the nymphs of the last larval instar prolonged the duration of this phase only in the presence of the corpora allata. The effect of benserazid can be connected to elimination of central inhibition of the corpora allata involving dopaminergic neurons of the brain.

Animals↗
PubMed1993

cDNA cloning and expression of Rhodnius prolixus vitellogenin.

It was shown that Rhodnius prolixus vitellogenin (Vg) is synthesized as precursors of 205 and 190 kDa. Each Vg subunit is antigenically related to a domain in the precursor molecules. Since Vg has been previously detected in R. prolixus male adults, protein synthesis by fat bodies from 5th instar male nymphs was investigated and no Vg synthesis could be detected. Also, a 6.1 Kb RNA is present in female adults but not in 5th instar male nymphs. Therefore, cDNAs from female adult and 5th instar male fat bodies were used for differential screening of a female fat body cDNA library leading to the isolation of several female specific clones. All the clones hybridizing to the female specific 6.1 Kb RNA species were identical. We also describe the construction of new expression vectors, pGex-A and pGex-B, derived from the previously described plasmid pGex-1N. The new vectors, together with pGex-3X, comprise a set of expression plasmids with cloning sites in all three possible reading frames that give a fusion polypeptide with the glutathione S-transferase. This carrier protein can be cleaved by digestion with factor Xa in all three plasmids; one of the Vg cDNA clones was subcloned in pGex-A. Antibodies affinity purified from the fusion protein Vg/glutathione S-transferase recognized both large Vg subunits, suggesting an antigenic relationship between them. Furthermore, the small Vg subunits were not recognized, indicating that they may be localized at the N-terminal region of Vg precursors.

Amino Acid Sequence↗
PubMed2026

Microbial allies in a cotton pest: A descriptive account of associated microbiota dynamics in Dysdercus cingulatus across development.

BACKGROUND: Hemipteran insects harbour several symbiotic partners, mainly bacteria, which play pivotal roles for hosts like dietary provision, support overall physiology, xenobiotic degradation and manipulate/regulate behaviour. Most of these symbionts usually reside and operate from the digestive tracts of the animals. Cotton is one of the major cash crops in India and Dysdercus cingulatus (D. cingulatus) though a secondary pest, is causing significant destruction of cotton bolls, poor lint quality and reduce oil content of seeds. Premature opening of cotton bolls often leads to bacterial and fungal infections, thus resulting in extensive economic loss worldwide. D. cingulatus is a hemimetabolous insect that comprises of developmental stages like egg, nymph (5 instar stages), and adult. The present work explored the ontogeny specific diversity in the associated microbiota and predicted their probable functional inputs in D. cingulatus. RESULTS: The data obtained using 16S rRNA gene sequencing (NovaSeq 6000) revealed presence of members of Proteobacteria (65.83%), Firmicutes (24%), Actinobacteria (10%) phyla throughout the ontogeny of D. cingulatus. Highest alpha diversity of these symbiotic bacteria was recorded in the third instar nymphs in contrast to rest of the developmental stages. Among all the observed genera, Stenotrophomonas, Hungatella and Glutamicibacter were predominant from egg to adult stages. MicFunPred, a tool used for predicting the probable functional inputs of these symbionts, hinted at their probable stage specific contribution in crucial biochemical pathways such as polyketide biosynthesis, ascorbate/aldarate metabolism, pentose phosphate and glyoxylate cycles, steroid hormone and peptidoglycan biosynthesis, and glycolysis/pyruvate metabolism. CONCLUSIONS: The primary investigations on the ontogenetic composition and diversity of associated microbiota, suggest dynamic shifts in D. cingulatus, concurrent with their probable functions/roles in the host development and metabolism. To the best of our knowledge, this is the first report on symbiotic microbiota variation across the developmental stages of D. cingulatus that provides preliminary descriptive observations that may guide future functional and experimental investigations into microbiota-based pest management.

Animals↗
PubMed2005

Use of carbon and nitrogen stable isotope ratios to assess the effects of environmental contaminants on aquatic food webs.

In this study, the value of carbon (delta13C) and nitrogen (delta15N) stable isotope ratios were determined in nymphs of a top-predator, the common backswimmer (Notonecta glauca L.), collected in 18 m3 outdoor freshwater mesocosms used to assess the fate and ecotoxicological effects of a diphenyl ether herbicide, fomesafen, applied alone or in combination with Agral 90 (mixture of polyethoxylated derivatives of nonylphenol). Both treatments had a negative effect on delta13C values which may reflect changes in carbon fluxes across food webs in the treated ponds associated with a shift in phytoplankton structure. A decrease in delta15N values was observed in the nymphs collected in mixture-treated ponds, which was presumably due to an increase in the abundance of rotifers and Chironominae larvae in these ponds. These preliminary results indicate that stable isotope ratios may be used as shortcuts to detect qualitative or quantitative shifts in the structure of aquatic food webs caused by pollutants.

Animals↗
PubMed2006

Ixodes ricinus: the potential of two-dimensional gel electrophoresis as a tool for studying host-vector-pathogen interactions.

Ixodes ricinus is a three-host tick, with three active instars. For moulting to occur the tick has to find a host where it can take a blood meal. Throughout feeding I. ricinus can be infected or infect the host with different pathogens, e.g., Tick-Borne Encephalitis virus or Borrelia burgdorferi. The host-vector-pathogen interaction is very complex, making a detailed study difficult. Here we analyse the potential of two-dimensional gel electrophoresis (2DE) to study the host-vector-pathogen interaction. We examined 20 nymphs, which as larvae parasitised either mouse or hen. After moulting, they were kept alive for up to 30 weeks, to analyse whether tick ageing influenced host determination, and for comparison of the 2D-gels. Even though the number of proteins in the gel decreased during ageing, some proteins of the host determination persisted for all 30 weeks. We also discovered persisting proteins in relation to nymphs. These findings showed that 2DE is suitable as a tool for studying host-vector-pathogen interactions.

Actins↗
PubMed2006

Biological activity of Schinus molle on Triatoma infestans.

Hexanic extracts from leaves and fruits of Schinus molle were tested for repellent and insecticidal properties against first instar nymphs and eggs of Triatoma infestans, the vector of Chagas' disease. Leaf and fruit extracts were highly repellent for first nymphs. Fruit extracts had also ovicidal activity.

Anacardiaceae↗
PubMed2006

RNA interference of the salivary gland nitrophorin 2 in the triatomine bug Rhodnius prolixus (Hemiptera: Reduviidae) by dsRNA ingestion or injection.

Mass sequencing of cDNA libraries from salivary glands of triatomines has resulted in the identification of many novel genes of unknown function. The aim of the present work was to develop a functional RNA interference (RNAi) technique for Rhodnius prolixus, which could be widely used for functional genomics studies in triatomine bugs. To this end, we investigated whether double-stranded RNA (dsRNA) can inhibit gene expression of R. prolixus salivary nitrophorin 2 (NP2) and what impact this might have on anticoagulant and apyrase activity in the saliva. dsRNA was introduced by two injections or by ingestion. RT-PCR of the salivary glands showed that injections of 15 microg of NP2 dsRNA in fourth-instar nymphs reduced gene expression by 75+/-14% and that feeding 1 microg/microL of NP2 dsRNA into second-instar nymphs (approx. 13 microg in total) reduced gene expression by 42+/-10%. Phenotype analysis showed that saliva of normal bugs prolonged plasma coagulation by about four-fold when compared to saliva of knockdown bugs. These results and the light color of the salivary gland content from some insects are consistent with the knockdown findings. The findings suggest that RNAi will prove a highly valuable functional genomics technique in triatomine bugs. The finding that feeding dsRNA can induce knockdown is novel for insects.

Animals↗
PubMed2006

Babesia microti: prevalence in wild rodents and Ixodes ricinus ticks from the Mazury Lakes District of North-Eastern Poland.

Infections of Babesia microti (Apicomplexa, Piroplasmida), a common erythroparasitic protozoon of Holarctic rodents, are not widely acknowledged in Poland. The presence of this parasite in various species of wild rodents has been well documented throughout the northern temperate zone of North America, Europe, and Eurasia. However, human babesiosis attributable to infection with B. microti has been reported only from the north-eastern and upper midwestern United States and Japan. We recently carried out an epizootiological survey investigating the prevalence of B. microti both in the tick Ixodes ricinus and in wild rodents in North-Eastern Poland. Blood samples were collected from a total of 483 animals comprising three species: Apodemus flavicollis, Microtus arvalis, and Microtus oeconomus trapped at Urwitałt near Mikołajki in the Mazury Lakes District. Questing adult I. ricinus ticks were collected in the study sites by blanket dragging of vegetation in heterogeneous, deciduous woodland, and, in addition, rodents were carefully examined for feeding larvae and nymphs. Altogether, B. microti was detected in 9 out of 1513 I. ricinus ticks (0.6%) examined by PCR. This included 163 adults (92 females and 71 males), 50 nymphs, and 1300 larvae 3%, 8%, and 0% of which were PCR-positive, respectively. Of 85 A. flavicollis, 374 M. arvalis and 24 M. oeconomus, 1%, 12.8%, and 42% were parasitaemic, respectively, as determined by microscopic examination of blood smears stained with Giemsa. B. microti DNA, extracted from 53 M. arvalis and 5 M. oeconomus and examined by nested PCR, targeting a piroplasm-specific portion of the 18S ribosomal DNA, revealed 72% and 40%, respectively, to be PCR positive. Sequence analysis showed that all PCR-positive samples had rDNA sequences identical (100% homology) to that of the Munich B. microti strain isolated from Mus musculus. The results of this study indicate that the B. microti commonly encountered among Microtus spp. rodents is probably not a zoonotic strain and, therefore, that it is most unlikely to represent a risk to public health in the Mazury Lakes District of North-Eastern Poland.

Animals↗
PubMed2006

Extension of Ixodes ricinus ticks and agents of tick-borne diseases to mountain areas in the Czech Republic.

Along with the shift of the hard tick Ixodes ricinus to higher altitudes observed in the Czech Republic a corresponding shift of tick-borne infections to higher altitudes has been expected. Therefore, I. ricinus ticks, mainly nymphs, were investigated for the presence of tick-borne viruses, tick-borne encephalitis (TBE), Tribec and Eyach, and the spirochaete Borrelia burgdorferi sensu lato in the Sumava and Krkonose Mountains (Czech Republic). The TBE virus and different genospecies of B. burgdorferi s.l. were detected by RT-PCR and PCR, respectively. TBE virus was detected in ticks at 620 and 720 m above sea level (a.s.l.), B. burgdorferi s.l. was detected in ticks up to 1065 m a.s.l. Four genospecies of B. burgdorferi s.l. were identified, B. afzelii, B. garinii, B. burgdorferi sensu stricto, and B. valaisiana. Some nymphs carried multiple Borrelia infections. The conditions of tick-borne agents' distribution and potential epidemiological consequences are discussed.

Altitude↗
PubMed2006

Within-species variability of the response to 20-hydroxyecdysone in peach-potato aphid (Myzus persicae Sulzer).

Phytoecdysteroids have been proposed as new tools for controlling crop pests because of their endocrine disruption and deterrent effects on insects and nematodes. There is increasing evidence of variability between taxa in sensitivity to phytoecdysteroids, but the genetic variability of this sensitivity within species is unknown. However, knowledge about this intraspecies variability is required for predicting evolution of the pest's response to new control methods. We assessed the variability of the response of the aphid Myzus persicae Sulzer, a major agricultural pest, to 20-hydroxyecdysone (20E). We determined the number of nymphs produced by six clones of M. persicae exposed to various concentrations of 20E and the capacity of these clones to detect 20E in choice experiments. High concentrations of 20E significantly decreased the number of nymphs produced for two clones and both increases and decreases in the number of offspring were detected at low concentrations. Two clones significantly avoided food with 20E, while one significantly preferred it, suggesting that 20E does not always act as a deterrent in this species. We conclude that genetic variability in the response to 20E exists in natural populations of M. persicae. The consequences of this finding on the sustainability of control methods using 20E are discussed.

Animals↗
PubMed2006

Differential expression of cytochrome c oxidase subunit III gene in castes of the termite Reticulitermes santonensis.

Social insects such as termites live in colonies in which cooperation is assumed by all individuals developing into castes to which specific tasks are allocated. Little has been reported about molecular aspects underlying termite caste-specific gene expression. Genetic regulation has recently been hypothesized to govern caste-specific traits and physiology in social insects. Cytochrome c oxidase (COX) has been shown to be an interesting candidate for expression study in insects. We used the cytochrome c oxidase subunit III gene (COXIII) that was cloned from mRNA in a lower termite, Reticulitermes santonensis De Feytaud (Isoptera; Rhinotermitidae). The full-length cDNA encodes a protein of 262 amino acids that shows high degree of homology with other insects COXIIIs. Reverse transcriptase-PCR and real-time PCR were performed to compare gene expression between larvae, workers, nymphs and soldiers. Analyses performed on head cDNAs revealed that COXIII is differentially expressed between castes. The level of COXIII is caste-regulated with an increase in workers (approximately 1.9-fold) and nymphs (approximately 2.8-fold) and a decrease in soldiers (0.8-fold) compared to the expression level in larvae (1.0-fold). These results may emphasize the physiological importance of COX in the termite brain at different developmental stages.

Amino Acid Sequence↗
PubMed2006

Energetics of emergence in the cicadas, Cyclochila australasiae and Abricta curvicosta (Homoptera: Cicadidae).

The final moult in cicadas marks a major transition in lifestyle and is a behaviour that makes the cicada vulnerable to predation. Consequently, emergence times are short and, we predict, therefore the rate of energy consumption would be high. Hence, we measured the energetic cost of emergence in Cyclochila australasiae (green grocer) and Abricta curvicosta (floury baker) cicadas during the final moult from nymph to adult cicada. Maximum energy expended whilst emerging was compared between the sexes and species. Even though C. australasiae take longer to emerge than A. curvicosta, the mass-specific cost of emergence is not different between the two species (C. australasiae: 11.34+/-2.55 J g(-1); A. curvicosta: 12.91+/-1.90 J g(-1)). The mass-specific metabolic rates of fully emerged adults of both species are approximately twice those of the nymphs and the maximum metabolic rate during emergence is about 1.5 times higher than the resting metabolic rate of emerged adults. Emergence times, as indicated by rates of oxygen consumption, are longer than expected and probably reflect limitations in the oxygen capacity of the cicadas during moulting.

Animals↗