scholarly journals Host-finding behaviour in the nematode Pristionchus pacificus

2011 ◽  
Vol 278 (1722) ◽  
pp. 3260-3269 ◽  
Author(s):  
Federico D. Brown ◽  
Isabella D'Anna ◽  
Ralf J. Sommer
Keyword(s):  
Galleria Mellonella ◽  
Laboratory Strain ◽  
Host Finding ◽  
Foraging Strategies ◽  
Life History Strategies ◽  
New Approach ◽  
Pristionchus Pacificus ◽  
Defective Mutant ◽  
Ecological Functionality ◽  
La Réunion Island

Costs and benefits of foraging have been studied in predatory animals. In nematodes, ambushing or cruising behaviours represent adaptations that optimize foraging strategies for survival and host finding. A behaviour associated with host finding of ambushing nematode dauer juveniles is a sit-and-wait behaviour, otherwise known as nictation. Here, we test the function of nictation by relating occurrence of nictation in Pristionchus pacificus dauer juveniles to the ability to attach to laboratory host Galleria mellonella . We used populations of recently isolated and mutagenized laboratory strains. We found that nictation can be disrupted using a classical forward genetic approach and characterized two novel nictation-defective mutant strains. We identified two recently isolated strains from la Réunion island, one with a higher proportion of nictating individuals than the laboratory strain P. pacificus PS312. We found a positive correlation between nictation frequencies and host attachment in these strains. Taken together, our combination of genetic analyses with natural variation studies presents a new approach to the investigation of behavioural and ecological functionality. We show that nictation behaviour in P. pacificus nematodes serves as a host-finding behaviour. Our results suggest that nictation plays a role in the evolution of new life-history strategies, such as the evolution of parasitism.

Entomopathogenic nematode host finding: response to host contact cues by cruise and ambush foragers

Parasitology ◽  
1992 ◽  
Vol 105 (2) ◽  
pp. 309-315 ◽  
Author(s):  
E.E. Lewis ◽  
R. Gaugler ◽  
R. Harrison
Keyword(s):  
Entomopathogenic Nematode ◽  
Nematode Species ◽  
Host Finding ◽  
Steinernema Carpocapsae ◽  
Foraging Strategies ◽  
Popillia Japonica ◽  
Search Behaviour ◽  
Search Area ◽  
Steinernema Glaseri ◽  
Host Cues

SUMMARYSearch behaviour of two entomopathogenic nematode species with different foraging strategies was compared by measuring parameters of unrewarded search after contact with host cues. Steinernema glaseri cruises in search of hosts. Steinernema carpocapsae ambushes hosts. Nematodes should respond to contact with relevant host cues by shifting their search from ranging to localized after contact with them. We predicted that cruising foragers rely on chemical cues more heavily than ambushers. These species were also tested for host affinities. Nematodes were tracked by image analysis after exposure to faeces, cuticle or food of either Popillia japonica or Spodoptera exiqua. Steinernema glaseri responded to selected host cues by shifting from ranging to localized search, characterized by decreased locomotory rate, distance travelled, search area and the proportion of the test period spent moving. Steinernema carpocapsae did not respond to host cues. Steinernema glaseri responds to selected chemical host cues for host location, whereas S. carpocapsae does not.

scholarly journals Transcriptional variation and divergence of host-finding behaviour in Steinernema carpocapsae infective juveniles

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Neil D. Warnock ◽  
Deborah Cox ◽  
Ciaran McCoy ◽  
Robert Morris ◽  
Johnathan J. Dalzell
Keyword(s):  
Galleria Mellonella ◽  
Entomopathogenic Nematode ◽  
Gene Families ◽  
Nematode Species ◽  
Host Finding ◽  
Steinernema Carpocapsae ◽  
Differentially Expressed ◽  
Infective Juvenile ◽  
Neuronal Genes ◽  
Sodium Transporter

Abstract Background Steinernema carpocapsae is an entomopathogenic nematode that employs nictation and jumping behaviours to find potential insect hosts. Here we aimed to investigate the transcriptional basis of variant host-finding behaviours in the infective juvenile (IJ) stage of three S. carpocapsae strains (ALL, Breton and UK1), with a focus on neuronal genes known to influence behaviour in other nematode species. Identifying gene expression changes that correlate with variant host-finding behaviours will further our understanding of nematode biology. Results RNA-seq analysis revealed that whilst up to 28% of the S. carpocapsae transcriptome was differentially expressed (P < 0.0001) between strains, remarkably few of the most highly differentially expressed genes (> 2 log2 fold change, P < 0.0001) were from neuronal gene families. S. carpocapsae Breton displays increased chemotaxis toward the laboratory host Galleria mellonella, relative to the other strains. This correlates with the up-regulation of four srsx chemosensory GPCR genes, and a sodium transporter gene, asic-2, relative to both ALL and UK1 strains. The UK1 strain exhibits a decreased nictation phenotype relative to ALL and Breton strains, which correlates with co-ordinate up-regulation of neuropeptide like protein 36 (nlp-36), and down-regulation of an srt family GPCR gene, and a distinct asic-2-like sodium channel paralogue. To further investigate the link between transcriptional regulation and behavioural variation, we sequenced microRNAs across IJs of each strain. We have identified 283 high confidence microRNA genes, yielding 321 predicted mature microRNAs in S. carpocapsae, and find that up to 36% of microRNAs are differentially expressed (P < 0.0001) between strains. Many of the most highly differentially expressed microRNAs (> 2 log2 fold, P < 0.0001) are predicted to regulate a variety of neuronal genes that may contribute to variant host-finding behaviours. We have also found evidence for differential gene isoform usage between strains, which alters predicted microRNA interactions, and could contribute to the diversification of behaviour. Conclusions These data provide insight to the transcriptional basis of behavioural variation in S. carpocapsae, supporting efforts to understand the molecular basis of complex behaviours in nematodes.

scholarly journals Use of an embedded fruit by Nicobar Long-tailed Macaque Macaca fascicularis umbrosus: II. Demographic influences on choices of coconuts Cocos nucifera and pattern of forays to palm plantations

2020 ◽  
Vol 12 (11) ◽  
pp. 16407-16423
Author(s):  
Sayantan Das ◽  
Rebekah C. David ◽  
Ashvita Anand ◽  
Saurav Harikumar ◽  
Rubina Rajan ◽  
...  
Keyword(s):  
Macaca Fascicularis ◽  
Environmental Changes ◽  
Cocos Nucifera ◽  
Food Resource ◽  
Foraging Strategies ◽  
Life History Strategies ◽  
Forest Plantation ◽  
Age Classes ◽  
Patterns Of Use ◽  
Demographic Patterns

Adaptive pressures of human-induced rapid environmental changes and insular ecological conditions have led to behavioral innovations among behaviorally flexible nonhuman primates.  Documenting long-term responses of threatened populations is vital for our understanding of species and location-specific adaptive capacities under fluctuating equilibrium.  The Nicobar Long-tailed Macaque  Macaca fascicularis umbrosus, an insular sub-species uses coconuts Cocos nucifera, an embedded cultivar as a food resource and is speculated to have enhanced its dependence as a result of anthropogenic and environmental alterations.  We explored demographic patterns of use and abandonment of different phenophases of fresh coconuts.  To study crop foraging strategies, we recorded daily entry and duration of forays into coconut plantations.  We divided age-classes into early juvenile (13–36 months), late juvenile (37–72 months), and adults (>72 months) and classified phenophase of coconuts into six types.  Consistent with the theory of life history strategies, late juveniles were found to use a greater number of coconuts, which was considerably higher in an urban troop but marginally higher in a forest-plantation dwelling group.  Except in late juveniles, males consumed a higher number of coconuts than females in the remaining age-classes.  Owing to developmental constraints, juveniles of both types used higher proportion of immature coconuts though adults showed equitable distribution across phenophases.  Pattern of entries to plantations and duration of forays were uniform through the day in the urban troop but modulatory in the forest-plantation group, perhaps due to frequent and hostile human interferences.  Observations corroborating adaptations to anthropogenic disturbances are described. 

scholarly journals Oxygen-induced social behaviours in Pristionchus pacificus have a distinct evolutionary history and genetic regulation from Caenorhabditis elegans

2016 ◽  
Vol 283 (1825) ◽  
pp. 20152263 ◽  
Author(s):  
Eduardo Moreno ◽  
Angela McGaughran ◽  
Christian Rödelsperger ◽  
Manuel Zimmer ◽  
Ralf J. Sommer
Keyword(s):  
Caenorhabditis Elegans ◽  
High Altitude ◽  
Evolutionary History ◽  
Genetic Regulation ◽  
Nematode Species ◽  
Pristionchus Pacificus ◽  
C Elegans ◽  
Oxygen Conditions ◽  
La Réunion Island ◽  
Social Behaviours

Wild isolates of the nematode Caenorhabditis elegans perform social behaviours, namely clumping and bordering, to avoid hyperoxia under laboratory conditions. In contrast, the laboratory reference strain N2 has acquired a solitary behaviour in the laboratory, related to a gain-of-function variant in the neuropeptide Y-like receptor NPR-1. Here, we study the evolution and natural variation of clumping and bordering behaviours in Pristionchus pacificus nematodes in a natural context, using strains collected from 22 to 2400 metres above sea level on La Réunion Island. Through the analysis of 106 wild isolates, we show that the majority of strains display a solitary behaviour similar to C. elegans N2, whereas social behaviours are predominantly seen in strains that inhabit high-altitude locations. We show experimentally that P. pacificus social strains perform clumping and bordering to avoid hyperoxic conditions in the laboratory, suggesting that social strains may have adapted to or evolved a preference for the lower relative oxygen levels available at high altitude in nature. In contrast to C. elegans , clumping and bordering in P. pacificus do not correlate with locomotive behaviours in response to changes in oxygen conditions. Furthermore, QTL analysis indicates clumping and bordering to represent complex quantitative traits. Thus, clumping and bordering behaviours represent an example of phenotypic convergence with a different evolutionary history and distinct genetic control in both nematode species.

Host-finding ability of three entomopathogenic nematode isolates in the presence of plant roots

Nematology ◽  
2003 ◽  
Vol 5 (4) ◽  
pp. 601-608 ◽  
Author(s):  
G. Christopher Cutler ◽  
John Webster
Keyword(s):  
Entomopathogenic Nematodes ◽  
Galleria Mellonella ◽  
Entomopathogenic Nematode ◽  
Petri Dish ◽  
Host Finding ◽  
Plant Roots ◽  
Tomato Root ◽  
Tomato Seedling ◽  
Bean Plants ◽  
Tomato Roots

Abstract The effect of plant roots on the host-finding ability of three isolates of entomopathogenic nematodes (EPN), Heterorhabditis bacteriophora D-H-Da1, Steinernema sp. Dongrae and Steinernema sp. BJ was studied. In Petri dish experiments the overall response of the infective juveniles (IJ) of these isolates differed from one another, but all were attracted to a Galleria mellonella larva and to a tomato seedling when either of these targets was presented with a blank control. The BJ and D-H-Da1 IJ aggregated more around a tomato root than a G. mellonella larva when these targets were presented separately, but showed no preference for a G. mellonella-tomato seedling combination over a blank control. Dongrae IJ showed no preference for a G. mellonella larva or tomato seedling when each was presented simultaneously in the same Petri dish. In experiments in pots of soil, plant roots did not affect the host-finding ability of Dongrae IJ. In contrast, compared to control pots with no roots, roots of bean plants hindered the ability of BJ IJ to infect a G. mellonella larva, but tomato roots increased host-finding by D-H-Da1 IJ. Roots of certain plant species modify the host-finding ability of EPN, but the extent and direction of the response varied with the EPN applied.

scholarly journals An Assessment of Steinernema rarum as a Biocontrol Agent in Sugarcane with Focus on Sphenophorus levis, Host-Finding Ability, Compatibility with Vinasse and Field Efficacy

Agriculture ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 500
Author(s):  
Mateus Salviano Oliveira Silva ◽  
Jorge Franco Maringoli Cardoso ◽  
Maria Elizia Pacheco Ferreira ◽  
Fernando Berton Baldo ◽  
Raphael Satochi Abe Silva ◽  
...  
Keyword(s):  
Galleria Mellonella ◽  
Control Method ◽  
Liquid Fraction ◽  
Entomopathogenic Nematode ◽  
Saccharum Officinarum ◽  
Host Finding ◽  
Alcohol Production ◽  
Field Efficacy ◽  
Sphenophorus Levis ◽  
Sugarcane Pests

In Brazil, countless insect species attack and damage sugarcane (Saccharum officinarum L.), which is an extremely important crop since it is planted on more than 10 million hectares. Among these insects, the sugarcane billbug, Sphenophorus levis (Coleoptera: Curculionidae), is of great importance as the larvae open tunnels in the rhizome of the plant, causing high damage and losses. This insect is attracted mainly to vinasse, which is the liquid fraction generated from the alcohol production and discarded onto the sugarcane fields for fertigation. Toward a novel control method for S. levis, the native entomopathogenic nematode Steinernema rarum (Pam 25) was compared with S. carpocapsae (IL 1) and Heterorhabditis bacteriophora (HBEN01) in respect to their ability to search for larvae of two insect hosts (Galleria mellonella and S. levis) within the cane rhizome. The selected nematode S. rarum was also assessed for rate effects, its survival in vinasse and field efficacy to control sugarcane pests S. levis, Hyponeuma taltula (Lepidoptera, Erebidae) and Leucothyreus alvarengai (Coleoptera: Melolonthidae). Steinernema rarum exhibited superior virulence to G. mellonella and S. levis larvae inserted into the cane rhizomes (75–78% mortality) compared to S. carpocapsae (30–53%) and H. bacteriophora (18–28%). Vinasse affected S. rarum when infective juveniles were suspended in the liquid compost for more than 6 h but did not affect the nematode when kept on the straw and soil treated with the compost. Steinernema rarum tested at 1–3 × 108 infective juveniles/ha on the sugarcane field caused 74.1, 56.3 and 50.6% control of S. levis, L. alvarengai and H. taltula, respectively.

scholarly journals Assessment of rockfall hazards using databases and considering triggering meteorological events

2014 ◽  
Vol 2 (2) ◽  
pp. 1333-1365
Author(s):  
A. Delonca ◽  
Y. Gunzburger ◽  
T. Verdel
Keyword(s):  
Risk Management ◽  
High Frequency ◽  
Meteorological Factor ◽  
Temperature Variations ◽  
New Approach ◽  
Analysis Techniques ◽  
Triggering Events ◽  
The Rich ◽  
La Réunion Island ◽  
Transportation Routes

Abstract. Rockfalls are major and essentially unpredictable sources of danger, particularly along transportation routes (roads and railways). Thus, assessment of their probabilities of occurrence is a major challenge for risk management. From a qualitative perspective, experience has shown that rockfalls occur mainly during periods of rain, snowmelt, or freeze–thaw. Nevertheless, from a quantitative perspective, these generally assumed correlations between rockfalls and their possible meteorological triggering events are often difficult to identify because (i) rockfalls are too rare for the use of classical statistical analysis techniques and (ii) all intensities of triggering factors do not have the same probability. In this study, we propose a new approach to investigate the correlation of rockfalls with rain, freezing periods, and strong temperature variations. This approach is tested on three French rockfall databases, the first of which exhibited a high frequency of rockfalls (approximately 950 events over 11 yr), whereas the other two databases were more common (approximately 140 events over 11 yr). These databases were for (1) the national highway RN1 on La-Réunion Island, (2) a railway in the Bourgogne region, and (3) a railway in the Auvergne region. Whereas a basic correlation analysis is only able to highlight an already obvious correlation in the case of the "rich" database, the newly suggested method appears to detect correlations in the "poor" databases. This new approach, easy to use, leads to identify the conditional probability of rockfall, according to the selected meteorological factor. It will help to optimize risk management in the considered areas with respect to their meteorological conditions.

scholarly journals Deletion of the Alternative Sigma Factor ςB in Staphylococcus aureus Reveals Its Function as a Global Regulator of Virulence Genes

1998 ◽  
Vol 180 (18) ◽  
pp. 4814-4820 ◽  
Author(s):  
Ines Kullik ◽  
Philipp Giachino ◽  
Thomas Fuchs
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Genes ◽  
Laboratory Strain ◽  
Stationary Growth Phase ◽  
Wild Type ◽  
Global Regulator ◽  
Stationary Growth ◽  
Defective Mutant ◽  
Increased Sensitivity ◽  
Type Strains

ABSTRACT A deletion of the sigB operon was constructed in three genetically distinct Staphylococcus aureus strains, and the phenotypes of the resulting mutants were analyzed. Compared to the corresponding wild-type strains, the ΔsigB mutants showed reduced pigmentation, accelerated sedimentation, and increased sensitivity to hydrogen peroxide during the stationary growth phase. A cytoplasmic protein missing in the ΔsigB mutants was identified as alkaline shock protein 23, and an extracellular protein excreted at higher levels in one of the ΔsigB mutants was identified as staphylococcal thermonuclease. Interestingly, mostsigB deletion phenotypes were only seen in S. aureus COL and Newman and not in 8325, which was found to contain an 11-bp deletion in the regulator gene rsbU. Taken together, our results show that ςB is a global regulator which modulates the expression of several virulence factors in S. aureus and that laboratory strain 8325 is a ςB-defective mutant.

scholarly journals Kpi, a chaperone-usher pili system associated with the worldwide-disseminated high-risk cloneKlebsiella pneumoniaeST-15

2020 ◽  
Vol 117 (29) ◽  
pp. 17249-17259
Author(s):  
Eva Gato ◽  
Juan Carlos Vázquez-Ucha ◽  
Soraya Rumbo-Feal ◽  
Laura Álvarez-Fraga ◽  
Juan A. Vallejo ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
High Risk ◽  
Antimicrobial Resistance ◽  
Galleria Mellonella ◽  
Carbapenem Resistant ◽  
Defective Mutant ◽  
Gastrointestinal Colonization ◽  
Sequence Types ◽  
Host Tissues

Control of infections caused by carbapenem-resistantKlebsiella pneumoniaecontinues to be challenging. The success of this pathogen is favored by its ability to acquire antimicrobial resistance and to spread and persist in both the environment and in humans. The emergence of clinically important clones, such as sequence types 11, 15, 101, and 258, has been reported worldwide. However, the mechanisms promoting the dissemination of such high-risk clones are unknown. Unraveling the factors that play a role in the pathobiology and epidemicity ofK. pneumoniaeis therefore important for managing infections. To address this issue, we studied a carbapenem-resistant ST-15K. pneumoniaeisolate (Kp3380) that displayed a remarkable adherent phenotype with abundant pilus-like structures. Genome sequencing enabled us to identify a chaperone-usher pili system (Kpi) in Kp3380. Analysis of a largeK. pneumoniaepopulation from 32 European countries showed that the Kpi system is associated with the ST-15 clone. Phylogenetic analysis of the operon revealed that Kpi belongs to the little-characterized γ2-fimbrial clade. We demonstrate that Kpi contributes positively to the ability ofK. pneumoniaeto form biofilms and adhere to different host tissues. Moreover, the in vivo intestinal colonizing capacity of the Kpi-defective mutant was significantly reduced, as was its ability to infectGalleria mellonella. The findings provide information about the pathobiology and epidemicity of Kpi+K. pneumoniaeand indicate that the presence of Kpi may explain the success of the ST-15 clone. Disrupting bacterial adherence to the intestinal surface could potentially target gastrointestinal colonization.

Host finding behaviour as a predictor of foraging strategy in entomopathogenic nematodes

Parasitology ◽  
1994 ◽  
Vol 108 (2) ◽  
pp. 207-215 ◽  
Author(s):  
P. S. Grewal ◽  
E. E. Lewis ◽  
R. Gaugler ◽  
J. F. Campbell
Keyword(s):  
Filter Paper ◽  
Entomopathogenic Nematodes ◽  
Foraging Strategy ◽  
Host Finding ◽  
Steinernema Feltiae ◽  
Foraging Strategies ◽  
Directional Response ◽  
Sand Column ◽  
Steinernema Glaseri ◽  
Volatile Cues

SUMMARYForaging strategies of eight species of entomopathogenic nematodes were predicted from their response to host volatile cues and dispersal behaviour on 2-dimensional substrates. Positive directional response to chemical cues and similar distances travelled on smooth (agar) or nictation substrates (agar overlaid with sand grains) by Heterorhabditis bacterio-phora, Heterorhabditis megidis, Steinernema anomali, and Steinernema glaseri suggest their cruising approach to finding hosts. The absence of directional response and less distance travelled on nictation substrate, than on smooth agar by Steinernema carpocapsae and Steinernema scapterisci suggest their ambushing mode of foraging. Steinernema feltiae and Steinernema sp. responded directionally to host volatiles, but travelled less distance on the nictation substrate than on smooth agar; the two species also did not nictate. The cruiser species located hosts more effectively in the sand columns, whereas the ambushers were more effective at finding hosts on filter paper. Steinernema feltiae and Steinernema sp. performed equally on filter paper and in the sand column. We conclude that H. bacteriophora, H. megidis, S. anomali and S. glaseri cruise to find hosts, whereas S. carpocapsae and S. scapterisci ambush hosts. Steinernema feltiae and Steinernema sp. are intermediary in the search continuum sharing some characteristics of both ambush and cruise foragers.

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