Variation In Infestation Research Articles

Prevalence, intensity, and attachment sites of larval mites (Acari: Erythraeidae) infesting Erginulus clavotibialis, a Neotropical harvestman (Opiliones: Cosmetidae) from Belize

Larval erythraeid mites of the genus Leptus Latreille, 1796 are common ectoparasites of terrestrial arthropods, including harvestmen (Order Opiliones). In this study, we investigated sexual, ontogenetic, and geographic variation in infestations of the Neotropical cosmetid harvestmen Erginulus clavotibialis (Cambridge, 1904) by larval mites across multiple sampling locations in Belize. We did not observe any significant differences in the prevalence or intensity of mite infestation with respect to sex of the host or between juveniles and adults. However, there was significant variation in the prevalence of infestation between field sites, varying from 18-71%. The overall mean intensity of infestation was 3.2 mites/host. Larval mites exhibited a non-random distribution with respect to attachment sites, with significantly more mites occurring on femur IV. Larval mites were absent from the tarsi of the walking legs and were rarely observed attached to the pedipalps or chelicerae of the harvestmen. Of the ten mites attached to hosts that were examined with SEM, six larvae were found in close association to abandoned attachment cones.

Host-related and environmental factors influence long-term ectoparasite infestation dynamics of mouse lemurs in northwestern Madagascar.

Parasite infestations depend on multiple host-related and environmental factors. In the case of ectoparasites, which are exposed to the environment beyond the host, an impact of climate, expressed by seasonal or yearly variations, can be expected. However, long-term dynamics of ectoparasite infestations are rarely studied in nonhuman primates. We investigated the yearly variations in ectoparasite infestations of two small primates, the gray (Microcebus murinus) and the golden-brown (Microcebus ravelobensis) mouse lemur. For a more comprehensive evaluation, we also analyzed the potential effects of yearly and monthly climatic variation (temperature, rainfall) in addition to habitat, host sex, age, species, and body mass, on ectoparasite infestation. Individuals of both host species were sampled in two study sites within the Ankarafantsika National Park in northwestern Madagascar during several months (March-November) and across 4 years (2010, 2011, 2015, 2016). Our results show significant monthly and yearly variations in the infestation rates of three native ectoparasite taxa (Haemaphysalis spp. ticks, Schoutedenichia microcebi chigger mites, Lemurpediculus spp. sucking lice) and in ectoparasite species richness in both mouse lemur species. In addition, significant impacts of several host-related (species, sex, body mass) and environmental factors (habitat, temperature, rainfall) were found, but with differences in relevance for the different parasite taxa and partly deviating in their direction. Although some differences could be attributed to either permanent or temporary presence of the parasites on the host or to ecological differences between the host species, the lack of specific knowledge regarding the life cycle and microhabitat requirements of each parasite taxon precludes a complete understanding of the factors that determine their infestation dynamics. This study demonstrates the presence of yearly and monthly dynamics in lemur-parasite interactions in tropical, seasonal, dry deciduous forests in Madagascar, which call out for broad ecological long-term studies focusing both on primate hosts and their parasites.

Role of abiotic factors on the seasonal variation in infestation of the major insect pests of rice (Oryza sativa L.) in Odisha

Role of abiotic factors on the seasonal variation in infestation of the major insect pests of rice (Oryza sativa L.) in Odisha

Parasite intensity is driven by temperature in a wild bird

Increasing awareness that parasitism is an essential component of nearly all aspects of ecosystem functioning, as well as a driver of biodiversity, has led to rising interest in the consequences of climate change in terms of parasitism and disease spread. Yet empirical knowledge on the extent and ways in which climatic factors affect parasite prevalence and intensities remains scarce. In an 18-year, multi-site, correlative study we investigated the contributions of weather variables and other factors to spatio-temporal variation in infestation by blowfly parasitic larvae (Protocalliphora spp.) in nests of Corsican blue tits (Cyanistes caeruleus). We found that ambient temperature during the nestling stage is strongly and positively related to parasite load (number of parasites per chick), both across broods when controlling for year, and across years. In addition, annual mean parasite load also increased with minimal spring temperature, and decreased with increasing average temperature in the previous summer. There was no indication of a dependence of parasite dynamics on host dynamics in this system, likely due in part to the wide host range of blowflies that do not solely rely on blue tit hosts. This suggests a major effect of temperature during the blowfly life cycle, with potential implications for blowfly host interactions across their geographical range as climate keeps warming up. Finally, given that ambient temperature increases throughout the breeding season and that blowflies negatively affect survival and recruitment of blue tits, these results also mean that parasites, along with caterpillar availability, can drive selection for breeding date in this system.

Epidemiology and Seasonal Variation of Ixodid Ticks and Piroplasmida Detection in Cattle of Basrah Province, Iraq

Four hundred and twenty cattle belonging to different breed and age groups were investigated for infestation by ticks during the period from October 2018 to September 2019 in Basrah governorate, Iraq . Investigated cattle were found to be infested by four species of hard ticks namely (Hyalomma anatolicum anatolicum, Hyalomma marginatum turanicum Rhipicephalus (Boophilus) annulatus, Rhipicephalu sturanicus) .No significant difference in infestation rate was observed according to the method of cattle raising (X²=0.455, p=0.500),however, seasonal variation in infestation with significant difference was found , higher infestation rate reported in June ( 63.3%) and the lowest was in January (20%) (X² =76.740 ,p = 0.05). In the meantime blood smears samples from the same cattle were also examined by microscopy for hemoprotozoan pathogens .The examination revealed that those cattle are infected by Babesia spp. (27.14%) and Theileria spp.(19.52%). No, significant difference in infection rate was found between male and females, but a significant variation was seen among age groups, however, age group 1-3 years revealed a high rate of infection .Seasonal variation in the infection rates were observed in infected cattle. Higher infection rates of Babesiosis and Theileriosis reported in June (50%) and (36.7%) respectively.

Seasonal pattern of infestation by the carob moth Ectomyelois ceratoniae in pomegranate cultivars

Pomegranate (Punica granatum L.) orchards in the Middle East are typically composed of a mix of different cultivars in which variation in fruit infestation by carob moth Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae) has been observed. However, seasonal variation in infestation and adaptation of the carob moth to this cropping system have not been explored. We monitored the progress of fruit infestation in 10 pomegranate cultivars during the growing season of two consecutive years in pomegranate orchards of Iran. Overall, levels of infestation in fruits were strongly correlated with susceptibility to fruit cracking in pomegranate, so that cracked fruits and cracking-susceptible cultivars were infested the most. However, this pattern changed during the season. Infestation was first observed on cracking-susceptible cultivars. At this point almost all cracked fruits were infested. Towards the end of the season, infestation in uncracked fruits and cracking-resistant cultivars increased. Uncracked fruits seem better overwintering sites for carob moth as under simulated winter conditions, survival of insect larvae in uncracked fruits was >3 times higher than in cracked fruits. Taken together, our data reveal that cracked fruits of pomegranate are the better host during the growing season, while uncracked fruits better sustain carob moth population in winter. It seems therefore advisable not to grow cracking-susceptible and cracking-resistant cultivars together in the same area.

Seasonal variation in infestations by ixodids on Siberian chipmunks: effects of host age, sex, and birth season.

In mammalian hosts, macroparasite aggregation is highly heterogeneous over space and time and among individuals. While the exact causes of this heterogeneity remain unclear, it has mainly been attributed to individual differences in exposure and susceptibility. Although some extrinsic (e.g., parasite availability) and intrinsic (e.g., sex or age) factors are well known to affect infestation patterns, the joint and possibly interacting effects of these factors are poorly understood. Here, we study the infestation of hard ticks (mainly Ixodes ricinus) in a small rodent, the Siberian chipmunk (Tamias sibiricus), introduced to an oak-hornbeam forest in France. We investigate the seasonal variation in infestation according to the sex, age, birth season (spring-born or summer-born), and body weight of individual hosts while controlling for interannual variability. During the 10-year study period, 3421 tick count events were recorded involving 1017 chipmunks monitored by the capture-mark-recapture procedure. Our results reveal a male-biased parasitism in the Siberian chipmunk, which is not consistent among individuals born in different seasons. This sex bias is observed among spring-born juveniles from July to the beginning of hibernation. For adults, this difference becomes apparent along the reproduction period (May-September) for summer-born adults only. These complex interactions between sex, age, and birth season suggest overall that the seasonal variation of tick load is critically linked to the reproductive behavior of this small ground sciurid.

The use of trap captures to forecast infestation by the olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), in traditional olive groves in north-eastern Portugal

A study was carried out during a three-year period (2006 to 2008) in traditional olive groves in the Terra Quente region of north-eastern Portugal to evaluate the potential of two commercially available traps for predicting infestations by olive fly, Bactrocera oleae (Rossi). We used yellow sticky traps baited with pheromone, and McPhail traps baited with diammonium phosphate. The results show that the variation in infestation is explained by captures of adults in both traps. Thus, even if infestation has changed significantly between years as well as groves and olive tree varieties, captures obtained by both types of trap can be valuable indicators of fruit infestation in Terra Quente, and probably in other regions that have a continental Mediterranean climate. The information obtained can enable growers and consultants to time treatments, and so avoid the use of more labour-intensive visual sampling methods.

Eco-Bio-Social Determinants for House Infestation by Non-domiciliated Triatoma dimidiata in the Yucatan Peninsula, Mexico

BackgroundChagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control.Methodology/principal findingsWe investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation.Conclusions/significanceThese results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control.

Technologies for Smart Chemical Control of Broomrape (Orobanchespp. andPhelipanchespp.)

Broomrapes (OrobancheandPhelipanchespp.) are obligate root parasites that spend most of their life cycle in the soil subsurface, making them hard to detect. In these underground developmental stages, broomrapes are highly sensitive to herbicides, and therefore knowledge of the dynamics of their parasitism is essential to precisely apply herbicide for their control. To address these complexities, two approaches have been proposed: (1) estimating the temporal variation in parasitism dynamics and predicting broomrape parasitism on its host by thermal time; (2) characterizing the spatial variation in infestation within and between fields by using a geographical information system and a global positioning system. In addition, the use of molecular markers to identify broomrape infestation (species and amount) in the field can contribute to determining its spatial distribution, which can then be used for site-specific weed management. In this paper, we discuss how technology can be optimized for control of the root-parasitic broomrapes. Special attention is given to the development of integrative approaches. An example of a decision support system for the rational management of Egyptian broomrape in processing tomato is given.

Seasonality and prevalence of the protistan trichomycete Enterobryus halophilus (Ichthyosporea: Eccrinales) in the mole crab Emerita portoricensis

In Puerto Rico the protist Enterobryus halophilus (Ichthyosporea: Eccrinales) has been reported associated with a new host, Emerita portoricensis (Malacostraca: Hippidae). A study on prevalence and abundance in populations of E. halophilus was conducted during 18 mo to determine whether sex-dependent infection exists in Em. portoricensis, as suggested (1958) for the original description of E. halophilus in Em. talpoida. Individuals (1440) of Em. portoricensis were collected and their guts dissected on microscope slides. The thalli of E. halophilus were counted under a microscope with random grid squares. A factorial ANOVA with interaction revealed that the prevalence and the abundance of E. halophilus do not depend on the sex of its host. Furthermore the data indicate that E. halophilus populations undergo seasonal variations in infestation following the population dynamics of the host.

First record of Mothocya melanosticta Schioedte and Meinert, 1884 (Isopoda: Cymothoidae) from Egyptian pinecone soldierfish with special reference to its infestation status

Cymothoidae are cosmopolitan, ubiquitous, and nonspecific parasites of fish of different biotopes causing a significant economic loss to fisheries either by killing and stunting or simply by damaging their hosts. This study represents the first record of Mothocya melanosticta from the Red Sea, with a new host record in Myripristis murdjan (pinecone soldierfish), the other resident species of the fish-parasitic isopod family Cymothoidae in Egypt. The recovered Mothocya melanosticta was of moderate body size (17.7 × 8.2 mm) and had a cephalon with widely truncated rostrum, short pleotelson with uropod rami not extending beyond the telson, and the presence of a small rounded protrusion ranging in size from 0.3 to 0.5 mm on the lateral side of pereonite II. The overall prevalence was 31.25% and it was only found in the branchial cavity. The monthly and seasonal variation in infestation is reported.

The potential of geostatistics and geographic information systems in pest eradication.

Abstract Complex environmental and agricultural problems require geomatics solutions and soft computing applications that combine knowledge, techniques and methodologies from different sources, for decision-support improvement. It has been even more necessary to use those methodologies in order to optimize resources for environmental impact assessments and to reduce costs in quality control programmes. Thus, this work aims to provide topics about recent developments and initiatives related to environmental and agricultural solutions supported by geographic information systems (GIS) and geostatistics methods. A spatial analysis approach enabled the detection of spatial variation in infestations of pest organisms in the field, indicating the possibility of developing strategies to provide more effective control, less environmental impact and sustainability of the agro-ecosystem, consistent with the philosophy of integrated pest management and precision agriculture.

Experimental evolution of resistance against a competing fungus in Drosophila melanogaster

Competition between microorganisms and arthropods has been shown to be an important ecological interaction determining animal development and spatial distribution patterns in saprophagous communities. In fruit-inhabiting Drosophila, variation in insect developmental success is not only determined by species-specific effects of various noxious filamentous fungi but, as suggested by an earlier study, also by additive genetic variation in the ability to successfully withstand the negative impact of the fungi. If this variation represents a direct adaptive response to the degree to which insect breeding substrates are infested with harmful fungi, genetic variation for successful development in the presence of fungi could be maintained by variation in infestation of resource patches with fungi. We selected for the ability to resist the negative influence of mould by maintaining replicated Drosophila melanogaster populations on substrates infested with Aspergillus nidulans. After five cycles of exposure to the fungus during the larval stage, the selected populations were compared with unselected control populations regarding adult survival and reproduction to reveal an evolved resistance against the fungal competitor. On fungus-infested larval feeding substrates, emerged adults from mould-selected populations had higher survival rates and higher early fecundity than the control populations. In the unselected populations, females had higher mortality rates than males, and a high proportion of both females and males appeared to be unable to lay eggs or fertilise eggs, respectively. When larvae developed on non-infested food we found indications of a loss of resistance to abiotic and starvation stress in the adult stage in flies from the selected populations. This suggests that there are costs associated with an increase in resistance against the microbial competitor. We discuss the underlying mechanisms that might have selected for increased resistance against harmful fungi.

Usefulness of Community Participation for the Fine Temporal Monitoring of House Infestation by Non-Domiciliated Triatomines

The irregular presence and low abundance of wild triatomines inside domiciles make their detection more difficult than that of domiciled species, so that vector surveillance and evaluation of Chagas disease transmission risk are more challenging. We compared timed manual searches, considered as the gold standard, with community-based collections, for their efficacy at monitoring domestic and peridomestic infestation by non-domiciliated Triatoma dimidiata, and community-based collection was the most sensitive and cost effective. Scaling up community participation permitted investigation of fine temporal variations in infestation by T. dimidiata in over 700 houses. We confirmed a large seasonal infestation during March-July, but weekly and daily collections showed a rather stochastic pattern of bug presence in the houses, even during this period. These data are of key importance for the successful implementation of vector control, and community participation is a method of choice for sustained monitoring of infestation by non-domesticated triatomines.

Effects of food abundance, age, and flea infestation on the body condition and immunological variables of a rodent host, and their consequences for flea survival

Temporal variation in body condition and immunological variables of animals that harbor parasites may explain patterns of variation in infestation, as well as parasite impact on the host. We emulated such variability in Sundevall's jirds by manipulating food availability and flea infestation in juveniles and adults and examining how these changes affect survival of fleas on their hosts. Body condition of food-restricted jirds deteriorated, but there was no change in their immunological variables. Adult jirds were in better body condition and had higher immunocompetence than juveniles, however there were no significant effects of flea infestation on any of the variables examined. The main effects of flea infestation were a decrease in the response to phytohaemagglutinin injection, and an increase in the negative effects of food restriction on body mass. Flea survival was higher on juveniles, but fleas did not respond to temporal variability in body condition and immunocompetence of the jirds. We concluded that changes in body condition and immune responses due to growth or variability in food abundance are more important than changes caused by the fleas themselves. Flea infestation is more detrimental to jirds when they are not able to compensate for mass loss through increased food consumption.

Relationships between the parasitic mite Spinturnix andegavinus (Acari: Spinturnicidae) and its bat host, Myotis daubentonii (Chiroptera: Vespertilionidae): seasonal, sex- and age-related variation in infestation and possible impact of the parasite on the host condition and roosting behaviour

Host-parasite relationships between the Daubenton's bat, Myotis daubentonii Kuhl, 1817 (Chiroptera: Vespertilionidae), and its haematophagous ectoparasite, the mite Spinturnix andegavinus Kolenati, 1857 (Acari: Spintumicidae), were subjected to analyses based on data gathered during a six-year study (1999-2004) within a single study area in South Bohemia, Czech Republic. Seven hundred and fifty-one Daubenton's bats were examined by screening wing membranes with an intensive light source, resulting in 4,690 recorded mites. Sex, age, weight and reproductive state were evaluated for each bat. A body condition index was calculated as a ratio of weight to forearm length. The seasonal course of mite infestation displayed distinct dynamics with the peak during the lactation and post-lactation periods coinciding with occurrence of the most numerous colonies of Daubenton's bats in the study area. Infestation rates differed between the two sexes, being higher in adult females than adult males. Juvenile bats of both sexes (with no differences between males and females) were the most infested group of all. Pregnant females had a significantly higher parasite load than non-pregnant ones, while no differences in infestation rates were found between lactating and non-lactating females. The analyses of the relationship between parasite load and body condition of bats revealed no common trends for all sex- and age-related groups. Two possible explanations are suggested and discussed: (1) There is no true relationship between the two tested variables and, thus, the significant results were attained due to a random statistical effect. (2) Different underlying causal mechanisms may exist that influence parasite load and, especially, body condition, with respect to the particular sex and age category of bats. The seasonal roosting dynamics of the Daubenton's bat are suggested to be the result not only of changing energetic demands of resident population members, but also of coevolutionary strategies within host-parasite relationships.

Habitat-related variation in infestation of lizards and rodents with Ixodes ticks in dense woodlands in Mendocino County, California.

During the spring and early summer of 2002, we examined the relative importance of Borrelia-refractory lizards (Sceloporus occidentalis, Elgaria spp.) versus potential Borrelia burgdorferi sensu lato (s.l.)-reservoirs (rodents) as hosts for Ixodes pacificus immatures in 14 woodland areas (six oak, five mixed oak/Douglas fir, and three redwood/tanoak areas) distributed throughout Mendocino County, California. Lizards were estimated to serve as hosts for 93-98% of all larvae and > or =99.6% of all nymphs infesting lizards or rodents in oak woodlands and oak/Douglas fir sites in the southern part of the county. In redwood/tanoak woodlands and oak/Douglas fir sites in northern Mendocino County, the contribution of rodents to larval feedings reached 36-69% but lizards still accounted for 94-100% of nymphal bloodmeals. From late April to mid-June, I. pacificus larvae were recovered from 95 to 96% of lizards and dusky-footed woodrats (Neotoma fuscipes) and from 59% of Peromyscus spp. mice. In contrast, 99% of lizards but few woodrats (15%) and none of the mice were infested by nymphs. Comparisons of tick loads for 19 lizard-Peromyscus spp. mouse pairings, where the lizard and mouse were captured within 10m of each other, revealed that the lizards harbored 36 times more larvae and >190 times more nymphs than the mice. In oak woodlands, loads of I. pacificus larvae decreased from late April/early May to late June for S. occidentalis lizards but increased for Peromyscus spp. mice. We conclude that the relative utilization of Borrelia-refractory lizards, as compared to rodents, by I. pacificus larvae was far higher in dry oak woodlands than in moister habitats such as redwood/tanoak and oak/Douglas fir woodlands in northern Mendocino County. Non-lizard-infesting potential enzootic vectors of B. burgdorferi s.l. (I. angustus and I. spinipalpis) were recorded from rodents in three of six oak woodland areas, two of five oak/Douglas fir woodland areas, and two of three redwood/tanoak woodland areas.

Cause of death in blue penguins (Eudyptula m. minor) in North Otago, New Zealand

I necropsied 213 blue penguins (Eudyptula m. minor) collected during 1994 to 1998, mainly from Oamaru Harbour and urban areas, the remainder from sites south to Otago Peninsula. The dominant categories were malnutrition (16%), and cause of death (15%). Where malnutrition was involved, it was usually unclear whether it was the direct cause of death or the consequence of undiagnosed natural disease or infestation. Twenty five per cent of birds died from animal attacks. Aspergillosis was the commonest natural disease (3.3%). Endoparasitism was uncommon (1.3%). This study provides significant evidence of geographic variation in infestation of blue penguins.

Variations in parasitic caligid infestations on farmed salmonids and implications for their management

In order to evaluate the performance of various sea lice management strategies, data sets from a number of salmon farm sites on the west coast of Ireland were examined. These data sets were collected as part of the ongoingNational Sea Lice Monitoring Programme in Ireland. Temporal and geographic variations in infestations of Lepeophtheirus salmonis and Caligus elongatus are described from two species of farmedsalmonids, Salmo salar L. and Oncorhynchus mykiss Walbaum. Patterns of lice transmission, both within and between fish populations, are discussed and environmental and biotic influences considered. Clear differences in infestation parameters, which persist over a number of seasons, are identified between sites. Where infestation parameters are observed to change over successive seasons, these are linked to changing husbandry practices.