Ectoparasite-induced lesions in mite pockets of the Yarrow's spiny lizard, Sceloporus jarrovii (Phrynosomatidae).

Histopathological effects of the chigger, Eutrombicula lipovskyana, on the mite pockets of neonatal, juvenile and adult Yarrow's spiny lizard, Sceloporus jarrovii, were investigated. Focal ulcerative dermatitis was noted in all age classes. This reaction was more diffuse in older animals in which penetration as deep as the panniculus occurred. Based on the occurrence of inflammatory reactions in neonatal lizards, S. jarrovii appears capable of recognizing foreign antigens shortly after birth. There was an increased inflammatory response in older lizards that may have been an augmented host sensitivity following repeated exposure to chiggers. Granulomas, which were interpreted as an attempt to isolate the effects of chigger bites, were noted in juveniles and adults. We propose that S. jarrovii does not develop resistance after repeated exposures to E. lipovskyana.     

Prevalence and abundance of Ixodes pacificus immatures (Acari: Ixodidae) infesting western fence lizards (Sceloporus occidentalis) in northern California: temporal trends and environmental correlates.

The prevalence and abundance of immature Ixodes pacificus ticks on western fence lizards (Sceloporus occidentalis) were examined in relation to time of year, host attributes (i.e., age, gender, and presence or absence of blood parasites), and 5 environmental characteristics, including topographic exposure and ground cover substrate, over a 2-year period in northern California. Lizards were infested with subadult ticks from early March until late July or early August, with peak median numbers of larvae and nymphs recorded in late April and early May of both years. Peak larval and nymphal abundances differed between years. The overall ratio of larvae to nymphs on adult male lizards was low, ranging from 0.80 in 1999 to 2.41 in 2000. Such intensive feeding of nymphs versus larvae on these lizards, which are reservoir-incompetent for Borrelia burgdorferi spirochetes, may explain previous observations of decreasing spirochetal infection prevalence from the nymphal to adult stage in northwestern California. Adult male lizards were more likely to be infested with nymphs and harbored greater abundances of larvae and nymphs than adult females. Lizards uninfected with blood parasites had more nymphs than infected lizards. The measured environmental characteristics could explain only a small percentage of the total variation observed in larval prevalence (22%) and in larval and nymphal abundance (12 and 3%, respectively).     

Larval nematodes (Ascarops sp.) in stomach granulomas of the sagebrush lizard, Sceloporus graciosus

Wild populations of the sagebrush lizard (Sceloporus graciosus) are reported as paratenic hosts for third stage larvae of Ascarops sp. Larvae were found in stomach submucosal granulomas which averaged 350 microns in diameter and consisted of histiocytes and layers of fibrocytes. Prevalence of infection was 16% (27 of 170 infected); mean intensity was 3 (1 to 8 nematodes/host). Prevalence was significantly higher in male than female lizards.     

Dispersal of Steinernema glaseri (Nematoda: Steinernematidae) in adult Japanese beetles, Popillia japonica (Coleoptera: Scarabaeidae)

Japanese beetle adults, Popillia japonica, can become infected with and disperse the entomopathogenic nematode, Steinernema glaseri, under laboratory and field conditions. After a 24-h exposure to 10 000 infective juveniles/20 adult beetles, 45% of the beetles died within 4 days post-treatment, but only 59% of these were infected with the nematode. Corresponding control mortality was 6.5%. An average of 238 infective juveniles were produced/beetle. Beetles exposed to 4000 and 10 000 infectives/10 adults carried with them an average of 17 and 59 infectives/adult on external body surfaces respectively. When beetles that had been exposed to 4000 infectives/20 adults were transferred to, and held in, cages containing soil for 2 weeks, up to 89% of the adults died, as did 74% of the P. japonica larvae that were subsequently placed in the cages. When adults that had been exposed to 50 000 infectives/250 beetles in moist sand for 16 h were released into screened cages in the field at soil temperatures of over 25 C, the soil beneath 83% of the cages tested positive for the nematode, using Galleria mellonella larvae as bait, 2 weeks after releasing the beetles. No nematodes were detected in control plots. The potential of infected adult P. japonica for dispersing S. glaseri by flight was investigated by exposing adults to 50 000 infectives/250 beetles, marking and releasing them in the field and recapturing them in lure-baited Japanese beetle traps. Less than 1% of the treated beetles were recaptured, but 33% of these had one or more nematodes in their hemocoels. Accordingly, this approach does not appear to be feasible for large-scale augmentation and dispersal of the nematode using currently developed methods of infection. If improvements in mass-inoculation methods can be made that enable a rapid high percentage of infection while still permitting flight, this concept could be employed to establish new foci of infection or for the introduction of other species of nematodes.     

Susceptibility of Delia radicum to steinernematid nematodes

Isolates of different Steinernema species (S. affine, S. bicornutum, S. feltiae and Steinernema C1) were used in mortality assays with third instar larvae of Delia radicum (L.) (Diptera: Anthomyiidae). The nematode isolates had been obtained by baiting soil regularly grown with cabbage. One isolate (S. feltiae) was the result of a natural infection of a D. radicum puparium. The highest mortality (77%) was obtained with an isolate of S. feltiae (DK1). The isolate DK1 was also used in tests with all larval stages of D. radicum. Mortality around 60% was observed for second and third instar larvae, while first instar larvae showed very low or no susceptibility. Maximum mortality of second and third instar larvae was reached applying only 25 nematodes per larva. Observations of larvae that pupated revealed that some of these puparia contained nematodes. Experiments with hatching puparia showed that a high proportion was infected by nematodes if the flies were prevented from leaving nematode-containing soil. In addition to mortality, the ability of the nematodes to successfully reproduce in the insects was studied. It was found that the species S. feltiae and S. bicornutum reproduced in D. radicum larvae and adults with S. feltiae being the most successful.     

Gastrointestinal helminths of the lizard Chalcides ocellatus from Benghazi, Libya

Chalcides ocellatus, a scincid lizard, sampled during October 1998 to December 1999 from Benina (farmland) and Al-Kueffia (a rocky area) in Benghazi, Libya, was found to harbour three intestinal nematodes, Pharyngodon mamillatus, Thelandros alatus and Parapharyngodon micipsae, and an intestinal cestode, Oochoristica tuberculata. Thelandros alatus, P. micipsae and O. tuberculata were recorded for the first time in C. ocellatus. Parapharyngodon micipsae was detected in C. ocellatus from Benina and O. tuberculata from lizards in Al-Kueffia. The majority (87.6%) of C. ocellatus were infected with helminth parasites and the levels of infection were higher in males than in females but this difference was not significant. Pharyngodon mamillatus recorded the highest number of nematode parasites in C. ocellatus, although there was no relationship between the number of nematode parasites recovered and host density. In lizards infected with the cestode O. tuberculata, males had shorter snout-vent lengths than females. From a total of 153 C. ocellatus, 120 (78.4%) showed single and 14 (9.2%) showed mixed parasitic infections. Mixed infections between different species of nematodes were not observed.     

Effect of the Entomogenous Nematode Nemplectana carpocapsae on the Tachinid Parasite Compsilura concinnata (Diptera: Tachinidae)

The entomogenous nematode Neoaplectana carpocapsae and its associated bacterium, Xenorhabdus nematophilus, could not infect the pupal stage of the tachinid Compsilura concinnata through the puparium. N. carpocapsae had an adverse effect on 1-, 2- and 3-day-old C. concinnata larvae within the armyworm host in petri dish tests. All 1-day-old larvae treated with nematodes died in their hosts, whereas 61% and 69% of 2- and 3-day-old larvae treated with nematodes, respectively, died. However, the survivors developed to adults. Nine to thirty-seven percent of adult tachinids which emerged from nematode-treated soil (50 nematodes/cm²) were infected with N. carpocapsae. The nematode adversely affects C. concinnata directly by the frank infection of the tachinid and indirectly by causing the premature death of the host which results in tachinid death.     

Seasonal dynamics of Skrjabinoptera phrynosoma (Nematoda) infection in horned lizards from the Alvord Basin: temporal components of a unique life cycle

The nematode Skrjabinoptera phrynosoma is a stomach parasite of horned lizards in the genus Phrynosoma. This nematode demonstrates a distinctive life cycle wherein entire gravid females harboring infective eggs exit with lizard feces. Pogonomyrmex spp. harvester ants collect these females and feed them to their larvae, which are the only stages of the intermediate host that can become infected. We hypothesized that the seasonal dynamics of nematode abundance within lizard hosts would be correlated with the seasonal availability of suitable intermediate hosts. To describe seasonal variation of nematode population variables and elucidate the timing of critical events in the parasite life cycle, nematodes were collected from both hosts across three collection periods in the ant-and-lizard activity season of 2008 in the Alvord Basin of southeastern Oregon. Among 3 collection periods, and across the activity season, nematodes were harvested from individual Phrynosoma platyrhinos , and the distribution of developmental categories and body lengths of nematodes was analyzed to determine the seasonal change in nematode population composition. Pogonomyrmex spp. ants were collected in pit-fall traps and dissected to determine infection prevalence. The abundance of non-gravid female and juvenile nematodes collected from lizards' stomachs decreased significantly between the early and late collection period, which was likely a consequence of the sequential conversion of these developmental categories to gravid females. The presence of gravid female nematodes peaked in cloacal and fecal collections during mid-season. The body lengths of male nematodes increased as the activity season progressed, perhaps due to growth, but their abundance remained the same. Smaller juvenile nematodes were present in late-season collections from lizards, possibly indicating new acquisitions from infected ants. We propose that once a set population of male nematodes establishes in lizards' stomachs, newly acquired juvenile nematodes develop into non-gravid females that mate, become gravid females, and exit the lizard mid-season. We additionally suggest that the exit of females may be timed with the peak foraging activity of ant intermediate hosts and access to larval ants in the nests. Infection prevalence in the intermediate host was low, with only 1 of 6,000 dissected harvester ants containing a single larval nematode. The temporal dynamics of S. phrynosoma populations within P. platyrhinos at this northern locale is most likely driven by the seasonal availability of harvester ant intermediate hosts.     

Phocanema decipiens: Pathology in seals

Infective larvae of the anisakine nematode, Phocanema decipiens from cod (Gadus morhua), were fed to harbor seals (Phoca vitulina) and gray seals (Halichoerus grypus). At termination of the experimental infections, 6 of 8 harbor seals were infected with 34(6–64) P. decipiens, while the remaining 2 seals had relatively heavy infections of 250 and 547 nematodes, respectively; 10 of 11 gray seals were infected with 128 (68–229) P. decipiens, but only 2 nematodes were recovered from the 11th seal. Larvae and adults of P. decipiens occurred throughout the gastrointestinal tract, but mainly in the fundic portion of the stomach; the anterior extremities of the nematodes were embedded in mucosa and submucosa. Clusters of adult P. decipiens were associated with ulcerous gastric lesions in harbor seals and raised inflammatory areas in stomachs of gray seals. Singly occurring larvae from challenge transmissions were associated with raised inflammatory areas in the stomachs of both host species. Histological examinations revealed that the lesions and inflammatory areas were eosinophilic granulomata. Anisakis sp. larvae from the viscera of cod were also fed to 1 of the gray seals. Eighty of these larvae were subsequently found in association with a general inflammation in the cardiac area of the stomach in this seal. Natural anisakine infection were surveyed in 16 harbor and 53 gray seals from the Nova Scotia mainland. The natural incidence of P. decipiens was 62(5–177) in harbor seals and 577(11–1694) in gray seals. Clusters of adult P. decipiens were found in association with gastric lesions in 2 juvenile harbor seals; however, in gray seals, the nematodes neither occurred in clusters nor in association with gastric lesions.     

Susceptibility of the Colorado Potato Beetle and the Sugarbeet Wireworm to Steinernema feltiae and S. glaseri

In laboratory tests, larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), and the sugarbeet wireworm (SBW), Limonius californicus (Mannerheim), were exposed to the nematodes Steinernema feltiae Filipjev (Mexican strain) (= Neoaplectana carpocapsae) and S. glaseri Steiner in soil. S. feltiae caused significantly higher mortality in SBW larvae than did S. glaseri, but both nematode species were equally effective against CPB larvae. The minimum concentration of S. feltiae for 100% mortality of CPB larvae after 13 days was 157 nematodes/cm² of soil, and the LC₅₀ based on 6-day mortality was 47.5 nematodes/cm²; in contrast, 100% mortality of SBW larvae was not achieved with even the highest concentration tested, 393 nematodes/cm². CPB adults emerging from nematode-contaminated soil were not infected. In field cage tests, S. feltiae applied to the soil surface at the rates of 155 and 310 nematodes/cm² soil caused 59% and 71% mortality, respectively, of late-fourth-instar spring-generation CPB, and 28% and 29% mortality, respectively, of SBW. No infection was obtained when larvae of summer generation CPB and SBW were placed in the same cages approximately 6 weeks after nematodes were applied to the soil. Inundative soil applications of S. feltiae, though cost prohibitive at present, were effective in reducing caged CPB and SBW field populations.     

Prevalence of the nematode Spauligodon giganticus (Oxyurida: Pharyngodonidae) in neonatal Yarrow's spiny lizards, Sceloporus jarrovii (Sauria: Iguanidae).

Examination of the digestive tracts of 31 field-collected neonatal Sceloporus jarrovii Cope, 1875, estimated to be between 1 day and 2 wk of age revealed a prevalence of 74% (23/31) infection for eggs and/or larvae of the nematode Spauligodon giganticus (Read and Amrein, 1953) Skrjabin, Schikhobalova, and Lagodovskaja, 1960, and a prevalence of 3% (1/31) for the cestode Oochoristica sp. Twenty-two captive-born neonatal Sceloporus jarrovii, no older than 1 day revealed a prevalence of 14% for eggs of Spauligodon giganticus. Substrate licking, a behavior evident soon after birth, apparently is responsible for this almost immediate infection by S. jarrovii.     

Mortality of Immature Houseflies (Musca domestica L.) in Artificial Diet and Chicken Manure after Exposure to Encapsulated Entomopathogenic Nematodes (Rhabditida: Steinernematidae, Heterorhabditidae)

The entomopathogenic nematodes, Steinernema felitae (=bibionis) and Heterorhabditis megidis, were encapsulated in calcium alginate and their efficacy was tested against immature houseflies. Aliquots of capsules (15 ml) containing either 1 000 000, 500 000, 250 000 or 125 000 nematodes were added to 70-ml portions of grassmeal diet containing either eggs of first, second or third instar larvae. After 2 days, the treatment with 1 000 000 encapsulated S. feltiae (=bibionis) had killed 94% of housefly eggs and 90% of first instar larvae. By day 6, both of these mortalities had increased significantly (P 0.005) to 100%. By day 2, in the same medium, 1 000 000 encapsulated H. megidis had killed 71.4% of eggs and 90% of first instar larvae. This increased significantly (P 0.01) by day 6, to 99.2% and 100% respectively. Another experiment was carried out where immature houseflies were placed in chicken manure. The emergence of houseflies as adults was used to measure the effect of the encapsulated nematodes. Depending on the numbers of nematodes and the original stage of the housefly, the treatment with encapsulated S. feltiae resulted in 55-96% reduction in adult housefly emergence, whereas treatment with encapsulated H. megidis resulted in 35-98% reduction in emergence. Finally, when encapsulated nematodes were presented as a bait to adult houseflies, little infectivity was observed.     

Larvae of Elaphostrongylus cervi in a population of free-living red deer in Italy

Hunter-killed red deer (n = 68; Cervus elaphus) harvested from the Italian provinces of Bologna (Emilia Romagna) and Pistoia (Tuscany) (44 degrees 00'N 11 degrees 00'E) from October 2001 to January 2002 were examined for protostrongylid larvae. Twenty-eight animals (41%) had protostrongylid larvae in feces, lungs, and inguinal and iliac lymph nodes. Of these 28 animals, 20 were adults (71%), four were yearlings (14%), and four were calves (14%). Shape, length, width, and the location to the nematodes were consistent with Elaphostrongylus cervi, which has not been previously reported in Italy.     

Survey of pathogens and parasitoids of Popillia japonica (Coleoptera: Scarabaeidae) in northwest Arkansas

The impact of pathogens and parasitoids on the recently established population of Popillia japonica Newman in northwest Arkansas has been unknown. In this study, we quantified the prevalence of natural enemies: Stictospora villani Hays, Ovavesicula popilliae Andreadis and Hanula, Paenibacillus spp. (Dingman), nematodes and parasitic Diptera and Hymenoptera in third instar and adult populations in 2010 and 2011. S. villani was found in 38.4% and 35.5% of larvae in 2010 and 2011, respectively. S. villani was not found in adult beetles. Paenibacillus bacteria were not found in either larvae or adults in either year. In 2010, the microsporidian O. popilliae was not found in larvae but was present in 0.2% of adults. In 2011, 2.6% of larvae were infected with O. popilliae, but the microsporidian was not found in adults. A previously unknown Adelina sp. was found infecting 0.4% of adult beetles in 2010 and 1.3% of larvae in 2011. Nematode infections were found in 1.8% of larvae and 0.1% of adults in 2010 and not found in either life stage in 2011. No parasitic Hymenoptera or Diptera were found in either year. Apparently, pathogens and parasitoids currently provide little control of the Japanese beetle population within northwest Arkansas.     

Control of Codling Moth,Cydia pomonella (Lepidoptera: Tortricidae), with Steinernema carpocapsae: Effects of Supplemental Wetting and Pupation Site on Infection Rate

Infection of cocooned codling moth (cydia pomonella) larvae by the entomopathogenic nematode Steinernema carpocapsae was studied in three field experiments. Factors that varied within or between experiments included method of application, type of substrate containing cocooned larvae, time when nematodes were applied, seasonal effects, and supplemental wetting before or after nematode application. Conventional air-blast sprayer applications of 0.5–5.0 million infective juveniles (IJs)/tree in fall resulted in ca. 30% mortality of larvae in cardboard trap bands, whereas hand-gun application (2 million IJs/tree) produced mortality of ca. 70%. Application in the evening caused higher larval mortality than application in the morning when no supplemental wetting was used after treatments. Morning and evening applications caused equivalent larval mortality when a postwetting treatment was included. In a trial conducted in midsummer, supplemental wetting, either before or after hand-gun application of 1 million IJs/tree, enhanced nematode-produced mortality. Mortality approached 100% if both pre- and postwetting was used. Larvae in exposed cocoons on apple wood were infected at a higher rate (86%) than those on wood in less exposed positions (73%) or in nonperforated cardboard (72%). Mortality rates for larvae in perforated cardboard were intermediate (77%). Application volumes used to deliver nematodes slightly enhanced infection rate of larvae in some substrates but not others. In one trial, parasitism of codling moth by the wasp Mastrus ridibundus (Ichneumonidae) was negatively correlated with nematode infection of codling moth larvae. Dissections showed that ca. 10% of larvae infected by nematodes had been attacked by the wasp.     

Susceptibility of the Carrot Weevil (Coleoptera: Curculionidae) to Steinernema feltiae,S. bibionis,and Heterorhabditis heliothidis

Larvae, pupae, and adults of the carrot weevil (Listronotus oregonensis) were infected and killed by the three entomophagous nematodes (Steinernema feltiae, S. bibionis, and Heterorhabditis heliothidis) under controlled conditions. Third-stage larvae were more susceptible than pupae or adults. S. feltiae and S. bibionis were the most aggressive nematode species, causing larval mortality after 24-48 hours in both continuous and 2-hour contact with nematode suspension. The nematodes multiplied sufficiently in all insects at all stages of development; however, production of infective-stage larvae per host cadaver was variable.     

Spatio-temporal dynamics of the parasitic nematode Anguillicola crassus in Flanders, Belgium

Despite Egusa's earlier warning of the damage that the parasitic nematode Anguillicola crassus could inflict on the European eel Anguilla anguilla, its introduction in Europe was a fact in the early 1980s. Based on an elaborate dataset on Anguillicola crassus infection of 11 river catchments, this paper presents the results of a detailed study on the dispersal of the parasite in Flanders, Belgium, and the host-parasite relationship. In addition, data from 1986 and 1997 are used for comparative purposes, providing a perspective on the temporal infection pattern over 15 yr. The presence of A. crassus in Flanders was first discovered in 1985; 2 yr later a survey revealed a prevalence of 34.1% and a mean infection intensity of 5.5, based on adult nematodes only, and 10 yr later the parasite was present at all 11 sites sampled. Prevalence had increased to 62.5 % but the mean infection intensity had decreased to 3.9 adults per infected eel. Finally, in the year 2000, a third study revealed that A. crassus was present in 139 of 140 investigated sites; a further increase in prevalence to 68.7% and a decrease in mean infection intensity to 3.4 adults per infected eel was observed. When all larval stages were taken into account, mean prevalence amounted to 88.1% and mean intensity to 5.5 adults. The high infection level in Flanders is thought to be the result of restocking with glass eel and yellow eel, both of which are susceptible to A. crassus. The general infection parameters were similar in all 11 river catchments. It is possible that in Flanders both prevalence and mean infection intensity are stabilizing due to density-dependent regulation of the parasite infrapopulation. Fibrotic swimbladder walls were observed, mainly in large eels, and 20% of the total number of nematodes consisted of encapsulated larvae in the surveys of 1997 and 2000; 8 cases of swimbladder regeneration were observed.     

Investigations on the parasitism ofOtiorrhynchus salicicola andO. Sulcatus [Col.: Curculionidae] byHeterorhabditis sp. [Nematoda]

Experiments were conducted to study the efficacy of the insect parasitic nematodeHeterorhabditis sp. (HW79) as a biological control agent ofOtiorrhynchus salicicola. This weevil species is reported as a pest of ornamental plants in Switzerland and Italy. Dipping plastic boxes containing heavily infested cuttings of laurel (Prunus laurocerasus) in a nematode suspension resulted in approximately 100% parasitisation of full-grown larvae, pupae and non-emerged young adults. The average dose resulting from dipping varied between 56,000 and 62,000 nematodes per liter soil. This experiment was run under natural outdoor conditions. In a further outdoor experiment, pottedLigustrum plants were inoculated with eggs ofO. salicicola and later 20,000 infective juvenile nematodes per liter soil were added to the soil surface. The resulting weevil mortality in the treated pots was 78%. In seven greenhouse tests using the same nematode dose in pots with horticultural soil to which weevil larvae had been added, weevil mortality varied between 76% and 100%, the arithmetic average being 90%. These results indicate that Heterorhabditid nematodes may provide an effective means of controllingO. salicicola. In an other experiment usingO. sulcatus larvae, the influence of application time on nematode efficacy was investigated. When nematodes were added a few days before weevil larvae had hatched from the eggs, no parasitic effect was obtained. Nematode applications done shortly after larval hatching however, resulted in complete weevil control. These results are of significance in timing nematode applications in practice.      

Efficacy of soil treatments of entomopathogenic nematodes against the larvae, pupae and adults of Tuta absoluta and their interaction with the insecticides used against this insect

The efficacy of soil treatments of three native entomopathogenic nematodes (Steinernema carpocapsae, S. feltiae and Heterorhabditis bacteriophora) against Tuta absoluta larvae, pupae and adults was determined under laboratory conditions. The effect of three insecticides commonly used against T. absoluta, in the survival, infectivity and reproduction of these nematode strains was also evaluated. When dropped into soil to pupate, soil application of nematodes resulted in a high mortality of larvae: 100, 52.3 and 96.7 % efficacy for S. carpocapsae, S. feltiae and H. bacteriophora respectively. No mortality of pupae was observed and mortality of adults emerging from soil was 79.1 % for S. carpocapsae and 0.5 % for S. feltiae. The insecticides tested had a negligible effect on nematode survival, infectivity and reproduction. No sublethal effects were observed. Infective juveniles that survived to insecticide exposition were able to infect Galleria larvae with no significant differences from the control. The Galleria larvae affected by the three insecticides tested served as suitable hosts for the infection and reproduction of the nematodes. These results suggest that larvae of T. absoluta, falling from leaves following insecticide application, could be suitable hosts for nematodes, thereby increasing their concentration and persistence in the soil.