One season of pasture exposure fails to induce a protective resistance to cyathostomes but increases numbers of hypobiotic third-stage larvae

The development of acquired resistance to cyathostome challenge after 1 season's exposure to a cyathostome-contaminated pasture was investigated using 17 parasite-naive ponies, which were 2-3 yr of age. These were divided into 3 groups: 1 to graze a cyathostome-contaminated pasture for 4 mo (exposed ponies), 1 to graze a "clean" pasture not previously grazed by parasitized animals (nonexposed ponies), and 1 group to remain in the barn under helminth-free conditions (parasite-free ponies). After pasture exposure all ponies were housed in stalls in the barn dewormed with ivermectin (200 micrograms/kg) and oxibendazole (100 mg/kg), a treatment that eliminated most cyathostomes encysted in the mucosa as well as all luminal parasites, on the basis of necropsies of 5 animals, after 17 days. Remaining ponies were challenged with 100,000 cyathostome-infective third-stage larvae (L3) per os 3 wk after anthelmintic treatment. Necropsies were performed 7 wk after the challenge. Total cyathostome burdens (luminal plus encysted stages) were not significantly different among any of the groups. However, a significantly higher percentage of hypobiotic early L3 (EL3) and a lower percentage of adults were found in exposed ponies. This observation supports the hypothesis that resistance acquired through exposure promotes cyathostome hypobiosis. This increase in EL3 in exposed ponies was associated with a significant increase in weight of cecum and ventral colon biopsies.     

Gastrointestinal helminths of ponies in Louisiana: a comparison of species currently prevalent with those present 20 years ago

A survey in Louisiana of gastrointestinal helminths recovered at necropsy from 117 ponies with minimal exposure to anthelmintics between 1989 and 2000 is compared with a survey conducted 20 yr earlier in the same region. An objective of this study was to determine whether species diversity has been affected by the advent and use of the macrocyclic lactone (ML) parasiticides and by the increased anthelmintic pressure on the helminth species infecting the general equine population. Twenty-six cyathostome species and 8 strongyle species were recovered. Two cyathostome species that were not found before, Cylicostephanus asymetricus and C. bidentatus, and 1 species of large strongyle, Oesophagodontus robustus, were added to the list of species found in Louisiana. All cyathostome and large strongyle species found previously were still present. But prevalences and intensities were significantly reduced for almost all large and small strongyle species. Prevalences and intensities of Oxyuris equi adults and larvae were reduced, whereas the prevalence of Parascaris equorum remained constant. The tapeworm Paranoplocephala mamillana was added to the list of parasite species found in Louisiana. Anoplocephala perfoliata remained the most common cestode. This species was found at the same level of intensity but increased slightly in prevalence. Anoplocephala magna was found less frequently than previously. The overall diversity of species remained reatively unchanged. The reasons for the differences in intensity and prevalence of strongyles between these 2 periods are unknown but might be related to the development and use of the broad-spectrum ML anthelmintics in the intervening period, a difference in the population of equids surveyed, different techniques used to identify the parasites, or differences in numbers of parasites identified (or to all).     

Seasonal transmission of gastrointestinal parasites of equids in southern Louisiana.

Parasite-naive pony foals were used as sentinels to monitor transmission of gastrointestinal parasites of equids in Louisiana during 4 seasons of the year. Two annual periods were studied, 1988-1989 and 1992-1993. Two or 3 foals each season were turned out to graze a contaminated pasture along with resident parasitized mares and their foals. After a grazing period of 8 wk, sentinel ponies were held in a parasite-free box stall for a period of 6 wk to allow parasites to develop, thus enhancing the evaluation of hypobiotic stages. Following this holding period, necropsies were performed for complete parasite recoveries. Data show that transmission of large and small strongyles occurs during all seasons in southern Louisiana, with highest levels of transmission occurring in the winter and only minimal transmission taking place in the summer. Numbers of mucosal cyathostomes, as well as total cyathostome numbers, were highest in the winter, and luminal cyathostome numbers were highest in the spring. Transmission of Anoplocephala perfoliata and Parascaris equorum occurred during all seasons of the year, although numbers of P. equorum were reduced in spring 1989 and 1993. Gasterophilus intestinalis instars were recovered from fall and winter sentinels only. Oxyuris equi L4 were found all seasons 1 yr, but only during the fall and winter of the final year.     

Prevalence and biodiversity of helminth parasites in donkeys from South Africa

Seven donkeys (Equus asinus) from North-West and Mpumalanga Provinces in South Africa were examined at necropsy. Quantitative samples were collected from the gastrointestinal tract for recovery of helminth parasites from the stomach, small intestine, cecum, ventral colon, dorsal colon, descending colon, and cranial mesenteric artery. Fifteen genera and 29 species of helminths were identified comprising 27 species of nematodes in the Ascarididae, Atractidae, Habronematidae, Onchocercidae, Oxyuridae, and Strongylidae; 1 species of cestode in the Anoplocephalidae; and 1 species of trematode in the Paramphistomatidae. In addition, 2 species of oestrid fly larvae in the Gastrophiliidae were identified. The most abundant group in number of species was the cyathostomes (small strongyles) and, of these, Cyathostomum montgomeryi, Cylicocyclus sp. (a), and Cylicostephanus minutus were the most numerous. The most prevalent cyathostomes were C. montgomeryi and Cylicocyclus sp. n. (a). Strongylus vulgaris was the most abundant and prevalent large strongyle species. The occurrence of small strongyle species and their prevalences in this study are compared with 3 other studies on donkeys in Africa.     

Occurrence of Gasterophilus intestinalis and some Parasitic Nematodes of Horses in Sweden

A survey was performed on the occurrence of some internal parasites in 461 horses (1–30 years old) slaughtered from October 1992 to September 1993 at the Linköping abattoir in central Sweden. Macroscopical examination was carried out specifically for parasites of the tear ducts and conjunctival sacs of the eyes, and of selected parts of the alimentary tract and car-dio-vascular system. The following parasites were found in selected parts of the large intestine: encapsulated cyathostome larvae (in 35.6% of the horses), and mature strongyle worms (17.4%); in the stomach: Gasterophilus intestinalis (12.3% during October-June) and Habronema muscae (1.1%); and in the conjunctival sac: Thelazia lacrymalis (3.1%). Significantly more encapsulated cyathostome larvae were found during January to June than during other times of the year, and horses aged 1–5 years harboured significantly more larvae than older horses. Severe damage to the cranial mesenteric artery and its main branches was noticed in 16 (6.1%) out of 263 horses specifically examined. However, the 4th stage larva of Strongylus vulgaris was only recovered in 6 (2.3%) of the horses. Quantitative and qualitative faecal egg counts were done on 412 and 384 of the horses, respectively. Eggs of strongyles, Parascaris equorum and Strongyloides westeri were found in 78.1%, 1.9% and 0.2% of the faecal samples, respectively. Highest prevalence of strongyle eggs was found during July to September. Third stage larvae of the following nematodes were recovered from faecal cultures: subfamily Cyathostomum sensu lato (78.1%) Triodontophorus spp. (6.5%), Strongylus vulgaris (3.6%), Trichostrongylus axei (1.3%), while Gyalocephalus sp., Oesophagodontus sp., Poteriostomum sp. and Strongylus edentatus each comprised less than 0.5%.     

Detection and semi-quantification of Strongylus vulgaris DNA in equine faeces by real-time quantitative PCR

Strongylus vulgaris is an important strongyle nematode with high pathogenic potential infecting horses world-wide. Several decades of intensive anthelmintic use has virtually eliminated clinical disease caused by S. vulgaris, but has also caused high levels of anthelmintic resistance in equine small strongyle (cyathostomin) nematodes. Recommendations aimed at limiting the development of anthelmintic resistance by reducing treatment intensity raises a simultaneous demand for reliable and accurate diagnostic tools for detecting important parasitic pathogens. Presently, the only means available to differentiate among strongyle species in a faecal sample is by identifying individual L3 larvae following a two week coproculture procedure. The aim of the present study is to overcome this diagnostic obstacle by developing a fluorescence-based quantitative PCR assay capable of identifying S. vulgaris eggs in faecal samples from horses. Species-specific primers and a TaqMan probe were designed by alignment of published ribosomal DNA sequences of the second internal transcribed spacer of cyathostomin and Strongylus spp. nematodes. The assay was tested for specificity and optimized using genomic DNA extracted from identified male worms of Strongylus and cyathostomin species. In addition, eggs were collected from adult female worms and used to evaluate the quantitative potential of the assay. Statistically significant linear relationships were found between egg numbers and cycle of threshold (Ct) values. PCR results were unaffected by the presence of cyathostomin DNA in the sample and there was no indication of PCR inhibition by faecal sources. A field evaluation on faecal samples obtained from four Danish horse farms revealed a good agreement with the traditional larval culture (kappa-value=0.78), but with a significantly higher performance of the PCR assay. An association between Ct values and S. vulgaris larval counts was statistically significant. The present assay can reliably and semi-quantitatively detect minute quantities of S. vulgaris eggs in faecal samples.     

Seasonal changes of gastrointestinal nematode populations in yearling beef cattle in Louisiana with emphasis on prevalence of inhibition in Ostertagia ostertagi

Investigation of seasonal changes in the composition of nematode populations, principally Ostertagia oslertagi, was conducted over 3 years at three locations in Louisiana. This is the most commonly occurring parasite of cattle in the state. Naturally infected yearling cattle were killed monthly over extended periods and tracer calves were grazed for monthly intervals from late autumn to summer at two locations in 1978–1979. Major objectives were to determine seasonal incidence of common gastrointestinal nematodes and for O. ostertagi, in particular, the time period during which larval inhibition was prevalent, circumstances under which larvae were conditioned to inhibition, and the duration of inhibition. Small numbers of inhibited O. ostertagi were recovered between November and February. Large numbers were found initially in March and increased numbers in April and May. Both normally developing and inhibition prone larvae were acquired during late winter-early spring, with the proportion of the latter being more prevalent in April and May. Evidence from tracer calves indicated that few O. ostertagi larvae were acquired after early June. Large burdens of inhibited larvae persisted in yearling cattle through summer; numbers of developing larvae and adults were minimal. Maturation of inhibited larvae occurs from August to October and in one instance was associated with cases of clinical parasitism. Factors responsible for inhibition were not defined, but increasing temperatures of late winter-early spring, host resistance, and density-dependence of populations were considered. Other abomasal genera were most prevalent in spring while intestinal genera were most common during autumn through spring.     

Flower herbivory and seed predation in Silene vulgaris (Caryophyllaceae): effects of pollination and phenology

Pollination and seed predation were studied in Silene vulgaris populations during two seasons, one with much lower pollinator abundance than the other. Among the pollinators, noctuid moths of the genus Hadena also acted as seed predators. Nectar-foraging female moths oviposited in flowers, and their larvae consumed flowers and seed capsules.
Despite a lower percentage of pollinated flowers in the year of low pollinator abundance, similar numbers of flowers set fruit in both years, because fewer flower buds and flowers were eaten by Hadena larvae during the year of low pollinator visitation. The number of seed capsules preyed upon was also lower in the year with low pollinator abundance, resulting in a higher seed set. The positive correlation between the percentage of pollinated flowers and the percentage of seed capsules destroyed was also observed when comparing flowers opening in different parts of the season.
Early flowering plant individuals had the same pollination success but suffered higher seed predation than late flowering ones. Selection for maximized pollination success through synchronous flowering, is probably the main reason for the compressed flowering period in 5. vulgaris , but the high level of predation early in the season may further increase the reproductive success of synchronous flowering individuals.     

Prevalence and abundance of equine strongyles (Nematoda: Strongyloidea) in tropical Australia

A postmortem survey of 57 horses in tropical northern Queensland revealed 41 (89%) infected with intestinal strongyles. Thirty-five strongyle species (8 large strongyles and 27 small strongyles [Cyathostominae]) were recorded of which 9 species are reported from Australia for the first time. The 14 most prevalent small strongyles were Cyathostomum catinatum (in 76% of horses), Cyathostomum coronatum (65%), Cyathostomum pateratum (33%), Cyathostomum labiatum (30%), Cylicostephanus calicatus (70%), Cylicostephanus longibursatus (67%), Cylicostephanus goldi (43%), Cylicostephanus minutus (26%), Cylicocylus nassatus (67%), Cylicocyclus leptostomus (41%), Cylicocylus insigne (41%), Cylicocyclus radiatus (33%), Cylicocyclus brevicapsulates (22%), and Poteriostomum imperidentum (24%). The remaining cyathostomes were each found in less than 15% of horses. The 4 most common large strongyles were Triodontophorus serratus (30%), Strongylus vulgaris (28%), Strongylus equinus, and Strongylus edentatus (both 22%). The number of species of small strongyles per horse showed a marked variation (mean 10.3, range 2-21) but bore no relationship to either the total number of strongyles per horse, age, sex, and breed of horse, or season. Total number of strongyles per horse (mean 15,890, range 20-165,000) was less than in recent surveys in Europe and the U.S.A. Most horses had low worm burdens, whereas a very small number were heavily infected. Ninety-seven per cent of the total strongyle counts were small strongyles. Strongylus species contributed just over 1%. Small numbers of large strongyles per horse were usual with T. serratus (mean 570), S. vulgaris (mean 330), and S. equinus (mean 330) the most numerous.(ABSTRACT TRUNCATED AT 250 WORDS)     

Feeding of an Iberian stream cyprinid assemblage: seasonality of resource use in a highly variable environment

Food resource use by seven cyprinids from an Iberian stream was analysed over 9 months. Differences in food resource use were found both between species and within species between seasons. Plant material was a more important food for carp, nase, goldfish and barbel than for gudgeon, roach and chub, irrespective of the season. Chironomid larvae were the staple animal food for the former five species throughout the year. Roach and chub, especially the latter, displayed large seasonal variations in prey use, with chironomid larvae only being important during autumn. Ephemerellid nymphs and ephemeropteran imagos dominated the animal diet of chub during spring and summer, respectively. Dipteran adults and Formicidae were the most important prey for roach during spring and summer, with other common prey being ephemerellid nymphs and hydropsychid larvae. Food resource overlap among the three dominant species (roach, barbel and chub) displayed a large seasonal variation. High overlaps were observed during autumn when these species used the same resources. During summer overlaps were much lower with each species specialising on different prey. The remaining less abundant species had large diet overlaps amongst themselves and with barbel, over all seasons. It is suggested that morphological constraints, habitat partitioning and temporal changes in food resource limitation may be involved in producing these patterns of food resource use.     

No overlap in song repertoire size between yearling and older Starlings Sturnus vulgaris

We recorded the song of 25 male Starlings Sturnus vulgaris to investigate differences in song characteristics between yearling and older males. Older males had significantly larger repertoire sizes and sang significantly longer average song bouts than yearling males. Since older males had almost twice as large a repertoire size as yearling males and since there was no overlap in repertoire size between yearling and older males, our data indicate that the repertoire size of Starlings increases after the first year of life. The largest difference between yearling and older males occurred in the 'variable song types' which are the song types containing most of the heterospecific imitations sung in a song bout.     

Winter survival of immature instars of Mansonia indubitans Dyar & Shannon and Mansonia titillans Walker (Diptera: Culicidae), in Buenos Aires, Argentina

We conducted a whole year research on the ecology of Mansonia indubitans and Ma. titillans in Macáes Pond, Costanera Sur Reserve, Buenos Aires, Argentina. The usage of different floating plants by immature instars and their overwintering was analyzed. The percentage of usage of the available floating macrophytes (Pistia, Limnobium, and Salvinia) by the larvae and pupae was studied. Also, we defined positivity (P+) as the percentage of plants with immature instars for each plant genus on a monthly basis. Ma. immature instars were captured throughout the year and Pistia was the resource most commonly exploited by the mosquitoes. The percentage of fourth-instar larvae and pupae on Pistia roots with respect to total immature instars captured was assessed on a monthly and seasonal basis. The proportion of fourth-instar larvae and pupae from both species of Mansonia on water lettuce roots, showed significant differences between months and seasons. Our results suggest that the populations of Ma. indubitans and Ma. titillans in Macáes Pond, survive during winter mainly as fourth-instar larvae.     

Seasonal and demographic factors influencing gastrointestinal parasitism in ungulates of Etosha National Park

Host-parasite dynamics can be strongly affected by seasonality and age-related host immune responses. We investigated how observed variation in the prevalence and intensity of parasite egg or oocyst shedding in four co-occurring ungulate species may reflect underlying seasonal variation in transmission and host immunity. This study was conducted July 2005-October 2006 in Etosha National Park, Namibia, using indices of parasitism recorded from 1,022 fecal samples collected from plains zebra (Equus quagga), springbok (Antidorcas marsupialis), blue wildebeest (Connochaetes taurinus), and gemsbok (Oryx gazella). The presence and intensity of strongyle nematodes, Strongyloides spp. and Eimeria spp. parasites, were strongly seasonal for most host-parasite combinations, with more hosts infected in the wet season than the dry season. Strongyle intensity in zebra was significantly lower in juveniles than adults, and in springbok hosts, Eimeria spp. intensity was significantly greater in juveniles than adults. These results provide evidence that acquired immunity is less protective against strongyle nematodes than Eimeria spp. infections. The seasonal patterns in parasitism further indicate that the long dry season may limit development and survival of parasite stages in the environment and, as a result, host contact and parasite transmission.     

In vitro induction of lymphocyte responsiveness by a Strongylus vulgaris-derived mitogen

Proliferation in vitro of peripheral blood lymphocytes both from horses infected with Strongylus vulgaris and from helminth-free ponies was observed in the presence of extracts of the fourth and fifth stage larvae and adults of S. vulgaris. In addition, S. vulgaris extracts induced transformation in cultures of peripheral blood lymphocytes from sheep and dogs and in mouse spleen cell cultures. Nylon wool non-adherent, T cell enriched fractions of lymphocytes from both mice and horses were stimulated by the S. vulgaris larval mitogen while no proliferation was observed in cultures containing nylon wool adherent, B cell enriched fractions. Macrophage co-operation appeared not to be necessary for S. vulgaris mitogen-induced transformation of spleen cells. The S. vulgaris mitogen stimulated a subpopulation of mouse spleen cells different from those responsive to PHA, Con A and LPS. These cells might be T helper cells since B cells were stimulated to proliferate in the presence of both T cells and S. vulgaris larval mitogen. In addition, the supernatant of in vitro cultured larvae of S. vulgaris induced slight, but significant transformation of equine peripheral blood lymphocytes. Therefore, it is possible that the S. vulgaris mitogen released by both viable parasites and degenerating larvae might induce T cell dependent production of immunoglobulin in vivo and account for the beta-globulinaemia, of which IgG(T) is a major component, in S vulgaris infected horses.     

Growth and size of Triturus vulgaris and T. cristatus (Amphibia) in different parts of Norway

The growth and size of the newts, Triturus vulgaris (L.) and T. cristatus (Laurenti) in different parts of Norway (+ Jämtland, Sweden) were studied. Age was estimated from skeletal growth marks, size-frequency histograms and, for the males, from the number of testis lobes.
On average, the T. vulgaris Larvae in central Norway and Jämtland are smaller than those in southeastern Norway, although in good localities, at the same altitude, they are of approximately the same size and complete their development already within 2½–3 months. Larvae living in eutrophic habitats are larger than those in oligotrophic-dystrophic habitats. In bog habitats at similar times of year the T. cristatus larvae from central Norway are about the same size as those from similar habitats in southwestern and southeastern Norway, but somewhat smaller than those from eutrophic ponds in the Oslofjord area.
No significant differences in the mean size of adult T. vulgaris from southeastern Norway and from central Norway were found. The maximum lengths attained were recorded from central Norway, however. In eutrophic habitats T. vulgaris adults BK usually larger than those in oligotrophic/dystrophic habitats.
In southeastern Norway, where growth is rapid, T. vulgaris may become sexually mature when 2+ yr-old, in central Norway usually a year later, in Jämtland. on average, still later, and in their northernmost locality (Vefsn) they probably do not breed until 5+ or 6+ yr-old.
On average, T. cristatus adults from southeastern Norway are slightly larger than those from central Norway, and may become mature at 2+ yr-old. compared with 4 + yr-old, at the earliest, in the latter area. The differences in the growth rates of both larvae and metamorphosed stages, of both species, most probably represent a response to climatic differences, although biotope quality is also an important factor.     

Species-specific identification of equine cyathostomes resistant to fenbendazole and susceptible to oxibendazole and moxidectin by macroarray probing

Cyathostome populations in horses on two farms located in central Italy with a history of fenbendazole (FBZ) resistance were investigated with the Faecal Egg Count Reduction Test to evaluate the susceptibility to oxibendazole and moxidectin. Faecal eggs were collected pre- and post-treatment on each farm and molecularly examined with a Reverse Line Blot (RLB) assay able to unequivocally detect and identify 13 cyathostome species. Resistance to FBZ was confirmed on both farms, while oxibendazole and moxidectin demonstrated 97% and 100% efficacy, respectively. Overall eight species of cyathostomes (Coronocyclus labiatus, Cylicocyclus ashworthi, Cylicocyclus nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, Cylicostephanus goldi, Cylicostephanus calicatus and Cylicocyclus insigne) were identified in pre-treatment samples. Coronocyclus labiatus and C. goldi were identified after treatment with FBZ while C. calicatus and C. labiatus were shown to be <100% susceptible to oxibendazole. These data confirm that resistance to benzimidazoles is established in cyathostome populations from horse farms in Italy and that they are susceptible to moxidectin. The oxibendazole has been successfully demonstrated for the first time as effective against Italian populations of cyathostomes resistant to other benzimidazoles. The RLB assay herein used showed to be useful to study the distribution of these parasitic populations at species level under field conditions and could represent a powerful tool in broader investigation of drug resistance in horse farms from several countries.     

An ecological study of the macrophytic vegetation of the Doodhadhari Lake,Raipur, M. P., India 1. Distribution and seasonal change in aquatic plants

Summary The distribution of aquatic plants in Doodhadhari lake, Raipur, M.P., India was studied by establishing eight stations. Permanent belt transects were run from all these eight stations every month for a year to assess the seasonal change in vegetational composition. Each transect was taken from the shore to the maximum depth. A contour survey was made and the total area during different seasons were determined. The fluctuation of water level was marked almost every fortnight for a year. The percentage frequency and percentage cover of different species were found to exhibit significant changes during different seasons. Except a few submerged aquatic plant species which are perennial all other species appear and disappear as the seasons progress. The perennial species which are not much affected by the seasonal change are heavily eaten by cattles. The pattern of succession has been outlined after evaluating the changes.     

大针茅草原蛴螬群落特征研究

内蒙古典型草原的主体植被类型——大针茅(Stipa grandis)草原中,有蛴螬4科9种．构成大针茅草原蛴螬群落的4个科中,以鳃金龟科种类数、个体数为最多,主要种群的重要值排序为黑皱鳃金龟、东方绢金龟、马铃薯鳃金龟及弓斑常丽金龟．几种蛴螬在发生上大致呈3种类型：春季和秋季大量发生．如东方绢金龟;一年中密度波动较小,如弓斑常丽金龟;秋季大量发生,如黑皱鳃金龟和马铃薯鳃金龟．大针茅草原蛴螬群落的多样性特征在于秋季群落多样性和物种的丰度较高,而夏季相对较低．春季蛴螬群落种群丰度较高,但群落结构相对较单调．     

Role of the eosinophil in serum-mediated adherence of equine leukocytes to infective larvae of Strongylus vulgaris.

The adherence of equine leukocytes to Strongylus vulgaris infective larvae (L3) in the presence of normal and immune sera was examined in vitro. Immune sera promoted adherence of buffy coat cells from ponies with S. vulgaris-induced eosinophilia (eosinophilic ponies) to S. vulgaris L3. However, eosinophils in the buffy coat cells were the predominant adherent cell type. Studies using leukocyte populations enriched for eosinophils, neutrophils, and mononuclear cells from eosinophilic ponies support the observations using buffy coat cells that eosinophils were the main effector cells. Adherent eosinophils from eosinophilic ponies immobilized L3. Neutrophils were less adherent and did not immobilize L3. Mononuclear cells failed to adhere. Normal eosinophils from strongly-naive ponies did not immobilize S. vulgaris L3 in the presence of immune serum, suggesting the in vivo activation of eosinophils in eosinophilic animals. Immune serum promoted less adherence of buffy coat cells to Strongylus edentatus or mixed species of Cyathostominae L3, suggesting that the serum-mediated cellular adherence phenomenon was species-specific. Normal serum promoted less cellular adherence to S. vulgaris L3 than immune serum. The adherence mediated by normal serum was removed by heat inactivation, suggesting that this nonspecific phenomenon was a complement-mediated reaction. Immune globulins promoted reactions similar to that seen using heat-inactivated immune serum, whereas normal globulins did not promote adherence. Immune globulins absorbed with pieces of S. vulgaris adult worms did not promote the adherence of buffy coat cells to S. vulgaris L3, suggesting that adult and L3 stages share antigens important in this phenomenon that resulted in the removal of specific adherence antibody during absorption.     

Prairie grasses as hosts of the northern corn rootworm (Coleoptera: Chrysomelidae)

We evaluated 27 prairie grass species thought to be among those dominant 200 yr ago in the northern midwest as larval hosts of the northern corn rootworm, Diabrotica barberi Smith and Lawrence. Maize (Zea mays L.), spring wheat (Triticum aestivum L.), and grain sorghum (Sorghum bicolor L.) were included as controls for a total of 30 species. Twenty pots of each species were planted in a randomized complete block design. Each pot was infested 5 wk later with 20 neonate northern corn rootworm larvae. Two pots within each species and block were assigned an extraction date of 7 or 14 d after infestation. The remaining two pots from each block were used to monitor adult emergence. The percentage of larvae recovered, change in larval head capsule width, and change in average dry weights varied significantly among the grass species. The highest percentage of larvae was recovered from slender wheatgrass, Elymus trachycaulus (Link), and this was significantly greater than the percentage recovered from all other species including maize for the 14-d sample date. Several additional species were also relatively good hosts, in that the percentage of larvae recovered from these species was not significantly different from maize. The average dry weight of larvae recovered was significantly greater for larvae recovered from maize than for larvae recovered from all other species except slender wheatgrass, when the two samples dates were combined. Overall, adults were produced from only 6 of the 28 species evaluated, and no analysis was performed because of the low numbers. The results of this study are discussed in relation to the potential of alternate hosts of northern corn rootworm to serve as a bridge to survival on transgenic maize.