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Internal parasites typically are associated with a range of negative effects on their hosts, including reduced energy, which can manifest in behavioral alterations. With this in mind, we examined effects of a naturally-occurring nematode parasite, Chondronema passali, on locomotor activity level in horned passalus beetles, Odontotaenius disjunctus from Georgia, USA. This parasite is not well-studied but can number in the thousands in severely parasitized hosts. Prior study in our lab revealed that parasitized beetles actually consume more wood than unparasitized ones do, leading us to ask here, if parasitized beetles are also more physically active. Beetles were collected from nearby forests and housed individually in our lab. We created a simple tabletop arena to observe beetle locomotor activity, which was gridded and included small stones and paper objects. We allowed individual beetles to traverse the arena for 5 min and recorded the number of grid squares crossed. Then, beetles were dissected to determine parasite presence and level of infection (on a categorical scale). A total of 140 beetles were examined across three collections. Statistical analyses of locomotor activity revealed parasite severity predicted locomotor activity, but paradoxically, lightly-infected beetles were twice as active as those without this nematode. Activity diminished with increasing worm burdens thereafter, but even the group with the most severe burdens did not move less than those with no worms. From these results we conclude that this parasite does not result in overall reduction in activity, but rather it appears to come with heightened locomotion. Alternatively, this result could stem from the fact that more active beetles are simply more likely to contract the parasite. [ABSTRACT FROM AUTHOR]

In this project, red-backed salamanders, Plethodon cinereus, were collected from the heart of their range (Mountain Lake, Virginia, USA), in an effort to document the typical, or baseline, leukocyte profile of this species in its natural state. From microscopic examination of thin blood films, we determined relative proportions of all leukocyte types and determined the ratio of neutrophils to lymphocytes, which is a useful index of stress levels. In addition, individuals were examined for three naturally occurring endoparasites: two gastro-intestinal (trematodes and a ciliated protozoan in the genus Cepedietta) and one in the blood (a Rickettsial bacteria). This allowed us to conduct statistical comparisons of leukocyte data across parasite infection groups. Of 36 salamanders, 11 (31%) had trematode parasites, 7 (19%) contained Cepedietta parasites, 6 (17%) were parasitized by Rickettsia, and 12 had no parasites. The most common leukocytes were lymphocytes (87.4%), followed by neutrophils (4.2%), monocytes (3.3%), eosinophils (2.6%), and basophils (2.5%). The average neutrophil/lymphocyte ratio for these salamanders was remarkably low (0.05) for an amphibian population. Statistical comparisons of leukocyte profiles among parasite infection groups indicated parasitized salamanders had twice as many circulating leukocytes as nonparasitized individuals, which could be considered an "inflammation response". There was a slight but significant elevation in relative eosinophil abundance in parasitized salamanders. There were few differences in leukocyte subsets between parasite types, nor was there evidence of any proliferation of phagocytic cells in any parasitized individual. [ABSTRACT FROM AUTHOR]

The rapid spread of the bacterial disease, Mycoplasma gallisepticum (MG), throughout the introduced range of house finches ( Carpodacus mexicanus) in eastern North America, compared to its slower spread through the native western range, has puzzled researchers and highlights the need to understand the relative differences in health state of finches from both populations. We conducted a light-microscope survey of hemoparasites in populations of finches from Arizona (within the western range) and from Alabama (within the eastern range), and compared our estimates of prevalence to published reports from house finches sampled in both ranges. Of the 33 Arizona birds examined, we recorded hematozoan infections in 16 (48.5%) individuals, compared to 1 infected Alabama bird out of 30 birds examined (3.3%). Based on independent surveys of seven western North American and five eastern North American populations of house finches the average prevalence of blood parasites in western populations is 38.8% (±17.9 SD), while the average prevalence within the eastern range is only 5.9% (±6.1 SD). The average rate of infection among all songbirds sampled in the east is 34.2% (±4.8 SD). Thus, our surveys of wild birds as well as previously published observations point to eastern house finches having a much lower prevalence of blood parasite infections than their western counterparts. Combined with the fact that eastern finches also tend to have lower rates of avian pox infections than do western birds (based on a literature review), these observations suggest that eastern birds have either strong resistance to these infections or high susceptibility and associated mortality. [ABSTRACT FROM AUTHOR]

Bullfrogs ( Rana catesbeiana) are widely believed to be nonclinical carriers of Batrachochytrium dendrobatidis (Bd), the fungal pathogen that invades keratinized tissues of amphibians and causes the disease, chytridiomycosis. Although most research on this disease focuses on adults, larval anurans are also susceptible to infections in their keratinized mouthparts, and this allows for visual diagnosis of the disease via the degree of mouthpart depigmentation. When an unplanned outbreak of chytridiomycosis occurred in a set of captive bullfrog tadpoles in our lab, we conducted the current investigation into its effects on the nonspecific immune system (i.e., the leukocyte populations) of the tadpoles. We compared leukocyte counts from blood smears of 27 tadpoles that had contracted the disease (evidenced by severe mouthpart depigmentation and confirmed by histology) to those of 21 tadpoles that had little depigmentation (i.e., with little evidence of the disease). Tadpoles with severe depigmentation had significantly more neutrophils and less eosinophils than those with little depigmentation, while numbers of lymphocytes, basophils, and monocytes were not statistically different. That there was any effect at all on circulating leukocyte numbers is surprising since leukocytes are usually not seen migrating to sites of infection in tissue sections of amphibians infected with Bd, and since most research points to this disease having little outward effect on bullfrogs. Since monocyte numbers were unchanged, the leukocyte alterations were likely not due to a simple inflammation response. It is possible that Bd infections elicit increases in glucocorticoid hormones, which can cause increased numbers of circulating neutrophils and lower numbers of eosinophils, although this is often accompanied by a reduction in lymphocyte numbers, which we did not see. Further research is warranted to clarify if this effect is limited to this species. [ABSTRACT FROM AUTHOR]

The migration of monarch butterflies ( Danaus plexippus) from Canada and the United States to overwintering sites in Mexico is one of the world’s most amazing biological phenomena, although recent threats make it imperative that the resources needed by migrating monarchs be conserved. The most important first step in preserving migration resources—determining the migration flyways—is also the most challenging because of the large-scale nature of the migration. Prior attempts to determine the flyways using mark-recapture techniques with wing tags gave some clues, but this important information has never been fully obtainable until now. In 2005 the citizen-science program, Journey North, initiated a project that asked participants to record sightings of overnight roosts of monarchs during their fall migration, and this project now provides an ideal way to illustrate the flyways used by monarchs on their way to Mexico, with the assumption that roost locations indicate migration routes. We used 3 years of this data to elucidate the flyways on a continent-wide scale, that revealed two distinct flyways, but only one appears to lead directly to Mexico. This main, ‘central’ flyway begins in the American Midwest states and southern Ontario, then continues south-southwest through the states of Kansas, Missouri, Oklahoma and Arkansas, and finally passes through Texas and northern Mexico. These data also highlighted a separate, smaller flyway along the eastern and coastal states, but there was a noticeable lack of roost sightings in this flyway at lower latitudes. Since there are few recoveries of marked monarchs in Mexico originating from coastal areas, we compared the timing of roost formation in this ‘eastern’ flyway with the main, central flyway. Roosts in the eastern flyway lagged behind the central roosts in timing, suggesting that monarchs traveling in this flyway have a reduced chance of making it to the Mexico wintering site. Combined, our evidence indicates that locations in the central flyway should be considered priority areas for conserving migration resources. [ABSTRACT FROM AUTHOR]

During a recent study of red-backed salamanders ( Plethodon cinereus), we discovered an intraerythrocytic organism typified by violet-staining, intracellular inclusions, consistent with descriptions of Cytamoeba or Aegyptianella (bacteria). Here we characterize its taxonomic status using molecular techniques and ask basic questions about its nature. Blood smears from 102 salamanders were examined from Pennsylvania, New York, and Virginia to determine prevalence, and whole blood from several infected animals was tested using a PCR which targets the 16S rRNA gene of bacteria. Phylogenetic analysis of partial 16S rRNA gene sequence (1201 bp) indicated this organism was in the order Rickettsiales and is likely a member of the family Anaplasmatacea. The organism differed from currently described taxa and was clearly differentiated from Aegyptianella pullorum of birds and “ Candidatus Hemobacterium ranarum” (formally A. ranarum) of frogs. Of all salamanders, 17 (16.7%) were infected and these were significantly larger (snout–vent length) and had higher body condition scores than uninfected ones, and males were more likely to be infected than females. Erythrocytes affected by the pathogen were 5% larger than unaffected ones, but otherwise similar in morphology. Infected animals tended to have a greater number of circulating white blood cells, based on estimates from smears, indicating a nonspecific response to the pathogen by the innate immune system. Given its phylogenetic position, this pathogen is likely transmitted by an arthropod vector, and the male-biased prevalence strongly implicates trombiculid mites, which also live in leaf litter and affect male salamanders more so than females. [ABSTRACT FROM AUTHOR]

Metamorphosis in amphibians is a fascinating phenomenon that offers physiologists a number of opportunities to study aspects of tissue growth and lysis in animals. In larval amphibians, tissues are formed early on during larval growth, then are vastly reorganized and broken down during metamorphosis, and the effects of this phenomenon on the relative distribution of white blood cells in circulation (i.e., leukocyte profiles) was first examined in the 1920s. Nearly a century later, there has been little work to continue this research avenue, although our knowledge of the roles of certain leukocyte types has improved. Moreover, recent interest in counts of leukocytes in amphibians for environmental monitoring purposes emphasizes the need to understand how white blood cells naturally vary throughout larval life. In this study, I examined blood smears from wild-caught larval and adult bullfrogs ( Rana catesbeiana) of varying developmental stages and quantified the proportions and abundance (estimated from blood smears) of all leukocyte types at each stage. Lymphocytes were the most common cell found and appeared most abundant during the early growth phases of larvae. Neutrophils were the second most common cell and were also associated most with earlier phases. Eosinophils appeared directly associated with metamorphosis, generally increasing in abundance to a peak at metamorphic climax. Monocytes were also found most frequently in individuals experiencing metamorphic climax. Results in this study concerning eosinophils are consistent with those of urodeles and point to their role in the breakdown of tissues, which may resemble their role in modulating inflammation responses. [ABSTRACT FROM AUTHOR]

Leukocyte profiles (relative numbers of white blood cell types) have been used by a growing number of ecological studies to assess immune function and stress in wild birds. House Finches (Carpodacus mexicanus) in eastern North America are susceptible to an eye disease caused by the bacteriumMycoplasma gallisepticum, providing the opportunity to examine whether leukocyte profiles are associated with infection status and other host characteristics. In this study, we compared blood smears from 297 wild House Finches with and without conjunctivitis to examine whether leukocyte profiles were associated with the presence and severity of mycoplasmal conjunctivitis. We also evaluated the influence of age, sex, and molt on leukocyte profiles in both diseased and nondiseased birds. Of 243 House Finches of known age and sex sampled, 30% showed clinical signs of mycoplasmal conjunctivitis. House Finches with conjunctivitis had significantly higher heterophil to lymphocyte (H/L) ratios and harbored greater numbers and proportions of heterophils and monocytes than nondiseased birds. Leukocyte profiles of noninfected birds did not differ significantly with respect to sex, but young birds had significantly greater numbers of lymphocytes and total white blood cells than adults. Molting birds had significantly more eosinophils than nonmolting birds. Finally, House Finches with the most severe outward signs of conjunctivitis showed the most dramatic leukocyte changes relative to noninfected individuals, and increasing H/L ratios and monocytes in diseased birds were paralleled in a subset of birds that were recaptured during the study period. These results are consistent with patterns observed in domestic poultry and suggest that understanding patterns of leukocyte differentials in this host-pathogen system could improve our understanding of innate immunity and infectious disease risk in other wild passerines. [ABSTRACT FROM AUTHOR]

A response by Andrew K. Davis and Kerry Holcomb to a letter to the editor about their article "The importance of publishing laboratory observations" in the February 2009 issue is presented.