Detection of Wolbachia in the Tick Ixodes ricinus is Due to the Presence of the Hymenoptera Endoparasitoid Ixodiphagus hookeri

The identification of micro-organisms carried by ticks is an important issue for human and animal health. In addition to their role as pathogen vectors, ticks are also the hosts for symbiotic bacteria whose impact on tick biology is poorly known. Among these, the bacterium Wolbachia pipientis has already been reported associated with Ixodes ricinus and other tick species. However, the origins of Wolbachia in ticks and their consequences on tick biology (known to be very diverse in invertebrates, ranging from nutritional symbionts in nematodes to reproductive manipulators in insects) are unknown. Here we report that the endoparasitoid wasp Ixodiphagus hookeri (Hymenoptera, Chalcidoidea, Encyrtidae) – strictly associated with ticks for their development - is infested at almost 100% prevalence by a W. pipientis strain belonging to a Wolbachia supergroup that has already been reported as associated with other hymenopteran parasitoids. In a natural population of I. ricinus that suffers high parasitism rates due to I. hookeri, we used specific PCR primers for both hymenopteran and W. pipientis gene fragments to show that all unfed tick nymphs parasitized by I. hookeri also harbored Wolbachia, while unparasitized ticks were Wolbachia-free. We demonstrated experimentally that unfed nymphs obtained from larvae exposed to I. hookeri while gorging on their vertebrate host also harbor Wolbachia. We hypothesize that previous studies that have reported W. pipientis in ticks are due to the cryptic presence of the endoparasitoid wasp I. hookeri. This association has remained hidden until now because parasitoids within ticks cannot be detected until engorgement of the nymphs brings the wasp eggs out of diapause. Finally, we discuss the consequences of this finding for our understanding of the tick microbiome, and their possible role in horizontal gene transfer among pathogenic and symbiotic bacteria

Comparative Phylogeography of a Coevolved Community: Concerted Population Expansions in Joshua Trees and Four Yucca Moths

Comparative phylogeographic studies have had mixed success in identifying common phylogeographic patterns among co-distributed organisms. Whereas some have found broadly similar patterns across a diverse array of taxa, others have found that the histories of different species are more idiosyncratic than congruent. The variation in the results of comparative phylogeographic studies could indicate that the extent to which sympatrically-distributed organisms share common biogeographic histories varies depending on the strength and specificity of ecological interactions between them. To test this hypothesis, we examined demographic and phylogeographic patterns in a highly specialized, coevolved community – Joshua trees (Yucca brevifolia) and their associated yucca moths. This tightly-integrated, mutually interdependent community is known to have experienced significant range changes at the end of the last glacial period, so there is a strong a priori expectation that these organisms will show common signatures of demographic and distributional changes over time. Using a database of >5000 GPS records for Joshua trees, and multi-locus DNA sequence data from the Joshua tree and four species of yucca moth, we combined paleaodistribution modeling with coalescent-based analyses of demographic and phylgeographic history. We extensively evaluated the power of our methods to infer past population size and distributional changes by evaluating the effect of different inference procedures on our results, comparing our palaeodistribution models to Pleistocene-aged packrat midden records, and simulating DNA sequence data under a variety of alternative demographic histories. Together the results indicate that these organisms have shared a common history of population expansion, and that these expansions were broadly coincident in time. However, contrary to our expectations, none of our analyses indicated significant range or population size reductions at the end of the last glacial period, and the inferred demographic changes substantially predate Holocene climate changes

The Parent Participation Engagement Measure (PPEM): Reliability and Validity in Child and Adolescent Community Mental Health Services

Parent participation in community-based child mental health services is an important yet understudied process associated with treatment effectiveness. This paper describes the development and psychometrics of the Parent Participation Engagement Measure (PPEM) in a sample of 1374 parents and 563 youth receiving publicly-funded mental health services. Analyses indicated excellent internal consistency, and model fit indices/factor loadings supported a one-factor model. Convergent and discriminant validity were supported, although some coefficients were modest in magnitude. Psychometric results were consistent for Caucasian versus Hispanic, parent versus youth, and English versus Spanish-language respondents. The clinical and research utility of this measure are discussed

A Streptococcus pneumoniae infection model in larvae of the wax moth Galleria mellonella

The bacterium Streptococcus pneumoniae is a leading human opportunistic pathogen. The limitations of the current vaccine have led to increased recognition of the need to understand bacterial behaviour and competitive dynamics using in vivo models of infection. Here, we investigate the potential application of the larvae of the wax moth Galleria mellonella as an informative infection model. Larvae were challenged with a range of doses of S. pneumoniae isolates differing in known virulence factors to determine the LD(50) values. Infection dynamics were determined by obtaining bacterial counts from larvae over a time course. Differences in virulence between serotypes could be distinguished in this host. Infection with strains differing in known virulence factors demonstrated predicted differences in virulence. Acapsulate and pneumolysin-negative strains were less virulent than their respective wild types. A large reduction in virulence was seen in strains lacking cell wall D-alanylation. The mortality of G. mellonella larvae is attributable to bacterial growth within larvae, while surviving larvae are able to clear infections by reducing bacterial numbers. These data demonstrate that G. mellonella larvae represent an in vivo infection model with applications for investigating aspects of bacterial-host interactions such as the role of antimicrobial peptide activity and resistance