Hybridization and adaptation to introduced balloon vines in an Australian soapberry bug.

Contemporary adaptation of plant feeding insects to introduced hosts provides clear cases of ecologically based population divergence. In most cases the mechanisms permitting rapid differentiation are not well known. Here we study morphological and genetic variation associated with recent shifts by the Australian soapberry bug Leptocoris tagalicus onto two naturalized Neotropical balloon vines, Cardiospermum halicacabum and C. grandiflorum that differ in time since introduction. Our results show that these vines have much larger fruits than the native hosts (Whitewood tree -Atalaya hemiglauca- and Woolly Rambutan -Alectryon tomentosus-) and that bugs living on them have evolved significantly longer beaks and new allometries. Genetic analyses of mitochondrial haplotypes and amplified fragment length polymorphic (AFLP) markers indicate that the lineage of bugs on the annual vine C. halicacabum, the older introduction, is intermediate between the two subspecies of L. tagalicus found on native hosts. Moreover, where the annual vine and Whitewood tree co-occur, the morphology and genomic composition of the bugs are similar to those occurring in allopatry. These results show that hybridization provided the genetic elements underlying the strongly differentiated 'Halicacabum bugs'. In contrast, the bugs feeding on the recently introduced perennial balloon vine (C. grandiflorum) showed no evidence of admixture, and are genetically indistinguishable from the nearby populations on a native host.

[Serodiagnosis of toxoplasmosis: a comparative multicenter study of a standard scale through various actual tests and expression of the results in international units. Groupe de travail toxoplasmose du Contrôle national de qualité en parasotologie. Syndicat des fabricants de réactifs de laboratoire. Groupe de travail standardisation des tests sérologiques du Réseau européen de lutte contre la toxoplasmose congénitale]. / Le sérodiagnostic de la toxoplasmose: etude comparative multicentrique d'une gamme étalon, par les différents tests actuels et avec expression des résultats en unités internationales. Groupe de travail toxoplasmose du Contrôle national de qualité en parasitologie, Syndicat des fabricants de réactifs de laboratoire, Groupe de travail standardisation des tests sérologiques du Réseau européen de lutte contre la toxoplasmose congénitale.

Reported are the results of a multicentre study involving 40 laboratories that was carried out in France to assess all the currently available methods used for the serodiagnosis of toxoplasmosis. For this purpose 10 batches of control sera were prepared with titres in the range 0-260 IU per ml. These sera were tested in nine laboratories using immunofluorescence methods; in three laboratories using dye tests; in forty laboratories using enzyme-linked immunosorbent assay; in four laboratories using direct agglutination and haemagglutination; in seven laboratories using the high-sensitivity IgG agglutination test; and in three laboratories using the latex agglutination test. In this way, 70 series of titrations were carried out using seven procedures and the results were compared with those obtained using the WHO reference serum in 15 cases, with the French national E6 serum in 16 other cases, and in 39 cases using 15 reference sera supplied by the reagent manufacturers. Rigorous comparison of the tests was not possible in all cases because one aim of the study was to ensure that the tests were carried out under the usual working conditions that prevailed in the participating laboratories. The results obtained indicate that the serological tests currently available for toxoplasmosis are acceptable for its serodiagnosis. Presentation of the titres in IU has advantages; however, caution is required since the definition of IU varies according to the test and reagents used. It is therefore essential that the conditions and limits for a positive reaction be carefully defined in each case, especially for commercially available kits.

Performance of European laboratories testing serum samples for Toxoplasma gondii.

One hundred twenty-nine European laboratories participated in a collaborative, multicentre study designed to evaluate the overall reliability of different serological techniques for diagnosis of Toxoplasma gondii infection. Five freeze-dried reference sera were distributed to each laboratory, each of which analysed the sera with its routine methods. The enzyme-linked immunosorbent assay was the technique used most frequently, followed by the immunofluorescent antibody technique. Only nine laboratories performed the Sabin-Feldman dye test. In general, there was good concordance between qualitative results, but for sera with low concentrations of Toxoplasma gondii-specific IgG antibodies, some false-negative results were found. For specific IgM and IgA antibodies, the immunosorbent agglutination assay proved the most sensitive. The present study demonstrates the need for regular assessment of laboratory serodiagnosis of Toxoplasma gondii infection.

Birds, bugs and blood: avian parasitism and conservation.

Parasitism has far-reaching implications not only for the ecology and evolution of species but also for conservation. The effects of blood-feeding ectoparasites on colonially nesting bird species have been wodely studied, but recent surprising reports show that solitarily nesting species are also commonly attacked, mainly by the larvae of flies. Most bird species are solitary nesters; as their habitats are increasingly fragmented, how will the potential for such parasitism be affected? One example is that of the endangered Puerto Rican parrot (Amazona vittata), in which habitat changes have introduced a deadly parasitic fly species in a complex and unpredicted manner. As theories on habitat fragmentation outpace the data, we need to carry out more field studies of the interactions between fragmentation and parasitism, and to include parasitism in species survival and recovery plans.

Evolution of regulatory genes and patterns: relationships to evolutionary rates and to metabolic functions.

In an effort to understand the forces shaping evolution of regulatory genes and patterns, we have compared data on interspecific differences in enzyme expression patterns among the rapidly evolving Hawaiian picture-winged Drosophila to similar data on the more conservative virilis species group. Divergence of regulatory patterns is significantly more common in the former group, but cause and effect are difficult to discern. Random fixation of regulatory variants in small populations and/or during speciation may be somewhat more likely than divergence driven by selection. Within the picture-winged group, we also have compared enzymes that fulfill different metabolic roles. There are highly significant differences between individual enzymes, but no obvious correlations to functional categories.

The cliff swallow bug Oeciacus vicarius (Hemiptera: Cimicidae) in Florida: ectoparasite implications for hole-nesting birds.

In May 1988, ten juvenile birds, not yet ready to fledge, jumped to their death from a colony of the purple martin, Progne subis near Okeechobee City, Florida. The martin house and nestlings were found to be infested with ectoparasitic Oeciacus vicarius Horvath, the cliff swallow bug, not previously reported from Florida. This ectoparasite infestation apparently led to early abandonment of two houses by the adult martins. Oeciacus vicarius therefore represents a possible threat to all hole-nesting birds.

Lyme disease in California: interrelationship of ixodid ticks (Acari), rodents, and Borrelia burgdorferi.

The association of immature ixodid ticks, several species of rodents, and the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, was studied in two habitats in northern California in spring and summer 1985 and year-round in 1986. A total of 428 rodents were collected from ecotonal chaparral and a woodland-grass-rock outcrop; the former habitat yielded six species, the latter three species. The deer mouse, Peromyscus maniculatus (Wagner), and the piñon mouse, P. truei (Shufeldt), were the dominant species year-round and collectively comprised 78% of rodents captured within chaparral and 87% from the rock outcrop in 1986. In both habitats, rodents were trapped most frequently in winter and spring, and least often in summer and fall. A total of 306 rodent blood films from all six species were assayed for spirochetes by direct immunofluorescence; of these, only one film prepared from P. truei (n = 123 films from 53 individual mice) was found to contain spirochetes. Immature western black-legged ticks, Ixodes pacificus Cooley & Kohls, and Pacific Coast ticks, Dermacentor occidentalis Marx, were collected from each species of rodent. Larvae of I. pacificus infested P. maniculatus and P. truei in low numbers year-round, but nymphs of this tick rarely parasitized these rodents. D. occidentalis larvae infested P. maniculatus and P. truei in spring and particularly in summer; nymphal ticks infested these mice primarily in summer. The efficiency of visual inspection for collecting immatures of these ticks from P. maniculatus ranged from 45 to 69% in spring and summer, whereas the efficiency of a drop-off technique appeared to be 100%. Spirochetes were detected in <1% of D. occidentalis larvae (n = 310) and nymphs (n = 120), and in approximately 4% of I. pacificus larvae (n = 75) derived from these hosts. The potential significance od these findings in the enzootiology of B. burgdorferi is discussed.

Lyme disease in California: interrelationship of Ixodes pacificus (Acari: Ixodidae), the western fence lizard (Sceloporus occidentalis), and Borrelia burgdorferi.

The relationship of immature western black-legged ticks, Ixodes pacificus Cooley and Kohls, to the western fence lizard, Sceloporus occidentalis Baird and Girard, and to the Lyme disease spirochete, Borrelia burgdorferi, was investigated in chaparral and woodland-grass habitats in northern California from 1984 to 1986. Immature ticks were found on lizards in spring and summer, but the prevalence and abundance of ticks on this host were considerably greater in spring. The peak of larval abundance preceded that of nymphs by several weeks, but there was considerable seasonal overlap between these parasitic stages. Larvae and nymphs attached primarily to the lateral nuchal pockets of lizards in chaparral (99.5%) and woodland-grass (91.8%). The numbers of larvae infesting lizards in spring fit the negative binomial distribution in woodland-grass but not in chaparral; insufficient data precluded similar analyses for nymphs. Tick loads did not differ significantly with respect to age or gender of the lizard. Spirochetal infection rates (range, 0-3.7%) in I. pacificus immatures were comparable in both habitats and were similar to those reported previously for adults of this tick. Overall, 1 (0.9%) of 117 larvae and 10 (1.8%) of 552 nymphs were infected with spirochetes resembling B. burgdorferi. Spirochetes were not observed in blood smears prepared from 261 wild-caught lizards, including five lizards fed upon by infected ticks at the time of collection. These and other findings suggest that S. occidentalis, although an important host of I. pacificus immatures, may be less important as a source for infecting ticks with B. burgdorferi.

[Prevention of AIDS transmission by syringes and needles in France and Africa]. / Prévention de la transmission par les seringues et aiguilles du V.I.H. en France et en Afrique.

A study made among drug addicts in the Northern suburbs of Paris enables establishing a stabilisation of positive H.I.V. serology prevalence among them, a fact related to the free sale of syringes and needles. In Africa, the nosocomial transmission of H.I.V. by non-sterilisable but reused needles and syringes is demonstrated, and two cases are described. Its importance is certain but must be precise. The prevention of this epidemiological modality must be done by systematic use of reusable and sterilisable injectable material.

PIP: Reuse of disposable needles and syringes plays an important role in the transmission of HIV in France as in Africa. From September 1985-March 1986, 51% of drug addicts systematically screened in the northern suburbs of Paris were found to be HIV positive. Studies in the same population through 1988 indicated that the rate of HIV infection had remained stable, as had the average age of addicts, duration of addiction, and sex ratio. Stabilization of seropositivity rates among drug addicts in the northern suburbs in believed to have been due to information programs alerting addicts to the risk of contamination through sharing of needles and to the legal sale of syringes and needles instituted in May 1987. HIV transmission through reuse of disposable needles and syringes has been demonstrated in Africa. It is attributable to the poverty of health services and of the general population. The significance of HIV transmission by reuse of disposable materials in the health services appears to be considerable but is difficult to quantify. Prevention of transmission by this means will require correct use of sterilizable needles and syringes.