First record in America of Aedes albopictus naturally infected with dengue virus during the 1995 outbreak at Reynosa, Mexico

Abstract Mosquito collections were conducted during a dengue outbreak in Reynosa, Tamaulipas, Mexico, July-December 1995. A total of 6694 adult mosquitoes (four genera and nine species) were captured, of which 2986 (78.3% females and 21.7% males) were Aedes albopictus and 2339 (39.7% females and 60.3% males) were Ae.aegypti. These two species comprised 84.2% of the total collection. Specimens were grouped into pools, nearly 50% of them processed for detection of virus by cythopathic effect in C6-36 and VERO cell cultures and by haemagglutination test. Five pools gave positive haemagglutin-ation reactions and were examined by immunofluorescence using monoclonal antibodies to flavivirus and to dengue virus. One pool of ten Ae.albopictus males was positive for dengue virus: serotypes 2 and 3 were identified by serotype-specific monoclonal antibodies arid confirmed by RT-PCR. This is the first report of Ae.albopictus naturally infected with dengue virus in America. Also, it is the very first time Ae.albopictus males have been found infected with dengue virus in the wild.     

Nitrogen fixation, stomatal response and transpiration in Medicago sativa, Trifolium repens and T. subterraneum under water stress and recovery

Stomatal behaviour, transpiration and nitrogen fixation were investigated in Medicago sativa L. (cvs. Tierra de Campos and Aragon, Hidalgo-Maynar 1966), Trifolium repens L. (cv. Aberystwyth S-184) and Trifolium subterraneum L. (cv. Clare) subjected to drought by withholding water and then to three days’ recovery after rewatering. Dawn leaf water potential was measured with pressure chamber, stomatal response with a diffusion porometer and nitrogen fixation by using acetylene reduction technique. At low water potentials, the leaf resistance was higher in Medicago than in Trifolium. As water stress developed all species decreased their transpiration, T. subterraneum being the one most affected by moderate deficits. During water stress ‘Tierra de Campos’ always maintained higher acetylene reduction levels than ‘Aragon’ and the Trifolium species, except for the lowest water potentials. During recovery from water stress only ‘Tierra de Campos’ reached predeficit transpiration rates. In ‘Tierra de Campos’ acetylene reduction recovery after rewatering was more rapid and intense than in ‘Aragon’. It is concluded that, of the plants investigated, ‘Tierra de Campos’ was best adapted to water deficits.     

Use of an encounter model to predict size-selective predation by a stream-dwelling cyprinid

1. The increased probability of detection of larger prey in the drift appeared to be the major determinant of prey consumption by red roach (Rutilus arcasi) in an Iberian stream. We developed a model of prey encounter incorporating this factor that explained 68% of the overall variation in the consumption of prey of different size. When the same model was applied to benthic size distributions the variance explained was 16%. 2. Gape-limited ingestion also was a significant factor influencing prey consumption and, when added to the model, the variance explained increased to 85% (32% for the benthos), but its importance was strongly dependent on both: (i) the maximum prey size available and (ii) fish size. 3. The exact shape of red roach reactive fields and, as a consequence, their degree of size-selectivity appeared to vary seasonally and ontogenetically. In summer, younger fish exhibited apparently reduced reactive fields. We hypothesize that this can be the result of factors such as microhabitat shifts or a reduced range of prey sizes.     

Isolation and characterization of microsatellite loci in the blue manakin,Chiroxiphia caudata (Aves,Pipridae)

We designed primers for amplifying 11 polymorphic microsatellite loci in the blue manakin, Chiroxiphia caudata, a neotropical passerine bird which inhabits a critically endangered tropical ecosystem, the Brazilian Atlantic forest. Based on genotypes from 24 individuals from a single population, we detected between four and 22 alleles per locus with observed heterozygosities ranging from 0.54 to 0.92. These highly variable loci will be useful for determining levels of population differentiation and assessing the impact of habitat fragmentation on levels of genetic variation in isolated populations of these birds.     

Isolation and characterization of new microsatellite loci in the Pacific white shrimp Litopenaeus vannamei and cross‐species amplification in other penaeid species

The goal of the present study was to obtain valuable microsatellite markers useful in genetic approaches of the shrimp Litopenaeus vannamei, an important aquaculture species of the world. Eight loci produced suitable polymorphic patterns with allele number ranging from two to 12 and expected heterozygosity from 0.18 to 0.89. Cross‐species amplification was successfully performed in five other penaeid species (Litopenaeus schmitti, Farfantepenaeus brasiliensis, Farfantepenaeus paulensis, Xiphopenaeus kroyeri and Rimapenaeus constrictus), indicating that some these loci can be useful in studies of other related species.     

Changes in sperm tail development associated with Y chromosome meiotic drive leading to an excess of males in the medfly Ceratitis capitata (Diptera: Tephritidae)

The Mediterranean fruit fly Ceratitis capitata (Wied.) normally produces the sexes in equal ratio but strains carrying the Y chromosome meiotic drive MP (male‐producing) factor show an excess of males. This is associated with a loss of sperm, and abnormal sperm structure in terms of multiple axonemes, atypical numbers of mitochondrial derivatives, and sometimes an incorrect initial orientation of paracrystalline bodies to the axoneme. Sperms are bundled together within spermatocysts, and those with depleted content and abnormalities occur in the same MP testes as normal spermatocysts. The maximum number of sperms per cyst in control strains was 256, each with a single axoneme originating from a single centriole (kinetosome). The maximum per cyst in MP strains was also 256 but MP cysts contained up to 300 axonemes, providing evidence of multiplication of centrioles. The structural changes in MP sperm are discussed in relation to similar abnormalities reported in the mosquito Aedes aegypti inheriting the Y chromosome meiotic drive haplotype MD. The evolutionary significance of this phenomenon is considered. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 351–359.     

Subtle topographical differences along a floodplain promote different plant strategies among Paspalum dilatatum subspecies and populations

It was hypothesised that subtle topographical differences might cause the existence of ecotypes along a floodplain. The apomict grass Paspalum dilatatum subspecies dilatatum inhabits flood‐prone lowlands as well as nearby uplands in the floodplains of Argentina, while the sexual P. dilatatum subspecies flavescens almost exclusively inhabits the uplands. The aim of the present study was to identify the different traits that allow these P. dilatatum populations to inhabit different habitats. Plants of P. dilatatum were reciprocally transplanted between uplands and lowlands. Morphophysiological traits related to flooding tolerance were measured during a flood. Subspecies dilatatum from the uplands and subspecies flavescens showed a high physiological performance in the uplands but a considerable decrease in stomatal conductance, net photosynthesis rates and tiller number in the flooded lowlands. In contrast, the subspecies dilatatum from the lowlands showed relatively lower and stable stomatal conductance, photosynthesis rates and leaf water potential at both sites. Subspecies dilatatum from the lowlands outperformed upland populations at the lowland site with respect to tillering. Leaves of subspecies dilatatum from the lowlands that had grown at the lowland habitat had a lower blade/sheath proportion than leaves of plants transplanted to the uplands. This behavior did not occur in both upland populations. Results suggest that dilatatum Lowland plants have the typical strategy of stress‐tolerant genotypes and that the upland populations are adapted to habitats where competitive species are selected. In conclusion, habitats with subtle differences in topographic level can favour both ecotypic differentiations within an apomict subspecies but also the maintenance of morphophysiological similitudes between coexisting upland populations belonging to different subspecies.     

Microsatellite loci in the Canary Islands endemic ground beetle Trechus flavocinctus and their applicability to cave‐dwelling related species

Six polymorphic microsatellite markers have been developed for the Canary endemic ground beetle Trechus flavocinctus, and the performance of primer pairs amplifying these loci in closely related taxa (including two cave‐obliged species) has been tested. The number of alleles in T. flavocinctus samples taken from three distant localities in two islands ranged from four to 14 per locus. Observed heterozygosities were from 0.333 to 0.933. These markers could be useful tools to study the population structure and the genetic consequences of island and cave colonization by ground beetles.     

Physical and chemical cues affect oviposition by Neoleucinodes elegantalis

Recognition and acceptance of a suitable host plant by phytophagous insects requires the integration of visual, physical and chemical cues. The present study investigates the host cues that a specialist insect integrates to optimize oviposition decisions and whether these cues are weighted in a specific way. The study also determines whether the tomato fruit borer Neoleucinodes elegantalis (Guenée) (Lepidoptera: Crambidae), an important pest on Solanaceae in Brazil, shows a preference for oviposition sites that differ in physical and/or chemical cues. When styrofoam balls are provided as artificial fruits, N. elegantalis deposit significantly more eggs on rough artificial fruits than on smooth ones. Hexane fruit extracts applied to the artificial fruits stimulate female oviposition strongly. Physical and chemical cues also affect the oviposition of females when offered together. Furthermore, certain parts of the artificial fruits are prefered, irrespective of the presence of chemical cues. Both physical and chemical cues affect oviposition decisions; hence, the fruit borer relies on cues of different sensory modalities.