BackgroundBiological invasions are recognized as a major cause of biodiversity decline and have considerable impact on the economy and human health. The African big-headed ant Pheidole megacephala is considered one of the world's most harmful invasive species.Methodology/Principal FindingsTo better understand its ecological and demographic features, we combined behavioural (aggression tests), chemical (quantitative and qualitative analyses of cuticular lipids) and genetic (mitochondrial divergence and polymorphism of DNA microsatellite markers) data obtained for eight populations in Cameroon. Molecular data revealed two cryptic species of P. megacephala, one inhabiting urban areas and the other rainforests. Urban populations belong to the same phylogenetic group than those introduced in Australia and in other parts of the world. Behavioural analyses show that the eight populations sampled make up four mutually aggressive supercolonies. The maximum distance between nests from the same supercolony was 49 km and the closest distance between two nests belonging to two different supercolonies was 46 m. The genetic data and chemical analyses confirmed the behavioural tests as all of the nests were correctly assigned to their supercolony. Genetic diversity appears significantly greater in Africa than in introduced populations in Australia; by contrast, urban and Australian populations are characterized by a higher chemical diversity than rainforest ones.Conclusions/SignificanceOverall, our study shows that populations of P. megacephala in Cameroon adopt a unicolonial social structure, like invasive populations in Australia. However, the size of the supercolonies appears several orders of magnitude smaller in Africa. This implies competition between African supercolonies and explains why they persist over evolutionary time scales.

The three most common Ixodes spp. ticks found on songbirds in Western Europe are Ixodes frontalis, I. arboricola and I. ricinus. As the latter species is a generalist, it shares several avian hosts with the two strictly ornithophilic species. Infestations of the three species can overlap in time and space, implying that tick-borne pathogens maintained by the ornithophilic ticks and their hosts could be bridged by I. ricinus to non-avian hosts. Whereas the endophilic Ixodes arboricola only occurs in cavities, I. frontalis has been collected frequently by flagging methods from understory vegetation, which is also the habitat of the field-dwelling I. ricinus. As the latter two species have rather similar morphological characteristics, they can easily be confused with each other. In this study, we present scanning electron photomicrographs of all developmental stages of I. arboricola and I. frontalis, and provide a differential diagnosis key to distinguish the ornithophilic ticks from I. ricinus. In addition, we interpreted their phylogenetic associations based on mitochondrial 16S rDNA with other Ixodes spp. ticks (I. lividus, I. turdus, I. brunneus, I. vespertilionis, I. trianguliceps, I. hexagonus, I. scapularis).

No abstract

The pupal morphology of the pest species Cameraria ohridella is described and compared with that of the genus Phyllonorycter. The most striking differences are the longer antennal appendages, the absence of a cremaster, the presence of strong lateral thorns on abdominal segments 1-5 and an area without small spines on the same abdominal segments in Cameraria.

The gracillariid genus Triberta gen. nov. (Lepidoptera: Gracillariidae: Lithocolletinae Stainton, 1854) is described to accommodate two species formerly assigned to the genus Phyllonorycter Hübner, 1822: Triberta helianthemella (HerrichSchäffer, 1861) comb. nov. and T. cistifoliella (Groschke, 1944) comb. nov. Triberta cistifoliella bona sp. is restored from synonymy based on morphological characters. The new genus is biologically associated with the plant family Cistaceae of the order Malvales and is endemic to the Palaearctics. Our molecular analysis of eleven nuclear genes failed to unambiguously place Triberta in the lithocolletine phylogeny, but revealed that this genus is distinct from either clade Phyllonorycter + Cremastobombycia and Cameraria. The distinctiveness of Triberta is also supported by inferred traits in wing venation, micro morphology of the last instar larva, pupa, genital morphology of the adult and life history. A key to the species of Triberta is provided. The interspecific homogeneity in external morphology, coupled with minor differences in genital traits, an apparent narrow specialization on Cistaceae host plants, restricted geographical range and molecular evidence based on multi-nuclear genes jointly suggest that the generic diversification of Triberta is a relatively old phenomenon and driven strongly by host selection.