Molecular phylogeny and host-plant use (Lamiaceae) of the Thymogethes pollen beetles (Coleoptera)

The 24 members of the Euro-Asiatic genus Thymogethes are highly specialized pollen beetles associated as larvae with flowers of Lamiaceae Nepetoideae. All members of the genus were analysed in within the framework of an integrative taxonomy approach, which was aimed to reconstruct the phylogenetic relationships, as well as the possible pattern of evolution of their larval-host-plant association. Evidence from multiple molecular markers [COI; 16S; H3], combined with an estimation of divergence times using an average rate of 0.0177 substitutions/site/My among branches, placed the origin of the genus at a minimum of 9–10 Mya. This date of origin approximates the known evolution of the host plants in Euro-Mediterranean areas. Evidence from combined molecular and cladistic morphological analyses resulted in suitable agreement with the previously established morphology-based systematics of the genus, although members of the exilis species-group were split into three clades. The only disagreement between results of this new combined phylogeny and previous classification is in the exclusion of “Thymogethes” grenieri. This species is herein positioned outside the genus, based on molecular evidence. Our analysis depicts several Thymogethes species differentiating in the last few Mys, specifically those included in the T. lugubris species-group. Combined evidence from DNA, morphology and ancestral state parsimony reconstruction of larval-host-plant associations suggests that subtribe Menthinae likely represents the ancestral host plants, with a series of independent host shifts during the radiation of the clade, in association first with Menthinae and subsequently with Lavandulinae and Nepetinae. Steno-oligophagy is the most frequent (86%) condition, while strictly monophagous species are less numerous (14%).     

Large-Scale Conformational Transitions and Dimerization Are Encoded in the Amino-Acid Sequences of Hsp70 Chaperones

Hsp70s are a class of ubiquitous and highly conserved molecular chaperones playing a central role in the regulation of proteostasis in the cell. Hsp70s assist a myriad of cellular processes by binding unfolded or misfolded substrates during a complex biochemical cycle involving large-scale structural rearrangements. Here we show that an analysis of coevolution at the residue level fully captures the characteristic large-scale conformational transitions of this protein family, and predicts an evolutionary conserved–and thus functional–homo-dimeric arrangement. Furthermore, we highlight that the features encoding the Hsp70 dimer are more conserved in bacterial than in eukaryotic sequences, suggesting that the known Hsp70/Hsp110 hetero-dimer is a eukaryotic specialization built on a pre-existing template.     

Aminergic neuron systems of lobsters: morphology and electrophysiology of octopamine-containing neurosecretory cells

In the American lobster (Homarus americanus) the biogenic amines serotonin and octopamine appear to play important and opposite roles in the regulation of aggressive behavior, in the establishment and/or maintenance of dominant and subordinate behavioral states and in the modulation of the associated postural stances and escape responses. The octopamine-containing neurosecretory neurons in the thoracic regions of the lobster ventral nerve cord fall into two morphological subgroups, the root octopamine cells, a classical neurohemal group with release regions along second thoracic roots, and the claw octopamine cells, a group that selectively innervates the claws. Cells of both subgroups have additional sets of endings within neuropil regions of ganglia of the ventral nerve cord. Octopamine neurosecretory neurons generally are silent, but when spontaneously active or when activated, they show large overshooting action potentials with prominent after-hyperpolarizations. Autoinhibition after high-frequency firing, which is also seen in other crustacean neurosecretory cells, is readily apparent in these cells. The cells show no spontaneous synaptic activity, but appear to be excited by a unitary source. Stimulation of lateral or medial giant axons, which excite serotonergic cells yielded no response in octopaminergic neurosecretory cells and no evidence for direct interactions between pairs of octopamine neurons, or between the octopaminergic and the serotonergic sets of neurosecretory neurons was found.     

Changes in Clonal Poplar Leaf Chemistry Caused by Stem Galls Alter Herbivory and Leaf Litter Decomposition

Gall-inducing insects are highly specialized herbivores that modify the phenotype of their host plants. Beyond the direct manipulation of plant morphology and physiology in the immediate environment of the gall, there is also evidence of plant-mediated effects of gall-inducing insects on other species of the assemblages and ecosystem processes associated with the host plant. We analysed the impact of gall infestation by the aphid Pemphigus spirothecae on chemical leaf traits of clonal Lombardy poplars (Populus nigra var. italica) and the subsequent effects on intensity of herbivory and decomposition of leaves across five sites. We measured the herbivory of two feeding guilds: leaf-chewing insects that feed on the blade (e.g. caterpillars and sawfly larvae) and skeletonising insects that feed on the mesophyll of the leaves (e.g. larvae of beetles). Galled leaves had higher phenol (35%) and lower nitrogen and cholorophyll contents (35% respectively 37%) than non-galled leaves, and these differences were stronger in August than in June. Total herbivory intensity was 27% higher on galled than on non-galled leaves; damage by leaf chewers was on average 61% higher on gall infested leaves, whereas damage by skeletonising insects was on average 39% higher on non-galled leaves. After nine months the decomposition rate of galled leaf litter was 15% lower than that of non-galled leaf litter presumably because of the lower nitrogen content of the galled leaf litter. This indicated after-life effects of gall infestation on the decomposers. We found no evidence for galling x environment interactions.     

Lasioseius Fimetorum: a soil-dwelling predator of glasshouse pests?

Female lifespan and reproduction, in terms of numberof larvae produced, of the soil-dwelling predatorymite Lasioseius fimetorum Karg (Acari:Podocinidae) fed on mould mites (Tyrophagusputrescentiae [Schrank] [Acarina: Acaridae]) wereinvestigated by laboratory experiments at 20 °C,as were the mite's consumption rates of various prey.After a preoviposition period of 10.7 days, L.fimetorum produced progeny at a daily rate of 0.7.The oviposition period lasted 23.6 days and a total of19.4 progeny were produced per female. Females livedfor 38.6 days. Eggs of the Collembola Isotomurusspp. (Collembola: Isotomidae) were consumed in thelargest amount by L. fimetorum followed by mouldmite nymphs, larvae and pupae of thrips (Frankliniella occidentalis [Pergande] [Thysanoptera:Thripidae]), eggs of the Collembola Micrisotomaspp. (Collembola: Isotomidae), Isotomurus spp.nymphs and sciarid larvae (Bradysia pauperaTuomikoski and B. tritici (Coquillet) [Diptera:Sciaridae]). Immature drain flies (Psychoda spp.[Diptera: Psychodidae]) were not consumed by L.fimetorum. The suitability of L. fimetorum forbiological control of glasshouse pests withsoil-dwelling stages is discussed in comparison withanother predatory mite Hypoaspis miles Berlese(Acarina: Hypoaspididae).