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In this paper are presented the results of optimizing the combination of some common techniques and classifiers applied to faces recognition by the using of genetic algorithms, the set of images used for this approach comes from infrared acquisition. It appears that the proposed scheme improve the system performance compared to the single technique developments. This research opens a wide range of possible applications in the fields of faces recognition. [ABSTRACT FROM PUBLISHER]

Examines the association between sodium channel mutation and resistance to DDT and pyrethroid insecticides in the peach-potato aphid, Myzuz persicae. Location of the mutation; Mechanism of resistance to deltamethrin resistance; Effectiveness of esterase mechanism.

The peach-potato aphid Myzus persicae (Sulzer) can resist a range ofinsecticides by over-producing detoxifying esterase and having mutant-insensitive forms of the target proteins, acetylcholinesterase (AChE), and the sodium channel. Using a combination of bioassays, biochemical and DNA diagnostics, it is now possible to diagnose all three mechanisms in individual aphids, and thereby establish their spatial distributions and temporal dynamics. A survey of 58 samples of wide geographic origin showed that all 46 resistant clones had amplified esterase genes (E4 or FE4) conferring broad-spectrum resistance to pyrethroids, organophosphates and carbamates. These occurred in combinationwith insensitive AChE (11 clones), conferring resistance to pirimicarb and triazamate, and/or mutant sodium channel genes (25 clones), conferring knockdown (kdr) resistance to pyrethroids and DDT. Amplifiedesterase genes were in linkage disequilibrium with both insensitive AChE and the kdr mutation, reflecting tight physical linkage, heavy selection favouring aphids with multiple mechanisms, and/or the prominence of parthenogenesis in many M. persicae populations. An ability to monitor individual mechanisms with contrasting cross-resistance profiles has important implications for the development of resistance management recommendations. [ABSTRACT FROM AUTHOR]

Knockdown resistance (kdr) is a target-site resistance mechanism that confers nerve insensitivity to DDT and pyrethroid insecticides. In the housefly, Musca domestica, molecular cloning of the para-type sodium channel gene has revealed two amino acid mutations that are associated with kdr and super-kdr resistance phenotypes. Both mutations are located in the domain II region of the channel; Leu1014 to Phe in the hydrophobic segment IIS6 and Met918 to Thr in the IIS4-IIS5 linker. To investigate whether these mutations also occur in other insects,we have designed degenerate primers based on conserved sequences in the domain II region of the sodium channel and used these to PCR amplify this region from insecticide-susceptible strains of eight diverseinsect species representing four different insect Orders: Helicoverpa armigera, Plutella xylostella, Spodoptera littoralis (Lepidoptera),Blattella germanica (Dictyoptera), Tribolium castaneum (Coleoptera),Myzus persicae, Aphis gossypii and Phorodon humuli (Hemiptera). The primers amplified closely related para-type sodium channel sequences from each insect with a minimum of 85% amino acid identity between species. All of the sequences contained 'susceptible' Leu and Met residues at the positions associated with kdr and super-kdr resistance in the housefly. Recent results detailing the presence of a kdr-type Leuto Phe mutation in pyrethroid-resistant strains of two important agricultural pests, P. xylostella and M. persicae, are discussed. [ABSTRACT FROM AUTHOR]

In the New World, the milliped family Platyrhacidae (Polydesmida) is known or projected for Central America south of southeastern Nicaragua and the northern ¼ of South America, with disjunct, insular populations on Hispaniola (Haiti), Guadeloupe (Basse-Terre), and St. Lucia. Male near-topotypes enable redescription of Proaspis aitia Loomis, 1941, possibly endemic to the western end of the southern Haitian peninsula. The tibiotarsus of its biramous gonopodal telopodite bends strongly laterad, and the medially directed solenomere arises at midlength proximal to the bend. With a uniramous telopodite, P. sahlii Jeekel, 1980, on Guadeloupe, is not congeneric, and Hoffmanorhacus, n. gen., is erected to accommodate it. Nannorrhacus luciae (Pocock, 1894), on St. Lucia, is redescribed; also with a biramous telopodite, its tibiotarsus arises distad and diverges from the coaxial solenomere. The Antillean species do not comprise a clade and are only distantly related; rather than introductions, they plausibly reflect ancestral occurrences on the "proto-Antillean" terrain before it rifted from "proto-South America" in the Cretaceous/Paleocene, with fragmentation isolating modern forms on their present islands. Existing platyrhacid tribes are formally elevated to subfamilies as this category was omitted from recent taxonomies. Without unequivocal evidence to the contrary, geographically anomalous species should initially be regarded as indigenous rather than anthropochoric.

Aphids are the leading pests in agricultural crops. A large-scale sequencing of 40,904 ESTs from the pea aphid Acyrthosiphon pisum was carried out to define a catalog of 12,082 unique transcripts. A strong AT bias was found, indicating a compositional shift between Drosophila melanogaster and A. pisum. An in silico profiling analysis characterized 135 transcripts specific to pea-aphid tissues (relating to bacteriocytes and parthenogenetic embryos). This project is the first to address the genetics of the Hemiptera and of a hemimetabolous insect.

Aphids constitute a monophyletic group within the order Homoptera (i.e., superfamily Aphidoidea). The Aphidoidea originated in the Jurassic about 150 my ago from some aphidiform ancestor whose origin can be traced back to about 250 my ago. They exhibit a mutualistic association with intracellular bacteria (Buchnera sp.) related to Escherichia coli. Buchnera is usually considered the aphids' primary endosymbiont. The association is obligate for both partners. The 16S rDNA-based phylogeny of Buchnera from four aphid families showed complete concordance with the morphology-based phylogeny of their aphid hosts, which pointed to a single original infection in a common ancestor of aphids some 100-250 my ago followed by cospeciation of aphids and Buchnera. This study concentrated on the molecular phylogeny of both the aphids and their primary endosymbionts of five aphid families including for the first time representatives of the family Lachnidae. We discuss results based on two Buchnera genes (16S rDNA and the beta subunit of the F-ATPase complex) and on one host mitochondrial gene (the subunit 6 of the F-ATPase complex). Although our data do not allow definitive evolutionary relationships to be established among the different aphid families, some traditionally accepted groupings are put into question from both bacterial and insect data. In particular, the Lachnidae and the Aphididae, which from morphological data are considered recently evolved sister groups, do not seem to be as closely related as is usually accepted. Finally, we discuss our results in the light of the proposed parallel evolution of aphids and their endosymbionts., (Copyright 2001 Academic Press.)

We report the isolation of cDNA clones containing the full 6.3-kb coding sequence of the para-type sodium channel gene of the housefly, Musca domestica. This gene has been implicated as the site of knockdown resistance (kdr), an important resistance mechanism that confers nerve insensitivity to DDT and pyrethroid insecticides. The cDNAs predict a polypeptide of 2108 amino acids with close sequence homology (92% identity) to the Drosophila para sodium channel, and around 50% homology to vertebrate sodium channels, Only one major splice form of the housefly sodium channel was detected, in contrast to the Drosophila para transcript which has been reported to undergo extensive alternative splicing. Comparative sequence analysis of housefly strains carrying kdr or the more potent super-kdr factor revealed two amino acid mutations that correlate with these resistance phenotypes. Both mutations are located in domain II of the sodium channel. A leucine to phenylalanine replacement in the hydro-phobic IIS6 transmembrane segment was found in two independent kdr strains and six super-kdr strains of diverse geographic origin, while an additional methionine to threonine replacement within the intracellular IIS4-S5 loop was found only in the super-kdr strains. Neither mutation was present in five pyrethroid-sensitive strains. The mutations suggest a binding site for pyrethroids at the intracellular mouth of the channel pore in a region known to be important for channel inactivation.

Holocyclic clones of the aphid Rhopalosiphum padi (L.) reproduce by cyclic parthenogenesis, whereas anholocyclic individuals are obligate parthenogens. Mitochondrial DNA and (mtDNA) and random amplified polymorphic DNA markers in R. padi as well as plasmid DNA markers of its bacterial endosymbiont, Buchnera aphidicola, were examined to determine the extent of genetic divergence between clones with these differing breeding systems. These analyses revealed that cyclically parthenogenetic lineages possessed differing mtDNA and plasmid haplotypes than most obligately asexual clones. The extent of sequence divergence between the maternally inherited molecules suggest a relatively ancient origin of asexuality. Our work also identified a random amplified polymorphic DNA marker linked to the life-cycle variation in R. padi. This marker not only permits the rapid diagnosis of breeding system but sets the stage for studies to identify the gene(s) controlling this variation in mode of reproduction.