Biology of Two-Spotted Spider Mite (<i>Tetranychus urticae</i>): Ultrastructure, Photosynthesis, Guanine Transcriptomics, Carotenoids and Chlorophylls Metabolism, and Decoyinine as a Potential Acaricide

Two-Spotted Spider Mites (TSSMs, Tetranychus urticae Koch 1836 (Acari: Tetranychidae)) is one of the most important pests in many crop plants, and their feeding activity is based on sucking leaf cell contents. The purpose of this study was to evaluate the interaction between TSSMs and their host Lima bean (Phaseolus lunatus) by analyzing the metabolomics of leaf pigments and the transcriptomics of TSSM guanine production. We also used epifluorescence, confocal laser scanning, and transmission electron microscopies to study the morphology and structure of TSSMs and their excreta. Finally, we evaluated the potential photosynthetic ability of TSSMs and the activity and content of Ribulose-1,5-bisphosphate Carboxylase/Oxigenase (RubisCO). We found that TSSMs express several genes involved in guanine production, including Guanosine Monophosphate Synthetase (GMPS) and decoyinine (DCY), a potential inhibitor of GMPS, was found to reduce TSSMs proliferation in infested Lima bean leaves. Despite the presence of intact chloroplasts and chlorophyll in TSSMs, we demonstrate that TSSMs do not retain any photosynthetic activity. Our results show for the first time the transcriptomics of guanine production in TSSMs and provide new insight into the catabolic activity of TSSMs on leaf chlorophyll and carotenoids. Finally, we preliminary demonstrate that DCY has an acaricidal potential against TSSMs

Transcriptome Pyrosequencing of the Parasitoid Wasp <em>Cotesia vestalis</em>: Genes Involved in the Antennal Odorant-Sensory System

<div><p><em>Cotesia vestalis</em> is an endoparasitic wasp that attacks larvae of the diamondback moth (<em>Plutella xylostella</em>), a herbivore of cruciferous plants. Females of <em>C. vestalis</em> use herbivore-induced plant odorants released from plants infested by <em>P. xylostella</em> as a host-searching cue. Transcriptome pyrosequencing was used to identify genes in the antennae of <em>C. vestalis</em> adult females coding for odorant receptors (ORs) and odorant binding proteins (OBPs) involved in insect olfactory perception. Quantitative gene expression analyses showed that a few OR and OBP genes were expressed exclusively in the antenna of <em>C. vestalis</em> adult females whereas most other classes of genes were expressed in the antennae of both males and females, indicating their diversity in importance for the olfactory sensory system. Together, transcriptome profiling of <em>C. vestalis</em> genes involved in the antennal odorant-sensory system helps in detecting genes involved in host- and food-search behaviors through infochemically-mediated interactions.</p> </div

Tissue and genderspecific expressions of OBP genes in <i>C. vestalis</i> adults.

<p>Transcription levels of genes for OBP1 to 10 were normalized to those of <i>C. vestalis</i> 60S ribosomal protein L10 (Cv_000471), and expressed relative to the normalized transcript levels in the body of <i>C. vestalis</i> males. Data represent the mean and standard errors (<i>n = </i>5). Means followed by different small letters are significantly different (<i>P</i><0.05, Tukey-Kramer HSD test).</p

The part of contigs from <i>Cotesia vestalis</i> with similarity to OR genes.

<p>Contigs which are regenerated at least from 10 reads are listed. *We identified genes whose E-values exhibited at least 1E-5 or less, with the BLAST searches.</p

The part of contigs from <i>Cotesia vestalis</i> with similarity to OBP genes.

<p>Contigs which are regenerated at least from 10 reads are listed. *We identified genes whose E-values exhibited at least 1E-5 or less, with the BLAST searches.</p

Distribution of transcriptome pyrosequencing from contigs/singletons.

<p>The major categories of level 2 molecular functions from a Gene Ontology (GO) analysis are shown (<i>n</i> = 10 642).</p

Tissue and genderspecific expressions of OR genes in <i>C. vestalis</i> adults.

<p>Transcription levels of genes for OR1 to 6 were normalized to those of <i>C. vestalis</i> 60S ribosomal protein L10 (Cv_000471), and expressed relative to the normalized transcript levels in the body of <i>C. vestalis</i> males. Data represent the mean and standard errors (<i>n = </i>5). Means followed by different small letters are significantly different (<i>P</i><0.05, Tukey-Kramer HSD test).</p