Behavioural Evidence and Chemical Identification of a Female Sex Pheromone in Anagrus atomus (Hymenoptera: Mymaridae).

Anagrus atomus (L.) is an egg parasitoid involved in the biological control of Empoasca vitis (Göthe) in vineyards. Sex pheromones play a crucial role in mate finding for several parasitoid species and could be used for monitoring under field conditions. We carried out laboratory and field studies aimed at assessing the existence and identity of a possible A. atomus sex pheromone. We found that males were significantly attracted by virgin females independent of age. Males were not attracted to individuals of the same sex, but they were attracted by a crude extract from an unmated female and its polar fraction. Eugenol (4-allyl-2-methoxyphenol) was identified as the attractive substance and proved to be attractive not only in the olfactometer but also in another laboratory bioassay and under field conditions. Attraction of males, but not females, confirms that this is not an aggregation pheromone. This is the first sex-pheromone component identified in Mymaridae, however more compounds could be involved in the mating behaviour of A. atomus. The utility of a sex pheromone in A. atomus is discussed in the context of fitness returns.

Identification of transcripts involved in digestion, detoxification and immune response from transcriptome of Empoasca vitis (Hemiptera: Cicadellidae) nymphs.

Tea production has been significantly impacted by the false-eye leafhopper, Empoasca vitis (Göthe), around Asia. To identify the key genes which are responsible for nutrition absorption, xenobiotic metabolism and immune response, the transcriptome of either alimentary tracts or bodies minus alimentary tract of E. vitis was sequenced and analyzed. Over 31 million reads were obtained from Illumina sequencing. De novo sequence assembly resulted in 52,182 unigenes with a mean size of 848nt. The assembled unigenes were then annotated using various databases. Transcripts of at least 566 digestion-, 224 detoxification-, and 288 immune-related putative genes in E. vitis were identified. In addition, relative expression of highly abundant transcripts was verified through quantitative real-time PCR. Results from this investigation provide genomic information about E. vitis, which will be helpful in further study of E. vitis biology and in the development of novel strategies to control this devastating pest.

Relative Infestation Level and Sensitivity of Grapevine Cultivars to the Leafhopper Empoasca vitis (Hemiptera: Cicadellidae).

The leafhopper Empoasca vitis (Göthe) (Hemiptera: Cicadellidae) feeds on veins of grapevine leaves, mainly on the phloem, causing physiological injury, color change and drying of leaf margins, yield and sugar content reduction. The relative infestation level (i.e., the probability that a plant is attacked by herbivores) of E. vitis on different grapevine cultivars and their sensitivity (i.e., the incidence of symptoms expression in response to herbivore feeding or other stimuli) to this pest were studied over four years in two vineyards located in northeastern Italy. Some cultivars (e.g., Carménère and Sauvignon Blanc) were usually more infested than others (e.g., Cabernet Sauvignon and Pinot Gris), although some differences were observed among years and sites. The sensitivity varied among cultivars, i.e., some of them showed more symptoms than expected on the basis of infestation levels (e.g., Carménère and Merlot), in contrast with others (e.g., Rhine Riesling and Chardonnay). Information obtained can be used within the framework of integrated pest management in vineyards. Action thresholds should differ on the basis of sensitivity. Sampling must first be carried out on the most susceptible cultivar and, if the action threshold is exceeded, it should be extended to the remaining cultivars based on their decreasing relative infestation level.

Comparison of Insecticide Susceptibilities of Empoasca vitis (Hemiptera: Cicadellidae) from Three Main Tea-Growing Regions in China.

Empoasca vitis (Göthe) is an important insect pest in tea-growing areas of China, and chemical control is the main tactic for the management of this pest. Due to the pressure of increasing insecticide resistance and more stringent food safety regulations, development of sound IPM strategies for E. vitis is an urgent matter. This study comparatively evaluated four field populations of E. vitis from three different tea-growing regions in China for their susceptibilities to eight insecticides using a simple leaf-dip methodology. E. vitis was found to be most sensitive to indoxacarb (LC50<0.5 mg/liter) and least sensitive to isoprocarb (LC50>5 mg/liter) and sophocarpidine (LC50>95 mg/liter, a botanical pesticide) regardless of populations. Population (geographical) variations were higher for indoxacarb and imidacloprid than other compounds. Judging by the 95% fiducial limits of LC50 values, all populations had similar susceptibilities to chlorfenapyr, bifenthrin, and acetamiprid or imidacloprid. Correlation analysis suggested that chlorfenapyr and indoxacarb or isoprocarb may have a high risk of cross resistance. Considering potency (LC50) and maximum residual levels, chlorfenapyr and bifenthrin are good insecticide options followed by acetamiprid and indoxacarb. These results provide valuable information to intelligently select insecticides for IPM programs that are efficacious against E. vitis while also managing insecticide resistance and maximum residual levels for tea production in China.

Complete mitochondrial genome of Empoasca vitis (Hemiptera: Cicadellidae).

The complete mitochondrial genome of Empoasca vitis was sequenced. The length of the mitogenome is 15,154 bp with 78.35% AT content (GenBank accession No. KJ815009). The genome encode 37 typical mitochondrial genes including 22 transfer RNA genes, 13 protein-coding genes, 2 ribosomal RNA genes and an A+T-rich region. The gene arrangement is similar to that of Drosophila yakuba, the presumed ancestral insect mitochondrial gene arrangement. Except for cox2 using GTG as start codon, other protein-coding genes (PCGs) share the start codons ATN. Usual termination codon TAA and incomplete stop codon T are using by 13 protein-coding genes. The A+T-rich region has a length of 977 bp with the AT content high to 88.95%.