Youqing Luo

Antennal transcriptome analysis of the Asian longhorned beetle Anoplophora glabripennis

Olfactory proteins form the basis of insect olfactory recognition, which is crucial for host identification, mating, and oviposition. Using transcriptome analysis of Anoplophora glabripennis antenna, we identified 42 odorant-binding proteins (OBPs), 12 chemosensory proteins (CSPs), 14 pheromone-degrading enzymes (PDEs), 1 odorant-degrading enzymes (ODE), 37 odorant receptors (ORs), 11 gustatory receptors (GRs), 2 sensory neuron membrane proteins (SNMPs), and 4 ionotropic receptor (IR). All CSPs and PBPs were expressed in antennae, confirming the authenticity of the transcriptome data. CSP expression profiles showed that AglaCSP3, AglaCSP6, and AglaCSP12 were expressed preferentially in maxillary palps and AglaCSP7 and AglaCSP9 were strongly expressed in antennae. The vast majority of CSPs were highly expressed in multiple chemosensory tissues, suggesting their participation in olfactory recognition in almost all olfactory tissues. Intriguingly, the PBP AglaPBP2 was preferentially expressed in antenna, indicating that it is the main protein involved in efficient and sensitive pheromone recognition. Phylogenetic analysis of olfactory proteins indicated AglaGR1 may detect CO2. This study establishes a foundation for determining the chemoreception molecular mechanisms of A. glabripennis, which would provide a new perspective for controlling pest populations, especially those of borers.

Genetic Characterization of the Gypsy Moth from China (Lepidoptera, Lymantriidae) Using Inter Simple Sequence Repeats Markers

This study provides the first genetic characterization of the gypsy moth from China ( Lymantria dispar ), one of the most recognized pests of forests and ornamental trees in the world. We assessed genetic diversity and structure in eight geographic populations of gypsy moths from China using five polymorphic Inter simple sequence repeat markers, which produced reproducible banding patterns. We observed 102 polymorphic loci across the 176 individuals sampled. Overall genetic diversity (Nei’s, H) was 0.2357, while the mean genetic diversity within geographic populations was 0.1845 ± 0.0150. The observed genetic distance among the eight populations ranged from 0.0432 to 0.1034. Clustering analysis (using an unweighted pair-group method with arithmetic mean and multidimensional scaling), revealed strong concordance between the strength of genetic relationships among populations and their geographic proximity. Analysis of molecular variance demonstrated that 25.43% of the total variability (F ST = 0.2543, P < 0.001) was attributable to variation among geographic populations. The results of our analyses investigating the degree of polymorphism, genetic diversity (Nei’s and Shannon) and genetic structure, suggest that individuals from Hebei may be better able to adapt to different environments and to disperse to new habitats. This study provides crucial genetic information needed to assess the distribution and population dynamics of this important pest species of global concern.

Comparative analysis of peach and pear fruit volatiles attractive to the oriental fruit moth, Cydia molesta

Cydia molesta is an important pest of peach and pear fruits late in growing season. We identified and quantified volatiles from immature and mature fruits of peach and pear using gas chromatography-mass spectrometry. Antennally, active compounds were identified by gas chromatography-electroantennogram detection and were further tested in the field. Consistent electroantennographic activity was obtained for nine compounds from headspace collections of the mature fruits of two peach and two pear varieties. Esters were the major components, but qualitative and quantitative differences were found among four odor profiles. Blends mimicking pear fruit volatiles were more attractive to both sexes than blends mimicking peach fruit volatiles in both orchards. Our finding indicated that mixtures mimicking peach and pear fruit volatiles attracted both females and males of C. molesta, and these host volatiles may also be involved in the host switch behavior from peach to pear in mid-late season.

DNA Barcoding of Gypsy Moths From China (Lepidoptera: Erebidae) Reveals New Haplotypes and Divergence Patterns Within Gypsy Moth Subspecies

Abstract The gypsy moth from Asia (two subspecies) is considered a greater threat to North America than European gypsy moth, because of a broader host range and females being capable of flight. Variation within and among gypsy moths from China (nine locations), one of the native countries of Asian gypsy moth, were compared using DNA barcode sequences (658 bp of mtDNA cytochrome c oxidase subunit 1 [COI] sequence), together with two restriction site mtDNA markers (NlaIII and BamHI in COI), which is the standard system used to distinguish European gypsy moths from Asian gypsy moths. Relatedness of these populations to gypsy moths from seven other world areas was also examined. The restriction site markers showed that two Chinese populations had both Asian and European haplotypes. DNA barcode sequence divergence between the Asian populations and the European populations was three times greater than the variation within each group. Using Bayesian and parsimonious network analyses, nine previously unknown barcode haplotypes were documented from China and a single haplotype was found to be shared by 55% of the Chinese and some Far Eastern Russian and Japanese individuals. Some gypsy moths from two Chinese populations showed genetic affinity with mtDNA haplotypes from Siberia, Russia, suggesting there could be a cryptic new subspecies in Lymantria dispar (L.) or human-aided movement of moths between these two locations at an earlier point in time. The previously unknown haplotype patterns may complicate efforts to identify Asian gypsy moth introductions and require changes in monitoring and exclusion programs.

Antennal transcriptome analysis and expression profiles of odorant binding proteins in Eogystia hippophaecolus (Lepidoptera: Cossidae)

BackgroundEogystia hippophaecolus (Hua et al.) (Lepidoptera: Cossidae) is the major threat to seabuckthorn plantations in China. Specific and highly efficient artificial sex pheromone traps was developed and used to control it. However, the molecular basis for the pheromone recognition is not known. So we established the antennal transcriptome of E. hippophaecolus and characterized the expression profiles of odorant binding proteins. These results establish and improve the basis knowledge of the olfactory receptive system, furthermore provide a theoretical basis for the development of new pest control method.ResultsWe identified 29 transcripts encoding putative odorant-binding proteins (OBPs), 18 putative chemosensory proteins (CSPs), 63 odorant receptors (ORs), 13 gustatory receptors (GRs), 12 ionotropic receptors (IRs), and two sensory neuron membrane proteins (SNMPs). Based on phylogenetic analysis, we found one Orco and three pheromone receptors of E. hippophaecolus and found that EhipGR13 detects sugar, EhipGR11 and EhipGR3 detect bitter. Nine OBPs expression profile indicated that most were the highest expression in antennae, consistent with functions of OBPs in binding and transporting odors during the antennal recognition process. OBP6 was external expressed in male genital-biased in, and this locus may be responsible for pheromone binding and recognition as well as mating. OBP1 was the highest and biased expressed in the foot and may function as identification of host plant volatiles.ConclusionsOne hundred thirty-seven chemosensory proteins were identified and the accurate functions and groups of part proteins were obtained by phylogenetic analysis. The most OBPs were antenna-biased expressed, which are involved in antennal recognition. However, few OBP was detected biased expression in the foot and external genitalia, and these loci may function in pheromone recognition, mating, and the recognition of plant volatiles.

Antifeedant Activity of Ginkgo biloba Secondary Metabolites against Hyphantria cunea Larvae: Mechanisms and Applications

Ginkgo biloba is a typical relic plant that rarely suffers from pest hazards. This study analyzed the pattern of G. biloba pest hazards in Beijing; tested the antifeedant activity of G. biloba extracts, including ginkgo flavonoids, ginkgolide, and bilobalide, against Hyphantria cunea larvae; determined the activities of glutathione transferase (GSTs), acetylcholinesterase (AChE), carboxylesterase (CarE) and mixed-functional oxidase (MFO), in larvae after feeding on these G. biloba secondary metabolites; and screened for effective botanical antifeedants in the field. In this study, no indicators of insect infestation were found for any of the examined leaves of G. biloba; all tested secondary metabolites showed significant antifeedant activity and affected the activity of the four larval detoxifying enzymes. Ginkgolide had the highest antifeedant activity and the most significant effect on the detoxifying enzymes (P<0.05). Spraying leaves with G. biloba extracts or ginkgolide both significantly repelled H. cunea larvae in the field (P<0.05), although the former is more economical and practical. This study investigated the antifeedant activity of G. biloba secondary metabolites against H. cunea larvae, and the results provide new insights into the mechanism of G. biloba pest resistance. This study also developed new applications of G. biloba secondary metabolites for effective pest control.

Female sex pheromone blends and male response of the legume pod borer, Maruca vitrata (Lepidoptera: Crambidae), in two populations of mainland China.

The legume pod borer, Maruca vitrata (Lepidoptera: Crambidae; syn. M. testulalis), is a serious pantropical insect pest of grain legumes. Comparative studies of M. vitrata female sex pheromone components in two different geographic populations in China, Wuhan and Huazhou, confi rmed that (E,E)-10,12-hexadecadienal (E10,E12 - 16:Ald) and (E)-10-hexadecenal (E10 - 16:Ald) were present in variable ratios in all pheromone gland extracts of both populations. (E,E)-10,12-hexadecadienol (E10,E12 - 16:OH) was always detected in minor amounts using polar DB-WAX columns, but was never detected using medium-polar DB-17 columns for the two populations. E10 - 16:OH was not found in any of the M. vitrata sex pheromone gland extracts. The average ratios of E10 - 16:Ald, E10,E12 - 16:Ald, and E10,E12 - 16:OH in the pheromone gland extracts of populations from Wuhan and Huazhou were 79.5:100:12.1 and 10.3:100:0.7, respectively. Electrophysiological testing suggested that E10,E12 - 16:Ald elicited the highest male electroantennography (EAG) response, followed by E10,E12 - 16:OH and E10 - 16:Ald. Field-trapping tests with single synthetic sex pheromone lures showed that E10,E12 - 16:OH alone could not attract males, whereas E10,E12 - 16:Ald or E10 - 16:Ald alone attracted few males. Wuhan and Huazhou males were most attracted by lures containing E10 - 16:Ald + E10,E12 - 16:Ald + E10,E12 - 16:OH in doses of (80 + 100 + 10) μg and (10 + 100 + 10) μg, respectively, per vial. Males could discriminate between the blends that were most attractive to their own geographic population and those that were most attractive to the reference population. Our fi ndings suggest that geographic variation exists in the sex pheromone system of M. vitrata in China. The results are discussed with regard to the mechanisms underlying the sex pheromone variation

Remote sensing of insect pests in larch forest based on physical model

A physical decision method was proposed here to monitor Larch forest insect pests at early stage. Three remote sensing indicators were defined, which are CWC (canopy water content), TVDI (Temperature/Vegetation Dryness Index) and LAI (Leaf Area Index). The Five-scale model and artificial neural network (ANN) were combined to inverse the three factors from Landsat data. Based on training samples of health or attacked pixels, a decision tree was built to classify pest-infected pixels. Field validation showed that the prediction of forest compartments with insect pest were highly consistent with the ground field data.

Sensilla on the Antennae and Ovipositor of the Sea Buckthorn Carpenter Moth, Holcocerus hippophaecolus Hua et al (Lepidoptera: Cossidae).

Holcocerus hippophaecolus Hua et al (Lepidoptera: Cossidae) is an important boring pest that damages the sea buckthorn Hippophae rhamnoides. Larvae of H. hippophaecolus cause major losses of this shrub in Northern China, with severe economic and ecological consequences. In this study, we used scanning electron microscopy to investigate the typology, morphology, and distribution of sensilla on the antennae and ovipositor of H. hippophaecolus. In total, seven subtypes of sensilla were found on the antennae, i.e., chaetica, trichodea (two subtypes), basiconica (two subtypes), coeloconica, and Böhm bristles. In addition, three types of sensilla were detected on the ovipositor, i.e., chaetica, trichodea, and basiconica. The identification of these sensilla types could provide morphological evidence to facilitate a better understanding of the host location, mate finding, and oviposition processes of this important species.

Antennal transcriptome analysis and expression profiles of olfactory genes in Anoplophora chinensis

Olfaction in insects is essential for host identification, mating and oviposition, in which olfactory proteins are responsible for chemical signaling. Here, we determined the transcriptomes of male and female adult antennae of Anoplophora chinensis, the citrus longhorned beetle. Among 59,357 unigenes in the antennal assembly, we identified 46 odorant-binding proteins, 16 chemosensory proteins (CSPs), 44 odorant receptors, 19 gustatory receptors, 23 ionotropic receptors, and 3 sensory neuron membrane proteins. Among CSPs, AchiCSP10 was predominantly expressed in antennae (compared with legs or maxillary palps), at a significantly higher level in males than in females, suggesting that AchiCSP10 has a role in reception of female sex pheromones. Many highly expressed genes encoding CSPs are orthologue genes of A. chinensis and Anoplophora glabripennis. Notably, AchiPBP1 and AchiPBP2 showed 100% and 96% identity with AglaPBP1 and AglaPBP2 from A. glabripennis, with similar expression profiles in the two species; PBP2 was highly expressed in male antennae, whereas PBP1 was expressed in all three tissues in both males and females. These results provide a basis for further studies on the molecular chemoreception mechanisms of A. chinensis, and suggest novel targets for control of A. chinensis.