Bacterial Symbionts, \u3cem\u3eBuchnera\u3c/em\u3e, and Starvation on Wing Dimorphism in English Grain Aphid, \u3cem\u3eSitobion avenae\u3c/em\u3e (F.) (Homoptera: Aphididae)

Wing dimorphism in aphids can be affected by multiple cues, including both biotic (nutrition, crowding, interspecific interactions, the presence of natural enemies, maternal and transgenerational effects, and alarm pheromone) and abiotic factors (temperature, humidity, and photoperiod). The majority of the phloem-feeding aphids carry Buchnera, an obligate symbiotic proteobacteria. Buchnera has a highly reduced genome size, but encode key enzymes in the tryptophan biosynthetic pathway and is crucial for nutritional balance, development and reproduction in aphids. In this study, we investigated the impact of two nutritional-based biotic factors, symbionts and starvation, on the wing dimorphism in the English grain aphid, Sitobion avenae, a devastating insect pest of cereal crops (e.g., wheat) worldwide. Elimination of Buchnera using the antibiotic rifampicin significantly reduced the formation of winged morphs, body mass, and fecundity in S. avenae. Furthermore, the absence of this primary endosymbiont may disrupt the nutrient acquisition in aphids and alter transgenerational phenotypic expression. Similarly, both survival rate and the formation of winged morphs were substantially reduced after neonatal (\u3c24h \u3eold) offspring were starved for a period of time. The combined results shed light on the impact of two nutritional-based biotic factors on the phenotypic plasticity in aphids. A better understanding of the wing dimorphism in aphids will provide the theoretical basis for the prediction and integrated management of these phloem-feeding insect pests

Comparative Profiling of MicroRNAs in the Winged and Wingless English Grain Aphid, \u3cem\u3eSitobion avenae\u3c/em\u3e (F.) (Homoptera: Aphididae)

MicroRNAs (miRNAs) are short single-stranded non-coding RNAs that regulate gene expression, particularly during development. In this study, 345 miRNAs were identified from the English green aphid, Sitobion avenae (F.), of which 168 were conserved and 177 were S. avenae-specific. Quantitative comparison of miRNA expression levels indicated that 16 and 12 miRNAs were significantly up-regulated in winged and wingless S. avenae small RNA libraries, respectively. Differential expression of these miRNAs was confirmed by real-time quantitative RT-PCR validation. The putative transcript targets for these candidate miRNAs were predicted based on sequences from a model species Drosophila melanogaster and four aphid species Acyrthosiphon pisum, Myzus persicae, Toxoptera citricida, and Aphis gosspii. Gene Ontology and KEGG pathway analyses shed light on the potential functions of these miRNAs in the regulation of genes involved in the metabolism, development and wing polyphenism of S. avenae

Variation in the transmission of barley yellow dwarf virus-PAV bydifferent Sitobion avenae clones in China

peer reviewe

Application of semiochemical releasers and intercropping to control aphid and related virus in east China

Peer reviewe

Application of information technologies in monitoring the population density of pests

Monitoring pest population density is the key to prediction precision, which has the significant guidance for integrated pest management in agricultural ecosystem. Based on the traditional monitoring technique of pests, the progress of monitoring pest density with modern information technologies was reviewed. The advantages and disadvantages in application of computer vision technology (CVT), acoustic technique, radar and remote sensing technology to estimate the pest population density were analyzed. CVT and sensor will be powerful and potential tools in assessing the pest density. The pathway and main prospects were expounded in automatic acquisition of the data of pest density. Those modern technologies were significant for pest prediction and integrated pest management (IPM) in the future. (41 refs.

Orco mediates olfactory behaviors and winged morph differentiation induced by alarm pheromone in the grain aphid, Sitobion avenae

Olfaction is crucial for short distance host location and pheromone detection by insects. Complexes of olfactory receptors (ORs) are composed of odor-specific ORs and OR co-receptors (Orco). Orcos are widely co-expressed with odor-specific ORs and are conserved across insect taxa. A number of Orco orthologs have been studied to date, although none has been identified in cereal aphids. In this study, an Orco gene ortholog was cloned from the grain aphid, Sitobion avenae, and named “SaveOrco”; RNA interference (RNAi) reduced the expression of SaveOrco to 34.11% in aphids, resulting in weaker EAG (electroantennogram) responses to plant volatiles (Z-3-hexene-1-ol; methyl salicylate, MeSA) and aphid alarm pheromone (E-b-farnesene, EBF). Aphid wing differentiation induced by EBF was investigated in both RNAi treated and untreated aphids. EBF induced production of winged aphids in both pre-natal and postnatal periods in untreated aphids, but no such induction was observed in the RNAi-treated aphids. We conclude that SaveOrco is crucial for the aphid's response to pheromones and other volatiles, and is involved in wing differentiation triggered by EB

Adaptation of Wheat-Pea Intercropping Pattern in China to Reduce Sitobion avenae (Hemiptera: Aphididae) Occurrence by Promoting Natural Enemies

The use of intercropping as a strategy for increasing biodiversity in fields has the potential to reduce pest damage and improve the crop production. Here, a study was undertaken to evaluate the role of different wheat-pea intercropping patterns in conserving arthropod natural enemies and suppressing cereal aphids in agroecosystems. Wheat-pea intercropping in an 8–2 row pattern of wheat and pea, respectively, preserved and augmented natural enemies more than a monoculture of wheat. The highest abundance of ladybeetles in 2008 and 2009 occurred in the 8–2 row pattern, whereas the highest densities of aphid parasitoids were found in the 4-2 row pattern in 2008 and the 8-2 row pattern in 2009. The distribution of aphid populations in the peak stage was spatially heterogeneous, and the highest density of aphids was shown visually in wheat monoculture fields. The land equivalent ratio of 1.121:1.187 for wheat-pea intercropping in 2008 and 1.114:1.174 for wheat-pea intercropping in 2009 showed that intercropping of wheat and pea has potential to improve the utilization of plant growth resources as compared to sole crops. Wheat-pea intercropping has potential to control English grain aphids effectively by enhancing the abundance of natural enemies, especially with an 8-2 row pattern of wheat-pea, respectively

Distribution, evolution and structural properties of Wushenqi paleo-uplift in Ordos Basin, NW China

This paper depicts the distribution of the Wushenqi paleo-uplift in the Ordos Basin by using the latest drilling and seismic data, and analyzes the tectonic evolution of the paleo-uplift with the support of Bischke curve and balanced section. The compressional Wushenqi paleo-uplift which developed in the Early Caledonian orogeny (Huaiyuan orogeny) is approximately a ellipse extending in S-N direction. Its long axis is about 194 km and short axis is about 55–94 km in nearly W-E direction. The denudation thickness and area of the Cambrian in the core are 170–196 m and 11 298 kmbrespectively. It was mainly formed during the Huaiyuan orogeny according to the chronostratigraphic framework. It was in the embryonic stage in the Middle–Late Cambrian, denuded after developed obviously at the end of Late Cambrian. The paleo-uplift of the 3rd member of the Ordovician Majiagou Formation was reactivated and reduced in area. In the sedimentary period of the Ma4 Member–pre-Carboniferous, the paleo-uplift experienced non-uniform uplift and denudation. It entered the stable period of burial and preservation in the Carboniferous and later period. The Wushenqi paleo-uplift was formed on the weak area of the basement and tectonic belts, into an compressional structure with irregular morphology, under the control of the non-coaxial compression in the south and north and the stress transmitted by the uplift in the basin. The Wushenqi paleo-uplift has a controlling effect on the sedimentary reservoirs and hydrocarbon accumulation