Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) of aphids are thought to be responsible for the initial molecular interactions during olfaction that mediate detection of chemical signals. Analysis of the diversity of proteins involved comprises critical basic research work that will facilitate the development of sustainable pest control strategies. To help us better understand differences in the olfactory system between winged and wingless grain aphids, we constructed an antennal transcriptome from winged and wingless Sitobion avenae (Fabricius), one of the most serious pests of cereal fields worldwide. Among the 133,331 unigenes in the antennal assembly, 13 OBP and 5 CSP putative transcripts were identified with 6 OBP and 3 CSP sequences representing new S. avenae annotations. We used qPCR to examine the expression profile of these genes sets across S. avenae development and in various tissues. We found 7 SaveOBPs and 1 SaveCSP were specifically or significantly elevated in antennae compared with other tissues, and that some transcripts (SaveOBP8, SaveCSP2 and SaveCSP5) were abundantly expressed in the legs of winged or wingless aphids. The expression levels of the SaveOBPs and SaveCSPs varied depending on the developmental stage. Possible physiological functions of these genes are discussed. Further molecular and functional studies of these olfactory related genes will explore their potential as novel targets for controlling S. avenae.

Wheat (Triticum aestivum L.) is one of the most cultivated crops in temperate climates. As its pests are mainly controlled with insecticides that are harmful to the environment and human health, alternative practices such as intercropping have been studied for their potential to promote biological control. Based on the published literature, this study aimed to review the effect of wheat-based intercropping systems on insect pests and their natural enemies. Fifty original research papers were obtained from a systematic search of the peer-reviewed literature. Results from a vote-counting analysis indicated that, in the majority of studies, pest abundance was significantly reduced in intercropping systems compared with pure stands. However, the occurrence of their natural enemies as well as predation and parasitism rates were not significantly increased. The country where the studies took place, the type of intercropping and the crop that was studied in the association had significant effects on these results. These findings show that intercropping is a viable practice to reduce insecticide use in wheat production systems. Nevertheless, other practices could be combined with intercropping to favour natural enemies and enhance pest control. © 2016 Society of Chemical Industry.

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The fragmentation mechanism of aconitine-type alkaloids in the flowers of Aconitum kusnezoffii (FAK) was investigated using electrospray ionization tandem mass spectrometry (ESI-MS(n)) firstly. The analysis of the collision-induced dissociation (CID) spectra of three purified aconitine standards and six previously reported aconitines indicated that the fragmentation of the protonated aconitines at low-energy CID follows a similar pathway. The elimination of a C(8)-substituent such as an acetic acid or a fatty acid is the dominant fragmentation mode in MS2. Successive losses of CH(3)COOH, CH(3)OH, H(2)O, BzOH, and CO are the main fragmentation pathways of aconitine-type alkaloids in MS(3) spectra. Based on these features, a rapid method for the direct detection and characterization of alkaloids from an ethanolic extract of FAK is described. All the known aconitum alkaloids are detected and a series of lipo-aconitines has been found for the first time in this plant.

1. Conservation biological control aims to control pests by promoting wild populations of natural enemies. One challenge is to attract and retain efficient natural enemies in crop fields, which often are a suboptimal environment. Towards this goal, the attract-and-reward strategy relies on combining attractive synthetically produced herbivore-induced plant volatiles (HIPVs) with companion plants (non-crop plants which provide alternative resources to the targeted natural enemies). Although severely overlooked, the spatial arrangement of HIPV dispensers and rewards inside crop fields may strongly influence the foraging behaviour and persistence of natural enemies and thus the success of this pest management strategy.2. We tested the impact of two contrasting spatial arrangements of HIPV dispensers and rewards, alternatively inside and around a block of target apple trees, on the efficacy of the biological control of Aphis citricola populations by the common predatory ladybird Propylea japonica in apple orchards in northern China. We used synthetic methyl salicylate (MeSA) as an attractant and the companion plant Calendula officinalis as a reward. To better understand how the spatial arrangement of MeSA dispensers and companion plants affected the attraction and foraging behaviour of adult ladybirds, we conducted indoor experiments in a flight mill, an olfactometer and a wind-tunnel. 3. Blocks of target trees treated with MeSA dispensers inside and companion plants around provided the most efficient pest control in orchards, compared with the opposite spatial arrangement. 4. The synthetic MeSA dispenser and the companion plant synergistically attracted ladybirds in the olfactometer and enhanced their flight activity in the flight mill. In the wind-tunnel, MeSA served as a spatial cue for ladybirds to find nearby prey, while companion plants were sought in the absence of prey. 5. Synthesis and applications. This study aims to further improve aphid control in apple orchards through a careful spatial arrangement of herbivore-induced plant volatiles dispensers (HIPVs) and rewards (companion plants) in optimized | 1177 Journal of Applied Ecology JAWORSKI et Al. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Jaworski CC, Xiao D, Xu Q, et al. Varying the spatial arrangement of synthetic herbivoreinduced plant volatiles and companion plants to improve conservation biological control.

Aphidius gifuensis Ashmead is a dominant endoparasitoid of aphids, such as Myzus persicae and Sitobion avenae, and plays an important role in controlling aphids in various habitats, including tobacco plants and wheat in China. A. gifuensis has been successfully applied for the biological control of aphids, especially M. persicae, in green houses and fields in China. The corresponding parasites, as well as its mate-searching behaviors, are subjects of considerable interest. Previous A. gifuensis transcriptome studies have relied on short-read next-generation sequencing (NGS), and the vast majority of the resulting isotigs do not represent full-length cDNA. Here, we employed a combination of NGS and single-molecule real-time (SMRT) sequencing of virgin females (VFs), mated females (MFs), virgin males (VMs), and mated males (MMs) to comprehensively study the A. gifuensis transcriptome. Behavioral responses to the aphid alarm pheromone (E-β-farnesene, EBF) as well as to A. gifuensis of the opposite sex were also studied. VMs were found to be attracted by female wasps and MFs were repelled by male wasps, whereas MMs and VFs did not respond to the opposite sex. In addition, VFs, MFs, and MMs were attracted by EBF, while VMs did not respond. According to these results, we performed a personalized differential gene expression analysis of olfactory gene sets (66 odorant receptors, 25 inotropic receptors, 16 odorant-binding proteins, and 12 chemosensory proteins) in virgin and mated A. gifuensis of both sexes, and identified 13 candidate genes whose expression levels were highly consistent with behavioral test results, suggesting potential functions for these genes in pheromone perception.

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BACKGROUND Climate warming has considerable effects on crop development and pest population dynamics. Crucially, the tri‐trophic responses of plants, herbivores and their natural enemies to warming are poorly understood. To delineate these interactive properties, a three‐system approach and integrating life table methodology were used to examine the responses of wheat plants, English grain aphid and parasitoids under open‐field infrared heating to simulate warming. RESULTS Warming significantly increased wheat biomass and grain weight, causing a phenological shift in plant growth. Importantly, warming significantly increased the number of aphids and the reproductive period, coupled with a higher net reproductive rate and intrinsic growth rate. Otherwise, duration of development, generation span, and population doubling time all decreased significantly. Warming had no effect on parasitoid abundance but resulted in a significant decrease in the rate of parasitism. CONCLUSION Warming may strengthen bottom‐up effects on aphids by increasing wheat biomass, resulting in reduced regulation of aphid populations. Warming had a different effect on parasitoids between 2015 and 2016. These findings provide an important characterization of ecological mechanisms in plant–herbivore–parasitoid systems and give a theoretical foundation for improved forecasting of aphid population dynamics under climate change. © 2019 Society of Chemical Industry