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Semiochemicals are involved in tritrophic interactions and affect the behaviors of both herbivores and beneficial insects. Many volatile molecules from the wheat plant [Triticum aestivum L. (Gramineae)] have previously been identified. To understand their effects on aphids and related auxiliaries. [Methods] The impact of four of these volatiles ; methyl-salycilate, cis-3-hexenyl acetate, hexenol, and 1-hexanol, was tested on the wheat aphid [Sitobion avenae (Fabricus)(Homoptera:Aphididae)] and two major predators of this pest encountered in field crops, the hoverfly (Episyrphus balteatus (DeGeer) (Diptera: Syrphidae)] and the multicoloured Asian ladybird [Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)].Different doses of these chemicals were tested by performing four arm-olfactometer and wind-tunnel assays. [Results] The results show that methyl-salycilate seemed to be attractive only toward H. axyridis but 3-hexenyl acetate and hexenol were attractive to both S. avenae and H. axyridis. However, these positive responses decreased with increased dose of the tested compounds. 3-hexenyl acetate also induced positive response in E. balteatus but 1-hexanol was more attractive to aphids than to their natural enemies. [Conclusion] In conclusion, these results highlight the potential benefit of combining methyl-salycilate,3-hexenyl acetate and hexenol in push and pull traps aimed to control S. avenae. Contrary to the three aforementioned compounds, 1-hexanol did not seem to have much potential as a semiochemical for the biological control of aphids. Key words wheat, volatiles, infochemicals, aphid, predator, behaviour

Aphids feed on the phloem sap of plants, and are the most common honeydew-producing insects. While aphid honeydew is primarily considered to comprise sugars and amino acids, its protein diversity has yet to be documented. Here, we report on the investigation of the honeydew proteome from the pea aphid Acyrthosiphon pisum. Using a two-Dimensional Differential in-Gel Electrophoresis (2D-Dige) approach, more than 140 spots were isolated, demonstrating that aphid honeydew also represents a diverse source of proteins. About 66% of the isolated spots were identified through mass spectrometry analysis, revealing that the protein diversity of aphid honeydew originates from several organisms (i.e. the host aphid and its microbiota, including endosymbiotic bacteria and gut flora). Interestingly, our experiments also allowed to identify some proteins like chaperonin, GroEL and Dnak chaperones, elongation factor Tu (EF-Tu), and flagellin that might act as mediators in the plant-aphid interaction. In addition to providing the first aphid honeydew proteome analysis, we propose to reconsider the importance of this substance, mainly acknowledged to be a waste product, from the aphid ecology perspective.

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. © Taylor & Francis Group, LLC.

L’objet de cette étude, menée dans des champs de la province du Shandong, Chine, consistait à déterminer la diversité et l’abondance de pucerons et d’insectes auxiliaires aphidiphages en courgettes et en pommes de terre. L’inventaire des populations de pucerons et d’auxiliaires aphidiphages a été réalisé entre le 9 mai et le 13 juin 2011, à l’aide de pièges jaunes et d’observations sur plante. Au total, 53.206 individus ont été piégés et 35.144 observés. Les pucerons sont largement majoritaires et ils exercent une forte pression sur ces deux cultures en début de saison. Seules, deux espèces ont été identifiées sur plante, à savoir Aphis gossypii essentiellement sur courgette et Myzus persicae sur pomme de terre. Les coccinelles sont les prédateurs aphidiphages les plus abondants, notamment l’espèce Coccinella septempunctata pour les courgettes et Propylea japonica pour les pommes de terre, la première étant plus précoce que la deuxième. Peu de syrphes et de chrysopes ont été capturés. Les micro-hyménoptères apparaissent plus tard dans la saison. L’espèce Aphidius gifuensis représente la majorité des Braconidae capturés, tandis que la famille des Aphelinidae est majoritaire au sein des aphidiphages. Mots-clés: diversité, abondance, pucerons, aphidiphages, courgettes, pommes de terre. The aim of this study was to evaluate the diversity and abundance of aphids and aphidophagous beneficials in courgettes and potato fields in the Shandong province, East of China. The assessment of aphid and related beneficial populations was conducted between May 9th and June 13th, 2011, using yellow traps and in situ observations on plants. A total of 53,206 insects were trapped and 35,144 observed on the plants. Aphids widely predominated in the traps and exerted a strong pressure on both crops early in the season. Two main species were identified on the plants, namely Aphis gossypii on the courgettes and Myzus persicae on the potatoes. Ladybirds were the most abundant aphidophagous pr

Aphidius ervi (Hymenoptera: Braconidae) is an entomophagous parasitoid known to be an effective parasitoid of several aphid species of economic importance. A reduction of its production cost during mass rearing for inundative release is needed to improve its use in biological control of pests. In these contexts, a careful analysis of its entire development phases within its host is needed. This paper shows that this parasitoid has some characteristics in its embryological development rather complex and different from most other reported insects, which can be phylogenetically very close. First,its yolkless egg allows a high fecundity of the female but force them to hatch from the egg shell rapidly to the host hemocoel. An early cellularisation allowing a rapid differentiation of a serosa membrane seems to confirm this hypothesis. The serosa wraps the developing embryo until the first instar larva stage and invades the host tissues by microvilli projections and form a placenta like structure able to divert host resources and allowing nutrition and respiration of embryo. Such interspecific invasion, at the cellular level, recalls mammal’s trophoblasts that anchors maternal uterine wall and underlines the high adaptation of A. ervi to develop in the host body.

An intracellular symbiotic bacterium was isolated from the flora of a natural clone of the black bean aphid Aphis fabae. The strain was able to grow freely in aerobic conditions on a rich medium containing 1% of each of the following substrates: glucose, yeast extract and casein peptone. Pure culture was achieved through the use of solid-phase culture on the same medium and the strain was designated CWBI-2.3T. 16S rRNA gene sequence analysis revealed that strain CWBI-2.3T was a member of the class Gammaproteobacteria, having high sequence similarity (.99 %) with ‘Candidatus Serratia symbiotica’, the R-type of secondary endosymbiont that is found in several aphid species. As strain CWBI-2.3T (5LMG 25624T5DSM 23270T) was the first R-type symbiont to be isolated and characterized, it was designated as the type strain of Serratia symbiotica sp. nov.

Colony collapse disorder (CCD), a syndrome whose defining trait is the rapid loss of adult worker honey bees, Apis mellifera L., is thought to be responsible for a minority of the large overwintering losses experienced by U.S. beekeepers since the winter 2006-2007. Using the same data set developed to perform a monofactorial analysis (PloS ONE 4: e6481, 2009), we conducted a classification and regression tree (CART) analysis in an attempt to better understand the relative importance and interrelations among different risk variables in explaining CCD. Fifty-five exploratory variables were used to construct two CART models: one model with and one model without a cost of misclassifying a CCD-diagnosed colony as a non-CCD colony. The resulting model tree that permitted for misclassification had a sensitivity and specificity of 85 and 74%, respectively. Although factors measuring colony stress (e.g., adult bee physiological measures, such as fluctuating asymmetry or mass of head) were important discriminating values, six of the 19 variables having the greatest discriminatory value were pesticide levels in different hive matrices. Notably, coumaphos levels in brood (a miticide commonly used by beekeepers) had the highest discriminatory value and were highest in control (healthy) colonies. Our CART analysis provides evidence that CCD is probably the result of several factors acting in concert, making afflicted colonies more susceptible to disease. This analysis highlights several areas that warrant further attention, including the effect of sublethal pesticide exposure on pathogen prevalence and the role of variability in bee tolerance to pesticides on colony survivorship.

The validation of a fast GC-FID analytical method for the quantitative determination of semiochemical sesquiterpenes (E-beta-farnesene and beta-caryophyllene) to be used in an integrated pest management approach is described. Accuracy profiles using total error as decision criteria for validation were used to verify the overall accuracy of the method results within a well defined range of concentrations and to determine the lowest limit of quantification for each analyte. Furthermore it allowed to select a very simple and reliable regression model for calibration curve for the quantification of both analytes as well as to provide measurement uncertainty without any additional experiments. Finally, this validated method was used for the quantification of semiochemicals in slow release formulations. The goal was to verify the protection efficiency of alginate gel beads formulations against oxidation and degradation of sesquiterpenes. The results showed that the alginate beads are adequate slow release devices which protect the bio-active molecules during at least twenty days. (C) 2010 Elsevier B.V. All rights reserved.

Essential oils of aromatic plants are nowadays cited as suitable tools for better protection of stored grains from insect pest attacks. These chemical insecticides are less attractive to producers because of their low persistence and difficulty to use as pure product There is therefore a need to formulate them as an easy handling chemical with better persistence. The present work aimed to study the formulation through adsorption of active components of Xylopia aethiopica Dunal (Annonaceae) essential oil on kaolin. X aethiopica essential oil was obtained by hydrodistillation in a Clevenger type apparatus unit Essential oil obtained was analysed by a GC-FID and a GC-MS. The adsorption measurements were performed with collected two kaolin fractions (F1 <100 mu m; F2 <50 mu m) and two kaolin fractions after H2O2 treatment (F3 <50 mu m; F4 <2 mu m). The kaolin was characterized by XRD, XRF, FTIR; its specific surface area was determined by the B.E.T method. The amount of essential oil adsorbed was inversely proportional to the particles size. Treatment of kaolin with hydrogen peroxide increased the adsorption capacity of essential oil components. The components adsorbed in highest amounts were sabinene, beta-pinene, alpha-pinene and beta-phellandrene. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.

The choice of oviposition site by female aphidophagous predators is crucial for offspring performance, especially in hoverflies whose newly hatched larvae are unable to move over large distance. Predator and parasitoid interactions within the aphidophagous guild are likely to be very important in influencing the choices made by predatory hoverfly females. In the present study, the foraging and oviposition behavior of the aphidophagous hoverfly Episyrphus balteatus DeGeer (Diptera: Syrphidae) was investigated with respect to the parasitized state of its aphid prey, Acyrthosiphon pisum Harris (Homoptera: Aphididae), that were parasitized by Aphidius ervi Haliday (Hymenoptera: Aphidiidae). We also recorded the number of eggs laid by hoverfly females when subjected to parasitized aphids. Furthermore, we studied the influence of being fed with parasitized aphids on hoverfly larval performance. Hoverfly females did not exhibit any preference for plants infested with unparasitized or aphids parasitized for 7 days. On the other hand, plants infested with mummies or exuvia were less attractive for E. balteatus. These results were correlated with (i) the number of eggs laid by E. balteatus females and (ii) larval performance. Thus, our results demonstrate that E. balteatus behavior is affected by parasitoid presence through their exploitation of aphid colonies. Indeed, hoverfly predators select their prey according to the developmental state of the parasitoid larvae.

Hyptis spicigera essential oils from seven localities in the North-Cameroon (Ngaoundere, Guirvidig, Kodeck, Lara, Toloum, Kaele, Tchecal-baila) were investigated by GC and GC/MS. Results showed differences within harvesting sites and between the different sites of collection but did not revealed clear tendencies in the evolution of the oil composition with regard to the sampling period. The main group of compounds in all the analyzed samples were: alpha-pinene (11.9%-42.1%), beta-pinene + sabinene (6.0%-39.8%) and beta-phellandrene + 1,8-cineole(8.8%-27.4%) except in one oil where beta-caryophyllene (23.4%) was the principal component. The insecticidal activity of H. spicigera and its principal terpenic components was evaluated against the cowpea weevil Callosobruchus maculatus F., the major cause of damages of cowpea (Vigna unguiculata (L.) Walp) in North Cameroon.