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Entomopathogenic fungi can adopt an endophytic lifestyle and provide protection against insect herbivores and plant pathogens. So far, most studies have focused onBeauveria bassianato increase plant resistance against abiotic and biotic stresses, while only little is known for other entomopathogenic fungi. In this study, we investigated whether root inoculation of sweet pepper (Capsicum annuumL.) by the entomopathogenic fungiAkanthomyces muscariusARSEF 5128 andB.bassianaARSEF 3097 can improve resistance against the tobacco peach aphidMyzus persicaevar.nicotianae. First, dual-choice experiments were performed to test the hypothesis that the fungi deter aphids via modifying plant volatile profiles. Next, we tested the hypothesis that endophytic colonization negatively affects aphid life history traits, such as fecundity, development and mortality rate. Aphids were significantly attracted to the odor of plants inoculated withA.muscariusover non-inoculated plants. Plants inoculated withA.muscariusemitted significantly higher amounts of β-pinene than non-inoculated plants, and significantly higher amounts of indole thanB.bassiana-inoculated and non-inoculated plants. Inoculation with the fungal strains also caused significantly higher emission of terpinolene. Further, both aphid longevity and fecundity were significantly reduced by 18% and 10%, respectively, when feeding on plants inoculated withA.muscarius, although intrinsic rate of population increase did not differ between inoculated and non-inoculated plants. Sweet pepper plants inoculated withB.bassianaARSEF 3097 did not elicit a significant behavioral response nor affected the investigated life history traits. We conclude that endophytic colonization by entomopathogenic fungi has the potential to alter olfactory behavior and performance ofM.persicaevar.nicotianae, but effects are small and depend on the fungal strain used.

Biosynthesis of (1R,4aS,7S,7aR)?nepetalactol (1) and (4aS,7S,7aR)?nepetalactone (2) in plants involves iridoid synthase (ISY), an atypical reductive cyclase that catalyses the reduction of 8?oxogeranial into the reactive enol of (S)?8?oxocitronellal, and cyclization of this enol intermediate, either non?enzymatically or by a nepetalactol?related short chain dehydrogenase enzyme (NEPS) that yields the nepetalactols. In this study, we investigated the biosynthesis in?vivo of 1 and 2 in the pea aphid, Acyrthosiphon pisum, using a library of isotopically?labelled monoterpenoids as molecular probes. Topical application of deuterium?labelled probes synthesized from geraniol and nerol resulted in production of 2H4?lactol 1 and 2H4?lactone 2. However, deuterium incorporation was not evident using labelled probes synthesized from (S)?citronellol. These results suggest that iridoid biosynthesis in animals, specifically aphids, may follow a broadly similar route to that characterised for plants.

BACKGROUND: The response of virgin females of the legume pest Acanthoscelides obtectus (Coleoptera: Bruchidae) to\ud headspace extracts of volatiles collected from flowers of a nectar plant, Daucus carota, was investigated using behaviour\ud (four-arm olfactometry) and coupled gas chromatography–electroantennography (GC-EAG).\ud RESULTS: Odours from inflorescences were significantly more attractive to virgin female beetles than clean air. Similarly, a sample\ud of volatile organic compounds (VOCs) collected by air entrainment (dynamic headspace collection) was more attractive to beetles\ud than a solvent control. In coupled GC-EAG experiments with beetle antennae and the VOC extract, six components showed EAG\ud activity. Using coupled GC–mass spectrometry (GC–MS) and GC peak enhancement with authentic standards, the components\ud were identified as -pinene (S:R 16:1), sabinene, myrcene, limonene (S:R 1:3), terpinolene and (S)-bornyl acetate. Females preferred\ud the synthetic blend of D. carota EAG-active volatiles to the solvent control in bioassays. When compared directly, odours of D.\ud carota inflorescences elicited stronger positive behaviour than the synthetic blend.\ud CONCLUSION: This is the first report of behaviourally active volatiles linked to pollen location for A. obtectus, and development\ud of the six-component blend is being pursued, which could underpin the design of semiochemical-based field management\ud approaches against this major pest of stored products.

BACKGROUND\ud \ud Agrilus bigutattus (Fabricius) is a forest pest of increasing importance in the United Kingdom. The larvae damage weakened native oaks and are thought to contribute to premature tree death. Suspected links with acute oak decline (AOD) are not yet confirmed, but AOD-predisposed trees appear to become more susceptible to A. biguttatus attack. Thus, management may be necessary for control of this insect. To explore the possibility of monitoring beetle populations by baited traps, the host tree volatiles regulating A. biguttatus–oak interactions were studied.\ud \ud \ud RESULTS\ud \ud Biologically active volatile organic compounds in dynamic headspace extracts of oak foliage and bark were identified initially by coupled gas chromatography–electroantennography (GC-EAG) and GC–mass spectrometry (GC-MS), and the structures were confirmed by GC coinjection with authentic compounds. Of two synthetic blends of these compounds comprising the active leaf volatiles, the simpler one containing three components evoked strongly positive behavioural responses in four-arm olfactometer tests with virgin females and males, although fresh leaf material was more efficient than the blend. The other blend, comprising a five-component mixture made up of bark volatiles, proved to be as behaviourally active for gravid females as bark tissue.\ud \ud \ud CONCLUSIONS\ud \ud These initial results on A. biguttatus chemical ecology reveal aspects of the role of attractive tree volatiles in the host-finding of beetles and underpin the development of semiochemically based surveillance strategies for this forest insect.

Conserving populations of environmentally vulnerable insect species requires a greater understanding of the factors that determine their abundance and distribution, which requires detailed knowledge of their population and community ecology. Chemical ecological tools such as pheromones can be used for non-destructive monitoring of scarab beetle populations, enabling European countries to detect and, in some cases, map the range of some of these species, proving a valuable technique for monitoring elusive saproxylic beetles. In this paper, we investigated the behavioural and chemical ecology of the noble chafer, Gnorimus nobilis L., a model insect species of conservation concern across a Europe-wide distribution, and a red-listed UK Biodiversity Action Plan priority species. We identified a potential pheromone of adult beetles using electrophysiological recordings, behavioural measurements and field trials in the UK. Gnorimus nobilis is highly unusual in that although both sexes produce, at high metabolic cost, the natural product 2-propyl (E)-3-hexenoate, it only attracts males. This pattern of chemical signalling makes the classification of the compound, based on current semiochemical terminology, somewhat problematic, but in our view, it should be termed an aggregation pheromone as a consequence of the production pattern. Since both sexes emit it, but apparently only males respond positively to it, 2-propyl (E)-3-hexenoate may reflect an intermediate evolutionary stage towards developing into a sex-specific signal. From an applied perspective, our study provides a model for the non-invasive surveillance of cryptic vulnerable insect species, without the need for habitat searching or disturbance, and continuous human monitoring.