Composition of Strawberry Floral Volatiles and their Effects on Behavior of Strawberry Blossom Weevil, Anthonomus rubi.

The strawberry blossom weevil (SBW), Anthonomus rubi, is a major pest in strawberry fields throughout Europe. Traps baited with aggregation pheromone are used for pest monitoring. However, a more effective lure is needed. For a number of pests, it has been shown that the attractiveness of a pheromone can be enhanced by host plant volatiles. The goal of this study was to explore floral volatile blends of different strawberry species (Fragaria x ananassa and Fragaria vesca) to identify compounds that might be used to improve the attractiveness of existing lures for SBW. Floral emissions of F. x a. varieties Sonata, Beltran, Korona, and of F. vesca, were collected by both solid-phase microextraction (SPME) and dynamic headspace sampling on Tenax. Analysis by gas chromatography/mass spectrometry showed the floral volatiles of F. x ananassa. and F. vesca were dominated by aromatic compounds and terpenoids, with 4-methoxybenzaldehyde (p-anisaldehyde) and α-muurolene the major compounds produced by the two species, respectively. Multi-dimensional scaling analyses separated the blends of the two species and explained differences between F. vesca genotypes and, to some degree, variation between F. x ananassa varieties In two-choice behavioral tests, SBW preferred odors of flowering strawberry plants to those of non-flowering plants, but weevils did not discriminate between odors from F. x ananassa and F. vesca flowering plants. Adding blends of six synthetic flower volatiles to non-flowering plants of both species increased the preference of SBW for these over the plants alone. When added individually to non-flowering plants, none of the components increased the preference of SBW, indicating a synergistic effect. However, SBW responded to 1,4-dimethoxybenzene, a major component of volatiles from F. viridis, previously found to synergize the attractiveness of the SBW aggregation pheromone in field studies.

The virome of Drosophila suzukii, an invasive pest of soft fruit.

Drosophila suzukii (Matsumura) is one of the most damaging and costly pests to invade temperate horticultural regions in recent history. Conventional control of this pest is challenging, and an environmentally benign microbial biopesticide is highly desirable. A thorough exploration of the pathogens infecting this pest is not only the first step on the road to the development of an effective biopesticide, but also provides a valuable comparative dataset for the study of viruses in the model family Drosophilidae. Here we use a metatransciptomic approach to identify viruses infecting this fly in both its native (Japanese) and invasive (British and French) ranges. We describe eighteen new RNA viruses, including members of the Picornavirales, Mononegavirales, Bunyavirales, Chuviruses, Nodaviridae, Tombusviridae, Reoviridae, and Nidovirales, and discuss their phylogenetic relationships with previously known viruses. We also detect 18 previously described viruses of other Drosophila species that appear to be associated with D. suzukii in the wild.

Identification of Novel Pesticides for Use against Glasshouse Invertebrate Pests in UK Tomatoes and Peppers.

To inform current and future pesticide availability to glasshouse vegetable growers, the current project trialled more than twenty products, including existing industry standards, against four key pests of glasshouse tomatoes and bell peppers. These included experimental conventional chemical pesticides as well as alternative biopesticide and biorational products based on phytochemicals, microbials and physically-acting substances. The results suggest that certain biopesticide products, particularly botanicals, provide good levels of pest control, with the same being true of experimental conventional chemical pesticides not yet recommended for use against these pests on these crops. Efforts are on-going to ensure that results of the current project translate to industry benefit via new pesticide approvals.

Further studies on sex pheromones of female Lygus and related bugs: development of effective lures and investigation of species-specificity.

Mirid bugs (Heteroptera: Miridae) are important pests of many crops worldwide. In previous work by others and ourselves, several species of Lygus bugs were shown to produce blends of three compounds, hexyl butyrate, (E)-2-hexenyl butyrate, and (E)-4-oxo-2-hexenal. These have been proposed as components of the female-produced sex pheromones, but attraction of males to synthetic lures has been difficult to demonstrate. We studied the volatiles released by females of four species: Lygus rugulipennis, Lygus pratensis, Lygocoris pabulinus, and Liocoris tripustulatus. Analyses of volatiles from individual, undisturbed insects showed that the three compounds were produced in species-specific blends, by females only, or in greater quantities by females than by males. The three compounds were loaded into pipette tips, which released the defined blends over at least 30 days. Traps baited with the blend for L. rugulipennis caught more males than traps baited with virgin females, with all three compounds required for maximum attractiveness. Traps baited with the specific blends for each of the four species caught males of three of the species, indicating considerable cross-attraction. There is evidence that other, non-chemical factors, such as time-of-day of production of pheromone, contribute to species-specificity of attraction. This is the first report of consistent attraction of Lygus bugs to synthetic lures in the field.

The chemical ecology of cecidomyiid midges (Diptera: Cecidomyiidae).

The family of cecidomyiid midges (Diptera: Cecidomyiidae) exhibits diversified patterns of life history, behavior, host range, population dynamics and other ecological traits. Those that feed on plants include many important agricultural pests; most cultivated plants are attacked by at least one midge species. Several features of the reproductive biology of cecidomyiid midges point to an important role for chemical communication, with this topic last reviewed comprehensively 12 years ago. Here, we review progress on identification of sex pheromones, chemicals involved in location of host plants, the neurophysiology of reception of volatile chemicals, and application of semiochemicals to management of pest species of cecidomyiid midges that has occurred during the last decade. We hope this review will stimulate and sustain further research in these fields.

(2S,8Z)-2-butyroxy-8-heptadecene: major component of the sex pheromone of chrysanthemum gall midge, Rhopalomyia longicauda.

The sex pheromone of the chrysanthemum gall midge, Rhopalomyia longicauda (Diptera: Cecidomyiidae), the most important insect pest in commercial plantations of chrysanthemum, Dendranthema morifolium (Ramat.) Tzvel., in China, was identified, synthesized, and field-tested. Volatile chemicals from virgin females and males were collected on Porapak in China and sent to the United Kingdom for analysis. Coupled gas chromatographic-electroantennographic detection (GC-EAG) analysis of volatile collections from females revealed two compounds that elicited responses from antennae of males. These compounds were not present in collections from males. The major EAG-active compound was identified as 2-butyroxy-8-heptadecene by gas chromatographic (GC) retention indices, mass spectra, in both electron impact and chemical ionization modes, hydrogenation, epoxidation, and derivatization with dimethyldisulfide. The lesser EAG-active compound was identified as the corresponding alcohol. The ratio of butyrate to alcohol in the collections was 1:0.26. Racemic (Z)-8-heptadecen-2-ol and the corresponding butyrate ester were synthesized from (Z)-7-hexadecenyl acetate, and the synthetic compounds found to have identical GC retention indices and mass spectra to those of the natural, female-specific components. Analysis of the volatile collections on an enantioselective cyclodextrin GC column showed the natural pheromone contained (2S,8Z)-2-butyroxy-8-heptadecene. Field tests showed that rubber septa containing racemic (Z)-2-butyroxy-8-heptadecene were attractive to R. longicauda males. The (naturally occurring) S-enantiomer was equally as attractive as the racemate, while the R-enantiomer was not attractive to males, and did not inhibit the activity of the S-enantiomer. The attractiveness of the butyrate was significantly reduced by the presence of even small amounts of the corresponding alcohol.

(S)-2-acetoxy-5-undecanone, female sex pheromone of the raspberry cane midge, Resseliella theobaldi (Barnes).

The raspberry cane midge, Resseliella theobaldi, is a widespread pest of cultivated red raspberry in Europe. Pheromone-baited traps could provide a much-needed, accurate means to monitor the pest. Volatiles collected separately from virgin female and male midges were analyzed by gas chromatography (GC) coupled to mass spectrometry (MS) to reveal four female-specific components. In analyses by GC coupled to electroantennographic (EAG) recording from the antennae of a male midge, at least three of these components elicited responses. Based on its GC retention indices and mass spectrum, we propose that the major component is 2-acetoxy-5-undecanone and confirm this by synthesis of the racemic compound in seven steps and 63% yield from 4-pentenoic acid. The three minor components were each present at approximately 30% of the major component and were identified as 2-undecanone, (S)-2-acetoxyundecane, and (S)-2-undecanol by comparison of GC retention times and mass spectra with those of synthetic standards. GC analyses of the female-produced volatiles on an enantioselective column showed that only one enantiomer of 2-acetoxy-5-undecanone was present, and this was found to be the S-enantiomer by hydrolytic kinetic resolution of an epoxide intermediate in the synthesis and also by enantioselective hydrolysis of the racemic acetate with a lipase enzyme. The two enantiomers were also separated by high-performance liquid chromatography on an enantioselective column for field tests. In two field trapping tests, (S)-2-acetoxy-5-undecanone was highly attractive to male R. theobaldi; the R-enantiomer was not attractive. The racemic compound was just as attractive as the S-enantiomer, and addition of the three minor components in racemic form at two different loads did not affect catches. The pheromone could be dispensed from both rubber septa and polyethylene vials for at least 1 month under field conditions, but the former was preferred as it gave more uniform release. 2-Acetoxy-5-undecanone belongs to a new group of pheromone structures in the Cecidomyiidae, most others being mono- or diesters.

Trapping Dasinuera mali (Diptera: Cecidomyiidae) in apples.

The midge Dasineura mali (Kieffer) (Diptera: Cecidomyiidae) is a significant pest of apples (Malus spp.), and the recent identification of the female sex pheromone is enabling new direct control tactics to be considered. Direct control using male suppression will require knowledge of the frequency of multiple mating, dispersal and colonization rates, and the efficiency of male removal. Males were able to mate up to five times, with a mean of 2.7 times when presented in a 10 female-to-1 male group, designed to simulate male suppression. Male catch in response to the pheromone loading was curvilinear over 4 orders of magnitude from 3 microg to 30 mg on rubber septa. Trapping using a high-dose pheromone lure was combined with oil-based traps similar to the inexpensive New Zealand "Lynfield trap" used for tephritid surveillance, to test male suppression in young orchard blocks at 500 traps per ha. Monitoring traps indicated 96% lower catch in the treated plots compared with control plots, over 137 d. However, a lack of shoot tip infestation in both treated and untreated plots indicated limited colonization and prevented an assessment of potential population suppression. Furthermore, a contribution to these results from communication disruption cannot be ruled out. Replicated transects of frequency of infested shoots from a mature orchard across the adjacent young block confirmed that colonization by ovipositing females was essentially limited to the first 30 m.

Endothelial dysfunction in uraemia.

Cardiovascular disease is a major cause of morbidity and mortality in chronic renal failure (CRF). The endothelium plays a central role in the control of many aspects of vascular function, and abnormalities may contribute to the generation of atherosclerosis. The endothelium produces a wide range of regulatory molecules which, in health, function in concert to provide a carefully balanced anti-atherogenic environment. Endothelial dysfunction has been repeatedly demonstrated in renal failure, is present in the absence of anatomically obvious disease and appears to be useful in the prediction of morbidity and mortality in other cardiovascular risk groups. One of the most intensively studied and important mediators of endothelial function is nitric oxide (NO), whose production is reduced in CRF. A number of possible mechanisms for reduced NO bioavailability have been investigated including substrate limitation, competitive inhibition of NO synthase by endogenous NO synthase inhibitors known to accumulate in renal failure, and premature quenching of NO by free radicals present in high concentrations in this group. A clearer understanding of the pathogenesis of endothelial dysfunction in CRF has potential clinical implications. It may provide avenues for therapeutic interventions before the onset of clinically obvious cardiovascular disease in this high-risk patient group.