Associative learning and memory retention of nectar yeast volatiles in a generalist parasitoid

Understanding how animals learn is crucial to interpreting animal behaviour. Flower-visiting insects, such as bees and parasitoids, are excellent animal models to study visual and olfactory learning, including memory phenomena. The diversity of resources flower-visiting insects exploit predisposes them to learn and remember the colours, shapes and odours associated with rewarding experiences (e.g. flowers), allowing them to focus on the most rewarding resources. Recent research has shown that nectar-living microbes release volatile organic compounds (VOCs) that contribute to overall flower scent. Nevertheless, little is known about the extent to which nectar microbiota mediate insect learning of floral preferences. In this study, we investigated whether VOCs produced by nectar microbes serve as a learning cue to parasitoids and how long any developed preference is maintained. Experiments were performed using the generalist aphid parasitoid Aphidius ervi and three nectar yeasts, including the nectar specialist Metschnikowia reukaufii and the generalist species Hanseniaspora uvarum and Sporobolomyces roseus. Results showed that naïve parasitoids had an innate preference for nectar fermented by the nectar specialist M. reukaufii, but not by the other two yeasts which had either a neutral (H. uvarum) or deterrent (S. roseus) effect. When parasitoids were conditioned with yeast-fermented nectar, they were strongly attracted to their odours 2 and 24h after conditioning, but not after 48h. Furthermore, when parasitoids were conditioned to one yeast-fermented nectar, they also showed increased attraction to other yeast-fermented nectars. This generalization suggests that their learning ability may have broader ecological consequences. However, this generalized response to other yeast VOCs lasted for only 2h. We conclude that parasitoids show conditioned responses to the scent of yeast-fermented nectar, and yeasts, therefore, may play an important but understudied role in shaping their foraging behaviour

Identification and application of bacterial volatiles to attract a generalist aphid parasitoid from laboratory to greenhouse assays

BACKGROUND: Recent studies have shown that microorganisms emit volatile compounds that affect insect behaviour. However, it remains largely unclear whether microbes can be exploited as a source of attractants to improve biological control of insect pests. In this study, we used a combination of coupled gas chromatography electroantennography (GC-EAG) and Y-tube olfactometer bioassays to identify attractive compounds in the volatile extracts of three bacterial strains that are associated with the habitat of the generalist aphid parasitoid Aphidius colemani, and to create mixtures of synthetic compounds to find attractive blends for A. colemani. Subsequently, the most promising blend was evaluated in two-choice cage experiments under greenhouse conditions. RESULTS: GC-EAG analysis revealed 20 compounds that were linked to behaviourally attractive bacterial strains. A mixture of two EAG-active compounds, styrene and benzaldehyde applied at a respective dose of 1 μg and 10 ng, was more attractive than the single compounds or the culture medium of the bacteria in Y-tube olfactometer bioassays. Application of this synthetic mixture under greenhouse conditions resulted in significant attraction of the parasitoids, and outperformed application of the bacterial culture medium. CONCLUSION: Compounds isolated from bacterial blends were capable of attracting parasitoids both in laboratory and greenhouse assays, indicating that microbial culture are an effective source of insect attractants. This opens new opportunities to attract and retain natural enemies of pest species and to enhance biological pest control

Bacterial phylogeny predicts volatile organic compound composition and olfactory response of an aphid parasitoid

There is increasing evidence that microorganisms emit a wide range of volatile compounds (mVOCs, microbial volatile organic compounds) that act as insect semiochemicals, and therefore play an important role in insect behaviour. Although it is generally believed that phylogenetically closely related microbes tend to have similar phenotypic characteristics and therefore may elicit similar responses in insects, currently little is known about whether the evolutionary history and phylogenetic relationships among microorganisms have an impact on insect‐microbe interactions. In this study, we tested the hypothesis that phylogenetic relationships among 40 Bacillus strains isolated from diverse environmental sources predicted mVOC composition and the olfactory response of the generalist aphid parasitoid Aphidius colemani . Results revealed that phylogenetically closely related Bacillus strains emitted similar blends of mVOCs and elicited a comparable olfactory response of A. colemani in Y‐tube olfactometer bioassays, varying between attraction and repellence. Analysis of the chemical composition of the mVOC blends showed that all Bacillus strains produced a highly similar set of volatiles, but often in different concentrations and ratios. Benzaldehyde was produced in relatively high concentrations by strains that repel A. colemani , while attractive mVOC blends contained relatively higher amounts of acetoin, 2,3‐butanediol, 2,3‐butanedione, eucalyptol and isoamylamine. Overall, these results indicate that bacterial phylogeny had a strong impact on mVOC compositions and as a result on the olfactory responses of insects

Identification and application of bacterial volatiles to attract a generalist aphid parasitoid: from laboratory to greenhouse assays

BACKGROUND Recent studies have shown that microorganisms emit volatile compounds that affect insect behaviour. However, it remains largely unclear whether microbes can be exploited as a source of attractants to improve biological control of insect pests. In this study, we used a combination of coupled gas chromatography‐electroantennography (GC–EAG) and Y‐tube olfactometer bioassays to identify attractive compounds in the volatile extracts of three bacterial strains that are associated with the habitat of the generalist aphid parasitoid Aphidius colemani, and to create mixtures of synthetic compounds to find attractive blends for A. colemani. Subsequently, the most attractive blend was evaluated in two‐choice cage experiments under greenhouse conditions. RESULTS GC–EAG analysis revealed 20 compounds that were linked to behaviourally attractive bacterial strains. A mixture of two EAG‐active compounds, styrene and benzaldehyde applied at a respective dose of 1 μg and 10 ng, was more attractive than the single compounds or the culture medium of the bacteria in Y‐tube olfactometer bioassays. Application of this synthetic mixture under greenhouse conditions resulted in significant attraction of the parasitoids, and outperformed application of the bacterial culture medium. CONCLUSION Compounds isolated from bacterial blends were capable of attracting parasitoids both in laboratory and greenhouse assays, indicating that microbial cultures are an effective source of insect attractants. This opens new opportunities to attract and retain natural enemies of pest species and to enhance biological pest control

Text-message reminders increase uptake of routine breast screening appointments : a randomised controlled trial in a hard-to-reach population

Background: There is a need for interventions to promote uptake of breast screening throughout Europe. Methods: We performed a single-blind randomised controlled trial to test whether text-message reminders were effective. Two thousand two hundred and forty women receiving their first breast screening invitation were included in the study and randomly assigned in a 1 : 1 ratio to receive either a normal invitation only (n=1118) or a normal invitation plus a text-message reminder 48 h before their appointment (n=1122). Findings: In the intention-to-treat analysis, uptake of breast screening was 59.1% among women in the normal invitation group and 64.4% in the text-message reminder group (χ2=6.47, odds ratio (OR): 1.26, 95% confidence intervals (CI): 1.05–1.48, P=0.01). Of the 1122 women assigned to the text-message reminder group, only 456 (41%) had a mobile number recorded by their GP and were thereby sent a text. In the per-protocol analysis, uptake by those in the control group who had a mobile number recorded on the GP system was 59.77% and by those in the intervention group who were sent a reminder 71.7% (χ2=14.12, OR=1.71, 95% CI=1.29–2.26, P<0.01). Interpretation: Sending women a text-message reminder before their first routine breast screening appointment significantly increased attendance. This information can be used to allocate resources efficiently to improve uptake without exacerbating social inequalities

Presymptomatic breast cancer in Egypt: role of BRCA1 and BRCA2 tumor suppressor genes mutations detection

<p>Abstract</p> <p>Background</p> <p>Breast cancer is one of the most common diseases affecting women. Inherited susceptibility genes, <it>BRCA1 </it>and <it>BRCA2</it>, are considered in breast, ovarian and other common cancers etiology. <it>BRCA1 </it>and <it>BRCA2 </it>genes have been identified that confer a high degree of breast cancer risk.</p> <p>Objective</p> <p>Our study was performed to identify germline mutations in some exons of <it>BRCA1 </it>and <it>BRCA2 </it>genes for the early detection of presymptomatic breast cancer in females.</p> <p>Methods</p> <p>This study was applied on Egyptian healthy females who first degree relatives to those, with or without a family history, infected with breast cancer. Sixty breast cancer patients, derived from 60 families, were selected for molecular genetic testing of <it>BRCA1 </it>and <it>BRCA2 </it>genes. The study also included 120 healthy first degree female relatives of the patients, either sisters and/or daughters, for early detection of presymptomatic breast cancer mutation carriers. Genomic DNA was extracted from peripheral blood lymphocytes of all the studied subjects. Universal primers were used to amplify four regions of the <it>BRCA1 </it>gene (exons 2,8,13 and 22) and one region (exon 9) of <it>BRCA2 </it>gene using specific PCR. The polymerase chain reaction was carried out. Single strand conformation polymorphism assay and heteroduplex analysis were used to screen for mutations in the studied exons. In addition, DNA sequencing of the normal and mutated exons were performed.</p> <p>Results</p> <p>Mutations in both <it>BRCA1 </it>and <it>BRCA2 </it>genes were detected in 86.7% of the families. Current study indicates that 60% of these families were attributable to <it>BRCA1 </it>mutations, while 26.7% of them were attributable to <it>BRCA2 </it>mutations. Results showed that four mutations were detected in the <it>BRCA1 </it>gene, while one mutation was detected in the <it>BRCA2 </it>gene. Asymptomatic relatives, 80(67%) out of total 120, were mutation carriers.</p> <p>Conclusions</p> <p><it>BRCA1 </it>and <it>BRCA2 </it>genes mutations are responsible for a significant proportion of breast cancer. <it>BRCA </it>mutations were found in individuals with and without family history.</p

Volatiles of bacteria associated with parasitoid habitats elicit distinct olfactory responses in an aphid parasitoid and its hyperparasitoid

To locate mating partners and essential resources such as food, oviposition sites and shelter, insects rely to a large extent on chemical cues. While most research has focused on cues derived from plants and insects, there is mounting evidence that indicates that micro‐organisms emit volatile compounds that may play an important role in insect behaviour. In this study, we assessed how volatile compounds emitted by phylogenetically diverse bacteria affected the olfactory response of the primary parasitoid Aphidius colemani and one of its secondary parasitoids, Dendrocerus aphidum. Olfactory responses were evaluated for volatile blends emitted by bacteria isolated from diverse sources from the parasitoid's habitat, including aphids, aphid mummies and honeydew, and from the parasitoids themselves. Results revealed that A. colemani showed a wide variation in response to bacterial volatiles, ranging from significant attraction over no response to significant repellence. Our results further showed that the olfactory response of A. colemani to bacterial volatile emissions was different from that of D. aphidum. Gas chromatography‐mass spectrometry analysis of the volatile blends revealed that bacterial strains repellent to A. colemani produced significantly higher amounts of esters, organic acids, aromatics and cycloalkanes than attractive strains. Strains repellent to D. aphidum produced significantly higher amounts of alcohols and ketones, whereas the strains attractive to D. aphidum produced higher amounts of the monoterpenes limonene, linalool and geraniol. Overall, our results indicate that bacterial volatiles can have an important impact on insect olfactory responses, and should therefore be considered as an additional, so far often overlooked factor in studying multitrophic interactions between plants and insects