Parasitic wasp responses to symbiont-based defense in aphids

BACKGROUND: Recent findings indicate that several insect lineages receive protection against particular natural enemies through infection with heritable symbionts, but little is yet known about whether enemies are able to discriminate and respond to symbiont-based defense. The pea aphid, Acyrthosiphon pisum, receives protection against the parasitic wasp, Aphidius ervi, when infected with the bacterial symbiont Hamiltonella defensa and its associated bacteriophage APSE (Acyrthosiphon pisum secondary endosymbiont). Internally developing parasitoid wasps, such as A. ervi, use maternal and embryonic factors to create an environment suitable for developing wasps. If more than one parasitoid egg is deposited into a single aphid host (superparasitism), then additional complements of these factors may contribute to the successful development of the single parasitoid that emerges. RESULTS: We performed experiments to determine if superparasitism is a tactic allowing wasps to overcome symbiont-mediated defense. We found that the deposition of two eggs into symbiont-protected aphids significantly increased rates of successful parasitism relative to singly parasitized aphids. We then conducted behavioral assays to determine whether A. ervi selectively superparasitizes H. defensa-infected aphids. In choice tests, we found that A. ervi tends to deposit a single egg in uninfected aphids, but two or more eggs in H. defensa-infected aphids, indicating that oviposition choices may be largely determined by infection status. Finally, we identified differences in the quantity of the trans-β-farnesene, the major component of aphid alarm pheromone, between H. defensa-infected and uninfected aphids, which may form the basis for discrimination. CONCLUSIONS: Here we show that the parasitic wasp A. ervi discriminates among symbiont-infected and uninfected aphids, and changes its oviposition behavior in a way that increases the likelihood of overcoming symbiont-based defense. More generally, our results indicate that natural enemies are not passive victims of defensive symbionts, and that an evolutionary arms race between A. pisum and the parasitoid A. ervi may be mediated by a bacterial symbiosis

Conversion of airborne nerolidol to DMNT emission requires additional signals in Achyranthes bidentata

AbstractDMNT biosynthesis was proposed to proceed via (E)-nerolidol in plants a decade ago. However, (E)-nerolidol function as airborne signal/substrate for in-vivo biosynthesis of DMNT remains to be investigated and the regulation of DMNT production and emission is largely unknown. We address both of these aspects using Achyranthes bidentata model plant in conjunction with deuterium-labeled d5-(E)-nerolidol, headspace, GC-FID, and GC/MS-based absolute quantification approaches. We demonstrate that airborne (E)-nerolidol is specifically metabolized in-vivo into DMNT emission, but requires airborne VOC MeJA or predator herbivore as additional environmental signal. In addition, we provide new insight into the complex regulation underlying DMNT emission, and highlight the importance of studying multiple environmental factors on emission patterns of plant VOCs and their mechanistic regulation

Propaganda, publicity and political violence : the presentation of terrorism in Britain, 1944-60

Through a series of case studies, this thesis examines British attitudes to 'terrorism' as practised during various post-war colonial insurgencies. What did British governments and colonial officials understand by this term, as applied to the Jewish insurgents in Palestine at the end of the Mandate, the Malayan Communists, Mau Mau, and EOKA in Cyprus? The thesis focuses particularly on the way in which propaganda has been seen as a crucial component of the terrorist strategy. Consequently, in the attempt to deny insurgents publicity, and to mediate the perception of politically motivated violence held by various domestic and international audiences, British governments have used a wide variety of propaganda and news-management techniques. The thesis thus assesses the role of government propaganda in counter-insurgency. While some attention is paid to the employment of propaganda within the affected colonies themselves (as part of the 'hearts and minds' strategy), the focus is largely on government attempts to influence wider international audiences and, especially, domestic public opinion in Britain. The need to maintain public support at home for campaigns fought against 'terrorism' in the colonies has been a neglected aspect of most writings on counterinsurgency. However, a detailed examination of the files of the Colonial Office and Foreign Office information departments reveals that in each of the selected case studies, particular attention was paid to keeping domestic opinion 'on side'. Not only have various Whitehall departments and the Central Office of Information produced official publicity material on these insurgencies, but the Foreign Office's anti-communist Information Research Department has disseminated more covert material through the Trade Union movement and other channels. In addition, successive governments have sought to influence the press, newsreel and television coverage of events in the disputed territories. How successful was the effort which went into official publicity work and newsmanagement? Gauging the effectiveness of any propaganda campaign is notoriously difficult. However, by looking at the contemporary press, the output of the major newsreel companies and the files of the BBC, I have attempted to assess how far the mass communications media presented a view of terrorism which accorded with the governmental interpretation. What becomes apparent is that while it may have been fairly easy to ensure that 'terrorists' were duly condemned, and labelled as such - language forming an important part of the battle for legitimacy - government publicists have often struggled due to an absence of policy in Whitehall over the future of the colonies concerned, and on account of the behaviour of the Security Forces. Creating favourable publicity for counter-terrorist measures has been a much harder task than the denigration of terrorism itself

The Mexican roots of the Indian lavender tree

Volume: 91Start Page: 27End Page: 3

Las raíces mexicanas de la lavanda de la India

The tree known as Indian lavender (Bursera delpechiana, Burseraceae) is a source of linalool. It was introduced to India from Mexico at the beginning of the 20th century for the exploitation of its essential oil. Its origin from Mexico was not well understood because the name B. delpechiana has been taxonomically obsolete for many years. We used molecular, phylogenetic, and chemical data to determine which currently recognized species it belongs to. This evidence regarding the Indian Lavender Tree’s identity all points to the Mexican species, Bursera linanoe. Our chemical analysis also revealed that linalyl acetate is the primary constituent of Indian Lavender oil as well as of Mexican B. linanoe rather than linalool as previously believed.El árbol conocido como Lavanda de la India (Indian lavender; Bursera delpechiana, Burseraceae) es una fuente de linalol. Esta planta fue introducida en India a principios del siglo XX para extraer el mencionado aceite esencial. Su origen hasta hace poco era incierto porque el nombre B. delpechiana fue declarado obsoleto desde hace muchos años. Usamos datos moleculares, filogenéticos y químicos para determinar a qué especie reconocida pertenecen estas plantas que se encuentran en India. Las evidencias señalan que la identidad de la lavanda de la India es la especie mexicana Bursera linanoe. Los análisis químicos revelan también que el constituyente químico principal de esta especie es el acetato de linalilo y no el linalol, como se había reportado

Germacrene D, A Common Sesquiterpene in the Genus Bursera (Burseraceae)

The volatile components of the leaves of five Bursera species, B. copallifera, B. exselsa, B. mirandae, B. ruticola and B. fagaroides var. purpusii were determined by gas chromatography–mass spectrometry (GC–MS). Germacrene D was one of the predominant components (15.1–56.2%) of all of these species. Germacrene D has also been found in other Bursera species and some species of Commiphora, the sister group of Bursera, suggesting that the production of germacrene D might be an ancient trait in the genus Bursera

Isovaleronitrile co-induced with its precursor, l-leucine, by herbivory in the common evening primrose stimulates foraging behavior of the predatory blue shield bug

<p>Herbivore-induced plant volatiles play important roles in plant–insect and plant–plant interactions. The common evening primrose, <i>Oenothera biennis</i>, is often infested by the flea beetle, <i>Altica oleracea</i>, on which the predatory blue shield bug, <i>Zicrona caerulea</i>, is usually found. This observation suggests that the predatory bug can discriminate infested plants from intact ones to locate its prey. In this study, l-leucine-derived nitrogen-containing compounds [isovaleronitrile (3-methylbutanenitrile), (<i>E</i>/<i>Z</i>)-isovaleraldoxime and 3-methyl-1-nitrobutane] and some terpenes were identified as a characteristic volatile blend from herbivore-infested <i>O</i>. <i>biennis</i> leaves by gas chromatography/mass spectrometry, chemical synthesis, and incorporation assays using deuterium-labeled l-leucine. Volatile emission was also elicited by exogenous methyl jasmonate (MeJA), but not by mechanical damage. l-Leucine accumulated temporarily in <i>O</i>. <i>biennis</i> leaves after MeJA treatment prior to isovaleronitrile emission. Behavioral assays revealed that <i>Z</i>. <i>caerulea</i> showed a strong preference for herbivore-infested leaves, their volatiles, and isovaleronitrile in laboratory conditions.</p> <p>Herbivore-induced volatiles, including l-Leu-derived isovaleronitrile, from Oenothera biennis leaves elicit foraging behavior of a predator, Zicrona caerulea.</p