Olivera Petrović-Obradović

Volatile exchange between undamaged plants - a new mechanism affecting insect orientation in intercropping

Changes in plant volatile emission can be induced by exposure to volatiles from neighbouring insect-attacked plants. However, plants are also exposed to volatiles from unattacked neighbours, and the consequences of this have not been explored. We investigated whether volatile exchange between undamaged plants affects volatile emission and plant-insect interaction. Consistently greater quantities of two terpenoids were found in the headspace of potato previously exposed to volatiles from undamaged onion plants identified by mass spectrometry. Using live plants and synthetic blends mimicking exposed and unexposed potato, we tested the olfactory response of winged aphids, Myzus persicae. The altered potato volatile profile deterred aphids in laboratory experiments. Further, we show that growing potato together with onion in the field reduces the abundance of winged, host-seeking aphids. Our study broadens the ecological significance of the phenomenon; volatiles carry not only information on whether or not neighbouring plants are under attack, but also information on the emitter plants themselves. In this way responding plants could obtain information on whether the neighbouring plant is a competitive threat and can accordingly adjust their growth towards it. We interpret this as a response in the process of adaptation towards neighbouring plants. Furthermore, these physiological changes in the responding plants have significant ecological impact, as behaviour of aphids was affected. Since herbivore host plants are potentially under constant exposure to these volatiles, our study has major implications for the understanding of how mechanisms within plant communities affect insects. This knowledge could be used to improve plant protection and increase scientific understanding of communication between plants and its impact on other organisms.

Parasitoids (Hymenoptera: Braconidae: Aphidiinae) attacking aphids feeding on Solanaceae and Cucurbitaceae crops in southeastern Europe: aphidiine-aphid-plant associations and key.

ABSTRACT Original information on aphidiine braconids attacking aphids feeding on Solanaceae (i.e., Capsicum annuum L., Lycium europaeum L., Lycopersicon esculentum Miller, Solanum spp.) and Cucurbitaceae (i.e., Citrullus vulgaris Schrad., Cucumis spp., Cucurbita pepo L.) plants in southeastern Europe is presented. A total of 13 species are keyed and illustrated with scanning electron micrographs, microscope micrographs and line drawings. The aphidiines presented in this work have been identified from nine aphid taxa. Two hundred four aphidiine-aphid-plant associations are presented, 176 of which are new. The results are discussed in relation to over-all parasitoid-aphid-plant associations in the area.

Aphids and parasitoids on willows and poplars in southeastern Europe (Homoptera: Aphidoidea; Hymenoptera: Braconidae, Aphidiinae)

Aphid and aphid parasitoid associations on willows (Salix spp.) and poplars (Populus spp.) in southeastern Europe are reviewed. In total 13 aphid parasitoid species were reared from aphids on these plants. The specific parasitoid complex of Acyrthosiphon cf. malvae (Mosley) on Salix retusa and the aphids and parasitoids composition on willows and poplars are discussed. The most frequently sampled and the most abundant parasitoid species in poplar aphid-aphid parasitoid associations was Adialytus salicaphis Fitch. Furthermore, Lysiphlebus confusus Tremblay & Eady was the most abundant species collected on willow-feeding aphids, whereas A. salicaphis, Euaphidius cingulatus (Ruthe) and Binodoxys heraclei (Haliday) were the most frequently sampled parasitoid species on willows. Trophic connections between aphids and parasitoids associated with willow agroecosystems are also discussed. A key for the identification of aphid parasitoids associated with aphids on willows and poplars in southeastern Europe is provided.ZusammenfassungBlattläuse und die mit ihnen assoziierten Parasitoiden an südosteuropäischen Weiden und Pappeln werden zusammen-fassend beschrieben. Insgesamt wurden 13 verschiedene Arten von Blattlausparasitoiden an Weiden und Pappeln befallenden Blattläusen angezogen. Der spezifische Parasoi-denkomplex von Acyrthosiphon cf. malvae (Mosley) an Salix retusa und die an Weiden und Pappeln vorkommenden Blatt-läuse und ihre Parasitoiden werden diskutiert. Die am häufigsten nachgewiesene und am weitesten verbreitete Para-sitoidenart in Pappelblattlaus-Blattlausparasitoiden-Gemein-schaften war Adialytus salicaphis Fitch. Daneben war Lysiphlebus confusus Tremblay & Eady die am weitesten an Weiden parasitierenden Blattläusen verbreitete Parasitoidenart, während A. salicaphis, Euaphidius cingulatus (Ruthe) und Binodoxys heraclei (Haliday) die am häufigsten an Weiden gefundenen Arten waren. Die trophischen Beziehungen zwischen Blattläusen und ihren Parasitoiden in Weiden-ökosystemen werden ebenfalls diskutiert. Die Arbeit schließt mit einem Bestimmungsschlüssel der an südosteuropäischen Weiden und Pappeln vorkommenden Blattlausparasitoiden.

Lysiphlebus orientalis (Hymenoptera, Braconidae), a new invasive aphid parasitoid in Europe - evidence from molecular markers

We report the occurrence of Lysiphlebus orientalis in Serbia, an aphid parasitoid from the Far East that is new to Europe and has the potential to become invasive. Our finding based on morphological characters is confirmed by analyses of mitochondrial cytochrome oxidase subunit I sequences. An increase in number and an expansion of the host range were observed during field studies over the past two years, and it is determined that the current host range encompasses nine aphid hosts on 12 different host plants, forming 13 tri-trophic associations. A host range determined for European populations of L. orientalis appears wider compared with that in its Far Eastern native habitats where Aphis glycines Mats. is the sole known host. Moreover, it overlaps considerably with the host ranges of European parasitoids that play an important role in the natural control of pest aphids.

Phylogenetic relationships among Praini (Hymenoptera: Braconidae: Aphidiinae) aphid parasitoids, with redescription of two species

Phylogenetic relationships among four genera and 25 species of the tribe Praini (Braconidae: Aphidiinae) were investigated on the basis of 15 characters (13 morphological and two life history characters) using parsimony analysis. Areopraon Mackauer and Pseudopraon Starý are basal within the tribe. Both genera include species in which the external and internal types of pupation exist simultaneously [for example, Pseudopraon mindariphagum Starý, Areopraon lepelleyi (Waterston) and A. pilosum Mackauer)]. It can therefore be asserted that the external type of pupation behavior in the Praini probably originated in the polymorphic pupation behavior of ancient genera such as Pseudopraon and Areopraon. The genera Areopraon, Pseudopraon, and Dyscritulus Hincks form a monophylum separate from Praon. Areopraon is not retrieved as monophyletic. Species of the genus Praon Haliday possess conical apical spines on the top of the ovipositor sheath as an apomorphic character state. Within the genus Praon, we recognized the following closely related species groups: Parapraon + Praon dorsale-yomenae; and Praon rosaecola. Two Praini species are redescribed. Mesopraon Starý is a new synonym of Areopraon. Areopraon silvestre (Starý) and Areopraon helleni (Starý) are new combinations. A key to the recent Praini genera is given.

The Effects of Aphid Traits on Parasitoid Host Use and Specialist Advantage.

Specialization is a central concept in ecology and one of the fundamental properties of parasitoids. Highly specialized parasitoids tend to be more efficient in host-use compared to generalized parasitoids, presumably owing to the trade-off between host range and host-use efficiency. However, it remains unknown how parasitoid host specificity and host-use depends on host traits related to susceptibility to parasitoid attack. To address this question, we used data from a 13-year survey of interactions among 142 aphid and 75 parasitoid species in nine European countries. We found that only aphid traits related to local resource characteristics seem to influence the trade-off between host-range and efficiency: more specialized parasitoids had an apparent advantage (higher abundance on shared hosts) on aphids with sparse colonies, ant-attendance and without concealment, and this was more evident when host relatedness was included in calculation of parasitoid specificity. More traits influenced average assemblage specialization, which was highest in aphids that are monophagous, monoecious, large, highly mobile (easily drop from a plant), without myrmecophily, habitat specialists, inhabit non-agricultural habitats and have sparse colonies. Differences in aphid wax production did not influence parasitoid host specificity and host-use. Our study is the first step in identifying host traits important for aphid parasitoid host specificity and host-use and improves our understanding of bottom-up effects of aphid traits on aphid-parasitoid food web structure.

Volatile interaction between undamaged plants affects tritrophic interactions through changed plant volatile emission

Volatile interactions between unattacked plants can lead to changes in their volatile emissions. Exposure of potato plants to onion plant volatiles results in increased emission of 2 terpenoids, (E)-nerolidol and TMTT. We investigated whether this is detectable by the ladybird Coccinella septempunctata. The odor of onion-exposed potato was significantly more attractive to ladybirds than that of unexposed potato. Further, a synthetic blend mimicking the volatile profile of onion-exposed potato was more attractive than a blend mimicking that of unexposed potato. When presented individually, TMTT was attractive to ladybirds whereas (E)-nerolidol was repellent. Volatile exchange between unattacked plants and consequent increased attractiveness for ladybirds may be a mechanism that contributes to the increased abundance of natural enemies in complex plant habitats.

Monitoring of aphid flight activities in seed potato crops in Serbia

Abstract Aphid flight activities in seed potato fields have been studied by the yellow water traps. It is a good method for monitoring aphids as vectors of viruses, but this study also showed it is a suitable method for insect-diversity research. During the four-year studies, over 11.500 specimens were collected and a total of 107 different taxa of aphids were identified. The most abundant species were polyphagous species, such as: Acyrthosiphon pisum (Haris), Aphis fabae Scopoli, Aphis gossypii Gloverand Brachycaudus helichrysi (Kaltenbach). The results of the studies show that diversity of aphids in different regions of Serbia is similar regardless of the altitude and the diversity of terrain. At most sites it ranged from 2 to 3. The highest value was recorded in Begeč, locality in northern part of Serbia, in year 2008, and it was 2.92. The maximum values of the Shannon-Weaver diversity index at all sites were recorded in the first weeks of the monitoring of aphid flight activities. Morisita-Horn similarity index shows no significant differences between sites regardless of altitudes. The sites are grouped by year, not by similarity of relief. In spite of these results, the Chi-square analysis showed highly significant difference in vector frequencies among seasons and sites with more pronounced differences for PVY. As a consequence of differences in vector frequencies, the vector pressure index in some regions was different also. The number of vectors and vector pressure index vary depending on the altitude of localities. At localities at altitudes under 1000 m, they were high. The highest index was at Kotraža, locality in central part of Serbia, in 2007, when PVY index exceeded the value of 180, while for PLRV it was 60. At high altitudes on mountain Golija, above 1100 m, the number of aphids was low, as well as the vector pressure index which indicates that these regions are suitable for producing virus-free seed potato.

Several new and one invasive aphid species (Aphididae, Hemiptera) caught by yellow water traps in Serbia

Eight aphid species were determined as new records for Serbia as a result of the evaluation of the specimens caught by yellow water traps used for monitoring vector activities in seed potato crops during the 4 years 2007–2010. The invasive aphid species Macrosiphum albifrons Essig 1911; and the new species Acyrthosiphon cyparissiae (Koch 1855), Ctenocallis setosus (Kaltenbach 1846), Myzodium modestum (Hottes 1926), Myzocallis castanicola Baker 1917, Myzocallis occidentalis Remaudiè et Nieto Nafria 1974, Tinocallis platani (Kaltenbach 1843) and Wahlgreniella ossiannilssoni Hille Ris Lambers 1949. M. modestum is very difficult to detect, as it lives hidden in moss. All species are presented with characteristic morphological information of alatae and line drawings.

Seven recommendations to make your invasive alien species data more useful

Science-based strategies to tackle biological invasions depend on recent, accurate, well-documented, standardised and openly accessible information on alien species. Currently and historically, biodiversity data are scattered in numerous disconnected data silos that lack interoperability. The situation is no different for alien species data, and this obstructs efficient retrieval, combination, and use of these kinds of information for research and policy-making. Standardization and interoperability are particularly important as many alien species related research and policy activities require pooling data. We describe seven ways that data on alien species can be made more accessible and useful: 1) Create data management plans; 2) Increase interoperability of information sources; 3) Document data through metadata; 4) Format data using existing standards; 5) Adopt controlled vocabularies; 6) Increase data availability; and 7) Ensure long-term data preservation. We identify four properties specific and integral to alien species data (species status, introduction pathway, degree of establishment, and impact mechanism) that are either missing from existing data standards or lack a recommended controlled vocabulary. Improved access to accurate, real-time and historical data will repay the long-term investment in data management infrastructure, by providing more accurate, timely and realistic analyses. If we improve core biodiversity data standards by developing their relevance to alien species, it will allow the automation of common activities regarding data processing in support of environmental policy. Furthermore, we call for considerable effort to maintain, update, standardise, archive, and aggregate datasets, to ensure proper valorisation of alien species data and information before they become obsolete or lost.