Netherlands
Netherlands

Time filter

Source Type

Korenko S.,Czech University of Life Sciences | Korenko S.,Masaryk University | Michalkova V.,Slovak Academy of Sciences | Zwakhals K.,Dr. Dreeslaan 204 | Pekr S.,Masaryk University
Journal of Insect Science | Year: 2011

Current knowledge about polysphinctine parasite wasps' interactions with their spider hosts is very fragmented and incomplete. This study presents the host specificity of Zatypota percontatoria (Mller) (Hymenoptera: Ichneumonidae) and its adaptation to varying host availability. Two years of field observations show that Z. percontatoria is a stenophagous parasitoid that parasitizes only five closely related web-building spiders of the family Theridiidae (Araneae). Within the Theridiidae it attacks only species belonging to a small group of species, here called the "Theridion" group. These hosts have a similar biology, but are available at different levels of abundance and at different sizes over the season. Laboratory experiments showed that this wasp species ignores linyphiid, araneid or dictynid spiders and accepts only theridiid spiders of the "Theridion" group. In the field study, wasp females preferred older juvenile and sub-adult female spider instars with intermediate body size. Only 5% of the parasitized spiders were males. Parasitism in the natural population of theridiid spiders was on average 1.3%. Parasitism was most frequent on two species, Theridion varians Hahn in 2007 and Neottiura bimaculata Linnaeus in 2008. The parasitization rate was positively correlated with spider abundance. The wasp responded adaptively to seasonal changes in host abundance and host body size and shifted host preference according to the availability of suitable hosts during, as well as between, seasons. In spring and summer the highest percentage of parasitism was on T. varians and in autumn it was on N. bimaculata. © This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed. © 2012 American Society of Mechanical Engineers.


Elzinga J.A.,University of Jyväskylä | Zwakhals K.,Dr. Dreeslaan 204 | Mappes J.,University of Jyväskylä | Grapputo A.,University of Padua
European Journal of Entomology | Year: 2011

This study describes the parasitoid species complex associated with seven closely related species of sexual (Siederia rupicollella, S. listerella, Dahlica lazuri, D. charlottae and D. lichenella) and parthenogenetic (Dahlica fennicella and D. triquetrella) Naryciinae (Lepidoptera: Psychidae) in Central Finland. A thorough ecological analysis of all the species of parasitoids recorded was combined with analyses of molecular data. Mitochondrial and nuclear DNA data were obtained from all the species in order to (1) detect cryptic species associated with host specialization, (2) assign undescribed males to females, and (3) verify the morphological identification of closely related species. A DNA barcoding technique was employed to identify host species from parasitized larval remains. By sampling more than 10,000 host larvae, of which 25.7% were parasitized, nine parasitoid species were identified morphologically, including both koinobionts (Ichneumonidae: Diadegma incompletum, Macrus parvulus, Trachyarus borealis, T. solyanikovi, T. fuscipes, T. brevipennis and Braconidae: Meteorus affinis) and idiobionts (Ichneumonidae: Orthizema flavicorne, Gelis fuscicornis). Ecological characteristics such as time and mode of host attack, time of emergence and level of specialization differed widely. The results show that differences in parasitoid biology need to be taken into account when studying differences in percentage parasitism of sexual and parthenogenetic Naryciinae. The molecular data revealed that one parasitoid species M. parvulus may consist of two cryptic forms associated with the sexual and parthenogenetic hosts, respectively. The data further establishes that T. brevipennis and some T. fuscipes are in fact morphotypes of one species. The large variation in mitochondrial DNA within species and its inconsistency with nuclear DNA demonstrate that current species and genus delimitation is inadequate in the Trachyarus species group. Our study shows that it is essential to use DNA barcoding methods when investigating host-parasitoid complexes.


Pham N.T.,Vietnam Academy of Science and Technology | Broad G.R.,Natural History Museum in London | Zwakhals K.,Dr. Dreeslaan 204
Zootaxa | Year: 2012

The genus Dolichomitus Smith, 1877 is recorded from Vietnam for the first time with description of a new species, D. lami sp. nov., from Hoang Lien National Park, Lao Cai Province. Besides, D. melanomerus (Vollenhoven) is recorded as new for the country from specimens collected in Tam Dao National Park, Vinh Phuc Province and Hang Kia-Pa Co Nature Reserve, Hoa Binh Province. Copyright © 2012 · Magnolia Press.


Schmitt M.,University of Duisburg - Essen | Richter D.,University of Duisburg - Essen | Gobel D.,University of Duisburg - Essen | Zwakhals K.,Dr. Dreeslaan 204
Arachnologische Mitteilungen | Year: 2012

We found the ichneumonid Polysphincta rufipes Gravenhorst, 1829 (tribus Polysphinctini) to be a koinobiont parasitoid of two species of araneid orb-weavers, Larinioides sclopetarius and Zygiella x-notata, in Central Europe. Some notes on the biology of P. rufipes are given, based on observations both in the field and in the laboratory. The wasps directly attack non-adult spiders sitting in the hubs of their webs. Parasitized spiders could be found from, at least, August to early December. The duration of the development of the wasp larvae, including the pupal stage, is about two months. It seems conceivable that at the end of the larval stage the larva somehow manipulates its host spider; i.e. the spider is forced to enter its retreat - a safe place where the larva can kill the host, complete its development and spin a cocoon for pupation (pupa libera).

Loading Dr. Dreeslaan 204 collaborators
Loading Dr. Dreeslaan 204 collaborators