Development and Nesting Behaviour of Trap-Nesting Wasps (Hymenoptera: Vespidae: Eumeninae)
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VILNIUS UNIVERSITY Žaneta Nevronytė DEVELOPMENT AND NESTING BEHAVIOUR OF TRAP-NESTING WASPS (HYMENOPTERA: VESPIDAE: EUMENINAE) Summary of doctoral dissertation Biomedical sciences: zoology (05 B) Vilnius, 2009 The research was carried out at Vilnius University and Institute of Ecology of Vilnius University Supervisor dr. Eduardas Budrys (Institute of Ecology of Vilnius University, biomedical sciences, zoology – 05 B) The defence of the doctoral dissertation is held at the Vilnius University council on zoology science: Chairman prof. habil. dr. Remigijus Noreika (Vilnius Pedagogical University, biomedical sciences, zoology – 05 B) Members: prof. dr. Sigitas Podėnas (Vilnius University, biomedical sciences, zoology – 05 B) prof. habil. dr. Jonas Rimantas Stonis (Vilnius Pedagogical University, biomedical sciences, zoology – 05 B) prof. habil. dr. Vincas Būda (Vilnius University, biomedical sciences, ecology and environmental science – 03 B) dr. Rimvydas Juškaitis (Institute of Ecology of Vilnius University, biomedical sciences, ecology and environmental science – 03 B) Oponentai: prof. dr. Virginijus Sruoga (Vilnius Pedagogical University, biomedical sciences, zoology – 05 B) prof. habil. dr. Rimantas Rakauskas (Vilnius University, biomedical sciences, zoology – 05 B) The official defence of the dissertation will be held on 23 December 2009 at 14.00 in the Vilnius University. Address: M. K. Čiurlionio g. 21, LT-03101 Vilnius, Lithuania The abstract of the dissertation was distributed on ____ November 2009. The dissertation is available in the library of the Vilnius University. 2 INTRODUCTION Relevance of the study. Aculeate Hymenoptera are essential ecosystem components that act as pollinators and predators (Lassalle & Gauld 1993). They provide examples of the most sophisticated reproduction and brood care behaviour among invertebrate animals (Ayasse et al. 2001). Since Hymenoptera Aculeate are known to be bioindicators, which are sensitive to environment change (Tscharntke et al. 1998), management and succession (Gathmann et al. 1994), diversity (Gathmann & Tscharntke 1999) and fragmentation (Morato 2001, Steffan-Dewenter et al. 2002) of habitats, antropogenous impact and climate change (Pekkarinen & Hulden 1991), these insects may have an importance in environment conservation. Most species in the family Vespidae belong to the subfamily Eumeninae (Carpenter 1986). These wasps are known to control populations of leafrollers (Klein 2004; Harris 1994; Yamane 1990; Jennings & Houseweart 1984), leaf beetles (Schenk & Bacher 2002, Sears et al. 2001) and weevils (Bohart et al.1982). Eumeninae is a sister group of the subfamilies Stenogastrinae, Polistinae and Vespinae of the family Vespidae (Carpenter 1981; Brothers 1999; Carpenter & Wheeler 1999; Hines et al. 2007). It was used as an outgroup in the phylogenetic studies of these social wasps. Thus, study of reproductive behaviour and behavioural ecology of Eumeninae can provide important data for understanding the evolution of sociality in Hymenoptera. Goal and objectives. The purpose of our study was to establish impact of nesting cavity parameters and prey abundance on the nesting behaviour of solitary xylicolous wasps. To achieve this goal, we set up the following objectives: • to survey a list of Hymenopteran species inhabiting trap-nests in Lithuania and estimate how the choice of a nesting cavity is affected by the width of a nesting cavity in different species; • to estimate the impact of nesting cavity parameters (diameter and length) on the nesting behaviour of trap-nesting wasps; 3 • to detail the development of Symmorphus allobrogus, the most common synanthropic xylicolous wasp in Lithuania; • to estimate the influence of prey quantity on the nesting behavior of S. allobrogus; • to evaluate the impact of the wasp’s individual parameters such as age, body size and insemination status on its nesting behaviour. Novelty of the study: • for the first time, the influence of nesting cavity parameters (width and length) on the nesting behavior of 7 to 13 xylicolous wasp species has been estimated: the relation between cell length, progeny size, sex ratio and the nesting cavity diameter has been established, as well as the relation between the number of cells and nest length has been investigated; • for the first time, the ranges of the head width of all five instars in 5 wasp species have been established; • for the first time, the development of the most common synanthropic xylicolous wasp in Lithuania, Symmorphus allobrogus, has been investigated: the assimilation of prey and weight loss during development from larva to adult in both sexes have been compared; • for the first time, using S. allobrogus as a model species, it has been demonstrated that the amount of prey available in the environment affects the number of cells in the nest of solitary wasp; • for the first time, the nests of virgin solitary wasp females have been attained under laboratory conditions. Significance of the results. The results of the study may be important for future ecological and ethological studies of cavity-nesting Hymenoptera as well as for application of trap-nest technique in Hymenoptera research: • the established preferred nesting cavity parameters may be applied in the species niche studies; 4 • the established dependence of the number of recorded species on sampling effort in a study site can be applied in comparative studies of species diversity using trap-nests for Hymenoptera; • the estimated influence of nesting cavity parameters on nest structure and sex ratio of studied species may be used in further studies of their nesting behaviour; • the established width of head and the parameters of larval development of 5 species may be used for approximate estimation of wasp nest age; • the established parameters of prey assimilation during the larval development and weight loss during development to adult wasp may be applied for estimation of the amount of consumed prey, using adult weight of a wasp; • the established relation between amount of available prey and cell number per nest in laboratory as well as effect of wasp’s aging on its nest structure may be applied in comparisons of ecosystem parameters using trap-nests for Hymenoptera in the field. Presentation and approval of the results. The materials of the dissertation were presented at the conference “Biodiversity, Molecular Ecology and Toxicology” (Palanga, Lithuania, 2005). The results have been published in 3 articles (1 published and 2 accepted for publication in 2009); other 2 have been submitted. Structure of the dissertation. The dissertation consists of the following parts: Introduction, Review of Literature, Material and Methods, Results and Discussion (containing 4 sub-chapters), Defended Conclusions, References (133 positions) and a list of the author’s publications promoting the results of the dissertation. The dissertation has 97 pages, containing 21 tables and 41 figures. It is written in Lithuanian, with its summary in English. Acknowledgements. First and foremost, I am greatly indebted to my supervisor, dr. Eduardas Budrys. This thesis would not have been possible without his substantial contribution in generation of ideas, preparation of publications and identification of insects. His abiding commitment to knowledge has been an inspiring example and I am grateful to him for his supervision and mentorship during all my studentship. This thesis would not have been possible without dr. Anna Budrienė, who prepared the wasps for the experiments in laboratory. I also extend my heartfelt thanks to 5 Reda Garmutė, Rasa Pilkauskaitė, Aušra Briliūtė, Dalia Kuveikytė and Rita Radzevičiūtė for their assistance in the laboratory. Moreover, I would like to thank Rūta Levulienė, a senior lecturer at the Department of Mathematics and Computer Science of the University of Vilnius, and Anastasija Jurolait for competent guidance in choosing appropriate statistical methods and applying them to practice. I am also grateful to Ieva Stasiūnaitė for editing English text, Dalia Jokubauskaitė for editing Lithuanian text and to prof. Vincas Būda for helpful comments regarding the presentation of the thesis. Last but not least, I would like to give my special thanks to my family and friends, whose love and support enabled me to complete this work. Review of literature. Herein available knowledge of nesting ecology of xylicolous wasps as well as available surveys of their nesting parameters and influence of mother body size on reproductive success of Aculeata are reviewed. Also a survey of application of trap-nesting Hymenoptera in various studies is presented. MATERIAL AND METHODS Material. The field research was carried out in Lithuania during 2002-2007 in 14 sinantropic sites with relatively similar rural or green urban environments (Table 1). We used internode fragments of reed (Phagmites australis) stems as trap-nests. The trap-nests were exposed on old Table 1. Trap-nest sampling sites, periods and effort. Sampling wooden or daubed buildings Years of Site Coordinates effort (trap- sampling inhabited by colonies of cavity- nest-seasons) Varnupys 55°24'N 25°17'E 1989-2007 137 nesting solitary Hymenoptera. Papiškiai 55°56'N 24°16'E 2002-2004, 2007 37 Bilšiai 55°08'N 25°16'E 2001-2007 36 They were exposed from May Kaunas 54°54'N 23°54'E 1989-1991, 2000 7 Taraldžiai 55°46'N 25°22'E 2003-2004 7 to the end of August. A trap- Merkinė 54°10'N 24°10'E 1989-1992, 2000 6 Kiemeliai 54°51'N 25°01'E 2007 4 nest exposed during one Paburgė 56°01'N 21°56'E 2007 4 Puvočiai 54°07'N 24°18'E 2007 4 summer season was considered Trečiokiškės 54°50'N 24°59'E 2007 4 Subartonys 54°12'N 24°11'E 2003 3 a sampling unit (a trap-nest- Pylimėliai 54°43'N 25°21'E 2003 2 Veržuva 54°45'N 25°26'E 2003 2 season). In the three main Antagavė 55°19'N 26°09'E 1989 2 Total 255 sampling sites (Table 1), the trap-nests were checked few times per season, and either the occupied reed internodes with visible external plugs were replaced by new internodes or the whole trap-nest was replaced by a new one.