I WAITE TNSTII'UTE ,4 .2 .83 LIBRARY THE BIOLOGY AND ECOLOGY OF CLUBTONA SPECIES (ARANEAE : CLUBIONIDAE) AND THXIR SCELIONID PARASITOIDS (HYMENOPTERA) By Andrew Donald Austin B.Sc. Ilons. (Sydney) A thesis submitted for Èhe Degree of Doctor of Philosophy in Èhe Faculty of Agricultural Science at the University of Adelaide. Department of Ent,omology, I,iaíte Agricultural Research Institute, Uníversity of Adelaide. February 1982 TO MY PARENTS l- TABLE OF CONTENTS SUMMARY DECLARATION vii ACKNOI{LEDGMENTS vl_t-t_ CHAPTER 1 INTRODUCTION 1 CHAPTER 2 NATURAL }IISTORY OT CLUBIOII/1 SPBCT.ES 2.L InErocluction 4 2.2 Maferials and Methods 5 2.2.L Study Síte and Climatological Data 5 tt') Collecting Techniques 7 n.r,) Laboratorv Crrltures 7 2.2.4 Development of Eggs 8 2.3 Results 9 2.3.I The Diversity of Spiders Under Bark and Taxonomy of CLubíorta 9 2.3 .2 Habitat Preferences 11 2.3.3 Prey of Clubiona L2 2.3.4 Number of InsÈars 13 2.3 .5 Nests and Moulting Chambers 15 2.3 .6 Mating Behaviour 18 2.3.7 Eggs, Fecundity, Seasonality and Juveniles 19 2.3.8 Development of Eggs 22 2.3.9 Causes of Mortality 22 2.4 Discussion 24 CHAPTER 3 BCOLOGY AND BEHAVIOUR OF CLUBIONA ROBUSTA 3.1 Introduction 30 3.2 Materials and Methods 31 3.2.r Sampling Spiders in the Field 32 3.2.2 Mortality of Eggs and Juveniles 32 3.2.3 Guarding Behaviour by Female Spiders 33 3.2.4 Behavioural Interactíons between Adult Spiders 34 3.3 Results 35 3.3.1 Phenology 35 3.3.2 Overwintering by Adu1t Females 36 3. 3.3 Mortality of Eggs and Juvenile Stages 37 3 .3.4 Populat-ion Dynami.cs and Lirniting Factors 39 3.3.5 Guarding Behavíour by Female Spiders 4t 3. 3.6 The Function of Eggmass Formation and Eggsacs 44 3.3"7 Aggressize Interact j,on between Ad-ult Spiders 45 3.4 Discussion. 49 CITAPTER 4 THE BT.O]-OGY OF CEN¿.TOBAEUS MASNERI 4.1 InÈroduction 55 4.2 l"laterials and Metl-rocls 56 4. 2,1. Culturing Tec.hniques 56 4. t') Longevity 57 4. 2.3 Effect of Age of tlost Eggs 57 4.3 Re sul.Ls -58 4 3.1 Oviposition and iËs Relationship with Temperature 5B 4 3.2 Ðevelopmental SÈages, Developmental Time, Emergence and l"tating 60 4.3.3 Fecundity 62 4 .3.4 Sex Ratio 63 11 4.3.5 Superparasitisrn and Discrimination between Par:asitized and Unparasitized Eggs 64 4.3.6 Overwintering 66 4.3.7 Effect of Age of Host Eggs 67 4.3.8 Host Specificity and Host Finding 70 4.4 Discussion 73 CHAPTER 5 THE MORPHOLOGY AND ]IMCT]ANICS OF THE OVIPOSITOR OF CERATOBAEU,S A.ND RNLATED GENERA 5.1 Introduction BO 5.2 Materials and Methods 83 5.3 Results B4 5 .3.1 General I'forphology of Ëhe Metasoma of. Cez,atobaeus masneri B4 5.3.2 Termiual Segments and Internal Apodemes 85 5.3.3 The Ovipositor B6 s .3.4 Musculature and Mechanícs of the Ovipositor BB 5.3.5 A Model for Ovipositor }fovement 90 5 .3.6 Anatony of Èhe Reproductive System 95 5 .3.7 Comparative ì'{orphology of the Ovipcsitor System for Related Species and Genera 96 5.4 Discussion 97 CHAPTER 6 HOST RELATIONSHIPS AND HOST SPECIFICITY IN SCELIONID PARASITOIDS OF SPIDERS 6.1 Introduction LO2 6.2 Materials and Methocls 1C5 6.3 Observat.ions and Re-sul.ts 106 6.3.1 Host Relationships 106 6.3.2 AdaptaEions of Spiders to protect their Eggs from Scelionid Parasitoids 108 6.3.3 Adaptations of Scelionids to penetrate the Egg.sacs of their Hosts 109 6.3.4 Eggsacs of Sp:Lders as a FacEor Contributing to Host Specificity in Scelionids 111 6.4 Discussion 1t-4 CHAPTER 7 GENERAL DISCUSSION 118 APPENDIX 1 THE TAXONOMY OF A.USTRAI,TAN SCELIONIDAE THAT ' PARASITIZE 'IHB EGGS OF SPIDERS 41.1 Introcl.ucÈion r23 41.2 Materials ancl Methods t24 41.3 Key to Australian Genera of Scelionidae that Parasít;íze the Eggs of Spiders L26 A.1..4 Revision of Gener:a I28 41. 4.r Genus Mi:robaeus Dodd 729 41. 4.2 Genus Baeus tlatriday 130 41. 4.3 Genus Miz,obaeoides Dodd 131 41. 4.4 Genus fdyis Foerster I32 Á.1. 4.5 Genus H'LcknaneLZa Austin 133 A1_. 4.6 Genus OContacoLr.¿s Kieffer L34 A1 .5 Genus Cez,atobc¿¿z.s Ashmead 135 A1 .6 Provisional Key to:Fernale.s c.f the Known AusÈralian Species oÍ. Ceratobaeus Ashmead L37 Al-.7 Descr:ipÈions of Species of Cenatobaeus Ashmead. L4T 41.7.I Cey,atobaeus clttbioitus sp.nov. L4t l-ar- A1 .7.2 euspíeovnutus sp.nov. 143 A1 ,7 .3 intz,udae sp.nov. L45 A1 .7 .4 Lønponae (Hickman) L47 Al- .7.5 masneri sp.nov. L49 A1 .7 .6 pLaty coz'nutus sp. nov . 150 A1 .7 .7 rieki sp .nov. t52 A1 .7.8 setosus Dodd L54 APPENDIX 2 KNOI,üN HOSTS OF SCELIONID SPECIES THAT PARASITIZE THE EGGS OF SPIDERS 1s6 APPENDIX 3 A MECHANISM FOR MOVEMENT OF EGGS ALONG INSECT see OVIPOSITORS inside back APPENDIX 4 THE TYPES OF AUSTRALIAN SPECIES IN THE TRIBES cover IDRINI, BAEINI AND EMBIDOBIINI (HYMENOPTERA: SCETIONIDAE:, SCELIONINAE) n APPENDIX 5 HICKMANELLA, A NEII GENUS OF SCELIONIDAE FROM AUSTRALIA (HYMENOPTEM: PROCTOTRUPOIDEA) It BIBLIOGRAPHY 158 l_v. SI]MMARY Spiders of the genus CLubiona are abundant under the bark of EucaLyptus Èrees at Mylor, South AusËralía, specificaLLy E. uimLnaLis and E. LeucoæyLon. CLtbiona z,obusta L.Koch, the largest species at this locatíon, has up to 9 juveníle j.nstars. It feeds on a varíety of insects that are associated with bark; and it constructs a specialized silk charnber in which it moults, overwínters, maÈes, lays and guards its eggs. Females Lay I-2 eggmasses per seasorìo Eggs are present in the field for up to B monËhs of the year, from August to April. Juveniles hatch, go through 2 moults inside Ëhe nest and then disperse" The majority undertake aerial díspersal (ballooning) to reach oÈher Èrees, buË a few remain on the same tree and disperse by walking. Other species of CLtþiorn that coexísE ín Ëhe same habitat have a símílar biology to that of C. z,obusta. Adult C. robustd. are most abundant in spring and stirnmer, but are present at all times of the year. Generations are not díscrete" There is a summer and wínËer generation, but spiders maturing late in sunmer can also overwínter to ovíposít ín Èhe following spring. Mortality occurs in 2 main phases; from parasitism on eggs by Ceratobaeus tnasneri sponov. (Scel-íonidae), and at the tíme of juvenile dispersal. C. rnasneri killed 22-257" of all eggs in the 3 seasons of the study. Although Èhis mortality is high, the very símílar results obtained in each season suggest ËhaÈ ít may be constant and therefore not ímportant in causing fluctuations ín C. robusta populations" Changes in the abundance of this spider are more likely to be caused by differences in mortality at dispersal. 0bservations in the fíeld indícate that aboux 60-70% of juveníles die from landíng ín tnfavourable habitats. It ís proposed that this species has a Type IV mortality pattern (Slobodkín I96L) (i"e. very high mortality in the early life history stages), and not v Type III (i.e. a constant raËe of mort.ality over all stages) as has been reported for other spíders. C. robusta guards,its eggs and the first 2 insËars by attacking intruders that attempt. to enter Èhe nest. All intruders larger than 2 mm are killed. Removal of spiders from nest.s in the field caused almost total mortality of the unguarded eggs. C. masneri escaped aËtack; experimental evidence suggests that this may be due to the small size of this species. It never patasítízes all the eggs in an eggmass. In all observed cases eggs on the periphery were likely to die, whereas those in the cenËre r¡/ere protected by being too deep for the ovipositor Ëo reach. Female C. robusta are more common than males in the field, but they occur in equal numbers in laboratory cultures. Behavioural trials show that males are much more aggressive than females and. can kill or injure each other. Male aggression is thus believed to result in theír low abundance and the biased sex ratio in this species. Studies on the biology of C. masneri show thaË the larval and pupal stages of the parasitoid develop inside its host. The host is not completely consumed until after the larval-pupal apolysis, i... the parasitoid continues to feed while it is a pharate pupa. This phenomenon has not previously been described for any Hymenoptera. Individuals emerge as adults; males emerge príor to females, then wait for Èhe latter and mate with their sibs. A limited amount of outbreeding occurs in the few eggmasses that are attacked by more than one female \¡rasp. ovarian developrnent of eggs conËinues for several days after emergence, even Ëhough females can successfully oviposit in Èhe interim. Females of C. masneyL overwinter as adults under bark and do noÈ feed or resorb their eggs. This species, as with other parasitic Hymenoptera, displays arrhenotokous parthenogenesis and has a sex ratio biased towards the female. They can discriminate between parasiEized and unparasitized eggs and also determine when hosts are too o1d to a1low for successful development. of their oppspring. HosË eggs can be successfully parasítízed up to early vl_ germ band sËage at 15 and 2Qoc, buÈ at 25"c d.evelopment occurs only up Èo germ disc stage, even though oviposition occurs up to germ band stage.