The embryogenesis and embryonic variability of Aulocara elliotti Thomas (Acrididae, Orthoptera) by Saralee Neumann Van Horn A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Entomology Montana State University © Copyright by Saralee Neumann Van Horn (1963) Abstract: The variability of A. elliotti embryos from laboratory reared populations of two successive years was investigated according to stage criteria formulated for this species. Statistically significant differences were found between these two populations with regard to stage-length, age-length, and age-stage relationships. In addition, comparisons were made between laboratory reared and wild population embryos, and between embryos from the same wild population from different years. Statistically significant differences were found in almost all instances with regard to length-stage relationships in the various populations. Experiments were conducted to test the requirements for diapause aversion and termination in this species. An histological study of the embryogenesis, with emphasis on the neuroendocrine system, revealed the presence of several structures thought to be new to Acrididian literature. These included paired peripheral ganglia in the labrum, mandibles, and maxillae, and a single ganglion of paired labial origin located in the hypopharynx. Investigation showed that the embryological origin of the ventral head glands was lateral hypoderm between the bases of the mandibular and maxillary appendages (formerly thought to be the site of corpora allata origin). The corpora allata appeared to arise from hypoderm near the basal dorsal wall of the anterior tentorial invagination. Labial glands (salivary glands) arose from lateral hypoderm between the maxillary and labial segments. All of these incretory organs and the peripheral ' ganglia arose prior to blastokinesis in A. elliotti as well as in five other Acrididian species examined. The differentiation of giant paired cells in the region of the protocerebral-optie lobe junctions and in the metathoraeic ganglia was first observed at Stage 19 when most embryos of A. elliotti entered the diapause state. The giant metathoraeic cells were found to he present and constant in their position throughout the embryology and persist in the adult, as well as in the embryos of seven other Acrididian species. The development and maturation of tissues and organs at all stages during the embryogenesis was described. Histological comparisons of diapause A. elliotti embryos of young and advanced ages revealed that deposition of fat body and increase in pleuropodial cell size continued during diapause. Study of embryos retarded in their external stages of development in relation to their ages showed that certain internal differentiation processes continued when external growth and mitotic activity had ceased. THE EMBRYOGEEESIS M D EMBRYONIC VARIABILITY OF AULOCARA ELLIOTTI .THOMAS (ACRIDIDAE,,ORTHOPTERA) ‘ 'by SARALEE EEUMAJH V M HORN >✓ A thesis submitted to the Graduate Ihculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHDLpSPHY in Entomology . HeadlNMajor Dep^rtfcent MONTANA STATE COLLEGE Bozeman., Montana June, 1963 iii ACOTOWLEroMENTS To my Advisor and Chairman of my committee, Lr., James H. Pepper, I want' to acknowledge my indebtedness and offer my deep gratitude for his interest, confidence, and assistance throughout the course of this study« I want to thank Dr. Pepper, Er. Harold Watling, Dr, P. D. Skaar, and Er.., David Blackmore for their advice and help in preparation of ' .the manuscript, % gratefulness is offered to the members of the Zoology-Entomology Department at Montana. State College, especially Mr. Ellsworth .Hastings, who gave assistance many times during this 'study, I wish to thank Er. Charles Mode and Dr. Glen Ingraham for help ^ith the statistical treatment of the data. gratitude is offered to the Anti-Locust Center in London, particularly Dr, P. Hunter-Jones, for sending embryonic specimens of Locusta migratoria and Schistooerca gregaria, to the .United States Department of Agriculture Bureau of Entomology, Bozeman, Montana, especially Mr. R. Connin and Mr. Erank Cowan, for embryos o f 'Melanoplus bruneri, Melanoplus bivittatus, Melanoplus sanguinipes, and Camnula pellucida, and to Dr, Carl Eettenmeyer at Kansas State University at Manhattan for obtaining embryos of Melanoplus differentialis for this study. sincere appreciation is offered to Dr. Guenter Schmalz, Chairman of the Department of Modern Languages at Montana State College, for all his help with the German translations and to Dr. Orazio Guisti, . Department of Modern languages, Arizona State College, Flagstaff, iv Arizona,, for his help with the Italian manuscripts. I want to acknowledge the fine work of Mr. Don Eritts5 who helped with the photomicrographs. And finally, I would like to thank the members of my family for their patience and understanding while this work was in progress. V TABLE OF CONTENTS Bage VITA, ...................... ii ACKNOWMDGEMENTS............. ..................... ill LIST OF TABLES a 'V^Ll LIST OF PM T E S ......... .*...................................... ix LIST OF FEOOBESx ABSTRACT xm GENERAL INTRODUCTION.................... .................... I EXTERNAL MORPHOGENESIS OF A. EMIOTTI EMBRYOS.............7.... * 3 lilt 3T O t x on. 3 MEttsinals and MstHods.......o.............................. ^ jEknbz’yo m c Sta^zLn^. % Differentiation of the External Genitalia........... 26 EMBRYONIC VARIABILITY IN LABORATORY REARED AND XCELD POPULATIONS OF A. ELLIOTTI...... 28 I n t r o d u c t i o n . 28 Materials and Methods........eo...............o...... 33 Variability'iri the Pre-Diapause Laboratory Reared Populcttions 3^ Diapause Variability ^*3 Post™Diapause Variability................................o. ^8 Data Group Comparisons....o..................o* 60 EXPERIMENTAL STUDIES CONCERNING THE CONDITION OF DIAPAUSE AVERSION AND TERMINATION IN A. ' ELLIOTT! EMBRYOS............... 66 HISTOLOGICAL STUDY OF A e ELLIOTTI EMBRYOG-ENESIS......... 73 I n t r o d u c t i o n . 73 I&terials and Methods7^* Pre«Diapause Histogenesis...............o....................... 75 vi Stage 7 - Beginning of neuroblast differentiation 0. • T9 Stage,8 ee,e«oe»eeeeoeeeh*eoeoeee'i>6 oodee»e»oeio®ee0 ''oe:6 etioooeoooo0 81 Stage 9 - Differentiation- of the subesophageal: body,........ 81 Stage 10.....................................................,O 83 Stage H ...........o.......... ......... 83 Stage1 12. - Appearance of the germ cells. 84 . Stage 13 - Origin of the optic ganglia, differentiation of " neuroendocrine system and oenocyte cells, invagination of the anterior tentorial arms, formation of the peripheral ganglia............... 85 Stage I^f" OOiOOO'. 00 0 . 0 . 0. 0 . I. o.o.,..,. .. o'. < 93 • Stage 15- - Invaginatiops of the ventral head glands, labial glands, and corpora allata................. 94 Stage l6 o. o o o o . e e . o. o o e o o o o o . oo6 ...., .■ .ooooooo. .. ot ■ 98 Stage 1 7...0 . .0 . A. oooooo.eoo.eo. 00. 0.. 000000000. eo.t 102 Stage 18 0.0. 000,0.00. ..00.00-000. ..0 0 0 0 .0 0.00. .00000.0 0. O,0.0. Ot io6 The" Diapause Embryo - Stage 19 - Differentiation of .. nerve cell t^pes......oo..o.oo.ooo.ooo..ooo.o..ooo.ooo...o..c108 Comparative Histology of Stage I9 Embryos of Various Ages ooooo'odoi 114. Post-Diapause Histogenesis, ooooodooooooododeoooooodooooootidooo'ooot119 Stage 20 - The embryo in.early blastokinesis tioeoooooooodooooc119 Embryonic Development Without Blastokinesis ooodocooo OOOOOOQOi 121 81 2 1 0 odooe'ooodo'poddoooooeododoeooooooooododooooooooooooot123 Stage 22 - Third stage of blastokinesis. , 125 Stage 23 - Completion of blastokinesisiQQOOOOOOOOOOOOOOOOOOOOi 127 Stage 2k - Blastokinesis completed pooooooooooddoooooo. olo 0 0 0 0129 0 < Stage 25 - Dorsal closure completed ooooooooooooooooooeooooooc133 Stage 2 6oooo. o.O,0.0 0 000000.0. OOi^ 00. .000600000006060000.. OO ..< 136 Stage. 27 - The definitive embryo........o o..-. ..o<138: Discussion. ...006. 0.00000 0.0 . 0.00000 00 00,0000. 000000. ... 0 0, ooooooooe< 142 Summary ..0.000...0000.0000000000000...0.00....0..000.0 0^0 .000000001 147 LITERATURE (^ITED. ,Oo.ooo..oo,ooooooo.oo.o.oo.ooooooooo.o.oooooooo<166 vii LIST OF TABLES Table I Age-Stage Lata for the Ere-Diapause 1959 Reared Population of A, elliotti Bnbryos........ ............ 35 Table II Age-Stage Eata for the Ere-Diapause i960 Reared Population of A. elliotti Embryos......... .......... 36 Table III Age-Length Eata for the Ere-Diapause 1959 Reared Population of A. elliotti Embryos..................... 39 Table IV Age-Length Eata for the Ere-Diapause i960 Reared Population of A. elliotti Embryos.... ................. 40 Table V Stage-Length Eata for the Pre-Diapause 1959 Reared Population of A. elliotti Embryos............... ..... 4l Table VI Stage-Length Data for the Ere-Diapause i960 Reared Population of A. elliotti Embryos................ 42 i Table VII Stage-Length Distribution of the 1959 Laboratory Reared Diapause A. elliotti Embryos........... ....... 44 Table VIII length Data for Diapause A.. elliotti Embryos From the Post-Diapause Reared 1959 Population............... 47 Table IX Statistical Data Obtained from the Regression Analysis of Length on Stage from Diapause Data Group... 49 Table X Stage Distribution of Diapause Groups of Wild Population A. elliotti Embryos......................... $0 Table XI Stage-Length Distribution of the 1959 Laboratory Reared Post-Diapause