A^COMPARATIVE MORPHOLOGICAL STUDl) OF THE AXILLARY RSXJIO^ OP SOME PTERYGOT2 INSECTS Rioh&rd M, Baranowakl, B.A.» M.S. Utica College of Syracuse University, 1951 University of Connecticut, 195? A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy at The University of Connecticut 1959 APPROVAL PAGE Dootor of Hilloaophy Oiasertatlon A COMPARATIVE MORPHOLOOICAL STUDY OP THE AXILLARY REGION OP SOME PT2RYGOTE INSECTS Proaontod by Rlohard M. B&ranovalel, B.A.( M.S. Major Advisor /] /// Aaaoolato Advlaor Aaaooiate Advlaor The Univeraity of Oonnootieut 1959 f' f* f* O O 11 ACKK0WLSDQEU2HT3 In making aoknoviodgoments, th® author must first of all deolare his indobtness to Dr. Russoll H. DoOoursoy for his adrioe throughout the oourso of this work and for his constructive aid in editing the manuscript. Acknowledgement is also made to Dr. Edward 0. Boettiger for his Invaluable aid and advioe» especially in respect to obtaining and interpreting the oscillograph records. This portion of the work would not have been possible without his aid. In particular the author gratefully acknowledges the advice and encouragement of Dr. Norman T. Davis» who was always willing to discuss the problem and offer valuable suggestions. The author also wishes to acknowledge the assistance of Dr. Ifeul V. Oman of the Entomology Research Divisionf United States Department of Agriculture, and his staff for the identification of some of the insects used in this study. ill TABLE OP CONTENTS Aoknowladgeaents ••••••••••••••••••••• ill List of Illuttratlon* •••••••••••••••••• v Introduotlon ••••••••••••••••••••••• 1 Materials and Methods • ........ ••••* ........ •• $ Dlssostelra Carolina (L«) (Orthoptera) •••• .......... 9 Aoanthooephala tenalnalls (Dallas) (Henlptera) •••••• 1? Magloloada septendeoln (L«) (Hoaoptera) ................ 18 Umbonla orassloornls (A* AS*) (Hoaoptera) •••••«•• 22 fhyllophaga drakll (Kirby) (Coleoptera) ••••••••• 26 Panorpa nebuloaa Westwood (Moooptera) ••«••••••• J2 Pyonopsyohe olroularls (Prov*) (Trlohoptera) ••••••• J6 Protoparoe aexta (Johan.) (Lepldoptera)* ........ •*•• 41 Vespula maoulata (L*) (Hymenoptera) .................. .. Discussion and Oonoluslon ••••••••■•••*••• $0 Literature Cited «•••*•••••••••••»•••• $7 List of Abbreviations ............ ................. .. 59 Illustrations •»••••••••••••»•••*••• 60 Iv LIST OP ILLUSTRATIONS Plat* X Intoot and elootrodo support. Plat* II Axillary rorion, Dltsostelra Carolina (L«)» Plat* III Axillary region. Aoanthooaphala terminalis (Dallas) Plat* X? Axillary rerlent Uarloloada septendeela (L.). Plato T Axillary region. Umbonla orastioomit (A. & 3.). Plat* TX Axillary region. Riyllophaga drakll (Kirby). Plat* YIX Axillary region. Ifenorpa nebulota Vestvood. Plat* YXII Axillary region. IVenopsyeh* olroularls (ftrov.). Plato XX Axillary region. Protoparoe aexta (Johan.). Plato X Axillary region. Vespula maoulata (L.). Plat* XX Otolllograph reoords showing wlngbeat frequency and thoraolo potentials. r INTRODUCTION With the steady increase in the use of insects in physiological research* there has developed an increasing need for studies of func­ tional morphology* Work on the physiology of insect flight has* for example* suggested the mechanical importance of exoskeletal structures directly or indirectly Influencing the functioning of muscles (Boettiger & Furshpan, 1952). Although the Diptera* as representatives of a group of insects which move their wings at a seemingly impossible rate* have been the subjects of considerable study in flight physiology* due in large part to the ease of keeping cultures in the laboratory* work on other groups is being undertaken* The literature on the morphology of insects is immense* perhaps second in volume only to the taxonomic literature* However* when the literature is confined to the comparative studies and in particular to the axillary region* one sees how meager our knowledge of this subject is* One of the earliest comparative studies of the axillary region is that of Amans (1885)* This work* typical of the studies of the period* is essentially descriptive morphology with little emphasis on the mechanisms involved in flight movements* Ohabrler (1320) and Straus-Durokheim (1823) made detailed morphological studies of Melolontha vulgaris* These studies did include the axillary region* Voss (1905) presents a very detailed description of a single species* Oryllus domeatlcus and also reviews the wing articulations in other orders* Two more recent studies are those of Snodgrass (1909* 1927). These works are invaluable to the student of thoracic morphology* According to Snodgrass* Jurine first described the scleritee of the 1 2 wing basa and gava thaa Individual naaaa in Xylooopa vlolaoaa« a aaabar of tha Hymanoptera. Tha noaanclatura used for tha axillary ragion has changed a great deal* For example, Lowne (1890-92) rafera to tha masopleural wing prooaae as tha hamulua, while Ritter (1911) calls it tha processus ptaralis thoracis V* Undoubtedly tha nomenclature used in vartabrata morphology had a strong influence on early authors in naming arthropod structures* The nomenclature used by Snodgrass (1935) is followed in this study. The axillary solerites are small plates located between the lateral margins of the noturn and the base of the wing-veins* It is believed that they are formed, in part, as detached portions of the lateral region of the notum, and in part as detached basal portions of the wing-veins, or as solerotized areas at the bases of the veins* These articulatory solerites enable the wing to be flexed more readily and also take part in flight movements* Studies by Pringle (19^9) and Boeder (1951) h**® shown that insect flight muscles must Include at least two types* The type found in insects such as roaches and dragonflies, ordinarily behaves as the muscles found in the legs of insects in that each contraction is the sequel of a single motor impulse, resulting in a single wing, beat* With the other type, found in flies and bees for example, each motor impulse results in a series of contractions, hence several wing- beats* For convenience the term synchronous flight is applied to those insects covered by the former condition and asynchronous flight for the latter* In a short paper Boettiger and Furshpan (1950) describe the 5 effect of placing files in carbon tetrachloride fumes and later (1951) presented evidence that the click phenomenon, described in the previous work, was a part of normal flight in these insects* In a study of the flight mechanics of Sarcophaga bullata Parker, Boettiger and Furshpan (1952) describe the axillary region and discuss the move, ments of the parts concerned in respect to this click phenomenon* The theory presented indicated that the mesopleural wing process moves in and out twice, once during the downstroke and once during the upstroke* According to earlier accepted ideas, the mesopleural wing process merely acted as a fulcrum, possibly moving outward on the upstroke and inward on the downstroke as a result of the contraction of the vertical and longitudinal muscles respectively. Later Boettiger (unpub*) by placing extremely minute mirrors on the mesopleural wing process and on the arm of the ecutellar lever of flies, was able to show that the mesopleural wing prooess does move in the manner described in the earlier work* Pipa (1955)i on the basis of a histological study of the flight muscles of several Insects, divided the flight muscles into three groups! the lamellar, fibrillar and microfibrillar* The insects which at that time were known to be asynchronous possessed the fibrillar type. Since the insects examined, in respect to flight, appeared to fall into fairly definite categories from the histological point of view and since the Diptera at least appear to have an unusual mechanism in the click phenomenon, this work was undertaken* A study was made to determine whether this mechanism, or a similar mechanism, is a morpho­ logical characteristic of other insects exhibiting asynchronous flight* k Oscillograph raoorda showing tha relationships betwoen the wing beat frequency and the nerve impulses have been obtained for only a few inseots* For this reason it was necessary to obtain the oscillograph flight records to determine into which category the various inseots studied fell* MATERIALS AND METHODS Tho specimens used for the morphological studies were, in most instances» preserved in "JOfi alcohol* In some oases the specimens were first placed in Xahle's Fixative and then kept in 7Q£ alcohol until used* For the study of the preserved material 70^ alcohol was used as a dissecting fluid and petrl dishes or metal pillboxes) vere used as dissecting pans* Some of the pillboxes had beeswax on the bottom and others had black dissecting pan wax. It was found advantageous to use both light and dark backgrounds* The petri dishes were used when transmitted light was desired. As an aid to examination some of the specimens were placed in hot potassium hydroxide (10^) for a short time to facilitate the removal of the tissuest but usually this was not necessary* At no time were specimens treated in this way used for the determination of movements of the various parts* Stains were at times used to differentiate certain structures* Thickened regions in the membranous areas are at times present and the stain served to define these ligaments more clearly* Mallory's Triple Stain and merourochrome were used* Of the two* mercurochrome proved to be more convenient to use