Biology of Snail-Killing Sciomyzidae Flies Lloyd Vernon Knutson and Jean-Claude Vala Excerpt More Information
Total Page：16
File Type：pdf, Size：1020Kb
Cambridge University Press 978-0-521-86785-6 - Biology of Snail-Killing Sciomyzidae Flies Lloyd Vernon Knutson and Jean-Claude Vala Excerpt More information 1 • Introduction All finite things reveal infinity. despite the ice which could cover it . And, finally, the Roethke (1964). hatching of the winged insect at springtime . .] But the finite cannot be extended into the infinite. The first report of the larval food of a sciomyzid was presented Leonardo da Vinci. by Perris (1850), who reared Salticella fasciata from larvae found in the terrestrial snail Theba pisana in southwestern Paris, 1846 and southwestern France, 1847. Then, a century France. He stated “Cette larve . devore . Helix pisana, later and continents apart, southwestern Alaska, 1950. In probablement apre`s qu’il est mort.”[“Thislarva...devours... terms of space and time, these critical points are the most Theba pisana, probably after it had died”]. The first conclusive important in the early work on sciomyzid life cycles. The evidence that several sciomyzid larvae kill and consume first description of the larva and puparium of a sciomyzid gastropods was presented one century later by Berg (1953). (that of Tetanocera ferruginea) was presented by Dufour Working in southwestern Alaska in 1950, he reared six species (1847a), in a poetic style, solely on snails (Dictya expansa, Elgiva solicita, Sciomyza dryomyzina, Sepedon fuscipennis, Tetanocera ferruginea,and Vers la fin de l’automne de 1846, je decouvris dans l’eau T. rotundicornis) and “found a third-instar larva of S. fuscipen- d’une mare, pre`s de Saint-Sauveur [near Paris], au milieu nis eating a small Lymnaea emarginata in nature.” The story des lemna et des callitriches, une larve dont . j’eus le of the original discovery by Berg in Alaska in 1950 was bonheur, vivement senti, de la voir prosperer, se transformer described in a personal account (Berg 1971a), in which he en chrysalide . La` ou` l’oeil du vulgaire n’aurait noted that he “stumbled onto a discovery.” The noted wasp certainement su voir qu’un fragment inerte de branche behaviorist, H. E. Evans (1985), in a vignette of the Cornell noircie par la pourriture, j’y voyais, moi, le berceau research, referred to Berg’s discovery as “a prime example hermetique d’une nymphe tendre, emmaillotee, immobile, of serendipity – the gift for making fortunate discoveries l’espoir de la prosperitedelaTetanoce`re . ce precieux accidentally” and noted the opportunities that the research conceptacle fœtal etait appele, par destination supreˆme, offered for a study of evolution of behavior and for biocontrol. a` braver la tempeˆte pendant cinq mois de la plus mauvaise In reviews of parasitoid and predatory insects, the Sciomy- saison . a` conserver sa vitalite malgre la glace qui zidae generally have been treated inadequately. This has pouvait l’ensevelir . Et, en definitive, l’eclosion de resulted, perhaps in part, because of the lack of a volume such l’insecte aile est venue, au printemps . as this that enables reviewers to encompass the extensive [Towards the end of fall of 1846, I discovered in the literature and because the behaviors of many species do not water of a pond close to Saint-Sauveur [near Paris], lend themselves easily to categorization. Forexample, Godfray among Lemna and Callitriche, a larva for which I felt (1994) does not mention Sciomyzidae in his Parasitoids: a deep happiness to see develop and change into a Behavioral and Evolutionary Ecology (disappointingly, despite chrysalide [puparium] . Where a vulgar eye would have his title, he refers only briefly to parasitoids other than certainly seen only an inert fragment of twigs blackened by Hymenoptera). Although until now no comprehensive review decay, I was seeing the hermetic cradle of a swaddled, still of sciomyzid biology has appeared, a few reviews of certain and tender nymph, the hopeful prosperity of the aspects have been published (e.g., Berg & Knutson 1978, Tetanoce`re . this precious foetal container was called, by Greathead 1981, Ferrar 1987,Barkeret al. 2004) and some supreme destination, to brave the storm during five reviews/compilations (primarily taxonomic in nature) on a monthsoftheworstseason...tomaintainitsvitality regional basis (e.g., Knutson 1970b, 1987,Vala1989a, 1 © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-0-521-86785-6 - Biology of Snail-Killing Sciomyzidae Flies Lloyd Vernon Knutson and Jean-Claude Vala Excerpt More information 2 INTRODUCTION Rozkosˇny´ 1984b, 1997a, 1998, 2002,Rivosecchi1992). In different mixtures of behavior. We recognize that these are developing this longer, holistic, world review and analysis we man-made divisions in a near continuum of behavior in have had the advantages of space and time to consider all nature. We often use the terms in conjunction as a kind of aspects more or less simultaneously. Thus we have had shorthand to indicate mixed and/or labile feeding behavior the advantages of relating to each other many aspects that have throughout the life cycle of some species, e.g., “saprophage– never before been treated in an integrated manner. We have parasitoid–predator” for Atrichomelina pubera,orforachrono- placed special emphasis on modifying generalizations in light logical sequence of behavior, e.g., “parasitoid-predator” for of recent data on Sciomyzidae and recent theoretical studies. the many species that begin larval life feeding in a mollusc Such an approach is useful for a group of insects such as the without killing it, but then become a true predator later. Sciomyzidae, about which studies of many aspects have been Saprophage. A saprophage feeds in dead plant (sapro- published, but usually quite separately (nearly 2000 publica- phytic) or dead animal (saprozoic) matter. Cyclorrhaphous tions since Linnaeus [1758] and more than 400 by more than Diptera larvae feeding in dead material have been shown by 100 authorsworldwide during the past 20 years). In addition to Keilin (1912, 1915), Hartley (1963), Dowding (1967, 1968), our primary objectives of review, synthesis, and analysis, and Roberts (1971) to have oral grooves leading into the including information from some unpublished documents, mouth and ventral cibarial ridges in the pharynx, the latter we provide work tools (e.g., keys to world genera, world serving as a filter mechanism to separate out micro-organ- checklist), information on methods of research, and sugges- isms and other particulate matter, which is the actual food. tions for additional research that we hope will be stimulating In the Sciomyzidae, only the plesiomorphic Salticella fas- and challenging to future researchers. ciata (Salticellinae) has been reared in the laboratory from Because our study is worldwide in scope and as it is often hatching to pupariation and successful emergence solely on instructive to compare features among species and genera dead, decaying tissue of snails and other dead invertebrates from different zoogeographical regions or to relate features (Knutson et al. 1970). It killed snails in laboratory rearings to regions, we occasionally indicate the regions after the but in nature it appears to attack moribund snails (Coup- species or genus names. Authors of valid species and genera land et al. 1994) (see Section 18.2). Salticella fasciata pos- of Sciomyzidae and Phaeomyiidae are given in the world sesses weakly developed oral grooves and weakly developed checklist of species (Chapter 21); of mollusc species in Ta ble s ventral cibarial ridges (Knutson et al. 1970, Dowding 1.2, 1.3,and1.4. Authors of genera of molluscs are given in 1971). The only record of a species of Sciomyzinae found Ta ble 1 .1, and authors of other organisms are given in Index in a dead non-gastropod in nature is that of Atrichomelina 3. In the figures and tables, first-, second-, and third-instar pubera found on the inner surface of a shell of a large larvae and larval stadia are indicated by L1, L2, and L3. In the unionid clam (J. B. Keiper, personal communication, figures, scales are in millimeters unless otherwise indicated. 2006). Fourteen puparia of A. pubera, from seven of which adults had partially or entirely emerged, were attached to the inner surface of one valve of a Lampsilis sp. collected on 1.1 DEFINITIONS OF SAPROPHAGE, the shoreline of a creek in Ohio. This probably was a dead PARASITE, PARASITOID, AND individual washed up onto the shoreline, the flies then PREDATOR, WITH EXAMPLES IN THE ovipositing onto it. Atrichomelina pubera and other Sciomy- SCIOMYZIDAE, AND OF APO/PLESIO- zidae appear to lack oral grooves and ventral cibarial ridges, MORPHIC AND APO/PLESIOTYPIC but cross-sections of the pharyngeal region of most species have not been examined. All of the 46 reared Sciomyzini A definition is the enclosing of a wilderness of ideas and many of the reared semi-terrestrial Tetanocerini com- within a wall of words. plete development on the putrid, liquified tissues of the Butler (1912). snails they have killed, beginning as early as the mid second Because the terms saprophage, parasite, parasitoid, and preda- stadium. Some Sciomyzini, e.g., A. pubera, have great flexi- tor, and their adjectival forms, are critical to discussions bility in switching back and forth between saprophagous, throughout this presentation, it is important that we explain parasitoid, and predatory feeding modes throughout larval our usage at the outset. We prefer somewhat narrow defin- development in the laboratory, depending upon the degree itions so as to provide as fine a level of discrimination among of crowding in the food snails and the relative sizes of the behaviors as possible and so as to provide the ability to describe larva(e) and snails(s) attacked (Foote et al. 1960). © in this web service Cambridge University Press www.cambridge.org Cambridge University Press 978-0-521-86785-6 - Biology of Snail-Killing Sciomyzidae Flies Lloyd Vernon Knutson and Jean-Claude Vala Excerpt More information 1.1 Definitions of saprophage, parasite, parasitoid, and predator 3 Table 1.1.