Showing papers in "Annual Review of Entomology in 1983"

Insects as Flower Visitors and Pollinators

Abstract: Pollination ecology has been a fast growing field since the 1960s. A previous review by Baker & Hurd (18) together with books (77, 84, 220, 221 , 244, 264) and various symposia (e.g. 5, 12, 17, 24, 149, 167, 239) have promoted anthecology so that it remains at the heart of evolutionary and ecological research. This review concentrates on the entomologically relevant litera­ ture published since 1967. Botanical works must be included, as both insects and flowers mutually aSsure reproductive success. We have attempted to cover concepts, related disciplines, and insect taxa by reference to publica­ tions through which the reader may delve deeper. We apologize to our colleagues for not citing their works more fully. We dedicate this review to the memory of Paul D. Hurd Jr. His en­ thusiasm for bees and their relations with flowers, and for insects in general, have been an inspiration to us. His contributions would form the hub of a separate review in itself and we have not attempted to cover his works.

Plant Architecture and the Diversity of Phytophagous Insects

Abstract: In general, trees have richer insect faunas than herbs. This familiar observa­ tion is but one of several ways in which "plant architecture" and insect species diversity are correlated. In this review I explore the nature of these correlations and ask how they are produced. To keep within reasonable bounds I have restricted attention to herbivorous insects that consume living, green plant material (93, 102). Pollinators, scavengers, predators and "travellers" on plants (60) are willfully ignored. For the same reason, single species of plants and their associated insects receive most attention. Ex­ trapolations to entire plant communities are made cautiously in the final section. Architecture in everyday English means the structure and design of things; I have used it as shorthand for a variety of plant attributes, particu­ larly size and growth form and the seasonal development, persistence, and variety of above-ground parts (48, 52). It will be convenient, first, to estab­ lish the broad effects of plant architecture on herbivore diversity before moving to more detailed studies in the second half of the review. Studies of many kinds of ecological systems reveal effects of habitat complexity (architecture) on species diversity (54). Hence, their discovery among plant-feeding insects is neither novel nor surprising.

Visual Detection of Plants by Herbivorous Insects

Abstract: There are hundreds of thousands of insect species for which plants provide a variety of resources such as adult food, mating encounter sites, oviposi­ tional sites, food for immatures, shelter from harmful biotic or abiotic agents, or transport (90, 149, 1 81). Yet our understanding of the process by which an insect detects a resource-furnishing plant is not well developed. This is particularly true for the visual aspects of plant detection by insects. To date, studies of this aspect have focused on the visual location of flowers by pollinators (80). Visual location of plants by herbivores, parasitoids, or predators has received no more than marginal or scattered attention (6, 64, 79, 82, 88, 98, 100, 104, 1 5 1 , 152, 1 56, 162, 169). Before focusing attention exclusively on insect vision, it is useful to briefly review some general aspects of animal vision. Here, vision is defined as the ability to perceive spatial patterns. The physical stimulus that defines a pattern can be regarded as a spatiotemporal distribution of photo flux that differs in total energy and frequency composition, and thus provides the visual color cues of brightness (intensity of perceived reflected light), hue (dominant wavelength of reflected light), and saturation (spectral purity of reflected light). The spatial distribution of photon flux provides information on shape, size, distance, and motion. Visual patterns depend upon the nature of the viewed surface, the optical background, the illuminant, and

Intrinsic Factors Affecting Vector Competence of Mosquitoes for Arboviruses

Abstract: that exist between the virus, the invertebrate host (vector), and the vertebrate host, each of which is influenced to varying degrees by environmental conditions. These interrela­ tionships have been reviewed elsewhere (17, 60,98, 109, 111, 113, 124) and are not discussed in depth here. Rather, this review focuses on vector competence or vector efficiency. Particular attention is given to recent studies that have contributed to our knowledge of intrinsic factors and mechanisms that control the ability of mosquitoes to vector arboviruses. No attempt is made to review transovarial transmission of arboviruses by ar­ thropods even though this is obviously an important aspect of vector com­ petence in certain arthropod-arbovi rus associations (35, 125, 140,

Ecology of Cave Arthropods

Abstract: Why some species of animals would lose such obviously adaptive characters as eyes and pigmentation to live only in the seemingly inhospitable environ­ ment of caves has long intrigued both laymen and biologists. Evidence that early man recognized cave invertebrates dates back to an engraving of a cave cricket, Troglophilus sp., on a bison bone, discovered in a cave in the French Pyrenees (161), and believed to be 18,000 years old (86). However, serious studies on cave faunas began only about 150 years ago (5, 6). Vandel's monograph (161) provides the most recent overview of the whole science of biospeleology from a worldwide perspective, with an em­ phasis on Europe where most work has been done. Barr provided a thor­ ough review of ecological and evolutionary studies, drawing primarily on work in North America (6). Poulson's review (131) of the ecology and physiology of cave fauna emphasized aquatic species; Poulson & White (139) pointed out the potential for further ecological studies; Ueno (159) reviewed lava tube faunas in Japan; and Reddell (144), the Central Ameri­ can cave faunas. In general, the science of bios pel eo logy in the United States has lagged far behind studies in Europe, and it was not until the 1950s that the modern period of cave biology began in North America (5). The early studies were primarily taxonomic, since detailed ecological and physi­ ological studies require an accurate base of properly identified species. Advances in cave biology have followed the development of cave explora­ tion techniques, and the improvements in the last few decades have allowed biologists to visit and study longer and more complex cave systems in relative safety (e.g. 36, 105). In addition, the increasing ease of world travel has made possible the exploration of the more inaccessible, rugged tropical caves (e.g. see 16, 73, 128).

Oribatids in Forest Ecosystems

Abstract: The most complex terrestrial ecosystems occur in forests, both temperate and tropical. These systems are so complex that our understanding of their structure and functioning is far from complete. Even by narrowing the terms of reference to the litter-soil subsystem, the provenance of oribatid mites, the task is not much simplified. Two particular problems add to the difficulty of defining the role of oribatids. First, in comparison with other soil arthropods rather little information is available on their relationships with other soil biota. To untangle such a web of interrelationships requires the attentions of multidisciplinary teams of research workers (56,66), or the application of systems analysis. However, it is frequently difficult for the working ecologist to apply the theoretical developments of systems analysis to his own ecological problems (64). Second, oribatids are no larger than the litter and soil particles among which they live, only rarely exceeding 1 mm in body length. Thus they have to be removed from their environment in most cases before they can be studied, necessitating the use of laboratory or field microcosms with their attendant degrees of artificiality (20, 43). Unlike the vast majority of other Arachnida, which have adopted a carnivorous mode of life, members of the acarine order Oribatida (more commonly known as Cryptostigmata) are, for the most part, vegetarian. In view of this, and since they normally exceed most other soil microarthro­ pods in abundance and diversity, they should be "key industry" animals in decomposer food chains. However, they remain something of an enigma since, despite their ubiquity, their participation in energy flow processes associated with decomposer activity is minimal. Just what then is the nature of the "key industry" that employs these animals? The answer may lie in

Biology of the Mecoptera

Abstract: One of the minor orders of insects, the Mecoptera comprise about 500 known extant species arranged in 32 genera and 9 families (22, 106). They have been of interest to entomologists out of proportion to their small numbers, however, because of their supposed ancestral relationship to the major orders Diptera and Lepidoptera. Certainly, Mecoptera are among the oldest neuropteroid or holometabolous insects known from the fossil record. They make up a relatively conspicuous part of the insect fauna of the Lower Permian, where the Holometabola first appear (32). The 348 species of Permian, Mesozoic, and Tertiary Mecoptera in fact show more diversity, based largely on wing venation, than modem ones and have been assigned to 87 genera in 34 families (171). Most species of Mecoptera are only rarely encountered by entomologists, and biological knowledge of them based on observations of the living insects has been scant until recent years (34). Even morphological studies of any but the more common species have been few. Purely taxonomic and taxo­ nomic-distributional accounts have made up much of the literature on the order. Kaltenbach (73) has recently summarized what is known of the Mecopt­ era, with emphasis on their morphology, histology, physiology, and behav-

Dispersal and Movement of Insect Pests

Abstract: Perspectives and Overview Until recently, the study of insect dispersal and movement received little attention. Even 50 years ago, many ecologists considered studies of move­ ment to be trivial or even worthless exercises (44). Although this view is no longer held, as late as 1972, Headley (61) wrote that "agricultural pest control is still handled as though pests were immobile .... " Since the publication of Southwood's (134) review and Johnson's (68) monographic work, the study of insect movement has received increasing attention. Numerous symposia and reviews on various aspects of insect movement have been published [e.g. evolutionary considerations (6, 35, 37, 38, 48, 59, 60, 112, 134, 135); pest management implications (53, 108, 113, 151)]. Our purpose in this review is not to present an exhaustive list of references; rather, we wish to compare views and approaches based on our own, admittedly biased, selection of key references. With few exceptions, we have limited our review to those works published since Johnson (68). Our presentation is separated, for organizational clarity only, into sec­ tions dealing with evolutionary studies, experimental considerations, and modeling efforts. These three areas of interest are obviously inseparable biologically. We shall not attempt here to deal with the numerous papers

Biology of tipulidae

Abstract: The family Tipulidae, comprising the subfamilies Tipulinae, Limoniinae, and Cylindrotominae (3), is the largest family in the Diptera, with 14,000 described species. A very old group of Diptera with many resemblances to the Mecoptera (118, 119), tipulids have a number of derived characters and are perhaps (with the Trichoceridae) the sister group of all other Diptera (56). Tipulids are characterized principally by wing venation, presence of a V-shaped mesonotal suture, deciduous legs, absence of ocelli, and, in larvae, a retractible hemicephalous head capsule. They also differ from other Nematocera in several less obvious characters such as the larval peritrophic membrane (102), sperm structure (5), and cerebral neurosecre­ tory cells (100). Tipulidae probably evolved from ancestors resembling or included in the Upper Jurassic Architipulidae (3), and Limoniinae and Tipulinae were differentiated in the mid-late Paleocene (137). Hennig (56) considers the Limoniinae and Tipulinae to be sister groups; Limoniinae have a distinctive karyotype (134) and aedeagal structure (35). The Cylindrotominae appears to be a relict group that was much better represented in the Tertiary (9); their larvae are distinctive and their tripartite aedeagus appears to represent a primitive condition from which the bipartite limoniine structure and unipartite tipuline condition may have been derived (35). According to Savchenko (119) archaic tipulids probably inhabited sub­ tropical forests, and Rohdendorf (118) states that the modern Tipulidea (Tipulidae and the small families Trichoceridae, Tanyderidae, and Ptychop­ teridae) reach their greatest diversity in the humid tropics. However, crane flies now occur over a very -wide range of latitude, although the distribution of individual species tends to be rather limited; they are common in far

Mosquito Host Bloodmeal Identification: Methodology and Data Analysis

Abstract: The first comprehensive series of reviews on the applicability and methodol­ ogy of serological techniques to bloodmeal identification in biting flies was by Weitz (85-87). The last of these reviews also surveyed the available information on the feeding habits of ticks, mosquitoes, sandflies, and tsetse flies. Since then, several reviews have appeared summarizing the large amount of information that has become available on host bloodmeal identi­ fication and the numerous changes and modifications in the serological techniques (5, 6, 35, 75). Tempelis (75) not only reviewed the status of the methodologies involved but thoroughly discussed the literature on the feed­ ing patterns of mosquitoes to that date. There are several other reviews concerning aspects affecting feeding. Included in these reviews are (a) physiological aspects of the digestive processes of hematophagous insects (43), (b) role of host blood in the feeding behavior of ectoparasites and behavioral aspects of chemoreception in blood-sucking invertebrates (39, 40), and (c) physical and chemical factors that affect feeding by blood-sucking insects (37). The present review summarizes the status of host bloodmeal identifica­ tion studies with emphasis on new developments in basic methodology and

Energy Transfer in Insects

Abstract: Living organisms maintain a thermodynamic steady state that is far from equilibrium and thus they require a constant source of free energy. A part of this energy may be transformed or stored for short or long periods of time, but most is degraded to heat through the performance of the internal work necessary for life. The direct connection between life and the produc­ tion of heat was first convincingly demonstrated in the late eighteenth century by Lavoisier & Laplace using a simple ice calorimeter [see discus­ sion in Lusk (61), p. 33ff.]. Since then, the study of energetics (molecular, cellular, and organismal) has interested generations of biochemists and physiologists. Energetics tells us much about the conditions and mecha­ nisms responsible for vital processes and transformations within organisms. Energy considerations also have an important effect on the behavior and interaction ofindividuals and populations. But not until well into the twen­ tieth century, following the development of ecology as a rigorous discipline, was this common knowledge subjected to scientific scrutiny. The relative ignorance that exists concerning the energetics of insects is surprising, especially if one considers their numerical dominance and diver­ sity. This lack of attention at the physiological level persisted until well into the twentieth century. Researchers were more concerned with investigating human energy needs and those of domesticated animals which, with a few notable exceptions, e.g. the honey bee, are all mammals. Then too, mam­ mals, like all homoiotherms, degrade a much larger proportion of as­ similated energy to heat than do poikilotherms, so measurements of respiratory heat loss dominated the early energetics scene. .

Changing Concepts in Biogeography

Abstract: The continuing goal of biogeography is to explain the structure, function, and history of animals and plants in relation to their geographic ranges and to correlate these results with phylogenetic systems. Because of their num­ bers, insects represent a significant part of biogeography. However, our much greater knowledge of vertebrates until recently has resulted in an inordinate emphasis on birds and mammals. Insect biogeography, however, has been carefully surveyed in the Annual Review of Entomology in articles by Gressitt (10), Munroe (32), and again Gressitt (11), reviewing the litera­ ture up to 1972. This review is not organized along the lines of others cited above, nor does it claim to be complete in covering the expanding field of either general or regional publications on biogeography of insects. Such restraint must be exercised in view of the ever increasing number of relevant publications, which is evident from the tremendous growth of the Zoological Record during the last decade. In addition, however, there is a growing conviction that much basic work of alpha and beta taxonomy (26) has to be done or redone for most groups of insects, and that many statements and theories, hitherto undisputed, now seem preliminary and premature. The following survey, therefore, is limited to the presentation of some impressively chang­ ing concepts of biogeography and to acknowledging the altered situation of entomology in the last decade.