Showing papers in "Annual Review of Entomology in 1974"

Fine structure of insect epidermal glands

Abstract: The present review is devoted to the exocrine glands derived from epidermis; glands associated with the preoral cavity (mandibular, salivary, etc) and genital apparatus are not dealt with except for the sake of comparison. As defined, the epidermal glands manifest an exceptional diversity as far as location, morphology, and func­ tion are concerned. In the past, the studies were mainly anatomical, very rarely cytological, but the interest in insect glands was recently renewed by the chemical approach and the recognized importance of the secretions as far as behavior and physiology are concerned. Concurrently, the high resolution of the transmission electron microscope permitted a far more precise elucidation of the structures, with the hope of establishing some correlations between these structures and the func­ tions. Additionally, the scanning electron microscope appeared well suited for the examination of some cuticular differentiations.

Courtship behavior in Drosophila.

Abstract: remain to be discovered. Amazingly, 25% of the known species are endemic to the Hawaiian Islands (12). Drosophila have a number of characteristics which enhance their value for behav­ ioral studies. They are small but not minute organisms (2-7 mm), have a short generation time (10-30 days), and an adult life span of several weeks to several months. Many species can be successfully reared and maintained in the laboratory. Single-pair matings are easily achiev ed, and thus flies of known pedigree can be studied. Field-captured specimens of species which cannot be bred in the laboratory can be maintained for periods of time in healthy condition on normal laboratory diets so that their behaviors may be studied. Significantly, laboratory-reare d or maintained specimens

Predator-Prey Relationships Among Aquatic Insects

Abstract: It is not surprising that the majority of studies concerning aquatic insect predator­ prey relationships involve the aquatic stages of mosquitoes as the prey (26, 40), and in some instances as the predator (14, 15, 68). Most mosquito larvae are easy to rear and maintain, and make excellent prey for a wide variety of aquatic organisms. In addition, the biting nuisance and disease vector significance of many species of adult mosquitoes has encouraged considerable attention being given to their natural enemies. Other than mosquito larvae, simuliid larvae ·and chironomid larvae are the most frequently studied invertebrate prey in the freshwater habitat. Neither of these groups, however, are as convenient to rear or as easy to observe for predation as are mosquito larvae. Most chironomid larvae dwell in tubes or in mud, while most blackfly larvae occur attached to rocks in fast-flowing streams (39). Predator-prey relationship studies involving other aquatic insects are few (18, 75). Laboratory studies of aquatic insect predation are fairly common, but field evalu­ ations have been relatively rare. These have been restricted mostly to rock pools (35, 60) and other small or container-like bodies of water (38). This is not surprising when one considers the difficulties involved in viewing insects through a reflective surface that is often moving and distorted, or obscured with plants, debris, or scum. Moreover, the water itself is often too murky from either algae or sediment for direct observation, and where it is clear many predators and prey are too small and too well camouflaged to be visible. Stationary underwater observation structures (3) permit a truer understanding of prey selection and predator behavior than can be obtained in aquaria, but quantitative assessment of predator effects are more difficult to obtain. Mosquito and chironomid midge larvae for instance, are quick to appear in newly filled depressions and temporary ponds. These prey are followed almost simultaneously by a large array of predators that feed also upon one another, and upon a constant rain of terrestrial insects that fall upon the water surface (19, 73).

Morphogenetic Action of Insect Hormones

Abstract: Two classes of hormones-ecdysones and juvenile hormones (JH)-regulate the morphogenetic changes of insect metamorphosis. Recent advances in structural analysis and synthesis have resulted in the ready availability of synthetic forms, analogues, and mimics of these hormones; and there has already been considerable speculation on their molecular modes of action (4, 26, 27, 68, 87.92, 102). However, the morphogenetic responses of the various experimental systems to these hormones must be more rigorously established and understood before final judgement can be passed on their molecular bases of action. The following questions summarize the key areas of active research which are amenable to morphological analysis: 1. Does JH exert an all-or-none action on an individual cell? 2. Does JH reprogram embryonic cells? 3. Does JH regulate changes in larval structure? 4. Can JH cause a reversal of metamorphosis? 5: What is the nature of the interaction of JH and ecdysone: synergism, antago­ nism, mimicry, or mutual interdependence? 6. Is regulation of DNA synthesis the key step in the action of ecdysone or JH? 7. Is ecdysone capable of initiating all of the steps needed for the completion of a new cuticle? Although these will comprise the main topics to be covered in this review;because of broad areas of overlap between some of these topics, I have found it more logical to organize the following discussion somewhat differently. Further, recent compre­ hensive reviews of insect endocrinology (12, 67, 70, 76, 98, 106) and morphogenesis (89) make a survey of all the pertinent literature unnecessary and I have selected

Economic Insect Pests of Bananas

Abstract: Bananas are commercially grown worldwide in equatorial and subtropical regions with an average annual temperature of 200e and an abundant. well-distributed rainfall of 200 cm per year (134, 181). In 1971 86% of exported bananas were grown in Central and South America (37) and this review will concentrate mainly on the pests in this region. The world market demand for high-quality, blemish-free fruit, together with increasingly strict governmental restrictions on pesticide use, has increased the importance of banana insect research.

Isozymes in Insects and Their Significance

Abstract: The basic determinant of a protein's characteristics is the sequence of the amino acids (primary structure) in the polypeptide chain or chains of which it is composed. This chain is formed into an a-helix which in tum is folded in a precise way, determined by its amino acid sequence, to give a globular structure called the tertiary level of structure. Relatively small proteins may consist of a single polypep­ tide, but those with a molecular weight in excess of 50,000 are generally oligomeric, consisting of two or more polypeptide chains. The resulting multimer is said to be at the quaternary level of structure. Many, if not most, of the enzymes discussed in this article are multimeric. A multimeric enzyme molecule may be one of two general types; it may consist of two different polypeptide chains, a heteromultimer, or it may consist of only one kind of chain, and be called a homomultimer. A well-known example of a hetero­ multimer is vertebrate lactic dehydrogenase, which is both tetrameric and consists of two different polypeptides. In lactic dehydrogenase, the A and B polypeptides may form five kinds of tetramers: AAAA, AAAB, AABB, ABBB, and BBBB (90). All five of these have specific activity as lactic dehydrogenase. but they are different multimers and are called isozymes. Combinations may be random or regulated (88). Isozymes are enzymes which have similar or identical functions as catalysts, but are by one means or another identifiably different with respect to structure (156). Many enzymes are homomultimers. An example is glyceraldehyde phosphate dehydrogenase. which is a tetramer made up of four identical polypeptide chains. Homomultimers with more than four identical chains may also exist in nature.

Integrated Control of Fruit Pests

Abstract: The concept, theory, and techniques of integrated control have been thoroughly discussed by several authors (42, 97, 98, 105, 116, 122, 126), and for the purposes of this paper the definition of integrated control presented by Smith & van den Bosch (116) will be used. The following discussion will attempt to relate this concept and these techniques to recent research on tree fruit pest management. From the advent of DDT for pest control in the mid 1940s until the 1960&, research on control of pests on tree fruits was strongly oriented toward the use of insecticides. Barnes' review of this subject in 1959 (8) points out the predominance of chemical control studies but does mention some of the early work on integration of chemical and biological control. More recently the control of pome fruit pests has been reviewed (76), and it is obvious that a considerable change in emphasis and philosophy toward research on control of fruit pests occurred in the decade between 1960 and 1970. Studies on biology, population dynamics, biological control, and integrated control received much greater emphasis. This change was, no doubt, related to the changing public attitude toward pesticides, but other factors have also played a part. Control of tree fruit pests by chemicals alone has been fraught with problems of pest resistance, resurgence, and elevation of minor pests to major pest status. Costs of pest control have mounted and in some cases ever-increasing amounts of pesticides were required to keep the large number of pest species under control or to substitute in controlling species resistant to pesticides. For these reasons the best pesticides available could be considered but temporary measures to be supplanted at a later date by another pesticide. To many research workers, the answer was a more broadly based approach to pest control. One of the outstanding examples of early integrated control programs occurred on apples in Nova Scotia (94). Subsequent to the research in Nova Scotia in the 1940s several refinements and changes have been made in the program and these have been thoroughly reviewed (72). The program developed in Nova Scotia and subsequent refinements are of major interest for two reasons. First, the early re­ search occurred at a time when most other research efforts were shifting to the use

Advances in Cytology and Genetics of Bees

Abstract: Seven previous papers have reviewed the genetics, cytology, and evolution of bees (33, 37, 41, 59, 60, 63, 64). As is the case in every field of science good progress in bee genetics is being made, not only by those whose contributions deal directly with bees but also by those whose interest is in other Hymenoptera (15, 26, 69) and whose studies have an indirect but important impact on our understanding of the genetics of bees.

Methods for assessing the density and survival of blood-sucking Diptera.

Abstract: In a review of the principles involved in sampling insect populations Morris (I 17) has described the process as a mixture of art, science, and drudgery. The drudgery is known to us all, the science lies in understanding the responses of insects to trapping devices and their movements into the sampling area, while the art comes from an appreciation of the variables inherent in every field situation. The sampling methods adopted for blood-sucking flies may also reflect the background and objec­ tives of the operators. Those concerned with pest species, for instance, often employ standard techniques on a large scale with the immediate aim of monitoring the efficiency of control measures. They are dependent on funds from local authorities and may be answerable to the community in which they live. On the other hand. those concerned with assessing a disease hazard usually have more long-term objec­ tives, and their funds may come from a central authority. They often work in considerable isolation and individual whims and preferences lead to a lack of stan­ dardization in the techniques employed. Muirhead-Thomson (119) has recently reappraised the diverse methods used for sampling vectors and emphasized the need for greater uniformity. His lead is to be welcomed but much remains to be done. In some branches of entomology the use of specific chemical attractants for trapping pest species is becoming increasingly common, and the list of available lures is growing rapidly (8). This trend is much less noticeable in the case of biting flies probably because warm-blooded animals themselves are such potent sources of attraction. Thus, regardless of whether the active components have been identified or not, the use of animals as baits has long been the basis of many sampling methods used in the assessment of populations. At the same time medical and veterinary entomologists have been looking more critically at the interaction of trapping de­ vices and host attractants and have been considering how such traps could be