Info

FIGURE 44-47 (44) Adult female small fruit fly (Drosophilidae Drosophila). (Photograph by R. D. Akre.) (45) Adult crane fly (Tipulidae). (Photograph by Department of Entomology, Michigan State University.) (46) Ventral view of larva of Blephariceridae showing suctorial discs. (47) Adult net-winged midge (Blephariceridae). (Photographs by G. W. Courtney.) FIGURE 44-47 (44) Adult female small fruit fly (Drosophilidae Drosophila). (Photograph by R. D. Akre.) (45) Adult crane fly (Tipulidae)....

Class Insecta Winged and Wingless Insects

The million or so species in the subclass Pterygota include all winged invertebrates and some insect species that have secondarily lost wings during evolution. They include two orders of ancient winged insects (Ephemeroptera and Odonata) and some 25 to 30 (depending on the classification system) orders of modern folding-wing insects. Most have 11 abdominal segments. The head features two antennae and compound eyes. Respiration is generally with internal tracheae, but aquatic species may use...

Economic Impact Of Galls

The majority of plant galls harm the host plant only by diverting plant resources and thus have little economic impact. The economic impacts of gallmaking insects include the benefits of fig pollination as well as some negative economic effects in the form of crop losses. Three examples of gallmaking insects with negative economic impacts are the Hessian fly (Diptera Cecidomyiidae), the grape phylloxera (Homoptera Phylloxeridae), and the oriental chestnut gall wasp (Hymenoptera Cynipidae). The...

Termite Biology And Ecology

Termites live in colonies that are social and can be long-lived. Colonies are composed of castes that conduct all tasks for survival (Figs. 1, 2, and 3). Some termite queens are larger than the length of a human thumb and can lay more than a thousand eggs per day. The king is also long-lived and mates intermittently to provide sperm to the queen. Some of the longest living insects are termites some termite mounds and their queens are thought to be more than 70 years old and Aborigine folklore...

Life History And Biology

Opiliones are oviparous and deposit between one (in cyphophthalmids) and several hundred (in phalangiids) eggs. Life cycles and longevity are variable. Many species live 1 year, with embryonic development occurring during the winter, with hatching in the spring, and reaching maturity in the fall, after five to seven molting periods. This is the typical seasonal life history of most Northern Hemisphere phalangiids. Others have an overlap of adults and juveniles throughout their life cycles...

Ecology And Life Cycle

Drosophila melanogaster originated in tropical west Africa and has spread around the world, primarily through its commensal associations with humans. This species is a generalist and breeds in a variety of rotting fruits in its natural environment. It was first recorded on the east coast of North America in the 1870s following the end of the American Civil War and the expansion of the fruit trade. Like all other members of the family Drosophilidae, D. melanogaster is holometabolous and...

Class Cirripedia Barnacles

The name barnacle evokes a rugged image of the sea in the minds of many people, but few recognize this taxon's kinship with familiar crustaceans like shrimp and crabs because the barnacle's body is hidden inside calcareous plates and free-living species are sedentary. The 1000 species in the class Cirripedia include free-living species that live directly on a hard surface or are raised on a stalk (peduncle). This surface may be an inanimate object (e.g., rocks, floating refuse, ship hulls) or...

Songs And Communication

In most cricket species the males chirp or trill, producing clear, rhythmic, musical sounds distinctive to their family. An upturned scraper on one forewing is rubbed along a row of fewer than 10 to more than 1300 teeth, on the underside of the other forewing tooth number, often species-specific, correlates with pulse rate and length. The dominant frequency in the sound depends upon the tooth-strike rate, FIGURE 4 Drawings from audiospectrographs of the songs of 7 of the 17 known species of...

Defense and Escape

Because they are among the most abundant phytophagous insects in many habitats, Auchenorrhyncha are an important food source for numerous vertebrate and invertebrate predators (see next section Natural Enemies). Species of Auchenorrhyncha exhibit myriad strategies for avoiding predation. These range from relatively simple behaviors, such as dodging around to the opposite side of a leaf or branch as a predator approaches, or hiding under a leaf sheath, to complex mutualistic associations and...

Phylogeny And Classification

Traditionally the Diptera have been divided into two or three suborders Nematocera (lower Diptera) and Brachycera (higher Diptera), with the latter sometimes divided further into the Orthorrhapha and Cyclorrhapha. Although there is general agreement that the Diptera, Brachycera, Cyclorrhapha, and a few other subordinate groups are monophyletic, there is comparably general agreement that the Nematocera is a paraphyletic or grade-level grouping. No synapomorphies (shared, derived characters)...

Role Of Amateur Entomologists

Professionalization and an improved image as scientists has been an issue for entomologists since the 19 th century. From their origin in amateur lepidopterist clubs and local societies of collectors interested in the taxonomic position of their specimens and little else, entomological societies grew into associations of applied scientists who recognized the contribution of a client base of agriculturalists but did not make a place for them or for hobbyist entomologists (amateurs) in their...

Description

Ladybugs are beetles of the family Coccinellidae. This family consists of about 5200 known species of small to medium-sized, oval, oblong oval, or hemispherical beetles. The dorsal surface is convex and the ventral surface is flat. The forewings, or elytra, are strong and are often brightly colored, sporting two or more strongly contrasting colors in a bold pattern. Not all species are red with black spots. Almost every color of the rainbow is found as the predominant color of some species of...

The Germ Band And Dorsal Closure

The germ band is a two-layered structure, comprising both ectoderm and mesoderm, that represents the outline of the final body plan along both axes. As the embryo grows, the germ band transforms from this essentially two-dimensional, two-layered sheet into a three-dimensional larva. From anterior to posterior, all the segments are represented. Individual segments first become visible near the anterior end, where the ectoderm differentiates into the brain and compound eyes. Protrusions develop...

Agricultural Entomology

The study of all economically important insects is the object of the subdiscipline economic entomology. Agricultural entomology, a branch of economic entomology, is dedicated to the study of insects of interest to agriculture because they help increase crop production (e.g., pollinators) help produce a commodity (e.g., honey, silk, lacquer) cause injury leading to economic losses to plants grown for food, feed, fiber, or landscaping cause injury to farm animals or are natural enemies of...

Folk Medicine

Folk remedies for the treatment of the innumerable ailments that befall humans and their animals are found worldwide. Although less important than herbal remedies, insects play a role in the folklore of healing and drug use. One of the most well-known insect-derived folk medicines is cantharidin. This powerful vesicant is derived from dried blister beetles, particularly Lytta vesicatoria. Although cantharidin can be extremely toxic to humans, as recently as the early 1900s cantharidin was used...

Host Habitat Finding

A female parasitoid may find herself far from potential hosts. This could occur if the host stage she emerges from is different from the one attacked. Also, many parasitoid females have a preoviposition period before eggs are ready to be laid. During this interval of a few days to several weeks, the parasitoid may leave the vicinity of the host to mate and obtain nourishment. For example, the ichneumonid wasp Pimpla ruficollis is a parasitoid of the European pine shoot moth, Rhyaciona buoliana....

Extracardiac Pulsations

First described in 1971, extracardiac pulsations of insects are the simultaneous contractions of intersegmental muscles, usually of the abdomen of insects, that cause a sharp increase in the pressure in the insect body. The amount of movement accompanying each pulse is too small to be seen, but it can be readily measured as a slight shortening or telescoping of the abdomen as measured from its tip. The extracardiac pulses should not be confused with larger overt movements of the abdomen,...

Subterranean Biome Caves and Voids

Caves are subterranean voids large enough for humans to enter, but intermediate-sized voids (i.e., mesocaverns) smaller than caves but larger than capillary spaces are also important for terrestrial cave insects. Terrestrial animals rarely exploit capillary-sized spaces underground, but water-filled pore spaces (i.e., interstitial habitats) are often inhabited by numerous tiny species of stygobites. Caves and voids can form in three ways solution, erosion, and volcanism. The largest and best...

Folklore Mythology And Religion

The derivation of stories and myths is a universal tendency of all human societies. Both myths and folk tales differ enormously in their morphology and their social function. They are used to mediate perceived contradictions in phenomena observed in the natural world, they serve as vehicles of wish fulfillment, they may embody a lesson, or they may serve to preserve a piece of a culture's history. Myth and folklore also differ from one another in their origin and purpose, but application of...

Historical Events Mediated By Insects

Finally, insects have made their mark on human cultures by influencing events that shape history, such as wars, or by changing the way societies can or cannot accomplish things. The Panama Canal was built and ultimately controlled by the United States in part because the earlier effort by France was thwarted by mosquito-borne yellow fever. As vectors of African sleeping sickness, Glossina spp. (Diptera) have made huge pieces of land in Africa uninhabitable by humans. Bubonic plague, spread by...

Subphylum Myriapoda

Myriapoda (many feet) is a subphylum of elongate arthropods with bodies divided into a head and trunk with numerous segments, most of which have uniramous appendages no pronounced tagmatization is evident. Myriapods range in length from 0.5 to 300 mm and are primarily terrestrial. Most live in humid environments, commonly in caves. Some have invaded arid habitats, but few are aquatic. Four classes are recognized Diplopoda (millipedes), Chilopoda (centipedes), Pauropoda, and Symphyla, with...

Bee Venom

Bee venom is a secretion from the venom glands of the worker or queen of a species of honey bee (Apis) it is not produced by stingless bees (Meliponinae). The main components of commercial freeze-dried venom from A. mellifera worker bees include 15 to 17 enzymes, including phospholipase and hyaluronidase 48 to 58 small proteins, including especially mellitin 3 physiologically active amines, including histamine 0.8 to 1.0 amino acids, and numerous minor components. Queen venom differs somewhat...

Bioluminescence

Light that is produced in a chemical reaction by an organism is called bioluminescence. This living light is most commonly produced in tissues or organs within and shines out of the emitter's body, but luminous secretions are produced by some organisms and oozed or squirted out, even smeared on attackers. Chemiluminescence is but one of several forms of light emission collectively known as luminescence, which occurs when atoms of a substance emit photons (packets of light energy) as their...

Hypermetamorphosis

Hypermetamorphosis is a form of complete insect metamorphosis or holometaboly in which at least one of the instars in the life cycle differs considerably from the others. The term heteromorphosis, preferred by some entomologists, carries a degree of ambiguity in that it also refers to the relatively minor differences characterizing consecutive instars in virtually all insects, as well as to the phenomenon of organ replacement following mutilation. Hypermetamorphosis is most common in...

Some Insects and Their Adaptations to Erosional Habitats

Adaptations of aquatic insects to torrential or rapid flow habitats include the dorsoventral flattening of the body, which serves two purposes it increases the organism's area of contact with the surface substratum, and it offers a mechanism by which animals can remain in the boundary layer when water velocity diminishes, thereby reducing drag under subsequent exposure to high velocities. However, this second idea may be an oversimplification. Indeed, some authors have suggested that the...

Structural Colors

There are many mechanisms by which structural colors can be produced. All depend directly or indirectly on the fact that a particular piece of material scatters or refracts different wavelengths of light to different degrees. This property of the material can be expressed in terms of its index of refraction, n, a measure of the degree to which a given wavelength of light entering the material is retarded or slowed down. For insect cuticle, n typically ranges from 1.5 for long-wave (red) light...

Polygenic Industrial Melanism

Of all categories of melanism, polygenic industrial melanism has been the least considered and is the most difficult to address. Examination of specimens collected over the past century and a half suggests that many species have experienced a gradual darkening of the colors and loss of patterning in industrial regions, irrespective of morph. Although some of this change may be attributed to the gradual fading that occurs in museum specimens with time, it is difficult to ascribe all of the...

Digestive System

The digestive system consists of the alimentary canal (gut) and salivary glands, and is responsible for all steps in food processing digestion, absorption, and feces delivery and elimination. These steps occur along the gut. The anterior (foregut) and posterior (hindgut) parts of the gut have cells covered by a cuticle whereas, in the midgut, cells are separated from the food by a filmlike anatomical structure referred to as the peritrophic membrane. Salivary glands are associated with the...

Feeding Groups

Insects can be assigned to feeding groups based on the part of the tree they attack and the method of feeding they use. In forest habitats, these feeding groups are A. Insects that feed on cones and seeds B. Insects that feed on shoots and tips C. Insects that feed on foliage D. Insects that feed on the trunk and large branches In the following discussion, species have been selected from each feeding group to demonstrate the great diversity of insect adaptations to their tree hosts. An example...

Partial Industrial Melanic Polymorphism

Melanic forms of many species of moth are independent of industrialization. The factors that can favor melanism are numerous and varied. These have been discussed in detail by Kettlewell and Majerus. Their relevance to industrial melanism is that in some moths, the presence of melanic forms prior to, and independent of, industrialization provided a repository of melanic variants that were favored as pollution levels increased. Indeed, it is likely that the majority of moths that exhibit melanic...

Neoendemic And Paleoendemic Islands

Neoendemics typically form on isolated islands that have been created de novo and have abundant empty ecological space into which those few colonists can diversify. Besides Hawaii, other volcanic archipelagoes, including the Marquesas, Societies, and Galapagos in the Pacific and the Canaries in the Atlantic, have provided ideal conditions for the formation of neoendemics. However, species can also form on fragment islands, formed as a mass of land has broken away from a larger continental...

Brain and Optic Lobes

Drosophila Optic Lobe

Authors variously use the term brain either to include all neuropils located within the head capsule or, restrictively, to refer to only those neuropils (called preoral neuropils) that lie dorsal to the esophagus. These are considered to lie anterior to the mouth. Preoral neuropils are also known as the supra-esophageal ganglion, which comprises three fused ganglia the protocerebrum, deutocerebrum, and tritocerebrum. The preoral brain of the larger Hymenoptera, such as the predatory wasp Pepsis...

Autotomy

Autotomy is a defensive response to attack involving the amputation or active breaking of a body part along a breakage plane and usually involves loss of a leg. Many invertebrates (e.g., crayfish, daddy-long-legs), including insects such as crickets, grasshoppers, and walkingsticks, and many vertebrates (e.g., salamanders) exhibit this ability. For example, walk-ingsticks (Phasmida) have weakened areas at the trochanter that break under stress, such as when an appendage is grasped by a...

Dorsal Diaphragm

A cross section of the abdomen of insects reveals a pericardial sinus near the dorsal cuticle. The dorsal diaphragm can be a thin sheet of muscular tissue, or it can be fenestrated (Fig. 1). In most cases, there are muscles present in the diaphragm, which are called alary muscles because when vitally stained they give the appearance of wings projecting laterally from each abdominal segment of the dorsal vessel. The presence of paired alary muscles and paired ostia in each segment of the dorsal...

Discovery And Characterization Of Cave Arthropods

Why an animal would abandon the lighted world and lose such adaptive characters as eyes, pigment, and dispersal ability to live permanently in perpetually damp, dark, barren caves has long fascinated both biologists and laymen. In fact, it is these pale, blind obligate cave species that one usually envisages under the rubric of cave animal, and it is this group that is featured in this article. However, numerous other animals live all or part of their life cycles in caves or are regular...

Survey Of Insect Taxa Displaying Type I Hypermetamorphosis

Only the Mantispidae have true hypermetamorphosis. Most of the species feed on spider eggs associated with a single egg sac. The first instar either enters a previously constructed egg sac or attaches onto a female spider and enters the sac as she constructs it. Other species feed on the larvae of various aculeate Hymenoptera. Several of these are phoretic and reach the food source by attaching to the adult bee or wasp. The only lepidopteran family with hypermetamorphosis is the Epipyropidae....

Farming Insects For Their Products And Byproducts

Not only living insects are marketed. Dead insects and products derived from them can also be of high commercial value. In fact, insect products and by-products probably account for the lion's share of insect commercialization. Insects provide critical basic tools for studying a great many aspects of biology. Because Drosophila melanogaster, a common fruit fly, is small, has a short life cycle, and is inexpensive and easy to rear, it is an extremely valuable organism for biological research,...

Honeydew As A Kairomone

The smell or taste of honeydew on the plant surface is used as cues by various predators and parasitoids of homopterans to locate their hemipteran prey or, for reproductive females, as a stimulus for oviposition. This has led to the use of artificial honeydew sugar sprays onto crops to increase the numbers and effectiveness of natural enemies. Aphids Auchenorrhyncha Food, Insects as Sternorryncha Further Reading Budenberg, W. J. (1990). Honeydew as a contact kairomone for aphid parasitoids....

Gut Morphology And Function

Branching Diagram Beetles

Figure 1 is a generalized diagram of the insect gut. The foregut begins at the mouth, includes the cibarium (preoral cavity formed by mouthparts), the pharynx, the esophagus, and the crop (a dilated portion, as in Fig. 2A, or a diverticulum, like Fig. 2K). The crop is a storage organ in many insects and also serves as a site for digestion in others. The foregut is lined by a cuticle that is nonpermeable to hydrophilic molecules and in some insects is reduced to a straight tube (Fig. 2F). The...

Serosal Formation

Only blastoderm cells destined to form the embryo coalesce to form the germ anlage, which later develops into the germ band. The cells that do not contribute to the germ anlage form an extraembryonic membrane called the serosa. In most species, the boundary between the future serosa and the future embryo ruptures, and the serosal cells migrate over and envelope the embryonic primordium and yolk cells (Fig. 1). However, there is variation in how the serosa is formed. In extreme cases like...

Insectariums Around The World

During the 19th century, expanding empires, increased trade, and improved transportation and communication stimulated interest in exotic wildlife. European powers sent expeditions to bring back specimens for potential domestication and commercial use. Illustrated publications on biological subjects appeared, and books recounting the adventures of naturalist explorers allowed the public the vicarious thrill of discovery. With the emergence of modern systematics, the number of described genera...

Crypsis

Organisms with bright and conspicuous color patterns tend to attract the most attention both scientifically and aesthetically. However, the majority of insects and other animals rely on camouflage or crypsis for survival from predators that hunt them by sight. Furthermore, crypsis may extend to include the other senses, namely, smell, touch, and sound. Indeed, any stimulus or signal that can alert a potential predator could be expected to become part of a FIGURE 1 Crypsis illustrated for...

Predators And Parasitizers

Vertebrate predators such as skunks, raccoons, birds, and moles may dig in infested areas to feed on the grubs. Indigenous predatory insects, including ants and ground beetles, feed on the eggs and young grubs. Birds, fish, and other insectivores eat the adults. From 1920 to 1933, entomologists searched for, and imported, numerous natural enemies from Asia and released them for biological control in areas infested with Japanese beetles. Only a few of these became established. The most widely...

The Evolution And Extinction Of Biodiversity

Evolution, simply speaking, is change through time. In genetic terms, evolution is an alteration in the frequency with which different genes are represented in a population, and it results primarily from the processes of natural selection and random drift. Natural selection operates through differential survival and reproductive success of individuals in a population, which determines their contribution to the genetic composition of the next generation. Natural selection acts on individual...

Central Processing Of Chemosensory Input

Over the past 20 years, studies of insect olfactory systems have produced a rich literature on the topic of central processing, particularly for pheromonal systems. Work on gustatory systems is far less advanced. The section on insect pheromones provides more information on olfactory processing. This section simply contrasts the gross morphology of the two systems. Both olfactory and gustatory sensory cells are primary neurons that is, they connect the periphery (sensillum) directly with the...

The Odor Path

Substances animals taste are usually much more water soluble than those that they smell, and the sensory dendrites of both gustatory and olfactory sensilla are in an aqueous medium. Thus, the problem of getting the stimulus to the receptor has received much more attention in olfactory research. In insects, odor molecules first contact the cuticular surface, and because it is waxy, they easily dissolve. From here they move in two dimensions, and some find their way into the opening of a pore...

Bioregions Or Biomes

Seashores, glaciers, high mountains, and deserts pose obvious physical limits to animal distribution. Even in the absence of physical barriers, however, most species inhabit only part of a major landmass, because of ecological constraints. It is rare that a single ecological factor, or a precise combination of factors, limits an insect's distribution. However, most ranges can readily be assigned to a particular biome or bioregion, that is, a large landscape with characteristic overall...

Insects As Omens And Soothsayers

Insects that are most commonly featured in human folklore are those that most closely associate with humans or impact human affairs. It is not surprising then that insects such as cockroaches, mosquitoes, and bees are some of the most common subjects in stories and superstitions in which an insect's presence or activity is related to significant events in people's lives. Because humans have practiced honey hunting and beekeeping for thousands of years, it is not surprising that there is much...

Subchromosomal Organization In Insects

Euchromatin and heterochromatin can be distinguished in insects in various ways. Euchromatin contains the active genes, and heterochromatin, contains mainly repetitious, transcriptionally inactive DNA. Heterochromatic segments of the chromosomes can be observed in meiosis because of their high degree of condensation during first prophase (Fig. 1). Heterochromatin may also be detected by hybridization in situ of repetitous DNA sequences, such as satellite DNA, to the chromosomes. The DNA of...

General Characteristics And Terminology

Two broad categories of hypermetamorphosis can be recognized in insects. In the most widespread form, there is a decoupling of oviposition site and the larval food in the other, the oviposition and larval feeding sites are identical. For convenience, these can be referred to as type I and type II hypermetamorphosis, respectively. Type I adult females do not oviposit directly at the larval feeding site instead, the first instars must find the food source. Such larvae are active, slender, and...

The Nekton and Plankton Communities

The nekton are swimmers able to navigate at will (e.g., Coleopera, Hemiptera, some Ephemeroptera), whereas plankton are floating organisms whose horizontal movements are largely dependent on water currents. The phantom midge Chaoborus sp. (Chaoboridae) (Fig. 3A) is normally regarded as the only planktonic insect and is abundant in many eutrophic (nutrient-rich) ponds and lakes. The tracheal system in these larvae is reduced to kidney-shaped air sacs that function solely as hydrostatic organs,...

What Is Pterogote

Hyperparasitism intrigues entomologists because of its multidisciplinary relationship to evolution, ecology, behavior, biological control, taxonomy, and mathematical models. More field studies are needed to determine whether hyperparasitoids are always detrimental to biological control programs. Perhaps, instead, they could have a beneficial influence by regulating the extreme detrimental population oscillations of the beneficial primary parasitoids. Godfray, H. C. J. (1994). Parasitoids...

Mechanisms Of Resistance And Their Homology

Depending on the mechanism involved, resistance has been shown to arise through structural alterations of genes encoding target-site proteins or detoxifying enzymes, or through processes affecting gene expression (e.g., amplification or altered transcription). Examples of the former include the following. Enhanced metabolism of insecticides by cytochrome 450 monoxygenases can potentially confer resistance to most chemical classes. Much of the evidence for this mechanism is indirect, based on...

The Benthos Community

Benthos, derived from the Greek word for bottom, refers to the fauna associated with the solid water interface and includes insects residing on the bottom or associated with plant surfaces, logs, rocks, and other solid substrates. In lentic habitats, many insects fall into this category as mentioned earlier, particularly the Chironomidae, which often represent over 90 of the fauna in the profundal (deep-water) zone of lakes and ponds. These inhabitants are mostly burrowers that feed on...

Vi

FIGURE 7 Male genitalia of a ditrysian moth (Tortricidae), venterolateral aspect with valvae reflexed. un, uncus tg, tegumen so, socii gn, gnathos tr, transtilla ju, juxta va, valva sa, sacculus vi, vinculum ph, phallus (aedeagus) ve, vesica co, cornuti. visible part of the genitalia externally. The phallus, which is separately articulated and passes through the diaphragma, is sclerotized and contains the membranous vesica, the intro-mittent organ. The vesica often is armed with cornuti, which...

Ddt 288

Development, Hormonal Control of 300 Richard W Merritt, Gregory W. Courtney, and Joe B. Keiper Division of Labor in Insect Societies 340 Scott Hoffman Black and Mace Vaughan Nancy C. Hinkle, Beverly Sparks, Linda J. Mason, and Karen M. Vail Katherine N. Schick and Donald L. Dahlsten Peter W Atkinson and David A. O'Brochta Teja Tscharntke, Ingolf Steffan-Dewenter, Andreas Kruess, and Carsten Thies Greenhouse Gases, Global Warming, and Insects 486 Martin B. Berg and Richard W. Merritt see...

Unusual Habitats

Because of adaptive radiation over evolutionary time, insects have colonized virtually every aquatic habitat on earth. Therefore, it is not surprising that these organisms are found TABLE V Summary of Ecological Data for Benthic Aquatic and Semiaquatic Diptera Larvae Inhabiting Lentic Habitats Ceratopogonidae (biting midges, no-see-ums) Corethrellidae Psychodidae (moth flies) Canacidae (beach flies) Ephydridae (shore and brine flies) Scathophagidae (dung flies) Sciomyzidae (marsh flies)...

Circulatory System

Insects have an open circulatory system. This means that the internal organs and tissues are bathed in hemolymph, which is propelled actively to all internal surfaces by specialized pumps, pressure pulses, and body movements and is directed by vessels, tubes, and diaphragms. Without such constant bathing, tissues would die. The internal organs and tissues depend on the circulatory system for the delivery of nutrients, both to carry away excretion products and as the chemical communication...

Important Families Of Termites

The earliest known fossil termites date to the Cretaceous, about 130 mya. There are > 2600 species of termites worldwide. Undoubtedly, more will be recognized with improved methods of discerning cryptic species and after intensive collecting of tropical and remote regions. Termites are most closely related to cockroaches and mantids. The greatest continental termite diversity is in Africa, where there are over 1000 species. Polar continents have none, and North America with 50 species and...

Causes Of Endangerment

Insects become endangered because of the same destructive forces faced by many other animals. According to the IUCN, the leading causes of animal endangerment are habitat destruction, displacement by introduced species, alteration of habitat by chemical pollutants (such as pesticides), hybridization with other species, and overharvesting. Many at-risk insects are threatened by more than one of these causes. For example, according to the Natural Heritage Program there are six tiger beetles and...

Modes Of Foundation Independent Swarming And Budding

Size versus number of propagules Insect colonies vary widely in the amount of investment they make in each of their offspring colonies. At the low end are independently founded colonies, wherein single inseminated females (such as eusocial thrips and aphids and some Hymenoptera) initiate new colonies alone. In these species, the colony passes through a solitary phase. Examples of independent founders include sweat bees (Halictidae), bumble bees (Bombus), several genera of paper wasps most...

Eyes and Vision

Insect eyes are of two basic types compound (or multifaceted) and simple (or single chambered). In adults, the principal organs of sight are nearly always compound eyes, although simple eyes often quite good ones are frequently present in immatures. Despite the major differences in their form and construction, compound and simple eyes perform essentially the same job of splitting up the incoming light according to its direction of origin (Fig. 1). Compound eyes are of two distinct and optically...

Insect Endangerment

A report by the World Commission on Environment and Development noted, there is a growing consensus that species are disappearing at rates never before witnessed on the planet but that we have no accurate figures on current rates of extinctions, as most of the species vanishing are the least documented, such as insects in tropical forests. Scientists and conservationists agree that insect species are going extinct. But how many have been lost and how many more are at risk remains unclear. The...

Interactions With Humans

Throughout history, humans have had diverse interactions with and perceptions of beetles. Coccinellid beetles were once perceived to have a close association with the Virgin Mary, hence their common name ladybugs. Ancient Egyptians recognized dung beetles (Scarabaeidae) as a symbol of Ra, the sun god, because of parallels between the beetles' behavior and cosmic activities credited to the deity. Much as the scarabs rolled dung balls across the desert, Ra was thought to guide the sun across the...

Cockroaches As Pests

The most important of the several reasons for considering some cockroaches to be pests is based on the species that invade people's homes and other buildings and become very numerous. Most people find such infestations to be objectionable, in part because the important pest species also have an unpleasant odor and soil foods, fabrics, and surfaces over which they crawl. However, on a worldwide basis less FIGURE 1 German cockroach. From left adult male, adult female, nymph, ootheca. FIGURE 1...

Germ Anlage Formation

The size of the germ anlage varies relative to the length of the egg. In nearly all species, the nuclei arrive at the periphery to form a blastoderm that encompasses the whole surface of the egg. In metamorphic species, such as fruit flies and honey bees, the germ anlage forms from nearly the entire blastoderm surface. However, in direct developing species (such as the grasshopper and cricket), after the formation of a uniform synctyial blastoderm, nuclei migrate and aggregate near the...

Chemistry And Evolutionary Origin

Bioluminescence chemistry varies widely among organisms. Bacteria use riboflavin phosphate, the sea pansy uses diphosphoadenosine, and fireflies use adenosine triphosphate (ATP) in the oxidative decarboxylation of substrates generically known as luciferins, with enzymes termed luciferases. The present, cautious conclusion would be that bioluminescence has evolved from many separate biochemical origins. Molecular structures and their alterations along light-producing pathways of some systems are...

Types Of Color

Light by definition involves wavelengths within the visible part of the electromagnetic spectrum. For humans it consists of wavelengths ranging from approximately 400 nm (violet) to approximately 725 nm (red). Many organisms, including insects, extend this range into the near ultraviolet (300-400 nm). White light for a particular organism consists of all wavelengths visible to that organism. Colored light has an incomplete spectrum in which only some wavelengths are represented. Matter...

Symbolism And Reverence

Throughout human existence, many insects have been admired for their ingenuity, beauty, fantastic shapes, and behaviors. In some instances, the use of insects as totemic figures that may symbolize ancestry or kinship of humans with these organisms leads to a deep sense of adoration and reverence. In other cases, the resultant admiration has developed into a reverence for their inspirational and historical nature and a medium for symbolizing a variety of aspects of human life. In these...

Marketing Living Insects

Flowering plants are fertilized by several groups of insects. By far the most common pollinators are bees, and the honey bee, Apis mellifera, plays the dominant role in pollinating large tracts of agriculture. The domestication of the honey bee for pollinating crops had its beginnings at least 4000 years ago. Since that time, beekeeping has flourished and is now a thriving industry. In the United States alone, 15 billion worth of crops (fruits, vegetables, flowers) are pollinated by...

Morphological Requirements

There is tremendous morphological diversity of insect ears (Fig. 1). The multitude of different ear designs and locations reflects the unique physical and behavioral challenges faced by each insect. Yet despite their many differences, most ears follow a similar morphological plan. Each typically consists of three identifiable substructures a tympanal membrane, a tracheal air chamber, and a chordotonal sensory organ. The tympanal membrane (eardrum) is a thinned region of exoskeleton, typically...

Accessory Pulsatile Organs

Because the circulation of hemolymph is vital to all insect tissues, several intricate structures ensure circulation of hemolymph through the appendages. Collectively, these are termed the accessory pulsatile organs (APOs), but modifications to ensure circulation in the appendages also include diaphragms and directed channels. When present, APOs occur at the bases of wings, antennae, legs, and cercal appendages at the back of the abdomen. Early studies of the neuromusculature of the locust leg...

Entognathous Hexapods Collembola Protura and Diplura

Entognathous hexapods include two small taxa (class Diplura and Ellipura, order Protura) living in moist forest litter and a large group of springtails (class Ellipura, order Collembola) with at least 4000 species in terrestrial and semiaquatic environments. Most springtails live in moist terrestrial environments, but some colonize the surface film of quiet fresh and marine waters. They occur at densities much higher than almost any other invertebrate in soil litter. Unlike insects, springtails...

Embryogenesis

Distinct patterns of embryonic development are observed in hemimetabolous and holometabolous insects. In both types, the embryo produces multiple cuticular layers, and the appearance of these coincides with pulses of ecdysteroids. Juvenile hormone levels are generally low during early embryogenesis, but climb later to program nymphal or larval cuticle formation upon appearance of an ecdysteroid peak. In the hemimetabolous grasshopper Locusta, four peaks of ecdysteroids are observed,...

Nontympanal Hearing Organs

Until now we have focused on tympanal ears, which are sensitive to traveling waves of changing pressure in air and water, known as the acoustic far field. In the broadest sense of the word, however, hearing encompasses the detection of near-field sounds, as well as vibrations traveling through solid substrates. By and large, the near field can be thought of as a short distance, a few body lengths, from the sound source. Substrate vibrational signals have also been described as seismic...

Summary Of The Insect Fossil Record

Figure 3 summarizes the chronology, approximate diversity, and possible relationships of major groups of living and extinct insects. The earliest remains of terrestrial animals are arthropods from the Silurian, including primitive scorpions, millipedes, and tTrigonotarbida (extinct, primitive arachnids). Two major hypotheses on the origins of the hexapods (including insects) are that they are most closely related to either the myriapods (centipedes and or millipedes) (all comprising the...

Insect Pigments

Insects can make most of their pigments (some apparently from waste products that were historically simply stored or excreted), whereas others must come from their diets. Several general classes of pigments are recognized. These differ in the color ranges they generate and in the precursors used to produce them. As they share the same underlying mechanism of color production (selective absorption of some wavelengths of light), they can be reviewed with a simple list. Melanins are black, brown,...

Habitat Habit And Trophic Classification System

The classification system used here for lotic and lentic habitats stresses the basic distinction between flowing water (i.e., streams, rivers) and standing water (i.e., ponds, lakes, swamps, marshes) habitats (Table II). This separation is generally useful in describing the specific microhabitats (e.g., sediments, vascular hydrophytes, detritus) in which aquatic insects may be found. Both stream river currents and lake shoreline waves often create erosional (riffle-type) habitats and may...

Pleural Regions Of The Thorax

Apterygota and Immature Plecoptera The anapleurite is the sclerotized area above the coxa (supracoxal area) (Fig. 8). The coxopleurite is a sclerotized plate situated between the coxa and the anapleurite (Fig. 8). It bears the dorsal coxal articulation, the anterior part of which becomes the definitive trochantin. The sternopleurite, or coxosternite, is the definitive sternal sclerite that includes the areas of the limb bases and is situated beneath the coxa (Fig. 8). Pterygota The basalare is...

Malekilling Bacteria And Ladybug Sex Ratios

The population sex ratio of the majority of sexually reproducing organisms is close to 1 1 selection will normally promote the production of the rarer sex, so that the stable strategy is for sex ratio equality. Female-biased sex ratios were first recorded in the ladybug A. bipunctata from Russia in the 1940s. Some females were found to produce only female offspring. The trait was inherited maternally. Subsequent research has shown that male embryos die while in the egg as a result of the action...

Folk Beliefs and Superstitions

California State University, Northridge An integral part of any society's cultural heritage is the collection of stories and traditions passed from generation to generation through the ages. Folklore serves to define a people's identity by mirroring its beliefs, concerns, and fantasies. The passing on of traditional tales thus creates a lasting, tangible bond between the living and their ancestors and provides meaning to a people's existence in the present. As with other aspects of human...

The Protocerebrum

The ground structure of the protocerebrum suggests its ancestral affinities with segmental ganglia. In the protocerebrum, as in postoral ganglia, ascending sensory interneuron tracts enter it ventrally, whereas premotor interganglionic interneurons exit dorsally. Afferents (here the optic lobe output neurons see later) distribute to local interneurons in a manner reminiscent of sensory afferents within postoral ganglia. Despite its basic similarities with segmental ganglia, the protocerebrum...

Biology Of Diptera

One of the major problems facing forensic entomologists is the accurate identification of the larvae collected from the remains. Too frequently, the entomologist must work with dead specimens collected by crime scene investigators and submitted in marginal states of preservation. Even when the local faunas are well known, identification of these specimens is difficult, especially for early instars. Work by Erzinclioglu in England and Liu and Greenberg in the United States has provided...

Diversity Cercopoidea

Cercopoidea (froghoppers and spittlebugs, Fig. 1) are characterized by the following combination of morphological characters head with frontoclypeus inflated median ocellus absent ocelli on crown distant from margin pronotum extended to scutellar suture body clothed with fine setae hind coxae conical, tibia without rows of setae but often with one or more conspicuous spines male subgenital plate present. The super-family comprises four families Aphrophoridae, Cercopidae, Clastopteridae, and...

Autonomic Nervous System

The tidal flow of hemolymph, the extracardiac pulsations, heartbeat reversal, and thermoregulation all imply a very sophisticated control of circulation by the central nervous system. The central nervous system also plays a role in regulation of the respiratory system. It seems increasingly clear that the activities of circulatory and respiratory systems are coordinated by the central nervous system, perhaps to an extent not fully appreciated, but strongly implied by the tidal flow of hemolymph...

Evolutionary History

The earliest beetlelike insects are known from Lower Permian (280 mya) fossil deposits in Moravia, Czech Republic, and the Ural Mountains of Russia. These insects, classified in the family Tshekardocoleidae, order Protocoleoptera, resemble present-day species of the archostematan families Ommatidae and Cupedidae. They differ from true beetles in having 13-segmented antennae, elytra with more well-developed venation and more irregular longitudinal ribbing, and an abdomen and ovipositor extending...

Factors Affecting Predators And Prey

The predator prey equation is never constant. Age and size of respective predator and prey, hunger levels, population sizes, presence of alternative prey, and behavioral factors are ever changing. Size of a potential predator relative to prey size is an obvious factor affecting defensive capabilities of an insect. For example, an ant's mandibles might be an effective defense against a small jumping spider, but likely are ineffective against an anteater. Hunger is an important, often overlooked,...

Superposition Eyes

From the outside, apposition and superposition eyes are almost indistinguishable. Both are convex structures with FIGURE 11 Section through the superposition eye of a dung beetle (Onitis westermanni ). c, cornea cc, crystalline cones cz, clear zone rh, rhabdoms. (Photograph by Dr. S. Caveney. Reproduced, with permission, from Land and Nilsson, 2002.) FIGURE 11 Section through the superposition eye of a dung beetle (Onitis westermanni ). c, cornea cc, crystalline cones cz, clear zone rh,...

Cecidia Plant Galls

Cecidia, or plant galls, are abnormal growths of plant tissue under the influence of a parasitic organism. Within the growing cecidium, plant cells proliferate (hyperplasy) and enlarge (hyptertrophy) into a characteristic structure specific to that particular gallmaking organism. The organism inducing cecidogenesis (gall formation) receives nourishment and shelter while the host plant seldom benefits. Plant galls are induced by a variety of organisms including bacteria, fungi, nematodes, and...

Biology And Ecology

Caterpillars are commonly encountered because many are leaf-feeders and are not concealed feeders, although they may be cryptically shaped or colored. The realistic twig mimicry (Fig. 2) and behavior found in some inchworms (Geometridae) are complete with body markings that resemble bark irregularities, scars, and stipules. Another excellent mimic is the caterpillar of the orangedog, Papilio cresphontes, whose black and white larvae resemble bird droppings in all instars (Fig. 3). Some other...

Learning Processes

Many associative learning processes that have been described for vertebrates have also been shown in insects. The following list of selected processes is derived mainly from work on honey bees, unless otherwise noted. Generalization refers to an animal's tendency to respond to stimuli that were not reinforced but that are related to a reinforced stimulus (A+) along some perceptual dimension. Moths and honey bees have been shown to generalize odors according to similarities in functional groups...

Larval Specialization

Larvas Coleopteros

Among the four suborders of Coleoptera, life histories of the predaceous Adephaga most closely resemble those of the beetles' phylogenetic sister group, the neuropteran orders. Adephagan larvae are generally campodeiform, that is, elongate and slightly dorsoventrally flattened, with long thoracic legs and a posteriorly tapered, dorsally sclerotized abdomen (Fig. 13). They typically have anteriorly directed mouthparts that often include elongate, sickle-shaped mandibles with a reduced mola (Fig....

Learning Characterized Characteristics

Learning eludes an easy, satisfying definition, but the following characteristics constitute a useful guide. Learning involves an enduring change in behavior with experience, the change usually progressing gradually with continued experience to some asymptote. Learned behavior is often modified by novel experiences, and effects of experience eventually wane if not reinforced. Associative vs Nonassociative Learning Learning can be categorized as nonassociative or associative. Nonassociative...

Digestive Physiology Overview

The study of digestive physiology involves the spatial organization of digestive events in the insect gut. Digestive enzymes that participate in primary digestion (cleavage of polymers like protein and starch), secondary digestion (action on oligomers exemplified by polypeptides and dextrans), and final digestion (hydrolysis of dimers as dipeptides and disaccharides) are assayed in different gut compartments. Samples of the ectoperitrophic space contents (Fig. 1) are collected by puncturing the...

Environmental Regulation

Obligatory diapause is not elicited by environmental cues. It simply occurs in each generation when the insect reaches a certain developmental stage. In the example of the gypsy moth, diapause occurs when the embryo has completed its development and the first instar is nearly ready to hatch. With the exception of a few aberrant individuals, the gypsy moth always halts development at this time, regardless of the environmental cues they receive. In this example, environmental conditions, mainly...

Conservation Of Cave Life

The fantastic adaptations displayed by obligate cave animals have long intrigued biologists. Their often narrow environmental tolerances, coupled with their island-like habitats, have reinforced the view that these animals are fragile, lead an endangered existence, and are in need of conservation. However, development of conservation programs is hampered by a severe lack of data about the species present and their status. Discoveries in the past few decades of cave ecosystems in a variety of...

Morphology

Fungus Gnats Myiasis

Because of the structural variety in Diptera, especially among larvae, it is difficult to generalize about morphology. Despite this variety, flies share a number of features. Except for certain forms (e.g., cave-dwelling species), adult flies usually possess large compound eyes. In some species, eyes meet or almost meet dorsally (holoptic) in other groups, eyes are widely separated (dichoptic). Further modifications include eyes that are divided into distinct dorsal and ventral components, a...

Abdomen

The abdomen is more conspicuously segmented than either the head or the thorax. Superficially, the abdomen is the least specialized of the body tagma, but there are notable exceptions such as the scale insects. The abdomen characteristically lacks appendages except cerci, reproductive organs, and pregenital appendages in adult Apterygota and larval Pterygota. The ground plan abdomen of an adult insect typically consists of 11 to 12 segments and is less strongly sclerotized than the head or...

Metamorphosis

The transition from immature to adult is signaled by the elevation of ecdysteroid levels in the absence of JH. This is a one-step process in hemimetabolous insects. During the last nymphal instar of the cockroach Nauphoeta, JH levels fall from 5 to 10 ng ml to less than 1 ng ml prior to the next ecdysteroid peak (Fig. 2). Appearance of ecdysteroids at this low JH level signals a commitment to an adult gene expression pattern. Some examples of cellular responses to this adult commitment peak...

Industrial Melanism And Crypsis

Perhaps the first analysis of crypsis and the evolution of a color pattern from the perspective of changes in camouflage involved industrial melanism in the salt-and-pepper moth, Biston betularia. Industrial melanism refers to an association of high frequencies of dark, melanic forms or phenotypes of a species with high levels of air pollution. The fundamental components of this classic example of the evolution of an adaptive trait also apply to numerous other species of moth and other insects...