Foreword

I would say that creating an encyclopedia of insects was a herculean task, but I think that sells the enterprise short. After all, Hercules only had twelve labors assigned to him, and twelve years to complete them with insects, there are over 900,000 different species and many, many more stories to tell. Twelve years from now, there will likely be even more. Why, then, would anyone undertake the seemingly impossible task of compiling an encyclopedia of insects To an entomologist, the answer is...

Division Of Labor

The relatively large biomass of ants in many ecosystems can be attributed not just to the way in which the ants interact with other organisms but to the way in which they interact with their nestmates in general and, in particular, to efficiencies that accrue from divisions of labor. One of the most dramatic traits associated with the division of labor among the workers is physical polymorphism, which is the presence of different physical worker forms within the same colony. In the African army...

Colonylevel Investment

Investment in Growth and Maintenance versus Reproduction One of the major challenges that faces growing organisms is the developmental decision of how many resources to invest in growth and how many to invest in reproduction. Insect colonies can be treated as organisms in this sense, since each colony must decide how much it will invest in different castes (i.e., in workers vs reproductives). To the extent that colonies are reproductive units, optimality theory predicts that natural selection...

Abc

FIGURE 8 Three mechanisms of dark adaptation in apposition eyes of insects (see text). (Reproduced, with permission, from Land and Nilsson, 2002.) FIGURE 8 Three mechanisms of dark adaptation in apposition eyes of insects (see text). (Reproduced, with permission, from Land and Nilsson, 2002.) this is to absorb the wave-guided light that travels just outside the rhabdom. This is replaced with light within the rhabdom, and this is absorbed in turn, so that light is progressively bled out of the...

Fossil Record

Auchenorrhyncha arose in the Paleozoic, first appearing in the fossil record in the Lower Permian (280 mya) and, judging from the abundance of forms described from Permian strata, they diversified explosively. These early auchenorrhynchans had adults with well-developed jumping abilities and somewhat resembled modern leafhoppers and spittlebugs, but nymphs (juveniles) associated with these insects were bizarrely flattened or biscuitlike, with short legs, foliaceous lobes on the head, thorax,...

Life Cycle

Eggs are laid in branches of trees and shrubs or in the stems of grasses (the nymphal food plants) in small slits cut into the surface by the female's spearlike ovipositor. The number of eggs laid in each slit varies between both species and individuals. Usually it is about 10 to 16, although the number laid per slit by a single female can range from 3 or fewer to more than 20. A female makes many egg slits and often distributes her eggs at more than one site. A batch of eggs can number 300 or...

Paleosymbiosis

Because of the sudden death of captured organisms in amber, symbiotic associations may be preserved in a manner unlikely to occur with other types of preservation. Also, the fine details of preservation may reveal morphological features characteristic FIGURE 3 Documentation of paleophoresis is provided by a pseudoscorpion grasping the tip of the abdomen of a platypodid beetle in Dominican amber. Similar rider carrier associations occur today, suggesting that this behavior is mandatory for...

Insecticide Resistance

Brown's landmark publication, Insecticide Resistance in Arthropods, established the principle that insects as well as other related invertebrates are capable of developing resistance to insecticides through natural selection. The probability of the development of resistance largely depends on (1) the frequency of the resistance-conferring gene in the given population, (2) the level of selection pressure, (3) the degree to which resistant gene density is diluted by susceptible...

Cocoon

A cocoon is commonly believed to be the silken protective covering within which the caterpillars of many moths and a few butterflies pupate. Other orders of insects also spin silk and form cocoons, including Siphonaptera (fleas), Hymenoptera (ants, bees, and wasps), Neuroptera (lacewings and antlions), and Trichoptera (caddisflies). Lepidoptera cocoons can be very thick and tough, such as that of the silkworm, Bombyx mori, or they can be limited to a relatively few strands of silk that keep the...

B K Mitchell

Insects are acutely aware of many aspects of their environment, as anyone knows who has tried to catch a fly perched on a slice of pizza. In the chemical realm, and depending on the chemicals and insects involved, insects are often outstandingly sensitive. The most famous and best-studied aspects of chemoreception in insects are mate recognition and finding. Like many, if not most animals, insects produce chemicals called pheromones that allow individuals of one sex in a species to recognize...

Context Of Anatomical Study

Terms of Orientation and Conventions Terms to describe orientation are not intuitive for insects. Most orientation terms are derived from the study of the human body a body that stands upright and their application to insects causes confusion. Some standard terms used with insects include anterior (in front), posterior (behind), dorsal (above), ventral (below), medial (middle), and lateral (side). Anatomical description usually follows in the same order, hence, we begin our discussion with the...

Simple Corneal Eyes In Insects

Insect simple eyes, or ocelli, fall into two main groups the larval eyes of holometabolous insects and the dorsal ocelli present in most winged adult insects. In both, the curved air tissue cornea interface is the main refracting surface, although as in vertebrate eyes, a lens of some kind often augments the optical power of the system and aids in the formation of the image. In insects with a distinct larval stage, the ocelli are the only eyes the larvae possess. They vary greatly in size and...

Egg Cleavage

Development in nearly all animals involves a period in which the egg is subdivided into increasingly smaller cells. Compared with other animals, insect eggs undergo an unusual type of cleavage. In most animals, cleavage involves subdivision of both cytoplasm and nuclear material, to form individual cells called blastomeres. In contrast, the early cleavages of most insects involve only nuclear subdivisions (karyokinesis) and are not accompanied by cleavage of the cytoplasm (cytokinesis). This...

Homeostasis Behavioral

Behavioral homeostasis refers to mechanisms of behavior that allow an insect or group of insects to maintain conditions within a certain range of values. These conditions may be the temperature of the body or the environment, internal water balance or environmental humidity, nutritional state or food stores, the balance between different activities of the individual or of the group, or the number and composition of individuals in a group. Behavioral mechanisms of homeostasis are important to...

Archaeognatha

Archaeognatha

The Archaeognatha (Microcoryphia part of the subdivided order Thysanura) are apterygote insects with a body size between 6 and 25 mm and a cylindrical shape (Fig. 1). The eyes are large and contiguous, and there are two lateral and FIGURE 1 A male archaeognathan (Machilis germanica), body length ca. 12 mm, lateral view for details see Fig. 2. FIGURE 1 A male archaeognathan (Machilis germanica), body length ca. 12 mm, lateral view for details see Fig. 2. one median ocelli (small single eyes with...

Thermoregulation

Before the extracardiac pulsations were reported and before the tidal flow of hemolymph had been described in insects, Bernd Heinrich wrote about the use of the hemolymph in thermoregulation of flying insects. The optimum temperature for flight muscle contraction in many insects, such as the tobacco hornworm, Manduca sexta, is surprisingly high, up to 45 C. Before this moth can fly, it must warm the thorax to near this temperature, which it accomplishes by means of a series of simultaneous...

Classification

All Diplura possess the following defining characters (1) elongate body, (2) 10th abdominal segment with a pair of caudal cerci or one segmented forcep-like pincers, (3) absence of eyes, (4) entognathous mouthparts, and (5) two pair of spiracles on the thorax (Fig. 1). There is no doubt that these organisms are primitive arthropods standing near the base of the evolutionary lineage that led to the class Insecta. Whether they should be included in the Insecta or merit a class unto themselves is...

Beetle Diversity

Although beetles share characters supporting their common evolutionary origin, remarkable variations have evolved on the beetle theme. For example, adult body size ranges from the 0.4-mm-long Nanosella fungi ptiliid feather-winged beetles of North America to the 200-mm-long Titanus giganteus ceram-bycid long-horned beetles of South America. A rough estimate based on maximum dimensions for adult length, breadth, and depth puts the disparity in volume at a factor of 2.8 X 107. Life cycles also...

Habits And Specialization

Except for short, hazardous dispersal of adults, embiids almost never leave the shelter of their self-created microenvironment, and most of the order's anatomical and behavioral characteristics foster very smooth, rapid, reverse movement in narrow galleries. Such specializations include the following 1. A linear, short-legged, supple body with the head projected forward (Figs. 1 and 2). FIGURE 1 Typical adult female 'Aposthonia n. sp. (family Oligotomidae) of Thailand body length, 18.00 mm....

Isoptera

The ordinal name Isoptera refers to the two pairs of straight and very similar wings that termites have as reproductive adults. The common name, of Latin origin, translates as woodworm. Termites are small and white to tan or sometimes black. They are sometimes called white ants and can be confused with true ants (Hymenoptera). However, a closer look reveals two easily observed, distinguishing features termites have straight antennae and a broad waist between the thorax and the abdomen, whereas...

Isoptera Termites

Termites are a highly regarded food throughout sub-Saharan Africa. They are eaten raw, fried, or roasted and are found widely in village markets. The fungus-growing termites of the genus Macrotermes (family Termitidae) are the most widely used as food. The large winged adults (sexual forms) are collected as they emerge from the nests on their mating flights at the beginning of the rainy season. They are strongly attracted to light and this behavior is utilized in harvesting them. The high...

Info

FIGURE 4 Crop phenology and pest phenology relationship between the phenology of soybean in the midwestern United States and three of its most common insect pests, the bean leaf beetle, C. trifurcata (Coleoptera Chrysomelidae) the green stink bug, Acrosternum hilare (Hemiptera Pentatomidae) and the green cloverworm, Hypena scabra (Lepidoptera Noctuidae). FIGURE 4 Crop phenology and pest phenology relationship between the phenology of soybean in the midwestern United States and three of its most...

Diversity Of Insectivory

A simple list of the insectivorous terrestrial animals would be lengthy and include many freshwater fishes, most frogs and salamanders, lizards and snakes, and birds and mammals. Because marine ecosystems do not include many insects, the incidence of insectivory among marine invertebrates and vertebrates is much less common. In freshwater fishes, insects are ubiquitous and widely consumed. In streams, for example, 70 to 90 of the macroinvertebrates are insects, comprising as much as 99 of the...

Class Pycnogonida Sea Spiders

The body shape and gangling legs of sea spiders call to mind their terrestrial namesakes. Most of the thousand species live in shallow benthic zones at higher latitudes. They are predominantly predators of hydroids, bryozoans, and polychaetes, but some consume microorganisms, algae, and even detritus. Food is either macerated with chelae or externally predigested and then sucked into the digestive tract with a proboscis. Sea spiders have a barely perceptible head and a body comprising four...

Habitats

Crickets live in virtually all terrestrial habitats from treetops to a meter or more beneath the ground. Members of multiple subfamilies live in or near treetops and in bushes, grasses, and other herbaceous plants (Oecanthinae, Mogoplistinae, Eneopterinae, Podoscirtinae, Trigonidiinae) (Fig 3) on the soil surface (Nemobiinae, Gryllinae) in caves (Phalangopsinae, Pentacentrinae) and in shallow or deep burrows (Gryllotal- FIGURE 3 Adult male Orocharis saltator. (Photograph courtesy of David H....

Orthoptera Grasshoppers Locusts Katydids Crickets

Family Acrididae (Shorthorned Grasshoppers) Grasshoppers and locusts are included among the foods of almost every culture having any history of using insects as food. In southern Africa, before there were crops to protect, the arrival of a locust swarm, some of which were dense enough to block out the sun, was hailed with rejoicing as a time of harvest. Villagers collected them in the evenings after the swarms had alighted and were benumbed by the cool of the night. The locusts were roasted or...

Selforganization Collective Intelligence And Decision Making

A rapidly developing approach to the study of ants and other social insects is the application of self-organization theories. Here self-organization can be defined as a mechanism for building spatial structures and temporal patterns of activity at a global (collective or colony) level by means of multiple interactions among components at the individual (e.g., worker) level. The components interact through local, often simple, rules that do not directly or explicitly code for the global...

Quiescence

Quiescence for aestivation may be found in arid regions. For example, the larvae of the African chironomid midge, Polypedilum vanderplanki, inhabit temporary pools in hollows of rocks and become quiescent when the water evaporates. Dry larvae of this midge can revive when immersed in water, even after years of quiescence. The quiescent larva is in a state of cryptobiosis and tolerates the reduction of water content in its body to only 4 , surviving even brief exposure to temperatures ranging...

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

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

Gastric Ceca Insect

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...