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

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

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...

Flea Suppression

Because fleas must have blood from a mammalian host to survive, treating host animals is the most efficient and effective means of suppressing fleas. There are several on-animal products that are effective for flea control. Many contain pyrethrins, which are safe, effective products but kill only fleas on the animal at the time of treatment and do not provide residual control. Other over-the-counter compounds include spot-on permethrin products, which are limited to canine use because they can...

Phylogeny And Distribution Of Dermaptera

Early in the 20th century, Burr established suborders of the Dermaptera recognized by most contemporary systematists. The four suborders (three of them recent) are as follows 1. Archidermaptera, represented by 10 fossil specimens from the Jurassic they are characterized by unsegmented cerci and tarsi having four or five segments. 2. Forficulina, the suborder containing most earwigs (i.e., 1800 described species, in 180 genera) cerci are unsegmented (except in a few primitive larvae) and...

Ecological Specialization

One means of estimating the ground plan feeding habits of Coleoptera uses observations of extant taxa, interpreted in context of phylogenetic hypotheses for the various lineages making up the order. By this method, we would deduce that the most primitive beetles were either saprophagous wood borers as larvae, such as extant Archostemata, or that they were campodeiform predators, such as the Adephaga and the sister group to Coleoptera, the Neuroptera+Raphidioptera+ Neuroptera. Examining the...

Defensive Froths From Diverse Glands

A surprising diversity of defensive secretions has been converted to froths that may literally bathe small adversaries with compounds that seem to adversely stimulate the olfactory and gustatory receptors of their predators. The independent evolution of deterrent froths by moths, grasshoppers, and ants demonstrates that this form of defensive discharge can be highly efficacious in adverserial contexts. Species in moth genera in the families Arctiidae (apose-matic tiger moths), Hypsidae, and...

Interspecific Interactions

Beetles exhibit defensive behavior that is mostly rooted in the attributes of their cuticle. Many beetles living an exposed portion of their life cycle on vegetation will use the dropoff reflex if disturbed (i.e., simply close the legs and tumble off the leaf or branch and fall to the ground, where their often cryptic coloration helps protect them from visually oriented predators). The drop-off reflex can be combined with thanatosis, in which the beetle lies still with legs appressed to the...

Lotic Habitats

Streams vary greatly in gradient, current velocity, width, depth, flow, sinuosity, cross-sectional area, and substrate type, depending on their position in the landscape with respect to geology, climate, and the basin area they drain. Anyone who has spent much time around or wading in streams is aware that these can be extremely diverse habitats, often manifesting great TABLE II Aquatic Habitat Classification System Lotic erosional (running-water riffles) Lotic depositional (running-water pools...

Significance In Natural And Human Communities

The major role of Lepidoptera in natural communities is primary consumer of plants. Moths and butterflies make up the largest single evolutionary lineage adapted to depend upon living plants, in terms of species numbers and, in many communities, in biomass as well. Females of most species produce 200 to 600 eggs within a few days, vastly more in some species (1000-30,000), releasing a potentially enormous load of caterpillars onto particular plant species or plant groups such as herbs or woody...

Nutritiondriven Evolution Life Cycles And Polymorphism

Aphid life cycles are complex and may be either monoecious or dioecious, involving holocycly or anholocycly. Because of this, aphids have evolved many specialized morphs a multitude of confusing, often synonymous names have risen among aphid biologists, but these are minimized here. In the simple and generalized monoecious holocyclic aphid life cycle (Fig. 1A), a single host plant species is used throughout the year and sexual morphs are produced in the fall, usually in response to decreasing...

Chemistry Of Juvenile Hormones

The juvenile hormones are lipophilic sesquiterpenoid derivatives of farnesoic acid. Their chemical nature came into focus in the early 1960s, beginning with observations that farnesoid components of beetle excreta had JH-like activity in bioassays. Although far less potent than the native hormone, these substances, including farnesol and its oxidized form farnesal, were suspected to be JH precursors. Subsequent synthesis of methyl farnesoate with an epoxide at position 10 11 by William Bowers...

Medical And Economic Importance

Earwigs are harmless to humans they carry no known pathogens of humans, and their mouthparts are incapable of biting humans (although some species can pinch). Some genera (e.g., Forf cula, Labidura, Euborellia) are repeatedly reported as a pest of homes, gardens, and orchards. Their thigmotactic nature, coupled with (known and suspected) aggregation pheromones, can lead to high densities of earwigs in and around homes. In gardens, earwigs may attack seedlings and soft fruit. Management in...

Sources And Preparation Of Chromosomes From Insects

Mitotic chromosomes undergoing the familiar stages of prophase, metaphase, anaphase, and telophase can be prepared from any insect somatic tissues with dividing cells. Embryos are the best sources of mitotic divisions, but they are also seen in the midgut ceca of adults and juveniles and in the follicle cells covering very early ova in females. Insect cytogeneticists now usually use colchicine or other mitostatic agents to arrest the chromosomes at metaphase of mitosis by inhibiting the...

Insect Zoos Defined

The term insect zoo has been applied to facilities of many different types. Defined broadly, an insect zoo or insectarium is an exhibit facility dedicated to the display of live insects housed in a separate room, building, or distinct exhibit hall and maintained primarily for public visitation. Insect zoos typically are permanent, year-round facilities that house live insects and related groups of arthropods (arachnids, centipedes, millipedes, and crustaceans) and occasionally representatives...

Digestion Of Lipids And Phosphates

Oils and fats are triacylglycerols and are hydrolyzed by a triacylglycerol lipase that preferentially removes the outer ester links of the substrate (Fig. 1D) and acts only on the water-lipid interface. This interface is increased by surfactants that, in contrast to the bile salts of vertebrates, are mainly lysophosphatides. The resulting 2-monoacylglycerol may be absorbed or further hydrolyzed before absorption. Membrane lipids include glycolipids, such as galactosyl-diacylglycerol and...

Digestion Of Carbohydrates

Initial and intermediate digestion of starch (or glycogen) is accomplished by a-amylase. This enzyme cleaves internal bonds of the polysaccharide until it is reduced to small oligosaccharides or disaccharides (Fig. 1B). The amylases are not very active in digesting intact starch granules, making mastication prior to ingestion important. Insect amylases depend on calcium ions for activity or stability, they are activated by chloride ions (amylases in Lepidoptera are exceptions), their molecular...

Ladybug Color Patterns

The bright, eye-catching color patterns of most ladybugs are their first line of defense against many predators. The bold markings of one bright color set on a background of another contrasting color provide a memorable image that warns potential predators that ladybugs have hidden defenses, being foul smelling and evil tasting. The chemical defenses of ladybugs involve a range of chemicals alkaloids, histamines, cardiac glucosides, quinolenes, and pyrazines, some of which are synthesized by...

Special Features of Beekeeping in the Subtropics and Tropics

The subtropics (between 23.5 and 34 N, and 23.5 and 34 S) include some of the most valuable world regions for honey production. Like the temperate zones, they have an annual cycle with a distinct seasonal rhythm and a well-marked summer and winter however, the climate is warmer and the winters are mild, so the bees can fly year-round. All the major honey-exporting countries include a belt within these subtropical latitudes China, Mexico, Argentina, and Australia. Between the Tropics of Cancer...

Role Of Cuticle In Taste And Smell

Insects, like all arthropods, are covered with a chitin protein complex called cuticle, which in turn is covered with wax to prevent desiccation. For the creature to taste or smell anything, there must be a pathway from the outside to the sensory cells inside. On various parts of the insect body, but particularly on the antennae, mouthparts, legs, and ovipositor (egg-laying structure) insects possess a variety of cuticular elaborations in which are housed chemically sensitive cells. These...

General Biology

Since Hymenoptera is a very large order, it is not surprising that a considerable number of biologies and life history strategies are exhibited by its various taxa. Broadly speaking, the basal lineages are phytophagous as larvae, feeding both ecto- and endophytically on a large range of herbs, shrubs, and trees few tropical pergid sawflies, even feed on slime molds The great majority of the remaining species are either parasitoids of other insects or predators of insects (e.g., the...

Coexistence Humans And Insects

Class Insecta has plagued and fascinated humans for all of their history. The most striking features of the Insecta are diversity and numerical superiority. Of the 5 to 30 million species estimated to compose the global flora and fauna, approximately 1.7 million have been named, more than half of them being insects. It is estimated that insects make up 75 of the known animal kingdom. Because insects occupy almost every conceivable terrestrial niche, they interact with humans in countless ways...

The Preoral Brain

Although there has been in the past endless debate about how many segments contribute to the head and to the brain, expression of homeobox genes now confirms three embryonic brain segments only. The main issue of contention focused on the neuromeric identity of the optic lobes, which were claimed by some to have a distinct segmental origin. Developmental studies, which are summarized by Meinertzhagen and Hanson's 1993 review, showed that the inner optic lobe neuropils in the adult insect brain...

Factors Delaying Invasion Of The Corpse

The initial invasion of the corpse by insects and other arthropods starts the clock that is ultimately interpreted to give the estimate of the time since death. The basic assumption underlying this is that the invasion occurs soon after death. In decomposition studies, fly activity begins as soon as 10 min after death, but there are factors that may delay this invasion. Invasion can be delayed by wrapping of the corpse or submersion in water. Adverse climatic factors such as cloud cover,...

Drosophila Melanogaster As A Genetic Model

Over the past 100 years, geneticists have built a large toolbox of specialized methods that allow them to manipulate the genome of D. melanogaster with more deftness than is possible with any other organism. These methods have largely taken advantage of some of Drosophilas inherent characteristics, such as the lack of recombination in males. Some widely used techniques include polytene chromosome visualization and in situ hybridization, using balancers and other cytological aberrations for...

Oldfielda Species

FIGURE 3 A graphic scene of firefly emissions, with alphanumeric coordinates to index text discussion. The diagram illustrates flash patterns, response flashes, a warning flash (3N), an attack flash (7E), illumination flashes, a flash pattern default (9D), some (probably ) meaningless flashes of stressed fireflies (6J, 7N, 9F), and a Photuris larval glow (8L-10L). given location. In Fig. 3 several examples are illustrated. A male Photinus macdermotti flies from 2E to 7E, repeating his two-flash...

Subphylum Trilobitomorpha

Trilobites probably played a crucial role in the evolution of living arthropods. Members of the now extinct subphylum Trilobitomorpha began roaming primeval seas in the Precambrian, reached their zenith in the late Cambrian with 4000-10,000 species, and then slowly went extinct around 230 to 275 mya. They were flattened, bilaterally symmetrical arthropods with bodies divided by longitudinal and transverse grooves unlike living arthropods (Fig. 1). Most adults were 2 to 7 cm in length, but...

Adult Behavior

Males usually begin emergence and peak in numbers a few days ahead of females. Both are sexually mature upon eclosion, and males of nearly all moths are attracted by chemical signals (pheromones) emitted by calling females. Hence, in most Lepidoptera mating takes place soon after female eclosion, and she has mature eggs ready to be fertilized and deposited within the first 24 h. Mate-seeking involves primarily visual cues in most butterflies, although there may be short-range pheromones...

Examples Of Prognathous Head Insects

Insect Morphology

The head is a controversial area for anatomical nomenclature, but it provides some of the best examples of evolutionary trends in anatomy. Most insect morphologists believe that the head of modern insects represents the fusion of several segments that were present in an ancestral condition. However, the number of segments included in the ground plan of the insect head has been a contentious issue among morphologists for more than a century. Any argument that attempts to explain head...

Larva

The term larva is currently used for all immatures that are not eggs, pupae, or adults. When larva is used in this comprehensive sense, the subcategories include exopterygote larva (for Hemimetabola, which have the wingpads developing externally) and endopterygote larva (for Holometabola, which have the wings developing internally as histoblasts in the larva, becoming external wingpads in the pupal stage). Larvae occur in a great diversity of sizes, shapes, and colors. Colorful ones almost...

Mosquito Vector

Ae. aegypti is uniquely adapted to a close association with humans and efficient transmission of dengue virus. Immature forms develop primarily in man-made containers. Highly anthropophilic adult females rest inside houses where they feed on human blood. Unlike most other mosquito species, which engage in a feeding duality of plant carbohydrates for synthesis of nutrient reserves and blood for egg development, female Ae. aegypti forego sugar meals and feed almost exclusively and frequently on...

Why Insects Have Discrete Meals

Although casual observation may give the impression that insects feed nonstop, many insects eat in discrete meals separated by periods of nonfeeding (Figs. 1A and 1B). This is most extreme in species that feed on vertebrate blood larval Rhodnius prolixus take a single meal in each developmental stage, and adult female mosquitoes usually have a single blood meal associated with each vitellogenic cycle. Nectar-feeding insects and phytophagous insects also feed in discrete meals, but the degree to...

Heteroptera True Bugs

Family Belostomatidae (Giant Water Bugs) A giant water bug, Lethocerus indicus, is widely eaten in Southeast Asia and is especially popular in Thailand, where it is known as ma-lang-da-na. The bugs are 5 to 8 cm in length and fierce predators on frogs, large insects, and small fish. They are caught using nets or at lights, to which they are attracted. There are many methods of preparation, including roasting, frying, steaming, and grilling. After cooking they may be pounded and used for...

Aphid Complex

Over many decades, studies of hyperparasitism have been conducted on the primary parasitoid microwasps in the Hymenoptera that attack the Hemiptera in the suborder Sternorrhyncha, and in particular the superfamily Aphidoidea, with special emphasis on the family Aphididae. The aphid-primary parasitoid-hyperparasitoid food web has been used as a model system in community ecology partly because of the economic importance of aphids as worldwide pests on a variety of agricultural crops and forests,...

Anatomy Of Emission

The ultrastructure of the flashing lantern was first seen in the 1960s, when the electron microscope revealed that a miniature and new type of structure, the tracheal end organ, occurred throughout the flashing lantern, and that each microunit was obviously involved in controlling the photocytes associated with it. The light-emitting layer of a flashing lantern is organized into a sheet of rosettes, each with a central channel (cylinder), through which air-supply tubes and nerve trunks pass,...

Family Tettigarctidae

The family Tettigarctidae includes the other two extant species, Tettigarcta crinita and T. tomentosa, both found only in Australia. This family also includes 13 genera known from Cenozoic fossils. The Tettigarctidae differ from other cicadas in several features. Most notable is the presence of tymbals in both sexes, but instead of producing airborne songs, they create low-level vibrations of the substrate below the adult. These substrate vibrations are detected by sensory empodia between the...

Midgut Secretory Mechanisms

Insects are continuous (e.g., Lepidoptera and Diptera larvae) or discontinuous (e.g., predators and hematophagous insects) feeders. Synthesis and secretion of digestive enzymes in continuous feeders seem to be constitutive that is, these functions occur continuously, whereas in discontinuous feeders they are regulated. It is widely believed (without clear evidence) that putative endocrine cells (Fig. 3I) occurring in the midgut could, like similar cells in vertebrates, play a role in regulating...

Biological Control Through Augmentation

Pros and Cons of Augmenting Natural Enemies Entomologists and farmers, working together, have developed methods to rear some species of predators and parasitoids that attack pest insects. This approach of deliberately rearing natural enemies and releasing them against target pests has been applied against insects and mites of both greenhouse and outdoor crops. The use of this practice in greenhouse-grown tomatoes was begun in the 1920s with the rearing by English growers of Encarsia formosa, a...

Art Language And Literature

Art draws its inspiration from the environment of the artist. It is therefore not surprising that insects have pervaded all forms and aspects of art. Images of insects are found as adornment on all types of objects from textiles and pottery to weapons and jewelry and even the tattoos on human bodies. Insects are also found, either as the primary subjects or merely as curious elements of lesser status, throughout all types of paintings. Like the illustration of other animals, insect illustration...

D

FIGURE 7 Paper model of right wing of Cantharis sp. arranged to demonstrate wing folding. Cross-hatched areas face ventrally in fully folded wing. In the extended wing (A) the principal veins radius (R) and cubitus (C) are apart by muscular action from the wing base. When this action ceases, the wing apex automatically folds (B, C) until wing is fully folded (D). From Hammond, P. M. (1979). Wing-folding mechanisms of beetles, with special reference to investigations of adephagan phylogeny. In...