Hippodamia glacialis, a predator the aphids. Photo: J.Ogrodnick


summary varieties of Natural adversaries Habitat of Natural opponents Index sources

Insect Biology and also Ecology: A inside wall

For the reader who is unfamiliar through the biologic or ecology that insects, this inside wall will provide needed lift information.

You are watching: What biological characteristics have contributed to the success of insects?

This segment is comprised of numerous paragraphs of general insect information and also five subsections:

Insects are the leading life-form on earth. Millions might exist in a single acre that land. About one million types have been described, and also there might be as plenty of as ten time that countless yet to it is in identified. Of all creatures on earth, insects are the key consumers of plants. They also play a significant role in the breakdown of plant and animal material and constitute a significant food source for countless other animals. Insects space extraordinarily adaptable creatures, having developed to live efficiently in most environments on earth, including deserts and the Antarctic. The only location where insects are not typically found is the oceans. If they are not physically equipped to live in a stressful environment, insects have embraced behaviors to prevent such stresses. Insects own an remarkable diversity in size, form, and behavior. that is believed that insects space so successful since they have actually a protective shell or exoskeleton, they room small, and also they have the right to fly. Their small size and ability to fly patent escape indigenous enemies and also dispersal to brand-new environments. Since they are tiny they call for only tiny amounts of food and also can exist in very small niches or spaces. In addition, insects have the right to produce huge numbers the offspring relatively quickly. Insect populations also possess significant genetic diversity and also a good potential because that adaptation to different or changing environments. This renders them specifically formidable insect of crops, maybe to adapt to new plant ranges as they are arisen or rapidly becoming resistant come insecticides. Insects room directly helpful to people by developing honey, silk, wax, and also other products. Indirectly, lock are vital as pollinators that crops, natural opponents of pests, scavengers, and also food for other creatures. At the very same time, insects are significant pests of humans and domesticated animals because they damage crops and vector diseases. In reality, much less than one percent the insect species are pests, and also only a few hundred of these are continuously a problem. In the paper definition of agriculture, pest is a pest if its existence or damages results in an economically important loss. The adage "know her enemy" is especially suitable when it pertains to insect pests. The an ext we know about their biology and also behavior, consisting of their natural enemies, the much more likely us will be able to manage castle effectively.

Insect Anatomy Insects and closely associated organisms have a lightweight, but strong exterior skeleton (exoskeleton) or integument. Their muscles and organs are on the inside. This multi-layered exoskeleton protects the insect from the environment and also natural enemies. The exoskeleton likewise has countless sense organs because that detecting light, pressure, sound, temperature, wind, and odor. Feeling organs might be located almost anywhere on the insect body, not just on the head. Insects have three human body regions: head, thorax, and also abdomen. The head features mainly because that food and sensory intake and also information processing. Insect mouthparts have progressed for chewing (beetles, caterpillars), piercing-sucking (aphids, bugs), sponging (flies), siphoning (moths), rasping-sucking (thrips), cutting-sponging (biting flies), and chewing-lapping (wasps). The thorax gives structural support for the foot (three pairs) and, if present, because that one or 2 pairs that wings. The legs might be adapted for running, grasping, digging, or swimming. The abdomen attributes in digestion and reproduction. The internal anatomy that insects is characterized by an open circulatory system, a multitude of breathing tubes, and also a three-chambered cradle system. V the exemption of a heart and an aorta, over there are few blood vessels; insect blood just flows about inside the human body cavity. Air enters the insect with a few openings (spiracles) in the exoskeleton, and makes its means to all locations of need by method of branching tubes, which pass through the body. The insect digestive system is long and also tube-like, often separated into three sections, each through a different function. The insect nervous system transports and processes info received indigenous the feeling organs (sight, smell, taste, hearing, and touch). The brain, located in the head, processes information, however some details is also processed in ~ nerve centers somewhere else in the body. Knowledge about the framework and role of the insect exoskeleton has proven an important in occurring insecticide formulations that are able to pass through this multi-layered protective covering. Researches of insect communication have resulted in the exploration of chemical compounds used by insects to situate each other or host plants, and also many that these have now been identified and produced synthetically. For example, pheromones are very certain compounds exit by insects to lure others that the exact same species, such together for mating. Synthetic pheromones are currently widely used to bait insect traps because that detecting the presence of a pest, to recognize its abundance, or for control. Control may indicate the usage of numerous traps to "trap out" the pest or the pheromones can be dispersed throughout the chop to "confuse" insects, making that more daunting for lock to find a mate. As simple as it may seem, discovering what form of mouthparts an insect has can be really important in deciding top top a management tactic. Because that example, insects with chewing mouthparts can be selectively regulated by part insecticides that are used directly to plant surfaces and are only effective if ingested; call alone will not an outcome in fatality of the insect. Consequently, natural opponents that feeding on various other insects, yet not the chop plant, will not it is in harmed. due to the fact that insects obtain oxygen with their spiracles, plugging these openings reasons death. That is exactly how insecticidal oils regulate insects. Materials of the microbial insecticide Bacillus thuringiensis get in the digestive system and failure the gut lining. Expertise of the nervous device of insects has led come the advancement of several species of insecticides designed to disrupt regular nerve function. Some of these are efficient simply by contacting the insect.

Insect Reproduction Most species of insects have actually males and also females that mate and also reproduce sexually. In part cases, males space rare or existing only at certain times of the year. In the absence of males, females of some types may still reproduce. This is common, an especially among aphids. In many types of wasps, unfertilized eggs become males while fertilized eggs become females. In a couple of species, females develop only females. A solitary embryo commonly develops within each egg, except in the case of polyembryony, where numerous embryos may construct per egg. Insects might reproduce by laying egg or, in part species, the eggs might hatch in ~ the mrs which soon thereafter store young. In one more strategy typical to aphids, the eggs hatch in ~ the female and the immatures continue to be within the female for part time before birth.

Insect development and advancement (Metamorphosis)

Insects generally pass v four distinct life stages: egg, larva or nymph, pupa, and also adult. Eggs space laid singly or in masses, in or ~ above plant organization or another insect. The embryo in ~ the egg develops, and eventually a larva or nymph increase from the egg. There are generally several larval or nymphal stages (instars), each significantly larger and also requiring a molt, or melted of the outer skin, between each stage. Most weight gain (sometimes > 90%) occurs during the last one or 2 instars. In general, neither eggs, pupae, nor adults prosper in size; all expansion occurs during the larval or nymphal stages.

complete Metamorphisis : Life cycle of the convergent lady bug

The two species of metamorphosis typical of insect pests and natural adversaries are gradual (egg > nymph > adult) and also complete (egg > larva > pupa > adult). In steady metamorphosis, the nymphal stages resemble the adult except that they absence wings and the nymphs may be colored in different way than the adults. Nymphs and adults usually occupy comparable habitats and also have similar hosts. Gradual metamorphosis is typical of true bugs and grasshoppers; finish metamorphosis is common of beetles, flies, moths, and also wasps. The immatures of this latter varieties do no resemble the adults, might occupy different habitats, and feed on different hosts. Some moth and wasp larvae weave a silken covering (cocoon) to protect the pupal stage; in flies, the last larval skin i do not care a puparium the protects the pupal stage.

gradual Metamorphisis : Life bicycle of the insidious flower bug

Insects are cold-blooded, so the the rate at i m sorry they construct is mainly dependent ~ above the temperature of their environment. Cooler temperatures result in slowed growth; greater temperatures speed up the growth process. If a season is hot, an ext generations may happen than throughout a cool season. A much better understanding of exactly how insects grow and also develop has contributed greatly to their management. For example, expertise of the hormonal regulate of insect metamorphosis resulted in the breakthrough of a new class that insecticides dubbed insect expansion regulators (IGR). The insect growth regulators are very selective in the insects lock affect. Based on information around insect expansion rates family member to temperature, computer models deserve to be provided to predict once insects will be most abundant during the farming season and, consequently, when crops are most at risk.

Insect Classification and also Identification the is essential to classify insects so that we have the right to organize what us know about them and also determine their relationship with various other insects. Because that example, all members that a particular varieties will feeding on comparable foods, have comparable developmental characteristics, and exist in similar environments. Many often, insect species are classified based on similarities in figure (morphology). The flies, because that example, deserve to be distinguished and classified individually from all various other winged insects due to the fact that they have only one pair of wings. The power structure used come classify the diamondback moth, a global pest of crucifers, is as complies with

Phylum - Arthropoda Class - Insecta Order - Lepidoptera Family - Plutellidae Genus - Plutella species - Plutella xylostella

This universal technique is provided to protect against confusion among geographic regions of the world. Consequently, Plutella xylostella describes the very same insect types in the United states as the does in Asia or everywhere else in the world. Usual names, however, can vary indigenous one ar to another.

Insect Ecology Ecology is the study of the interrelationships in between organisms and also their environment. One insect"s environment may be defined by physical determinants such as temperature, wind, humidity, light, and also biological factors such as various other members the the species, food sources, organic enemies, and also competitors (organisms using the same room or food source). An expertise or at least an evaluation of this physical and also biological (ecological) factors and how castle relate to insect diversity, task (timing that insect illustration or phenology), and abundance is vital for successful pest management. part insect types have a single generation every season (univoltine), while others may have several (multivoltine). The stripe cucumber beetle, because that example, overwinters together an adult, emerges in the spring, and also lays eggs close to the root of young cucurbit plants. The egg hatch, developing larvae that arise as adults later in the summer. These adults overwinter to begin the bicycle again the next year. In contrast, egg parasitoids like Trichogramma overwinter as immatures in ~ the egg of your host. Throughout the summer castle may have several generations. Insects it is adapted to many types of environmental problems during your seasonal cycle. To survive the harsh winters, cucumber beetles enter a dormant state. If in this dormant state, metabolic activity is minimal and no reproduction or expansion occurs. Dormancy can also occur at various other times of the year when conditions may be stressful for the insect. that is often better to take into consideration insects as populations rather 보다 individuals, particularly within the paper definition of one agroecosystem. Populations have features such as thickness (number every unit area), age circulation (proportion in each life stage), and birth and death rates. Expertise the attributes of a pest populace is crucial for an excellent management. Knowing the age circulation of a pest population may show the potential for crop damage. For example, if most of the strip cucumber beetles are immatures, direct damages to the over ground portions of the plant is unlikely. Similarly, if the thickness of a insect is known and can be concerned the potential because that damage, an action may be compelled to protect the crop. Information around death rates due to natural enemies can be very important. Natural opponents do nothing but reduce pest populations and understanding and also quantifying their impact is important to effective pest management. This is every the much more reason to conserve your numbers.

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Taken from: Hoffmann, M.P. And Frodsham, A.C. (1993) Natural enemies of vegetable Insect Pests. Cooperative Extension, Cornell University, Ithaca, NY. 63 pp.


Cotesia congregata, a parasitoid of caterpillars. Photo: K.Kester


The larvae that Sphenoptera jugoslavica feeding on the root of the plant pest diffuse knapweed. Photo: R.Richard