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Insect Bio Final
| Question | Answer |
|---|---|
| Sociality | Degree to which individuals in a population associate, Most insects are solitary but many form cooperative societies, Different degrees of sociality observed through recognized behaviors. |
| Degrees of Sociality | includes solitary behavior, subsocial behavior, and eusociality |
| Solitary Behavior | Majority of insects are solitary, Interactions limited to competition and copulation. |
| Subsocial Behavior | Protect or feed their own offspring, Leave before offspring become adults. |
| Eusociality | Highest degree of social organization, Pheromones used in communication and kin recognition, Three defining traits: Cooperative care of young, Overlapping generations in the same colony, Division of labor between castes. |
| Highly Eusocial | Distinguishably different castes: caste polyethism. |
| Social Hymenoptera | Social behavior in this order is by adult females, Holometabolous insects, larvae rarely contribute to colony welfare, collectively regarded as a superorganism. |
| Which Bees Are The Most Social | About 1000 species of Apoid bees are eusocial, Most highly social: honeybees, Primitively eusocial: bumblebees and sweat bees |
| Apis Mellifera | Best known and most useful social insect is the honeybee, Apis mellifera. Possibly studied more than any other insect. As a result of its influence, apiculture is now one of the most widely practiced agricultural activities in the world |
| Ants: Insects by Numbers | May comprise up to 25% of terrestrial animal biomass, Exclusively eusocial, Thought to be millions of ants for every one person on earth. |
| Superorganism Concept | Individual functions as part of a colony, exhibiting attributes of an organism. Basic units are not cells and tissues but closely cooperating individuals. Environmental success is a result of cooperative group behavior. |
| Evolution of Eusociality | Eusocial colonies have a solitary common ancestor. Over time, eusocial characteristics evolved to facilitate groups. Physiological and morphological changes accompanied these behavioral changes. |
| Anti-mating cue/signal | Chemical signal (cuticular profile changes) in mated females that prevents additional mating attempts by other males. |
| Dominance signal | Signal of ovarian activity used in facultatively eusocial groups where the female with the strongest signal becomes dominant/most fertile; others disperse or help. |
| Queen signal | Honest signal of ovarian activity in eusocial colonies that maintains the queen's reproductive monopoly while other females become non-reproductive workers. |
| Critical Transition | subsocial to eusocial involved transition to non-reproductive castes. Sterile individuals are altruistic, sacrificing their reproductive ability to benefit the colony. Selection acts on inclusive fitness. |
| Division of Labor | Parallels function of cells and organs in the entire organism. Each species adapted social organization to life history. Colony size: important attribute of evolution of behavior and division of labor. Caste systems are dependent on it |
| Drones (Hymenoptera): | Males considered a sexual form but not a caste. Winged with fully developed thorax and compound eyes. Fed by the workers, do no work. Haploid: single set of chromosomes. They mate and then die. |
| Queen (Hymenoptera): | Functional reproductive female. Larger than workers with longer abdomen. Emits pheromones to prevent production of another queen. Spermatheca is capable of storing sperm for her entire life. |
| Workers (Hymenoptera): | Sterile females with no ovarioles, wings or flight muscles. Most numerous members of a colony. Ant workers divided into subcastes based on size |
| Temporal Castes | individuals perform different roles or tasks at different stages of their life, rather than having distinct physical castes. Loose correlation means plasticity: workers revert tasks based on colony need (temporal caste). |
| Hamilton's Rule Formula: | — rB > C — William Hamilton developed genetic model to show altruistic allele could increase in frequency if condition satisfied — r = relationship coefficient of relatedness between actor and recipient — B = benefit to recipient — C = cost to actor |
| Hamilton’s Rule General Idea: | Genes increase in frequency when: genetic relatedness of recipient × benefit to recipient > cost to actor. An altruistic behavior (one that helps another at a cost to oneself) can evolve if the genetic gain from helping relatives outweighs the cost. |
| Two Mechanisms for Kin Selection: | Insects recognize relatives through chemical, visual, or auditory cues + Relatives tend to remain close because of limited dispersal and dense population structures. Even without active recognition, they interact more with kin. |
| Kin Selection (Genetic Relatedness): | an evolutionary process where behaviors boost inclusive fitness by helping relatives reproduce, with benefits weighted by the coefficient of relatedness (e.g., sons and daughters share 50% of a mother’s genes; sisters about 75%). |
| Kin Selection (Haplodiploidy): | A system in which haplodiploidy (females come from fertilized eggs, males come from unfertilized eggs) increases relatedness among sisters, facilitating altruistic behaviors that enhance inclusive fitness. Females are diploid and males are haploid. |
| Relatedness: | led to the mistaken belief that kin selection requires very high relatedness. Hamilton’s rule is just a mathematical equation: altruism evolves even with modest relatedness if costs are low and benefits high. Ecological factors must be considered. |
| Evidence Supporting Hamilton’s Rules | eusocial insects (workers are sterile but help raise sisters), helpers assist relatives in raising young, altruistic acts increase inclusive fitness, kin recognition (animals preferentially help relatives). |
| Evidence Against Hamilton’s Rules (Better Choice): | not all altruism involves high relatedness—some targets non-relatives (reciprocal altruism, mutualism). Low-cost helping can evolve with moderate r, and ecological factors like population structure, dispersal, and environment also affect altruism. |
| Dispersal: | Movement of individuals from one place to another. Enables access of resources over greater geographic range to reduce competition. Escape from predation and unfavorable conditions. |
| Passive dispersal | assistance from external sources or human-made structures |
| Active dispersal | move from one location to another without assistance |
| Passive Dispersal Benefits | Beneficial for insects to move long distances with little effort. If occurs during immature stage, increases window of opportunity for dispersal |
| Passive Dispersal Limitations | Little control over destination and survivability. Balance with high reproductive rates |
| Wind Dispersal (Ballooning): | Adaptations to capture wind currents such as long hairs or silken threads. Leave egg mass, climb to the end of the branch or shoot and drop down on a silk strand. Wait to be blown by the wind until landing on a suitable host |
| Passive Dispersal (Travel & Facilitation): | Trade and tourism aids spread. Facilitation by humans led to outbreaks of invasive insects into non-native habitats. Invasive species can threaten local ecosystems, biodiversity, and public health |
| Active Dispersal Benefits | Normal mode for most insects. Increases probability of finding a suitable habitat because movement not by chance |
| Adaptation for Locomotion | Requires efficient locomotory appendages and energy, specialized sensory and neuromuscular systems |
| Migration | Dispersal and migration both involve movement from one area to another. Insects can move incredible distances, thousands of miles. Migration is considered specialized behavior which differs from an animals' everyday behavior |
| What is Migration? | Extended movement to find new habitat is common, but not considered migration. Ranging will cease once a new habitat patch is discovered. Migration requires a temporary inhibition of stimuli which would normally cause a response (food, mates). |
| Persistent movement (Migration): | Uninterrupted, continuous movement over long distances without stopping. |
| Straight movement (Migration): | Directed travel along a relatively straight path toward a specific destination. |
| Unresponsive to most stimuli (Migration): | Reduced responsiveness to typical environmental cues (e.g., food, predators), distinguishing migration from foraging behavior. |
| Observable pre- and post-migratory behaviors (Migration): | Physiological and behavioral changes — like fat storage or muscle adjustment — that involve reallocating internal resources in preparation for or recovery from migration. |
| Migration Scale | movement of entire populations or large numbers of a single species. Migration can occur across multiple generations: populations returning to the site of origin may not be individuals that initiated the movement. |
| Multigenerational Migration Example (Green Darner Dragonfly): | migratory dragonfly in North America, migration considered adaptive strategy, spreads reproductive effort across multiple, widely separated water bodies. Lowers the risk of predation, competition and drought. |
| First generation (Green Darner): | migratory, emerges between February and May and dies in North |
| Second generation (Green Darner): | emerges in North, migrates South and dies |
| Third generation (Green Darner): | offspring of migratory individuals in fall, is non-migratory and emerges in South in November |
| Migratory Syndrome | anticipatory pre-migratory traits involving resource reallocation from reproduction to fuel and muscle, enabling long-distance movement but reducing adult reproductive capacity. |
| Monarch Butterfly | One of the world's most famous species. Annual migration is a natural wonder, involving 1 – 3 billion individuals and occurs over multiple generations. Moves from S. Canada to overwintering sites in Mexico and California. |
| Monarch Butterfly Migration Triggers and Behavior: | Regular event triggered by photoperiod and temperature not by population density. Allows them to avoid lethal winter conditions and track host plants, milkweed. Milkweed is the only plant that caterpillars feed on but adults feed on many flower nectars. |
| Monarch Butterfly Overwintering | Cluster together, remain largely inactive until spring. Females do not produce eggs before migration, state of reproductive diapause. Become reproductively active before trip back, lay eggs on journey on milkweed plants. |
| Monarch Butterfly Navigation | Genetic memory suggests individuals born with parental memories. Sun-based compass suggests orientation relative to sun as it changes using circadian rhythms. |
| Additional Monarch Butterfly Navigational Mechanisms | May use geographical features and landmarks to guide directionality. Chemical markers left on plants by previous generations. Area of current research to better understand complex navigation. |
| Monarch Conservation Status | Symbol of conservation in America: keystone species. Contrasting evidence that overall population numbers are declining. The major threat is not to overall population size but to migratory success due to habitat destruction. Flagship Species. |
| Keystone Species | A species whose impact on its ecosystem is disproportionately large relative to its abundance. |
| Flagship Species | A charismatic species used to raise public awareness or support for conservation efforts. |
| Habitat Loss | destruction of overwintering sites and reduction of host plants on migratory paths. Reduction of habitat limits ability to respond to environmental changes by shifting location. Use of insecticides, herbicides impacts survival. |
| Climate Change | Factor of migratory success, understanding how climate influences migratory insects is important in conservation and pest management. Large scale movement of some insects can cause considerable damage. |
| Migratory Locust | Example of a pest migratory insect. Generalist herbivores; polyphagous. Preference for crops such as cereals and grasses, can be significant pests of agriculture |
| Migratory Locust Phase Change | Orthoptera species experience developmental changes in response to overcrowding. Competition results in juveniles developing into migratory phenotypes. Phenotypic plasticity: Ability to change morphology and physiology in response to the environment. |
| Locusts & Serotonin | As population density increases, tactile stimulation of legs causes locusts to change phase. Morphological, behavioral, and physiology changes. Serotonin released in response to seeing more locusts, causes aggregation. |
| Swarm Formation | Associated with the end of dry season, onset of fast vegetation growth causes growth of grasshopper population density. Overcrowded conditions cause development into a gregarious (sociable) phase. Deposition of thousands of eggs during swarm outbreaks. |
| Locust Swarms | Large swarms of locusts can spread over hundreds of miles. Influence of climate change on rainfall can cause reoccurring outbreaks in historically dry places. Management is challenging because action must be taken immediately. |
| Locust Control Issues | Pesticide use could make insects unsuitable for consumption. Accumulate through bioaccumulation. When locust outbreaks are treated by spraying, people can not eat them. Problem since edible plants are consumed by the locusts themselves. |
| Odonata | an order of insects that includes dragonflies and damselflies, characterized by large compound eyes, two pairs of long membranous wings, and aquatic larvae. They are known for their agile flight and predatory behaviors. |
| Odonata as Semi-Aquatic Insects | Hemimetabolous insects: These insects have an aquatic immature stage (incomplete metamorphosis). Adults found near bodies of water: Adult dragonflies and damselflies remain in proximity to aquatic habitats |
| Odonata History | an ancient order of Paleopteran insects — alongside mayflies — that dates back roughly 300 million years and is characterized by the inability to fold their wings over the abdomen. They have remained morphologically similar to their early ancestors. |
| Meganeura | Group of extinct insects that resembled present-day Odonata → Iconic “giant dragonfly.” Point of debate: How were insects able to grow so large in the Carboniferous period? Might be attributed to more oxygen in the atmosphere and lack of predators. |
| Odonata As Predators | Adults & immatures are exclusively carnivorous. Adults are extremely effective predators, capturing up to 90% of prey. Nimble flight, excellent vision, and spines on limbs help track and capture prey. |
| To Identify a Predator | Predation is, by definition, a behavior. Interaction where one organism kills and eats another. Predators broadly fall into two categories: pursuit and ambush. |
| Predator Characteristics | Predators eat many insects over the course of their lifetime. Most are generalists and consume a wide variety of prey. Can be predatory in all or some of their life stages. |
| Examples of Predatory Insects | Lady Bugs (Predatory in both larval and adult stages), Lacewings (Only predatory in the larval stage; adults feed on nectar and pollen), and Odonata (Predatory in immature and adult stages, occupying different ecological niches). |
| Predation: Odonate Naiad (Immature Stage): | fully aquatic predators with a specialized labium forming an extendable “grasping arm” that shoots forward to seize prey— inspired the jaw in Alien. This rapid-strike mechanism and prey shifts shape their metabolism and predatory strategy. |
| Foraging | Predator must search and pursue prey and assess the cost-benefit. Cost-benefit determined by morphology of the prey and physiology of the predator. Energy can be expended killing and ingesting it. |
| How does the morphology of the prey and the physiology of the predator affect the attack? | affects how easily it can be detected, captured, and subdued. Simultaneously, the predator’s physiology—muscle power, sensory acuity, strike speed, and metabolic capacity—limits attack speed and force, shaping prey range and hunting efficiency. |
| Pursuit Predation | requires a predator to actively pursue and capture prey. Predators must be faster than prey and be able to maneuver as the prey flees. Morphology of Odonata creates advantage to this type of strategy. |
| Flight: Dragonflies | Agile and strong fliers, can propel in six directions. Special mechanisms in flight to produce speed and lift while conserving energy. Catch prey during flight and carry to a perch to eat |
| Odonata Direct Flight Mechanism | mechanism in which muscles attach directly to the wing base: direct muscles power the downstroke, while indirect dorsoventral muscles lift the wings. Because each wing operates independently, they achieve highly precise, agile, and asynchronous flight. |
| Odonata Vision Basics | rely on compound eyes for primary visual organs, perceiving light with reflected, absorbed, or transmitted wavelengths. The complexity of photoreceptors aligns with their life history, with advanced vision supporting a predatory, fast-flying lifestyle. |
| Insect Visual Structures: Compound Eyes: | compound eyes connect directly to the optic lobes, speeding visual signal transmission—dragonflies dedicate about 80% of their brain to vision. Each eye consists of many ommatidia, capturing a small part of the visual field to form a mosaic images. |
| Ommatidia | Each ommatidium is a lens and photoreceptor converting light into signals; more ommatidia increase motion sensitivity, with dragonflies having ~10,000. Their fixed focal length makes distant objects appear blurry. |
| Mosaic Vision | Each ommatidium sees a small part of the field, and the nervous system integrates them into a full image. Single ommatidia detect movement poorly, but across many, motion is strongly perceived—dragonflies excel with numerous ommatidial boundaries. |
| Note on Ommatidium | Large number of single units; popular media represents insect vision incorrectly. |
| Dragonfly Vision Vs. Human Vision | Vision adapted to movement acuity, different from humans. See much faster, around 200 images per second. Can see 360 degrees. |
| Odonatas as Territorial Hunters | Many species, especially males, are territorial and defend territory against members of the same species. Notice landmarks that confine the boundaries. Signal ownership with coloration. |
| Predator-Prey Interactions | Predation has a selective effect on prey. Prey develops adaptations to avoid predators: Creates an evolutionary arms race. Multiple mechanisms for avoiding predation exist. |
| Anti-Predator Defense | Anti-predator defense refers to evolutionary mechanisms developed to aid prey in the arms race with predators through avoidance. |
| These adaptations have evolved for individual stages of predator interaction: | avoiding detection, prevention of attack, fighting back, and escaping when caught. |
| Phasmatodea: Stick & Leaf Insects (General Characteristics): | Phasmatodea can be relatively large insects. Some phasmids are cylindrical and stick-like, while others are flattened and leaflike. They show anti-predation stages at every stage, making them a good model for studying these behaviors. |
| Avoiding Detection | The first line of defense is to avoid detection by the predator. |
| Camouflage | Camouflage involves materials and colors used to avoid detection. The majority of methods involve crypsis → the ability to conceal itself by blending into the environment. Visual crypsis is camouflage, but it can also be auditory or olfactory. |
| Mimicry & Mimesis | Mimicry and mimesis refer to the resemblance of a living organism to a feature in its surroundings. |
| Plasmatodea Plant Mimesis | Phasmids replicate sticks and leaves, and the bodies of some species are covered in mossy outgrowths. |
| Mimesis Behavioral Adaptations | Behavioral adaptations include a rocking motion that mimics the movement of leaves or twigs. They also maintain a state of motionless posture that can be maintained for long periods. Some species have the ability to change color as surroundings shift. |
| Prevention of Attack (Aposematism): | Aposematism is warning coloration. Prey can advertise that they are not worth eating with bright coloration. They are unprofitable if toxic, have venom, or have spines/structures. |
| Bright Coloration | Typically, bright coloration serves as warnings through honest signaling. The brighter they are, the more toxic they are. Another way to use color is to startle the predator with a flash of colors. |
| Flash of Colors | Some species startle predators by flashing bright colors that are normally hidden. When disturbed, some species drop to the undergrowth and open their wings during free fall to display colors that disappear when the insect lands. |
| Prevention of Attack: Mimicry | In this context, an insect mimics insects of another species that are toxic or other organisms that are dangerous. |
| Batesian Mimicry | In Batesian mimicry, a harmless species evolved to mimic signals of harmful ones. This is dishonest signaling, so it is advantageous to the mimic. If the population is high enough, the mimic can cause disadvantage to the model. |
| Mullerian Mimicry | Some species share honest signals for mutual benefit, displaying coloration that warns predators of toxicity. This occurs in Viceroy and Monarch butterflies, both unpalatable due to compounds from milkweed consumed as caterpillars. |
| Batesian Mimic (Example: Hoverfly): | A harmless organism that displays deceptive coloration or patterns resembling a dangerous species. Hoverflies look like wasps or bees but cannot sting. |
| Müllerian Mimics (Examples: Wasp and Bee): | Harmful species that share honest warning signals — such as yellow-black stripes—reinforcing predator learning. Both the wasp and bee can sting, so their resemblance strengthens predator avoidance. |
| Staying Out of Sight: Nocturnal Insects: | Nocturnal insects are active during the night, exhibiting behavioral crypsis. |
| Prevention of Attack: Predator Satiation: | A strategy for cicadas to avoid predators is to emerge at irregular intervals. Periodical cicadas emerge every 13 and 17 years. |
| Chemical Defense | Insects fight back using chemicals and by ejecting noxious materials. They can have scent glands which produce defensive secretions. Some species have glands that release toxic compounds that harm prey. |
| Bombardier Beetle | Bombardier beetles eject chemical spray from their abdomen. This is produced from a chemical reaction mixing hydroquinone and hydrogen peroxide that are stored separately. This is an exothermic reaction → the energy raises the temperature. |
| Suicidal Altruism | Social insects protect colonies with their lives. Workers can die after stinging to defend the colony, which aims to deter further attack. Social insects also pursue communal attacks as a group. |
| Communal Attack | Communal attack is seen in ants. They release alarm pheromones that recruit others to defend the hive. Ants have one pheromone to swarm and then another for synchronized stinging. |
| Asian Giant Hornet | The Asian giant hornet, the world’s largest hornet, is nicknamed the “Murder Hornet.” First detected in the Pacific Northwest in 2019, it is predatory, feeding on larger and eusocial insects that provide abundant resources in their nests. |
| Japanese Honeybee Defense | When a hornet enters, bees form a tight ball around it, blocking escape and defense. They vibrate their wings to raise the temperature above 100°F and increase CO₂ levels, creating conditions the hornet cannot survive. |
| Anti-Predator Defense: Escaping | Some species are able to escape by sacrificing body parts through autonomy. |
| Mantids (Mantodea): | Mantids are ambush predators sometimes confused with stick insects. |
| Mantids General Characteristics | Mantids have large compound eyes and have stereo vision, which is a component of depth perception. They are generalist predators of arthropods. Their forelegs are modified to grasp prey (raptorial). |
| Raptorial Legs | Raptorial legs show convergent evolution among insect taxa, including ambush bugs, mantisflies, giant water bugs, and water scorpions. The structure varies, but the function is shared among predators. |
| Ambush Predators | Stealth-based hunters that use camouflage and a sit-and-wait strategy to surprise nearby prey, attacking rapidly when prey approaches; typically solitary, opportunistic, and generalist feeders. |
| Crypsis: Camouflage | Mantodea can attack prey without them detecting their presence. There is a trade-off between detectability and mobility. They are usually confined to a single microhabitat. |
| Aggressive Mimicry | Aggressive mimicry uses a harmless model to avoid detection by prey. The model is its own prey or an organism that is beneficial. Potential prey are drawn toward the predator through lures. |
| Fireflies: Visual Cues | Fireflies are bioluminescent and able to control light generation to produce flashes. The communicative function is to attract mates. |
| Fireflies: Aggressive Mimicry: | Photuris is a predatory species that imitates signals of other firefly species. These signals attract the males, who they eat. |
| Camouflage: Lacewing Larvae: | Larvae in various families cover themselves in debris, including lichens, vegetation, and bodies of prey. This avoids detection by predators and prey. |
| Corpse Camouflage: Assassin Bugs: | A form of camouflage in which assassin bugs cover themselves with ant carcasses, likely making their shape unrecognizable or mimicking a cluster of ants; may function as olfactory camouflage as well. |
| Why Corpse Camouflage Might Work and Why Not: | Corpse camouflage may work by breaking up the predator’s outline, mimicking ants, and masking scent with ant odors, but its effectiveness is uncertain due to limited research, its rarity, and potential dependence on specific ecological conditions. |
| Ambush Predators: Behavioral Traits: | Ambush predators are not extremely mobile and are reliant on prey finding them rather than vice versa. They must maximize reward while minimizing effort (no prolonged engagements, must overcome defense and not let go). |
| Neuroptera: | includes lacewings, mantidflies, owlflies, and antlions. Larvae of most families are predators. |
| Antlions: | Predatory larvae dig pits composed of fine grains. These pits act to both conceal themselves and trap insects. They are generalist predators, but ants form a large percentage of their prey. |
| Antlions As Predators: | Antlions are ambush predators: food arrives unpredictably, creating risk for not attaining enough nutrients. Making and maintaining traps is costly. Larvae compensate by having low metabolic rates and can survive for long periods without food. |
| Antlion Pit: | The antlion creaIt digs a pit by moving backward in a spiral, minimizing construction time. The pit deepens as it moves to the center until the slope |
| Antlion Larvae: | When completed, the antlion buries itself at the bottom with jaws exposed. Prey falls into the pit; the steepness makes it collapse with slight disturbance. This guides prey into the larva's mouth. |
| Antlion Mandibles: | The mandibles are modified into hollow projections that inject venom and digestive enzymes, and the liquified prey is consumed. Despite their small size, they can subdue larger prey. |
| Neuroptera: Biocontrol | Green lacewings are the most familiar insect in this group. They are delicate insects but predaceous. They are used as biological control agents to specifically target aphids and mites in gardens. |
| Biological Pest Control | Biological pest control is a method of controlling insects using other organisms. It relies on predation, parasitism, and parasitoidism. It also involves active human management and is an important component of integrated pest management. |
| Hymenoptera: | Females have prominent ovipositors, Eusociality has arisen several times within this group, Divided into two suborders → Symphyta, Apocrita. |
| Apocrita (Wasp Waist): | Hymenopteran group characterized by a narrow petiole forming a “wasp waist,” enabling precise ovipositor maneuvering and encompassing most hymenopteran diversity. |
| Aculeate Hymenoptera (Stinger-bearing Apocrita): | Subgroup of Apocrita in which the ovipositor is modified into a stinger. |
| Schmidt Sting Pain Index: | A scale ranking the pain intensity of stings from various Hymenoptera species. |
| Parasitoid Wasps: | Hymenopterans that lay eggs on or in specific arthropod hosts, whose larvae develop by consuming and ultimately killing the host; they make up the majority of hymenopteran diversity. |
| Parasitoids vs Predators Similarities: | Both predators and parasitoids use animals as their food source. But they do have many key differences. |
| Parasitoid: | An organism whose larvae develop by feeding exclusively on a single arthropod host — internally or externally — and inevitably kill that host during their development. Only one host is needed to complete development. |
| Additional Parasitoid Characteristics: | Parasitoids are host-specific, targeting a particular species or life stage, unlike predators that consume multiple prey. Only females seek hosts, and the host dies only after the parasitoid fully develops, maximizing resource use. |
| Parasitoids vs. Predators Differences | Parasitoids use a single host for larval development, killing it only after growth is complete, whereas predators consume multiple prey throughout their lives, killing each quickly rather than relying on it for extended development. |
| Evolution of Parasitoids | Parasitoidism originated within Holometabola, with only one symphytan family (Orussidae) showing this lifestyle, while all other parasitic Apocrita form a single monophyletic lineage derived from a shared ancestor. |
| Evolutionary Origin: Wood Wasps: | Parasitoidism in Orussidae likely evolved from wood-feeding ancestors using fungal symbionts. Some lost their fungi, relied on fungi from other insects, and larvae gradually killed these insects, shifting to insect-feeding. |
| Life History of Parasitoid Wasps: | Most hymenopterans are parasitoids, laying eggs on or inside a host, with larval development ultimately killing the host to complete their life cycle. |
| Parasitoids vs. Parasites Types: | Parasitoids differ from true parasites in that they invariably kill their host, whereas parasites generally do not. They are classified into two main types: endoparasitoids, which develop inside the host, and ectoparasitoids, which develop externally. |
| Endoparasitoids: | Parasitoid wasps that lay eggs inside a host, allowing the host to continue growing while larvae feed internally. They are usually highly host-specific, and this strategy maximizes resources by letting the host develop during larval growth. |
| Ectoparasitoids: | Parasitoid wasps that lay eggs on the exterior of a paralyzed host, which does not grow. Larvae feed externally, are generally less host-specific than endoparasitoids, and targets are often concealed in burrows, nests, or other protected locations. |
| Adaptations of Parasitoid Wasps | Parasitoid wasps have several adaptations based on the prey they prefer like oviposters, venom, and paralysis. |
| Ovipositors: | Tube-like structures used by parasitoid wasps to lay eggs on or inside hosts. They can be extremely long to access hidden hosts, deliver eggs precisely, and overcome host defenses, which may include behavioral, physiological, or morphological responses. |
| Polyembryony: | A reproductive strategy in some parasitoid wasps where a single egg produces multiple genetically identical larvae. These larvae feed on the host’s tissues, allowing the wasp to maximize offspring from a single oviposition. |
| Parasitoid Wasps in Biocontrol: | Parasitoid wasps are valuable biological control agents because they target specific pest species and self-regulate as pest numbers decline. They are being explored to manage pests like the spotted lanternfly and brown marmorated stink bug. |
| Samurai Wasp (Trissolcus japonicus): | A parasitoid wasp that targets brown marmorated stink bugs by laying eggs inside their eggs. The developing larvae consume and kill the stink bug embryos, with one adult wasp emerging per host egg. |
| Polydnavirus: | A virus mutualistic with parasitoid wasps replicates in female oviducts and suppresses the host’s immune system to protect larvae. Integrated into the wasp genome, it acts as a biological weapon. |
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