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Aquatic insect
Aquatic insect
Aquatic insect
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A water beetle
A whirligig beetle

Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.

Breathing

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Aquatic insects must get oxygen while they are under water. Almost all animals require a source of oxygen to live. Insects draw air into their bodies through spiracles, holes found along the sides of the abdomen. These spiracles are connected to tracheal tubes where oxygen can be absorbed. All aquatic insects have become adapted to their environment with the specialization of these structures, enabling:

  1. Simple diffusion over a relatively thin integument
  2. Temporary use of an air bubble
  3. Extraction of oxygen from water using a plastron or blood gill
  4. Storage of oxygen in hemoglobin and hemocyanin molecules in hemolymph[1][2]
  5. Taking oxygen from surface via breathing tubes (siphons)

The nymphs of the hemimetabolous orders mayflies, dragonflies and stoneflies, and the larvae of the holometabolous orders megalopterans and caddisflies, possess tracheal gills, which are outgrowths of the body wall containing a dense network of tracheae covered by a thin cuticle through which oxygen in the water can diffuse. [3][4][5]

Some insects have densely packed hairs (setae) around the spiracles that allow air to remain near, while keeping water away from, the body. The trachea open through spiracles into this air film, allowing access to oxygen. In many such cases, when the insect dives into the water, it carries a layer of air over parts of its surface, and breathes using this trapped air bubble until it is depleted, then returns to the surface to repeat the process. Other types of insects have a plastron or physical gill that can be various combinations of hairs, scales, and undulations projecting from the cuticle, which hold a thin layer of air along the outer surface of the body. In these insects, the volume of the film is small enough, and their respiration slow enough, that diffusion from the surrounding water is enough to replenish the oxygen in the pocket of air as fast as it is used. The large proportion of nitrogen in the air dissolves in water slowly and maintains the gas volume, supporting oxygen diffusion. Insects of this type only rarely need to replenish their supply of air.[6]

Other aquatic insects can remain under water for long periods due to high concentrations of hemoglobin in their hemolymph circulating freely within their body. Hemoglobin bonds strongly to oxygen molecules. [7]

A few insects such as water scorpions and mosquito larvae have breathing tubes ("siphons") with the opening surrounded by hydrofuge hairs, allowing them to breathe without having to leave the water.

Locomotion

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Aquatic insects use different methods of locomotion in water.

Orders with aquatic or semiaquatic species

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EPT insects, an acronym for Ephemeroptera, Plecoptera and Trichoptera (mayflies, stoneflies and caddisflies), are sensitive to pollutants and are used as an indicator of water quality in streams, rivers and lakes.[8]

Marine aquatic insects

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Aquatic insects live mostly in freshwater habitats, and there are very few marine insect species.[9] The only true examples of pelagic insects are the sea skaters, which belongs to the order Hemiptera, and there are a few types of insects that live in the intertidal zone, including larvae of caddisflies from the family Chathamiidae,[10] the hemipteran Aepophilus bonnairei,[11] and a few other taxa.

References

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Aquatic insect

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Aquatic insects are a diverse group of that spend at least one life stage, typically the larval or nymphal stage, in freshwater environments such as , rivers, lakes, , and wetlands, while most are terrestrial and winged. They exhibit complex life cycles involving , larval/nymphal, pupal (in some orders), and stages, with the immature stages often showing specialized aquatic adaptations like gills or breathing tubes for respiration. Globally, aquatic insects comprise approximately 10% of all described species, totaling around 100,000 species across more than a dozen insect orders. The major orders include Ephemeroptera (mayflies), (dragonflies and damselflies), (stoneflies), Trichoptera (caddisflies), (true bugs), Coleoptera (beetles), and Diptera (true flies), each with unique morphological and behavioral traits suited to aquatic life. In alone, over 8,600 species are associated with freshwater habitats during part of their lives. These have evolved remarkable adaptations to thrive in varied aquatic conditions, including oar-like legs for , silken cases for (as in ), and predatory mouthparts in groups like nymphs. They inhabit a wide range of aquatic ecosystems, from fast-flowing riffles to stagnant pools, and demonstrate resilience across disturbance gradients, from stable springs to dynamic flood-prone rivers. Aquatic insects play crucial ecological roles as primary consumers, predators, and decomposers, facilitating nutrient cycling and serving as a vital food source for , birds, amphibians, and other . Their sensitivity to environmental changes makes them excellent bioindicators of , with diverse assemblages signaling healthy ecosystems and reduced diversity often indicating or degradation. Some , such as certain mosquitoes in the order Diptera, can also act as vectors for diseases affecting humans and animals.

Definition and Characteristics

Definition

Aquatic insects are defined as those insects that complete at least one life stage—primarily the immature larval or nymphal stages—in aquatic environments, while adults are often terrestrial and emerge from the water to reproduce or disperse. They represent approximately 10% of the roughly one million described insect species, totaling around 100,000 species, and dominate as macroinvertebrates in freshwater habitats, playing key ecological roles in nutrient cycling and food webs. These insects are secondarily aquatic, having evolved from terrestrial ancestors, and typically require both aquatic and terrestrial phases to complete their life cycles. This definition distinguishes aquatic insects from fully terrestrial species, which spend their entire life cycles on land without any submerged developmental stages. It also sets them apart from amphibious or semiaquatic forms, such as certain , which primarily exploit surfaces or margins for feeding and oviposition but do not complete a fully submerged life stage, instead visiting only briefly without true immersion. The systematic recognition of aquatic insects emerged in early entomology during the 18th century, notably through the efforts of Carl Linnaeus, who classified numerous species with aquatic immatures in his Systema Naturae (1758), integrating observations of their life histories into broader insect taxonomy.

Morphological Characteristics

Aquatic insects exhibit a range of morphological adaptations that facilitate their survival in water, primarily through modifications to body shape, integument, and appendages. Many species possess streamlined bodies to minimize hydrodynamic drag, such as the flattened, dorsoventrally compressed forms seen in heptageniid mayfly nymphs and perlid stonefly nymphs, which allow efficient navigation in fast-flowing currents. Hydrophobic hairs or setae cover the exoskeleton in surface-dwelling taxa like water striders (Gerridae) and whirligig beetles (Gyrinidae), enabling buoyancy and the retention of air films for movement across water surfaces. Respiratory structures are prominent morphological features, with gills serving as key adaptations for oxygen uptake. Tracheal gills, thin outgrowths of the body wall richly supplied with tracheae, are common in larval stages; for instance, (Ephemeroptera) nymphs often bear plate-like or feather-like abdominal gills that enhance gas exchange when briefly referenced in respiratory contexts. Stonefly () nymphs typically feature tuft-like or hair-like gills on the or behind the head, such as the feathery extensions at the leg bases in many species, which support in well-oxygenated streams. () nymphs possess internal gills within a rectal chamber at the abdomen's end, forming a branchial basket that functions in both respiration and . Appendages are modified for aquatic locomotion and attachment, including flattened legs for swimming in mayflies like Heptageniidae, where lateral projections reduce drag, and hooked or sucker-like tarsi in stoneflies for clinging to substrates in turbulent flows. Some Coleoptera, such as elmid riffle beetles, develop plastron structures—dense fields of rigid, hydrophobic setae that trap a stable air layer against the body, acting as a physical for prolonged submersion. These variations across orders reflect evolutionary responses to diverse aquatic pressures, with body segmentation often retaining the typical tripartite form (head, , ) but adapted for hydrophobicity and streamlining.

Physiological Adaptations

Respiratory Mechanisms

Aquatic have evolved diverse respiratory strategies to extract oxygen from aquatic environments, where dissolved oxygen levels are typically much lower than in air, often ranging from 5 to 10 mg/L compared to approximately 300 mg/L in air. These mechanisms rely primarily on across thin respiratory surfaces, supplemented by active ventilation in some species, allowing them to meet metabolic demands despite hypoxic conditions. Unlike terrestrial that use open tracheal systems connected to spiracles, many aquatic forms have adapted closed or modified systems to prevent entry while facilitating . Cutaneous respiration, or skin breathing, occurs through diffusion across the thin, permeable cuticle in insects with closed tracheal systems lacking spiracles, such as certain diving beetle larvae (Coleoptera: Dytiscidae). from the surrounding diffuses directly into the and then into internal tracheae, driven by concentration gradients, while diffuses outward; this method is efficient in well-oxygenated waters but limits activity in low-oxygen conditions. Gill-based respiration involves external or internal , such as the filamentous tracheal gills on the of caddisfly larvae (Trichoptera), where oxygen diffuses across the gill surface into densely tracheated tissues. These are often ventilated by rhythmic undulations of the , which generate currents to maintain diffusion gradients and enhance oxygen uptake. Tracheal gills, found in groups like damselfly nymphs (Odonata: Zygoptera), consist of leaf-like appendages with a thin overlying a network of tracheae, enabling direct of dissolved oxygen from into the tracheal system. These tracheal gills are modifications of the tracheal system derived from terrestrial ancestors, and their retention, along with spiracles as terrestrial atavisms, provides evidence that aquatic larvae in orders such as Odonata, Ephemeroptera, and Plecoptera represent a secondary return to aquatic environments after the initial colonization of land by insects. Plastron respiration utilizes a stable air layer trapped by hydrophobic hairs on the body surface, functioning as a physical gill in insects like (Coleoptera: Hydrophilidae) and some hemipterans; oxygen diffuses from the into this air film and then into the tracheae, while escapes, without needing frequent replenishment. This mechanism is particularly effective in moderately hypoxic waters, as the plastron maintains a constant gas volume governed by and hair structure. In low-oxygen environments, aquatic insects employ behavioral adaptations such as periodic surfacing to renew air stores in bubble-breathing species or enhanced gill ventilation through abdominal pumping, as seen in nymphs (Ephemeroptera). Some species, notably larvae (Diptera: ), possess hemoglobin-like proteins in their with exceptionally high oxygen affinity, allowing storage and release of oxygen to sustain during prolonged exposure to anoxic sediments. These respiratory controls not only enable survival but also influence thermal tolerance and vulnerability to environmental stressors.

Osmoregulation and Buoyancy

Aquatic insects, primarily inhabiting freshwater environments where they are hyperosmotic to the surrounding medium, actively regulate their internal and to counteract passive influx of water and loss of salts across their permeable . The Malpighian tubules, slender excretory organs branching from the , play a central role in this process by secreting a primary that is iso-osmotic to the , followed by selective of ions and water in the hindgut to produce hypo-osmotic urine for excess water excretion. In species like mosquito larvae (e.g., ), specialized rectal pads facilitate this ion recovery, enabling maintenance of hemolymph osmolality around 250-300 mOsm despite ambient freshwater osmolality near 0-5 mOsm. In rarer marine or aquatic insects, which are hypo-osmotic to saline environments, shifts to hypo-osmotic regulation, emphasizing salt excretion to manage osmotic loss and influx. Malpighian tubules in these taxa, such as certain brine flies (Ephydra spp.), adapt by enhancing active transport, often coupled with active transport in the , allowing survival in salinities up to 100-200 ppt. species like Ochlerotatus taeniorhynchus possess dedicated salt-secreting glands absent in strictly freshwater forms, which actively extrude ions to tolerate brackish conditions exceeding 35 ppt. These adaptations highlight the physiological plasticity in , with energetic costs increasing under stress, as evidenced by reduced growth rates in larvae exposed to elevated ions. Buoyancy control poses unique challenges for aquatic insects navigating hydrostatic pressures, with many relying on trapped air stores to achieve without specialized organs like swim bladders. Diving beetles (), for instance, utilize gas-filled tracheal systems and subelytral air bubbles to reduce body , enabling prolonged submersion while foraging; these bubbles, replenished at the surface, compress under pressure but maintain sufficient lift for mid-water positioning. In phantom midge larvae ( spp.), paired gas bladders filled with atmospheric air via tracheal connections provide adjustable , regulated by localized pH changes in the air-sac that control gas volume through mechanochemical processes in bands, allowing vertical migration to evade predators. Deep-water pressures, however, compress these air stores, increasing and limiting depth for most to shallow zones less than 10 m, where surface access for bubble renewal is feasible.

Taxonomy and Diversity

Major Orders

Aquatic insects are represented across multiple orders, with the majority exhibiting aquatic or stages, especially during the larval phase. These orders encompass approximately 94,000 to 130,000 described species, accounting for roughly 9-13% of the total estimated 1 million described species worldwide. The evolutionary history of dates to the period around 400 million years ago, with the oldest confirmed being wingless forms from approximately 385 million years ago; aquatic adaptations, particularly in larval stages, emerged early, as evidenced by a 370-million-year-old larval from a swamp environment. Primarily, aquatic belong to holometabolous orders (undergoing complete ), though some paleopterous orders (incomplete ) also feature aquatic nymphs, reflecting multiple independent colonizations of aquatic habitats. In particular, the aquatic larvae of orders such as Ephemeroptera, Odonata, and Plecoptera represent a secondary return to water after the initial terrestrial origins of insects, retaining tracheal respiratory systems including tracheal gills as modified tracheae rather than ancient gills, and spiracles as terrestrial atavisms that prove a post-land colonization reversal. The major orders containing aquatic or semiaquatic species include:
  • Ephemeroptera (mayflies): Nymphs are fully aquatic, often in running waters, with short-lived terrestrial adults; representative families include Baetidae and Heptageniidae.
  • Odonata (dragonflies and damselflies): Nymphs are predatory and aquatic in freshwater, using gills for respiration; key examples are from families like and .
  • Plecoptera (stoneflies): Nymphs inhabit cool, oxygenated streams, serving as indicators of ; examples include Perlidae and Pteronarcyidae.
  • Trichoptera (): Larvae are exclusively aquatic, often building protective cases from silk and environmental materials; prominent families are Hydropsychidae and Leptoceridae.
  • Megaloptera: Larvae of alderflies and dobsonflies are aquatic predators in streams and lakes, with examples from Corydalidae.
  • Neuroptera (some species): Certain lacewings, like spongeflies in , have aquatic larvae that feed on freshwater sponges.
  • Coleoptera (beetles): Many water beetles, such as predaceous diving beetles in , have aquatic larvae and adults; beetles (Gyrinidae) are semiaquatic surface dwellers.
  • Diptera (true flies): Larvae of families like (midges) and Simuliidae (blackflies) are aquatic, often in diverse freshwater habitats; alone comprise a significant portion of aquatic insect .
  • Hemiptera (water bugs): Semiaquatic or fully aquatic bugs, including water striders () on surfaces and giant water bugs () as submerged predators.
These orders highlight the repeated of aquatic lifestyles, predominantly in freshwater, with holometabolous groups dominating due to their larval adaptations for submerged existence.

Species Diversity and Distribution

Aquatic insects represent a highly diverse group within the Insecta class, with over 100,000 described worldwide, comprising approximately 9-13% of all known insect and an estimated total exceeding 200,000 when including undescribed taxa (as of estimates). This diversity is dominated by the orders Diptera (true flies, including midges and mosquitoes) and Coleoptera (beetles), which together account for more than 60% of aquatic insect ; Diptera alone harbor nearly half, with around 46,000 aquatic , while Coleoptera contribute over 10,000, particularly in the form of water beetles adapted to various aquatic niches. Global distribution patterns reveal a strong bias toward freshwater habitats, where over 95% of aquatic insect occur, reflecting multiple evolutionary invasions into inland waters from terrestrial ancestors. Marine environments host only a sparse fraction, with fewer than 1,000 truly marine across a handful of families, such as certain and springtails (Collembola), limited by physiological challenges like osmoregulation in saline conditions. In contrast, freshwater systems exhibit varied distributions, with lotic (flowing ) habitats supporting higher diversity in orders like Ephemeroptera and , while lentic (standing ) systems favor Coleoptera and . Biodiversity hotspots for aquatic insects are concentrated in tropical and subtropical regions, particularly in riverine systems of , the , and the , where warm temperatures, seasonal flooding, and habitat complexity drive elevated rates and levels exceeding 50% in some genera. Isolated ancient lakes further accentuate this pattern, with in serving as a prime example of ; it harbors unique radiations such as nine endemic species of apataniid caddisflies (Trichoptera) and multiple Sergentia chironomids (Diptera), representing adaptive bursts in profundal zones unmatched elsewhere. Despite this richness, aquatic insect diversity is under severe pressure from anthropogenic threats, particularly habitat loss through , dam construction, and urbanization, which have driven population declines of 20-50% in affected freshwater systems across regions like and since 1900. These losses contribute to broader extinction risks, with approximately 33% of assessed aquatic insect species classified as threatened globally, underscoring the urgency of conservation efforts to preserve distributional patterns and hotspot integrity.

Habitats and Ecology

Freshwater Environments

Aquatic insects occupy a wide array of freshwater habitats, broadly divided into lotic systems—such as rivers and with continuous flow—and lentic systems, including lakes, , and wetlands with standing or slow-moving . In lotic environments, turbulent riffles in favor oxygen-demanding species like stoneflies (), which thrive in the high-velocity, well-aerated conditions of these microhabitats. Conversely, lentic habitats support more tolerant taxa, such as mosquito larvae (Culicidae), which develop in the calmer, often vegetated waters of and marshes. Microhabitats like leaf packs in stream beds provide essential refugia and , enabling shredder insects to process while shielded from currents. Adaptations to hydrological dynamics are critical for survival in these variable freshwater settings. In fast-flowing lotic waters, (Trichoptera) construct silken cases incorporating sand, twigs, or leaves to increase stability and resist dislodgement. Blackflies (Simuliidae) employ burrowing behaviors into or , supplemented by threads for attachment, allowing them to filter-feed in high-current zones. These morphological and behavioral traits underscore the evolutionary responses of aquatic insects to the physical stresses of flowing freshwater ecosystems. Distribution patterns of aquatic insects are strongly shaped by abiotic conditions, including temperature, , and dissolved oxygen levels. Cold stenotherms, such as many species, are restricted to headwater where low temperatures (typically below 15–20°C) maintain optimal metabolic rates and prevent . Acidic environments (below 5.5) diminish , particularly impacting sensitive Ephemeroptera and Trichoptera by disrupting ion regulation and increasing aluminum . Oxygen availability, enhanced by in lotic habitats, supports diverse communities, whereas low-oxygen strata in lentic systems like profundals favor hypoxia-tolerant , though these conditions pose respiratory challenges for less adapted taxa.

Marine and Semiaquatic Environments

Aquatic insects are predominantly inhabitants of freshwater environments, with truly marine species representing a very small fraction (less than 0.1%) of the approximately 100,000 known aquatic insect worldwide. This rarity extends to forms in brackish and intertidal zones, where insects face intense competition from more dominant marine arthropods like crustaceans, as well as challenges from high , wave action, and limited suitable substrates for . While over 20 insect orders include some marine representatives, primarily in intertidal or coastal habitats, fully pelagic species are confined to a handful, mostly within the , Diptera, and Coleoptera. The most notable true marine insects are the ocean skaters of the genus (Hemiptera: ), with 46 described species, of which only five (H. germanus, H. hayanus, H. micans, H. sobinus, and H. whiteleggei) inhabit the open ocean as pelagics. These wingless adults live exclusively at the air-sea interface, preying on and using specialized hydrofuge hairs on their legs and body to exploit for propulsion and buoyancy, enabling them to "surf" waves and evade predators. Their eggs require floating debris like feathers or for attachment, limiting distribution to tropical and subtropical waters across the Pacific, Atlantic, and Indian Oceans, where densities can reach 500 individuals per square meter in protective flotillas. Other marine , such as Halovelia (Veliidae) and Hermatobates (Hermatobatidae), occupy intertidal rock pools and mangroves, with adaptations like elongated legs for navigating splash zones. In semiaquatic and brackish environments, such as estuaries and salt marshes, from orders like and Diptera dominate, tolerating fluctuations from 0 to over 30 ppt through behavioral and physiological mechanisms, including strategies that maintain internal balance (as detailed in sections). Shore bugs (Saldula spp., Saldidae) thrive in salt marshes like , enduring tidal submersion for up to 14 hours via plastron respiration and climbing vegetation to access air. Corixids such as Trichocorixa reticulata inhabit hypersaline pools in arid regions, producing hyperosmotic urine to excrete excess salts, while larvae (Chironomidae) form dense populations (up to 3,514/m²) in tidally influenced river estuaries, surviving immersions in 8.75‰ through gut-based . These adaptations allow semiaquatic to exploit nutrient-rich coastal niches, though their overall scarcity underscores the evolutionary dominance of crustaceans in saline habitats.

Life History and Behavior

Life Cycle Stages

Aquatic insects typically undergo , with life cycles consisting of , immature (larval or nymphal), pupal (in holometabolous species), and adult stages, where the immature phases are predominantly aquatic. The stage involves deposition in or near bodies, often on substrates like rocks or , with hatching times ranging from days to weeks depending on and oxygen availability. For instance, in mayflies (Ephemeroptera), eggs are broadcast into or attached to surfaces, hatching into aquatic nymphs within 1-2 weeks under optimal conditions. The immature stage, known as nymphs in hemimetabolous orders or larvae in holometabolous ones, is fully aquatic and involves multiple instars during which the feeds, grows, and molts. Nymphs or larvae typically undergo 3 to 45 molts, with mayflies often experiencing 10-15 or more instars before maturity. This phase can last from one month to three years, influenced by species, water temperature, and nutrient availability; for example, stonefly nymphs () may require 1-3 years in colder streams. In orders like , nymphs resemble miniature adults with developing wing pads and undergo incomplete , transitioning directly to winged adults without a pupal stage. In holometabolous aquatic insects, such as (Trichoptera), a pupal stage follows the larval phase and occurs submerged within protective cases or silken cocoons, lasting days to weeks as a non-feeding, transformative period. Emergence to adulthood happens via molting, often synchronized with environmental cues like water levels, where the insect splits its and ascends to the surface. Adults are generally short-lived, from hours in mayflies to months in some beetles, and while terrestrial, they return to water for egg-laying to complete the cycle.

Reproductive Strategies

Aquatic insects display a range of strategies tailored to their semi-aquatic or fully aquatic lifestyles, often involving transitions from underwater larval stages to aerial adult reproduction. In mayflies (order Ephemeroptera), mating typically occurs in massive aerial swarms formed by synchronized emergence of adults near water bodies, where males use visual cues and flight patterns to attract females, facilitating rapid pair formation despite short adult lifespans. In contrast, dragonflies (order Odonata) engage in elaborate aerial courtship displays, including tandem flights where the male clasps the female and leads her in synchronized hovering over water, ensuring mate guarding and successful copulation in the air before oviposition. While pheromones play a prominent role in terrestrial insect mating, their use in aquatic insects is more limited. Oviposition in aquatic insects is highly adapted to watery environments, with females depositing eggs directly on or into water to ensure larval access to aquatic habitats. Mosquitoes (family Culicidae), for instance, produce floating egg rafts consisting of 100–300 eggs embedded in a gelatinous matrix that keeps them at the water surface until hatching, protecting them from immediate submersion while allowing oxygen exchange. Other species, such as certain dragonflies, submerge parts of their bodies or fully dive to insert eggs into submerged vegetation or sediment using ovipositors, minimizing exposure to surface predators. These strategies often coincide with the transition to the adult stage, where females seek suitable water bodies post-mating for egg-laying, as detailed in life cycle descriptions. Parental care is uncommon among aquatic insects due to their generally r-selected life histories, but notable exceptions occur in some groups to enhance offspring survival in predator-rich waters. In giant water bugs (family ), males exhibit exclusive by carrying fertilized masses on their backs for weeks, aerating them through abdominal movements and defending against threats until hatching, which can increase survival rates significantly. To counter high and larval mortality from predation and environmental stressors, many aquatic insects employ high-fecundity strategies; for example, female mayflies can produce 500–3,000 eggs per individual, maximizing the chances that at least some offspring reach maturity.

Ecological and Human Significance

Role in Ecosystems

Aquatic insects occupy diverse trophic positions within food webs, functioning as primary consumers, predators, and prey. Many species, such as larvae (Trichoptera), act as grazers that scrape and from substrates, thereby regulating and algal in streams and lakes. In contrast, dragonfly nymphs (Odonata) serve as voracious predators, consuming , smaller , and even conspecifics, which helps control prey populations and influences community structure. As prey, aquatic insects form a critical link to higher trophic levels; for instance, they often comprise 50-80% of the diet by for stream-dwelling fish species, supporting populations of salmonids and other vertebrates, while also serving as food for birds, amphibians, and riparian predators. In nutrient cycling, aquatic insects facilitate the processing and transformation of , enhancing productivity. Shredder species, including certain stoneflies () and , decompose leaf litter and , contributing over 50% to leaf mass loss in temperate streams and releasing nutrients like and back into the water column. Additionally, their mass emergence events—such as annual "fly hatches" of mayflies (Ephemeroptera) and midges (Diptera)—export substantial and nutrients from aquatic to terrestrial , subsidizing riparian food webs and boosting predator abundances by up to threefold in some forested streams. This cross- flux, particularly rich in essential fatty acids, supports terrestrial consumers like spiders and birds during resource-limited periods. Aquatic insects play keystone roles in supporting overall by structuring and mediating interactions. Their burrowing and case-building activities aerate sediments and increase habitat complexity, fostering diverse assemblages of microbes, , and other macroinvertebrates. As both predators and prey, they maintain balance in webs, preventing dominance by any single group and promoting coexistence; for example, predatory odonates can enhance diversity by reducing herbivore . In freshwater environments, their presence correlates with higher macroinvertebrate richness, underscoring their foundational contributions to stability.

Importance to Humans

Aquatic insects provide significant benefits to humans through and . In , species such as mayflies (Ephemeroptera), caddisflies (Trichoptera), and stoneflies () serve as key models for artificial lures, with imitations like dry flies replicating their adult stages to attract and other fish. These insects are also vital as bioindicators of ; the EPT index, which measures the richness and abundance of Ephemeroptera, Plecoptera, and Trichoptera taxa, assesses pollution levels in streams, with higher EPT scores indicating cleaner water and healthier aquatic habitats. Certain aquatic insects, particularly mosquitoes (Diptera: Culicidae), pose major health risks as vectors for diseases affecting millions globally. Mosquitoes transmit , with an estimated 263 million cases in 2023, and dengue, with around 390 million infections each year, leading to substantial morbidity and mortality in tropical regions. To mitigate these threats, biological control methods like (Bti), a bacterium targeting mosquito larvae in standing water, have been widely adopted since the , offering an environmentally safer alternative to chemical insecticides without harming non-target organisms. Conservation efforts for aquatic insects address escalating threats from and , which disrupt habitats and distributions. from agricultural runoff and reduces oxygen levels and introduces toxins, while climate-driven warming alters water temperatures and flow regimes, potentially leading to declines in sensitive like those in the EPT orders. Since the , wetland restoration initiatives, including the U.S. Service's no-net-loss policy, have aimed to rehabilitate degraded sites, fostering recovery of communities and enhancing overall aquatic .

References

  1. https://www.usgs.gov/centers/southwest-biological-science-center/science/aquatic-insects
  2. https://aquaticpath.phhp.ufl.edu/waterbiology/handouts2011/aquatic_insects.pdf
  3. https://pmc.ncbi.nlm.nih.gov/articles/PMC7563230/
  4. https://www.pubs.ext.vt.edu/420/420-531/420-531.html
  5. https://lytlelab.ib.oregonstate.edu/sites/lytlelab.ib.oregonstate.edu/files/Lytle2008_AqInsectCh7.pdf
  6. https://fieldreport.caes.uga.edu/a-backbone-of-bugs-the-tiny-drivers-of-freshwater-ecology/
  7. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/aquatic-insects
  8. https://pmc.ncbi.nlm.nih.gov/articles/PMC4816856/
  9. https://archive.iwlearn.org/mrcmekong.org/download/free_download/invertebrates/Chap13-The-Aquatic.pdf
  10. https://esajournals.onlinelibrary.wiley.com/doi/10.1890/0012-9623(2007)88[72:AHOTES]2.0.CO;2
  11. https://andrewsforest.oregonstate.edu/pubs/pdf/pub1675.pdf
  12. https://faculty.ucr.edu/~legneref/entomol/ephemeroptera.htm
  13. https://www.macroinvertebrates.org/taxa-info/plecoptera-larva
  14. https://genent.cals.ncsu.edu/bug-bytes/aquatic-respiration/
  15. https://uq.pressbooks.pub/insect-science/chapter/living-with-water/
  16. https://royalsocietypublishing.org/doi/10.1098/rsbl.2013.0473
  17. https://entnemdept.ufl.edu/walker/ufbir/chapters/chapter_20.shtml
  18. https://journals.biologists.com/jeb/article/222/7/jeb196659/20624/Cutaneous-respiration-by-diving-beetles-from
  19. https://weta.ento.org.nz/index.php/weta/article/download/170/160/
  20. https://www.journals.uchicago.edu/doi/pdfplus/10.1086/physzool.4.3.30151148
  21. https://insecta.bio.spbu.ru/z/antidictionary/tergalii&gills.htm
  22. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-185X.1950.tb01590.x
  23. https://www.researchgate.net/publication/280327576_Respiratory_function_of_the_plastron_in_the_aquatic_bug_Aphelocheirus_aestivalis_Hemiptera_Aphelocheiridae
  24. https://pmc.ncbi.nlm.nih.gov/articles/PMC3971685/
  25. https://www.sciencedirect.com/science/article/pii/0022191094001206
  26. https://journals.biologists.com/jeb/article/207/13/2289/34959/Differences-in-the-effects-of-salinity-on-larval
  27. https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2023.1136966/full
  28. https://doi.org/10.1016/j.cub.2022.01.018
  29. https://pmc.ncbi.nlm.nih.gov/articles/PMC7827063/
  30. https://www.mdpi.com/1424-2818/14/7/573
  31. https://www.si.edu/spotlight/buginfo/bugnos
  32. https://sustainability.stanford.edu/news/insects-took-when-they-evolved-wings
  33. https://pmc.ncbi.nlm.nih.gov/articles/PMC6386717/
  34. https://site.caes.uga.edu/mchughlab/files/2018/07/Murray-et-al-2018-Ogeechee_Outreach_Booklet1.pdf
  35. https://genent.cals.ncsu.edu/insect-identification/order-hemiptera-suborder-heteroptera/
  36. https://thedragonflywoman.com/2012/05/25/marine-insects/
  37. https://royalsocietypublishing.org/doi/10.1098/rsbl.2015.1075
  38. https://www.science.org/doi/10.1126/science.aax1682
  39. https://www.researchgate.net/publication/317022419_Molecular_evolution_of_the_Lake_Baikal_endemic_caddisflies_Trichoptera
  40. https://link.springer.com/content/pdf/10.1134/S1022795415060083.pdf
  41. https://www.unep.org/news-and-stories/press-release/natures-dangerous-decline-unprecedented-species-extinction-rates
  42. https://freshwaterblog.net/2019/02/15/global-insect-declines-33-of-aquatic-species-threatened-with-extinction/
  43. https://www.nature.com/articles/s41586-024-08375-z
  44. https://escholarship.org/content/qt1pm1485b/qt1pm1485b.pdf
  45. https://www.researchgate.net/publication/228505809_The_marine_insect_Halobates_Heteroptera_Gerridae_Biology_adaptations_distribution_and_phylogeny
  46. https://www.nature.com/articles/s41598-020-64563-7
  47. https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2019.00408/full
  48. https://essig.berkeley.edu/documents/cis/cis21.pdf
  49. https://www.researchgate.net/publication/262951134_Aquatic_insects_in_an_estuarine_environment_Densities_distribution_and_salinity_tolerance
  50. https://www.mdpi.com/2075-4450/9/4/157
  51. https://www.sciencedirect.com/science/article/abs/pii/S0304380019304004
  52. https://pmc.ncbi.nlm.nih.gov/articles/PMC10666447/
  53. https://mdc.mo.gov/discover-nature/field-guide/mayflies
  54. https://www.livescience.com/43206-animal-sex-dragonflies.html
  55. https://extapps.dec.ny.gov/docs/administration_pdf/0820acrobats.pdf
  56. https://pmc.ncbi.nlm.nih.gov/articles/PMC4892440/
  57. https://uwm.edu/field-station/bug-of-the-week/mayfly-revisited/
  58. https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.71316
  59. https://resjournals.onlinelibrary.wiley.com/doi/10.1111/een.12245
  60. https://doi.org/10.1073/pnas.98.1.166
  61. https://pmc.ncbi.nlm.nih.gov/articles/PMC8207155/
  62. https://academic.oup.com/ieam/article/11/2/188/7732182
  63. https://www.takemefishing.org/fly-fishing/fly-fishing-flies/aquatic-fly-fishing-insects/
  64. https://cfb.unh.edu/StreamKey/html/biotic_indicators/indices/EPT.html
  65. https://www.mdpi.com/2073-4441/16/6/849
  66. https://www.who.int/teams/global-malaria-programme/reports/world-malaria-report-2024
  67. https://www.worldmosquitoprogram.org/en/learn/mosquito-borne-diseases
  68. https://www.epa.gov/mosquitocontrol/bti-mosquito-control
  69. https://pmc.ncbi.nlm.nih.gov/articles/PMC8360013/
  70. https://www.nps.gov/subjects/wetlands/restoring-wetlands.htm
  71. https://www.osti.gov/servlets/purl/1191534
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