3 Morphological Adaptations of Parasitic Arthropods

• Body shape:

  • Dorsoventrally/laterally flattening of the body - most common among ectoparasites, facilitates movement on the host and enable them to hide in tight spaces
• Body shape:

  • Dorsoventral flattening - e.g., bed bugs and bat bugs, lice, beaver beetles, parasitic dermapterans, louse flies, and ticks
  • Lateral flattening - e.g., fleas
• Mouthparts:

  • Chewing type - feed directly on host tissues, e.g., cockroaches
• Mouthparts: Chewing-type

  • Labium ("lower lip") for grasping, manipulating & retaining the food
• Mouthparts: Chewing-type

  • Mandibles and maxillae for manipulating and masticating the food
• Mouthparts:

  • Piercing-sucking type - mouthparts adapted for piercing and feeding on internal fluids
• Mouthparts: Piercing-sucking type

  • Solenophages - arthropods that pierce the capillaries and feed directly on host blood, with highly modified styletiform that typically leave little to no evidence of an actual wound puncture of the skin at the bite site; e.g., mosquitos, bed bugs and sucking lice
• Mouthparts: Piercing-sucking type of mosquitos

  • Fascicle (labrum, maxillae, mandibles, hypopharynx) and labium are very elongated, forming a feeding apparatus called the proboscis
• Mouthparts: Piercing-sucking type of mosquitos

  • Labium serves as a protective sheath and a guide for the fascicle that penetrates the host skin, delivers saliva, and transports host blood
• Mouthparts: Piercing-sucking type of fleas

  • Epipharynx (outgrowth of the body wall) and maxillae are in the form of stylets that are used to pierce the skin
• Mouthparts: Piercing-sucking type of fleas

  • Tip of epipharynx is inserted into a capillary during feeding
• Mouthparts: Piercing-sucking type of fleas

  • Palps help to guide the blood-feeding stylets
• Mouthparts: Piercing-sucking type of hemipterans (e.g., bed bugs)

  1. Maxillae and mandibles are styletiform and held within a sheathlike segmented labium
• Mouthparts: Piercing-sucking type of lice

  • Labrum forms the haustellum (snoutlike structure)
• Mouthparts: Piercing-sucking type of lice

  • Tip of the haustellum are prestomal, or haustellar, "teeth," which are used to anchor the mouthparts to the host
• Mouthparts: Piercing-sucking type of lice

  • Maxillae, hypopharynx, & labium are modified as stylets for piercing host tissues
• Legs

  • Bear specialized structures to facilitate attachment/grasping and movement
• Legs

  • Avoid being displaced or removed
• Legs

  • Heavily sclerotized, with muscle
• Legs

  • 5 segments: Coxa (basal segment), trochanter, femur, tibia, tarsus (apical structures)
• Legs of fleas:

  • Modified hind legs enable them to jump at remarkable distances to reach a host or to evade removal
• Legs of fleas

  • Enlarged, muscular femur and an elastic protein in the Integument called resilin
• Legs of fleas

  • Hind legs are linked to a zone where energy for jumping is stored
• Legs of ticks

  • Forelegs have enlarged claws for grasping and holding onto host skin
• Legs of mites

  • Have sucker-like empodia securing them to their hosts, and facilitating movement and holding onto the smooth surfaces of the body scales
• Legs of mites

  • Hindlegs for clasping
• Legs of mites

  • Legs with elongated apoteles with terminal suckers
• Sensory structures

  • Antennae have receptors that detect chemicals emanating from the skin and exhaled breath of potential hosts
• Sensory structures of mosquitoes

  • Attracted to carbon dioxide, lactic acid, octenol, estrogen, fatty acids, and amino acids
• Sensory structures of mosquitoes

  • Basal segment forms the Johnston's organ (for detecting airborne vibrations)
• Sensory structures of fleas

  • Antenna is short, flattened, and fits into a protective groove on the side of the head allowing it to be retracted so as not to become damaged or impede movement
• Sensory structures of mosquitoes & flies

  • Eyes are greatly enlarged = light perception and vision play in locating or orienting toward potential host
• Sensory structures: Others

  • Receptors are concentrated near the tip of the proboscis or rostrum (e.g., mosquitoes and bed bugs, respectively) and are used to detect the precise location of capillaries beneath the surface of the skin
• Sensory structures: Others

  • In fleas, the dorsal portions of the terminal abdominal segments are modified as a sensory organ, called the sensillum = specialized for detecting host-associated cues such as vibrations and temperature
• Sensory structures: Others

  • Trichobothria is common in mites and other arachnids for detecting airborne and substrate vibrations and other tactile cues
• Sensory structures: Others

  • In ticks, Haller's organ is located on the dorsal aspect of the tarsus of the first pair of legs and functions in detection of temperature, air movements and host idiots
• Sensory structures: Others

  • Wing gustatory sensory neurons -> Long range detection
• Sensory structures: Others

  • Leg gustatory sensory neurons -> Movement inhibition, proboscis extension
• Sensory structures: Others

  • Pharynx gustatory sensory neurons -> Ingestion regulation
• Sensory structures: Others

  • Oral lobe gustatory sensory neurons -> Proboscis extension, oral lobe opening?