Morphological Adaptations of Parasitic Arthropods PDF

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Saint Louis University

Norbert Q. Angalan

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arthropods morphology parasitic arthropods insect adaptations biology

Summary

This document discusses the morphological adaptations of parasitic arthropods. It covers topics such as body shape, including dorsoventral and lateral flattening; mouthparts of chewing and piercing-sucking types; the structure and function of legs; and sensory structures like antennae and the Johnston's organ. Key concepts relate to insect biology within the Saint Louis University context.

Full Transcript

CHAPTER 3: ARTHROPODS MORPHOLOGICAL ADAPTATIONS OF PARASTIC ARTHROPODS Norbert Q. Angalan, PhD Department of Biology School of Nursing, Allied Health and Biological Sciences...

CHAPTER 3: ARTHROPODS MORPHOLOGICAL ADAPTATIONS OF PARASTIC ARTHROPODS Norbert Q. Angalan, PhD Department of Biology School of Nursing, Allied Health and Biological Sciences Saint Louis University MEDICAL ENTOMOLOGY BODY SHAPE Dorsoventral or Lateral flattening of the body – common among ectoparasites that facilitate movement on the host and enable them to hide in tight spaces ○ 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 ○ labium (“lower lip”) for grasping, manipulating & retaining the food ○ mandibles and maxillae for manipulating & masticating the food MOUTHPARTS Piercing-sucking type – mouthparts adapted for piercing host skin to reach and feed on internal fluids ○ Solenophages – arthropods that pierce the capillaries then feed directly on host blood, with highly modified styletiform that typically leave little or no evidence of an actual puncture of the skin at the bite site E.g., mosquitoes, bed bugs and sucking lice MOUTHPARTS: Piercing-sucking type Mosquitos ○ fascicle (labrum, maxillae, mandibles, hypopharynx) and labium are very elongate, forming a feeding apparatus called the proboscis ○ labium serves as a protective sheath and a guide for the fascicle that penetrates the host skin, delivers saliva, and transports host blood MEDICAL ENTOMOLOGY MOUTHPARTS: Piercing-sucking type Fleas ○ epipharynx (outgrowth of the body wall) and the maxillae are in the form of stylets and are used to pierce the skin ○ tip of the epipharynx is inserted into a capillary during feeding ○ palps help to guide the blood- feeding stylets MEDICAL ENTOMOLOGY MOUTHPARTS: Piercing-sucking type Hemipterans: e.g., bed bugs ○ maxillae & mandibles are styletiform and held within a sheathlike segmented labium MEDICAL ENTOMOLOGY MOUTHPARTS: Piercing-sucking type Lice ○ labrum forms a haustellum (snoutlike structure) ○ tip of the haustellum are prestomal, or haustellar, “teeth,” which are used to anchor the mouthparts to the host ○ maxillae, hypopharynx, & labium are modified as stylets for piercing host tissues MEDICAL ENTOMOLOGY LEGS bear specialized structures - basal segment to facilitate attachment/ grasping and movement avoid being displaced or removed heavily sclerotized, with muscle - subsegments 5 segments: - apical structures LEGS Fleas modified hind legs enable them to jump at remarkable distances to reach a host or to evade removal enlarged, muscular femur and an elastic protein in the integument called resilin hind legs are linked to a zone where energy for jumping is stored LEGS Ticks forelegs have enlarged claws for grasping and holding onto host skin Mites have sucker-like empodia securing them to their hosts, and facilitating movement and holding onto the smooth surfaces of the body scales hindlegs for clasping legs with elongate apoteles with terminal suckers SENSORY STRUCTURES antennae have receptors that detect chemicals emanating from the skin and exhaled breath of potential hosts Mosquitoes attracted to carbon dioxide, lactic acid, octenol, estrogen, fatty acids, and amino acids basal segment forms the Johnston’s organ (for detecting airborne vibrations) MEDICAL ENTOMOLOGY SENSORY STRUCTURES 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 Mosquitoes & Flies eyes are greatly enlarged = light perception and vision play in locating, or orienting toward potential host MEDICAL ENTOMOLOGY 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 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 MEDICAL ENTOMOLOGY SENSORY STRUCTURES: Others Trichobothria is common in mites and other arachnids for detecting airborne and substrate vibrations and other tactile cues 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 odors MEDICAL ENTOMOLOGY 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 in fleas, the dorsal portions of the terminal abdominal segments are modified as a sensory organ, called the sensilium = specialized for detecting host-associated cues such as vibrations and temperature MEDICAL ENTOMOLOGY

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