Arthropod Bites or Stings
Jerome Goddard in Public Health Entomology, 2022
Direct tissue damage from stings or bites may lead to development of skin lesions. Arthropod mouthparts puncture skin in various ways (through a siphoning tube, scissor-like blades, and so on), leading to skin damage; hence damage may be a small punctum, dual puncta (from fangs), or lacerations. However, most lesions result from host immune reactions to salivary secretions or venom. Arthropod saliva is important during feeding in order to lubricate the mouthparts on insertion, increase blood flow to the bite site, inhibit coagulation of host blood, anesthetize the bite site, suppress the host’s immune and inflammatory responses, and aid in digestion. In contrast, venom from certain spiders may directly cause tissue death (necrosis) in human skin. In the United States violin spiders (Figure 20.2D) are primarily responsible for necrotic skin lesions, although sac spiders (Cheiracanthium spp.) and hobo spiders are sometimes reported to cause necrotic arachnidism.17,18 Brown recluse spider venom contains a lipase enzyme, sphingomyelinase D, which is the primary necrotic agent involved in the formation of the typical lesions. Neutrophil chemotaxis may be induced by sphingomyelinase D. The influx of neutrophils into the area contributes to the formation of the necrotic lesion.
Classification and Systematics
Jacques Derek Charlwood in The Ecology of Malaria Vectors, 2019
Flies (Diptera) have a mobile head with large compound eyes and three simple eyes (ocelli). The mouthparts are adapted for lapping and sponging liquids or piercing and sucking. A characteristic feature of the order is the possession of a single pair of membranous front wings, although some ectoparasitic species are wingless. The hindwings in all species are reduced to form a pair of balancing organs called halteres. These insects were given the name Diptera (Di – two, pteron – wings) by the Greek philosopher Aristotle around 500 BC so that Linnaeus did not need to find a new name when he first produced his classification.
Ticks
Gail Miriam Moraru, Jerome Goddard in The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Hard ticks display sexual dimorphism; males and females look conspicuously different (see box), and the blood-fed females are capable of enormous expansion (Figure 30.12). Their mouthparts are anteriorly attached and visible in dorsal view (Figures 30.13 and 30.14B). There is no true head, but their mouthparts appear as one (Figure 30.15). When eyes are present, they are located dorsally on the sides of the scutum.
Effect of Tagetes minuta oil on larval morphology of Plutella xylostella through scanning electron microscopy and mechanism of action by enzyme assay
Published in Toxin Reviews, 2022
Shudh Kirti Dolma, C. S. Jayaram, Nandita Chauhan, S. G. Eswara Reddy
After 24 h of treatment, setae of thoracic leg initiated to deform followed by rudimentary growth of thoracic leg and extra cuticular growth observed on thoracic legs which are modified into slender and elongated. Initially, the larvae treated with T. minuta oil showed shattering of crochets in pro-legs followed by separation of fleshy two segments of prolegs (planta). Later (72 h), legs of the cuticle initiated to lose granulation and third segment of the proleg were separated. After 96 h of treatment, granulation of the cuticle is fully crumbled and the first pair of the pro-leg is broken. Seta modified into clubbed/globose shaped after 24 h and then broken from the tip (48 h). The clubbed seta has swollen to a higher extent and left with broken bloated seta (after 72 h) and finally, setae fragmented from the hair socket. Similar setal modifications in the vicinity of stemmata, posterior abdominal segments, and ventral part of the mouthparts were also observed. In a similar study, significant deformation was observed on antennal segments after 96 h of treatment. In the flagellum, deformation seen in third flagellar segment which presented filamentous and knotted (Jayaram et al. 2020).
Effect of Azadirachta indica A. Juss (Meliaceae) on the serotonin rhythm of Spodoptera frugiperda (Lepidoptera: Noctuidae)
Published in Chronobiology International, 2021
Erick Oyarzabal-Armendariz, Jesús Alquicira-Mireles, Beatriz Zúñiga-Ruíz, José Luis Arreola-Ramírez, Patricia Guevara-Fefer, César Oliver Lara-Figueroa, Elsa G. Escamilla-Chimal
Azadirachtin is the secondary metabolite from Azadirachta indica that exerts a marked effect on the development and growth of insects, and it could even affect their biological rhythms. It mostly alters feeding, inhibitive such when it interacts with the chemoreceptors of the insect’s mouthparts. Alterations of neuroendocrine development that lead to the suppression of circadian rhythms were observed in species like the housefly (Musca domestica) and the Madeira cockroach (Leucophaea maderae) (Han and Engelmann 1987; Smietanko and Englemann 1989). Miranda-Anaya et al. (2002) characterized the locomotor activity rhythm of larvae and adults of S. frugiperda under two feeding regimes, finding that plant extracts administered with the diet affected its circadian rhythm. However, no studies have been carried out to determine if A. indica extract exerts any effect on the concentration and daily variations of 5HT in this larva. Because these extracts have already been reported to have repellent, insecticide, and antifeedant effects in this organism, an activity where they may either interfere with chemoreception or exert a negative effect on digestion may also affect ecdysteroid and juvenile-hormone levels through interference with serotonin pools (Banerjee and Rembold 1992). This could affect the growth and development of numerous insects, as well as the reproduction and sterility of adult females.
Inter-organ regulation by the brain in Drosophila development and physiology
Published in Journal of Neurogenetics, 2023
Sunggyu Yoon, Mingyu Shin, Jiwon Shim
The central brain area for processing feeding behaviors is the subesophageal zone (SEZ), which functions similarly to the brainstem in mammals (Ghysen, 2003; Kendroud et al., 2018). Pharyngeal nerves innervate the SEZ, and motor neurons relay information from the SEZ to pharyngeal nerves to drive the movement of mouthparts, called the proboscis, to control ingestion (Miyazaki & Ito, 2010). Specifically, motor neurons in the SEZ are separated and grouped depending on the response to sweet or bitter tastes: 36 motor neurons are activated by sweet chemicals, while bitter tastes trigger 32 motor neurons (Harris et al., 2015). In addition to neurons executing feeding behaviors, interneurons in the SEZ connect sensory inputs with motor outputs and fine-tune their connectome (Sterne et al., 2021). In summary, taste chemicals in food activate gustatory neurons in sensory organs, which consequently modulate feeding behaviors through muscle movements mediated by motor neurons from the SEZ.
Related Knowledge Centers
- Adaptation
- Appendage
- Evolution
- Mandible
- Morphology
- Seta
- Tick
- Mosquito
- Antenna