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Arthropod Bites or Stings
Published in Jerome Goddard, Public Health Entomology, 2022
Bites from arthropods may be defensive only or for purposely taking a bloodmeal. Mosquitoes, ticks, fleas, lice, and other bloodsucking insects are well adapted for blood feeding (Figure 20.2A–20.2C). In medical entomology, insect mouthparts are generally divided into three broad categories: (1) biting and chewing, (2) sponging, and (3) piercing-sucking. There are numerous adaptations or specializations within these mouthpart categories among the various insect orders (Figure 20.3 shows variations among the Diptera). Biting and chewing mouthpart types, such as those in food pest insects, and sponging mouthpart types, found in filth flies, are of little significance regarding human bites, but piercing-sucking mouth-parts, and especially the bloodsucking types, are considerably important. There is some variability in insect piercing-sucking mouthparts, mainly in the number and arrangement of needle-like blades (stylets) and the shape and position of the lower lip of insect mouthparts, the labium. Actually, the proboscis of an insect with piercing-sucking mouthparts is an ensheathment of the labrum, stylets, and labium. These mouthparts are positioned in a way that they form two tubes. One tube is narrow, being a hollow pathway along the hypopharynx, and the other is wider, formed from the relative positions of the mandibles or maxillae. During biting, saliva flows down the narrow tube entering the wound, and blood returns through the wider tube by action of the cibarial or pharyngeal pump.
Classification and Systematics
Published in Jacques Derek Charlwood, 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
Published in Gail Miriam Moraru, Jerome Goddard, The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Gail Miriam Moraru, Jerome Goddard
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.
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.
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).
Insecticide potential of two saliva components of the predatory bug Podisus nigrispinus (Heteroptera: Pentatomidae) against Spodoptera frugiperda (Lepidoptera: Noctuidae) caterpillars
Published in Toxin Reviews, 2022
Juliana Mendonça Campos, Luis Carlos Martínez, Angelica Plata-Rueda, Wolfgang Weigand, José Cola Zanuncio, José Eduardo Serrão
Insect venoms contain blends of biogenic amines, amino acids, organic acids, alkaloids, polysaccharides, proteins, and terpenoids (Upadhyay and Ahmad 2010, Walker et al. 2016). These substances are actively transferred to the prey by stings in Hymenoptera and mouthparts in Heteroptera, or are passively released through the contact with bristles and setae in Lepidoptera caterpillars (Schmidt 1982). Mouthparts of heteropterans are composed by stylets (mandible and maxilla) extensively elongated and modified to form a proboscis specialized for piercing and sucking (Cohen 1998). Heteropteran, hymenopteran, and lepidopteran venoms have been suggested as potential biopesticides (Baek et al. 2011, Santos et al. 2017, 2020, Martínez et al. 2018a).