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An Introduction to Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Phoresy is the association of one organism with another for transporting from one place to another with no physiological dependence. Many pseudoscorpions or free-living mites hitch rides on insects as shown in Figure 1.12A. The mites may be transported to a carcass where they disembark and may feed on eggs and larvae of flies also feeding on the carcass. A remarkable example of phoresy occurs when the female of the human bot fly Dermatobia hominis (Figure 1.12B) captures female mosquitoes in mid-air and oviposits on them (Figure 1.12C). When the mosquito approaches a human host to seek a blood meal, the bot fly eggs will hatch and the larvae will fall to the skin of the human, either penetrate the skin or enter the hole made by the mosquito and develop into a large larva or bot (Figure 1.12D), often under the skin of the scalp. Eventually, the larva falls to the ground, pupates and the adult bot fly emerges. By using a phoretic mosquito host, the female bot fly, which is large, scary and conspicuous, avoids the hazards of approaching a human host and leaves it up to the mosquito to do the dirty work. Many college students have come back from spring break somewhere in Central America with a bot fly larva as a souvenir.
Fly Larvae in Humans (Myiasis)
Published in Jerome Goddard, Public Health Entomology, 2022
In most cases of obligate myiasis, humans are not the ordinary hosts, but may become infested. Human infestation by the human bot fly is usually through a mosquito bite—the eggs are attached to mosquitoes and other biting flies; however, human screwworm fly myiasis may result from direct egg laying on a person, most often in or near a wound or natural orifice. I have known of several cases of screwworm infestation occurring in the human nose.
Flies (That Might Cause Myiasis)
Published in Gail Miriam Moraru, Jerome Goddard, The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Gail Miriam Moraru, Jerome Goddard
The condition of fly larvae occurring in human tissues is called myiasis. Some fly larvae develop in living flesh (also see Chapter 6); the human bot fly is one of them. This fly, Dermatobia hominis, is a parasite of humans, cattle, swine, cats, dogs, horses, sheep, other mammals, and a few birds in Mexico and Central and South America.1,2 The larvae (Figures 21.1 and 21.2) burrow into the host’s tissues, feeding and eventually emerging to drop to the ground and pupate. In people, the larvae have been recovered from the head, arms, back, abdomen, buttocks, thighs, and axilla. Human infestation is often characterized by painful discharging cutaneous swellings on the body. The condition is rarely fatal, except possibly in very young children (less than 5 years old); the larvae infesting the scalp may penetrate into the incompletely ossified skull and enter the brain.3 Although the parasite does not occur in the United States, cases are occasionally seen in travelers to endemic areas, particularly Belize, Bolivia, and Brazil.4 One such case was reported from Ohio in which a local physician submitted a second-stage larva to the Ohio Department of Health for identification.5 The larva had been removed from a patient who had recently returned from Brazil. The Mississippi Department of Health has been involved in at least four cases of people returning from Belize.
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
Serotonin (5-hydroxytryptamine or 5HT) is a monoamine that was first characterized in 1948 by Rapport et al. (Rapport et al. 1948), it acts as a neurotransmitter, neuromodulator, and neurohormone, and plays an important role in the nervous system, metabolic processes, and circadian rhythms of diverse organisms (Cardinali et al. 1994). It has been proposed as a candidate for the integration of photic and non-photic signals (e.g., light and feeding) in the central nervous system of vertebrates (Kirsz and Zieba 2012) and comparable processes of insects (Vleugels et al. 2015). Although insects and mammals are very different in their physiology, they are evolutionary-preserved mechanisms, as reported by Banerjee and Rembold (Banerjee and Rembold 1992); these authors state that the most extensively studied insect neurosecretory system, the pars intercerebralis-corpus cardiacum complex, exhibits in functional terms many parallels with the hypothalamus-pituitary complex of mammals and other vertebrates. It is involved in the foundations of memory and associative learning in insects (Sitaraman et al. 2008), and it modulates the response of neuronal populations in the olfactory center of Bombix mori (Gatellier et al. 2004). It also has been proposed as a circadian modulator of the visual system of invertebrates (Nadakavukaren et al. 1986). A circadian rhythm of this monoamine has been characterized in the brain of the silk moth (B. mori) and the cricket (Acheta domesticus) (Gatellier et al. 2004; Muzynska-Pytel and Cymborowski 1978), and the relevance of the neural regulation of serotonin in locomotor activity has been reported for crickets (Gryllus bimaculatus) (Nishinokubi and Tomioka 2000). Furthermore, the importance of serotonin as a mediator in the circadian changes of the visual system has been observed in the botfly (Calliphora vicina) (Cymborowki 1998). This monoamine has been found also in other tissues, for example, in the stomatogastric system of the stick insect (Carausius morosus) (Luffy and Dorn 1991).