Ectoparasite

Rotenone-containing iasecticides have been used as dusts of ground roots, dispersible powders, and emulsive extracts. Their principal uses have been for appHcation to edible produce just prior to harvest and for the control of animal ectoparasites and cattle gmbs. 

Lindane is used predominately as a seed dressing and soil insecticide, for the control of ectoparasites of humans and domestic animals, for the control of locusts and grasshoppers, and as a residual spray to control the Anopheles vectors of malaria. Because of its relatively high volatility it is useful to control wood-boring insects of timber, fmit trees, and ornamental plants. The mode of action is not well understood but is thought to be competitive blocking of the y-aminobutyric acid (GABA) transmitter of synaptic nerve transmission. 

Vinyl Phosphates. Dichlorvos [62-73-7] 0,0-dimethyl 0-(2,2-dichloroviayl) phosphate, (CH20)2P(0)0CH=CCl2 (bp 140°C at 27 kPa, d 1.314, vp 1.6 Pa at 20°C), is soluble ia water to about 10 g/L. The half-hfe ia water is 8 h. The rat oral LD qS are 80, 56 mg/kg. Dichlorvos is used ia aerosols and sugar baits to control flies and mosquitoes. Slow release formulations have been used ia plastic strips and pet collars to control animal ectoparasites. 

Ivermectin is the catalytic reduction product of avermectin, a macroHde containing a spiroketal ring system. Two other related antibiotics having significantly different stmctural features and biological properties, moxidectin and milbemycin oxime, were more recentiy introduced into the market. Although these compounds have no antimicrobial activity, they are sometimes referred to as antibiotics because they are derived from fermentation products and have very selective toxicities. They have potent activity against worms or helminths and certain ectoparasites such as mites and ticks. 

HCH, sometimes misleadingly termed benzene hexachloride (BHC), exists in a number of different isomeric forms of which the gamma isomer has valuable insecticidal properties. These were discovered during the 1940s, and HCH came to be widely used as an insecticide to control crop pests and certain ectoparasites of farm animals after the Second World War. Crude technical BHC, a mixture of isomers, was the first form of HCH to be marketed. In time, it was largely replaced by a refined product called lindane, containing 99% or more of the insecticidal gamma isomer. 

The first commercially available HCH insecticide sometimes misleadingly called benzene hexachloride (BHC) was a mixture of isomers, principally alpha HCH (65-70%), beta HCH (7-10%), and gamma HCH (14-15%). Most of the insecticidal activity was due to the gamma isomer (Figure 5.1), a purified preparation of which (>99% pure) was marketed as lindane. In Western countries, technical HCH was quickly replaced by lindane, but in some other countries (e.g., China) the technical product, which is cheaper and easier to produce, has continued to be used. HCH has been used as a seed dressing, a crop spray, and a dip to control ectoparasites of farm animals. It has also been used to treat timber against wood-boring insects. 

OPs are often applied as sprays. Commonly, the formulations used for spraying are emulsifiable concentrates, where the OP is dissolved in an organic liquid that acts as a carrier. OPs are also used as seed dressings and as components of dips used to protect livestock against ectoparasites. Some highly toxic OPs have been incorporated into granular formulations for application to soil or to certain crops. 

Brown SJ, Galli SJ, Gleich GJ, Askenase PW Ablation of immunity to Amblyomma atmricanum by antibasophil serum cooperation between basophils and eosinophils in expression of immunity to ectoparasites (ticks) inguineapigs.J Immunol 1982 129 790-796. 

A parasite that lives outside the body of the host is called an ectoparasite. Approximately 6 to 12 million subjects become infested with pediculosis (lice infestation) yearly in the United States. Pediculosis is usually associated with poor hygiene, and infections are passed from person to person through social and sexual contact. 

Marti, O.G., Rogers, C.E. and Styer, E.L. (1995) Report on intracellular bacterial symbiont in Noctuidonema guayanense, an ectoparasitic nematode of Spodoptera frugiperda. Journal of Invertebrate Pathology 66, 94-96. 

Walton, S.F., Currie, B.J. and Kemp, D.J. (1997) A DNA fingerprinting system for the ectoparasite Sarcoptes scabiei. Molecular and Biochemical Parasitology 85, 187-196. 

Keppler et al. (2001) found that there is less cannibalism in littered nests. This is probably due to the fact that hens in the standard nests, where the eggs disappear immediately after laying, are more restless, which may lead to pecks directed to the cloaca. With littered nests, there are also fewer misplaced eggs and the eggs seem to be cleaner (Keppler et al., 2001). However, the hygiene levels tend to be higher in non-littered nests, as there could be problems with broken eggs in nest litter and/or with ectoparasites (see Chapter 12). 

Copper sulfate is used to control protozoan fish ectoparasites including Ichthyopthirius, Tri-chodina, and Costia. The effectiveness of the treatment diminishes with increasing total alkalinity and total hardness of the water (Straus and Tucker 1993). Copper compounds now used to control protozoan parasites of cultured red drum (Sciaenops ocellatus) include copper sulfate, copper sulfate plus citric acid, and chelated copper compounds (forms of copper bound by sequestering agents, such as ethanolamine) chelated copper compounds are considered less toxic to fish than copper sulfate and at least as effective in controlling parasites (Peppard etal. 1991). 

Copper discharges to the global biosphere are due primarily to human activities, especially mining, smelting, and refining copper and the treatment and recycling of municipal and industrial wastes. Some copper compounds, especially copper sulfate, also contribute to environmental copper burdens because they are widely and intensively used in confined geographic areas to control nuisance species of aquatic plants and invertebrates, diseases of terrestrial crop plants, and ectoparasites of fish and livestock. 

Smith, H.G., Jr. and R.L. Goulding. 1970. Toxicological aspects of three organophosphorus compounds (cythioate, famphur, and fenthion) in the host-ectoparasite system. Jour. Econ. Entomol. 63 1640-1646. 

Sodium benzoate has been identified as a mild and efficient catalyst for the tandem Michael-aldol self-condensation of y,5-unsaturated-/3-keto esters, affording conjugated vinylcyclohexenonedicarboxylates, some of which exhibit biological activity against ectoparasites in cattle. 

Uses Contact and stomach insecticide used to control mosquito larvae, house flies, ectoparasites on cattie, sheep, and goats recommended for use in dairy barns. Effective against a wide variety of pests in fieid, forage, fruit, and vegetabie crops. Methoxychior is aiso used to controi househoid and industriai pests (Worthing and Hance, 1991). 

---