Arachnids

Arthropod Invertebrate with jointed body and limbs (includes insects, arachnids, and crustaceans). 

There are known to be about 30,000 disease-causing agents (fungi, viruses, nematodes, bacteria) in 3,000 types of cultivated plants. More than 10,000 species of arthropods (insects, ticks, arachnids) affect agricultural plants and animals. Along with agriculture, pesticides are also widely used in forestry and fisheries, in energy and railroads (to clear plants), in construction (to protect wood structures), etc. 

Mites are arachnids in the order Acari and should not be classified or referred to as insects. Mites are typically very small (about 0.5 mm) and have oval bodies with little or no differentiation of their two body regions. Over 50 species of mites have been found associated with stored products some feed directly on stored products, but others are predators, feed on fungi, or are parasites of other stored-product pests such as birds or rodents (Boczek, 1991). Mites can be important pests of stored food worldwide, but their economic importance varies considerably with location, commodity, and management practices. Some mite species can cause allergic reactions in... 

Kovoor, J. (1987). Comparative structure and histochemistry of silk-producing organs in Arachnids. In Ecophysiology of Spiders (W. Nentwig, Ed.), pp. 160-186. Springer, Berlin, Heidelberg, New York. 

Adverse hygienic conditions favor human infestation with multicellular organisms (referred to here as parasites). Skin and hair are colonization sites for arthropod ectoparasites, such as insects (lice, fleas) and arachnids (mites). Against these, insecticidal or arachnici-dal agents, respectively, can be used. Endoparasites invade the intestines or even internal organs, and are mostly members of the phyla of flatworms and roundworms. They are combated with anthelmintics. 

Ticks have a bad reputation for good reasons. Not only are they carriers of a number of diseases, the saliva of some can cause paralysis. North American natives were aware of tick paralysis, but the condition was officially noted as a disease of both animals and humans in 1912. The bites of at least 60 species of ticks can cause paralysis, which often does not appear until several days after the bite. The first indication is redness and swelling around the site of the bite. This is followed by neuromuscular weakness and difficulty in walking. If the tick is not removed, speech and breathing are affected, with eventual respiratory paralysis and death. Fortunately, removal of the tick results in a quick recovery of function. The exact mechanism of paralysis is not known but it appears to come from a substance that affects the neuromuscular junction. While not related to the venom of the tick saliva, the tick can also transmit diseases such as Lyme disease, Rocky Mountain spotted fever, Q fever, typhus, and others. Table 13.1 lists some venomous arachnids. 

Table 13.1 Venomous arachnids (scorpions, spiders, ticks)...

Arachnids (scorpions, spiders, and ticks) Scorpions Stinger - neurotoxin, no enzymes Localized pain, mostly dangerous to children... 

Schuster et al. (21) identified cotton plant resistance to the two-spotted spider mite (Tetranycus urtlca Koch) by mass screening seedlings. Later Schuster and Lane (22) were able to show that high tannin lines, particularly TX-1055, showed resistance to this arachnid and the bollworm. 

Spiders are an important order of carnivorous arachnids having a great impact on many ecosystems. Because most of their prey consists of insects, they can play an important role in controlling pest insects in agricultural crops. There are currently about 36000 described species, out of an estimated overall number of 60000-80000 species (Platnick, 1999). Unlike the situation with insects (Francke and Schulz, 1999), pheromones and other semiochemicals of arachnids, and especially spiders, have received little attention from researchers. What information is available on the use of semiochemicals by spiders will be reviewed and discussed in this chapter. 

Two of the three attractant pheromones identified to date are very close structurally to those used in primary metabolism. The biosynthesis of the estolide 5 probably starts from 3-hydroxybutyric acid (4), an intermediate in fatty acid biosynthesis (Fig. 4.3). Condensation of two units furnishes the pheromone 5. The formation of cupilure (3 Fig. 4.2) can be easily explained by two methylations from ubiquitous citric acid. Both compounds are unlike any known insect pheromones, whereas the third known attractant pheromone (ketone 1 Fig. 4.1), bears some resemblance to some insect pheromones. A proper comparison of the differences and similarities between insect and arachnid pheromones will require the identification of representative compounds from most of the families of both groups of organisms. 

Chemical cues from spiders are also used by non-arachnid predators to locate their prey. For example, the ichneumonid wasp Gelisfestinans parasitizes the spider Erigone atra, which lives in wheat fields. Contact with the silk of its host elicits increased searching behavior from the parasitoid, whereas contact with silk from other spider species does not, indicating a high degree of specificity (Baarlen et al.,... 

Evolution of mate-signaling in moths phylogenetic consideration and predictions from the asymmetric tracking hypothesis. In Evolution of Insect Mating Systems in Insects and Arachnids, eds. J. C. Choe and B. J. Crespi, pp. 240-256. Cambridge Cambridge University Press. 

Dusenostachys of the Calos Wasson clone was propagcit into the countryside, becom Arachnid.]... 

Arachnid note - Tables 1-4. X-ray crystallographic and ordering data - not reproduced.]... 

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Ticks, arachnids of the order Acarina, are bloodsucking parasites which are of major economic importance in cattle production. Infestation by ticks leads to losses in meat and milk production, reduction in hide quality and exposure of the host to any diseases for which the tick is a vector. Moreover, the resulting skin lesions are sites for infestation by other parasites and infection. Control of ticks of the Boophilus species is of major importance in view of their widespread distribution (Australia, South Africa, South America, Mexico and Southern North America). This task has been made more challenging by the emergence of strains resistant to one or more of the classes of compounds described below. 

Asci developing after fertilization by means of a trichogyne and spermatium minute parasites on insects and arachnids ... 

What venomous animal is an arachnidal arthropod with nipper-equipped front claws and stinger-equipped long, curved, segmented tails What are some significant aspects of its hazards ... 

Among the alkaloids, the most unusual example is an acaricidal (lethal to arachnids) monot-erpene derivative, altemicidin (Structure 18.3). This novel alkaloid was purified from amarine strain of Streptomyces sioyaensis SA-1758 isolated from marine sediments collected from the northern part of Japan. It yielded potent antitumor activity in vitro against L1210 murine leukemia and IMC carcinoma cell lines, but was toxic in vivo in mice. Altemicidin is a novel sulfur- and nitrogen-containing microbial metabolite with a monoterpene carbon skeleton.12... 

The following protocols can be used for the isolation and structural characterization of any natural bioactive peptides from the immune system of invertebrates. The different procedures that will be detailed below refer to the identification and primary structure determination of the Drosophila immune-induced peptides (19,20,23,27,30) and of bioactive peptides from the immune system of other Diptera (17,21,24,31). These approaches were also successfully used for the discovery of bioactive peptides from crustaceans, arachnids, and mollusks. These methods should be considered as a guideline and not as the exact procedure to follow (see Note 3). The suggested procedures will be reported following the normal order of execution, (1) induction of the immune response by an experimental infection, (2) collection of the immunocompetent cells (hemocytes), tissues (epithelia, trachea, salivary glands, etc.)... 

In Chapter 16 Trabalon and Bagneres present an overview of non-insect contact pheromones with emphasis on long-chain hydrocarbons and derivative compounds in Arachnids. Apart from studies on spider and scorpion venoms, the first semiochemical studies in these... 

The excellent book of Schmidt-Hempel (1998) describes the large variety of parasites that infest social insects. Various orders of insect (Lepidoptera, Diptera, Coleoptera, non-social Hymenoptera) and arachnid (Chelicerate Arachnids Aranea, Acari) parasites use chemical mimicry to manipulate social insect hosts, i.e., ants, bees and termites. Strangely, our perusal of the literature found no references describing this type of chemical interaction in social wasps, even though they are often parasitized by various macroparasites as well as other social insects from the same family, e.g. polistine wasps (see later). However, we found many references describing chemical manipulation by parasites of social hymenoptera and isoptera. 

Most of the present book is dedicated to one class of Arthropoda, the Insecta, because chemical communication research in this class is the most complete and broadly illustrated. This type of research on the chelicerate arthropods of the class Arachnida is, by contrast, poorly developed. We saw for example in Chapter 7, studies of chemical ecology interactions with Acari and particularly mite-insect interactions, and a few examples of chemical interaction with spiders were also shown in the same chapter on chemical mimicry, even though spiders are the most familiar and numerous of the arachnids. We undertook some work and about 15-10 years ago on contact chemical signal description and its relationship with behavior, physiology and reproduction, in different types of Aranea (spiders). We will present here a distillation of this work with a review of studies on the subject by different authors. Most notable here is the poverty of research on contact recognition signals and relative behavioral works on the order Scorpionida, the scorpions. Some of the few chemical data available are published here for the first time. 

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