Spiders , arthropods

Tissue accumulation of exogenously added tritiated PGs was shown for the spider crab Libinia emarginata [107]. The earliest report of possible oxylipin production in marine arthropods was from gill and stomach tissues of the lobster Homarus sp. [15]. These were tested for their ability to produce prostaglandins in incubations with all-cis-[8,9,ll,12,14,15-3H6]eicosatrienoic acid. Carrier PGEj was added and the PGErtype compounds from the extract were purified by TLC. Quantitation was done by UV absorption at 278 nm after... 

In this discussion, we have restricted ourselves to the consideration of only a few examples of arthropod chemistry. From these alone, it is evident that insects synthesize defensive compounds by using all of the major biosynthetic pathways, producing acetogenins, simple aromatics and quinones, isoprenoids, and alkaloids. In addition, some of the millipedes, coccinellid beetles, and spiders we have studied utilize biosynthetic pathways that have yet to be characterized. 

All spiders are predatory on Inseots and other arthropods, although eatehing systems vary and not all spiders use webs as traps. 

Kromp, B. and K.-H. Steinberger (1992). Grassy field margins and arthropod diversity a case study on ground beetles and spiders in eastern Austria (Coleoptera Carabidae Arachnida Aranei, Opiliones). Agriculture, Ecosystems and Environment AQ 71-93. 

Insects, spiders, scorpions, crabs, centipedes, millipedes, and even some plankton are arthropods, the largest and most diverse animal phylum. Some are capable of producing very powerful toxins as an aid in the quest for food. Humans come in contact with these toxins, usually by accident or as a result of the animal defending itself. Some insects, mosquitoes and ticks for example, are capable of transmitting other organisms to humans that cause disease. While these organisms may be toxic to humans, they are not toxins and will not be discussed in this chapter. 

Females of the desert spider Agenelopsis aperta emit a volatile pheromone that attracts conspecihc males (Riechert and Singer, 1995). This pheromone was identified as 8-methyl-2-nonanone (1 Fig. 4.1), a previously unknown arthropod semio-chemical. It was found by headspace analysis and abdominal washings of females 2 weeks after their hnal molt, when they become sexually receptive it was absent in females of other age classes. The pheromone attracted males in a three-choice arena system at doses as low as 500 ng (Papke et al., 2001). Another female-specific ketone, 6-methyl-3-heptanone (2), was not attractive. Very low doses of 1 (10-9 mg/ml applied to a hlter paper placed in empty juvenile female webs) also induced courtship behavior in males (Papke et al., 2001). The normal behavioral sequence was followed, except for phases which required input from the female. The ED50 value (mean effective dose) of 1 was 5.5x 10-4 mg/ml hexane. In contrast, ketone 2 only induced a response in some males at unnaturally high concentrations... 

The composition of lipids from the silk and cuticule has been reviewed by Schulz (1997a, 1999). These lipids consist primarily of alkanes, as found in other arthropods, with 2-methylalkanes with an even number of carbon atoms in the chain being most abundant, with lesser amounts of alcohols, acids, aldehydes, and wax esters. Recently, a thorough analysis of the silk lipids of N. clavipes (Schulz, 2001) revealed a unique class of lipids from spider silk and cuticle, consisting of straight-chain and branched methyl ethers (1-methoxyalkanes, Fig. 4.4) with chain lengths between 25 and 45 carbon atoms. 

Schoppmeier, M. and Damen, W.G. (2001) Double-stranded RNA interference in the spider Cupiennius salei the role of Distal-less is evolutionarily conserved in arthropod appendage formation. Developmental Genes and Evolution 21 1, 76-82. 

Many beneficial predatory arthropods, including ground beetles and spiders, are increased by no-till. For example, no-till soybean had 17.6 carabid beetles/m2, compared with 0.38/m2 in plowed soybean fields (House and Parmalee, 1985). Higher beneficial arthropod populations have been correlated with reductions in crop losses due to certain pests. 

Spiders may be collected from remains where they may be predaceous on other corpse-inhabiting arthropods (Goff and Catts 1990 Reed 1958 Smith 1986). They may be encountered beneath carrion capturing prey but as general predators with unpredictable arrival time at carrion are unlikely to be useful in estimation of PMI. 

One of the best documented examples of aggressive non-social arthropod mimicry is that of bolas spiders that use the female sex pheromones of their lepidopteran hosts, mostly noctuids, to attract moth males. In their study on the moth Tetanolita mynesalis, i.e., the... 

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. 

From the viewpoint of zootaxa, the silkworm and the spider belong to insect and arachnid of arthropod, respectively. Their silk proteins (fibroin for silkworm silk and spidroin for spider major ampullate silk) do not have any genetic heritage in common and their amino acids sequence compositions are different too. However, the silkworm and spider employ a similar spinning process to produce silk. Furthermore, the silkworm silk and the major ampullate silk have a number of similar structural characteristics, both at the level of the secondary protein structure and the condensed silk morphology. Therefore, for the sake of convenience, they are discussed together in some parts of this text. 

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