Arthropods and Insects

The arthropods were the first organisms to emerge from the sea, and insects were the first invertebrates to fly. The arthropods consist of Crustacea (crabs, lobsters, shrimp, barnacles and woodlice), Chelicerata (spiders, ticks, mites, scorpions and others), Hexapoda or Insecta, and Myriapoda (millipedes, centipedes and other minor groups). These classes separated a long time ago, so they have developed quite differently, but it is interesting to discover parallel developments. 

Spiders and millipedes have sometimes developed chemical defences or communication chemicals similar to those of insects. It is therefore useful occasionally to make comparisons. 

The isolation of insect chemicals began slowly. Kermesic acid or Venetian red, a pigment from beetles (Chapter 8) has been known and used from ancient times. Wray, in 1670, reported formic acid by distillation of formicine ants. It was not until the 1930s that it began to be recognized that some Lepidoptera males were chemically attracted to females, and 

Representation of the life cycles of a hemimetabolous and a holometabolous insect. The symbols JH and MH between stages indicate where the juvenile hormone (Chapter 6) and moulting hormone (Chapter 7), which regulate development, are produced 

Reprinted from Comprehensive Natural Products Chemistry, Vol. 8, E. D. Morgan and I. D. Wilson. Insect hormones and insect chemical ecology, pp, 263-375. Copyright 1999, with permission from Elsevier. 

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The first section. Bioregulation of Insect Behavior and Development, includes chapters on arthropod and insect repellents, the identification of a beetle pheromone, nonparalyzing factors fi om hymenoptera, endogenous regulation of pheromone biosynthesis and mating, and systems for controlled release of pheromones. 

Chitin is similar in structure to cellulose, but the amide moieties allow for more significant hydrogen bonding between neighboring strands, which renders the polymer even stronger than cellulose (wood). Chitin is the material used in the exoskeletons of arthropods and insects, and over a trillion pounds of this polymer are produced by living organisms each year. 

Fenvalerate-tolerant strains of arthropods include insect vectors of disease, flies and cockroaches, arthropods of veterinary importance, and agricultural pests (Sawicki 1985). But serious... 

The distribution of aquatic species sensitivities to cypermethrin is typical of SPs [7] (Giddings JM (2006) Compilation and evaluation of toxicity data for synthetic pyrethroids. Unpublished report of Compliance Services International, Rochester). Crustacean and insect species (from the phylum Arthropoda) tend to be more sensitive to pyrethroids compared to other invertebrates such as worms and mollusks, and fish tend to be less sensitive than arthropods. These sensitivities are... 

Forensic entomology is broadly defined as the interaction of insects and other arthropods with legal matters. The field includes a wide variety of applications, encompassing any situation that may involve an interaction between insects and other arthropods and the law. The applications are generally categorized as urban, stored-product, and medicolegal forensic entomology (Lord and Stevenson 1986). 

Pest Any species that interferes with human activities, property, or health, or is otherwise objectionable. Economically important pests of agricultural crops include weeds, arthropods (including insects and mites), microbial plant pathogens, and nematodes (roundworms), as well as higher animals (e.g., mammals and birds). 

Burmester, T. and K. Scheller (1996). Common origin of arthropod tyrosinase, arthropod hemocyanin, insect hexamerin, and dipeteran arylphorin receptor. J. Mol. Evol. 42 713-728. 

Freeze-tolerance is also noted in less extreme, cold temperate environments, in which certain species elect to become solid-state even when their neighbors mount successful freeze-avoidance strategies of the types just described for terrestrial insects like D. canadensis. In fact, even the latter species has been observed to rely on freeze-tolerance under extreme conditions. The adoption of freeze tolerance in winter is noted in a wide variety of animal taxa, including numerous arthropods and even a few lower vertebrates, the freeze-tolerant frogs and reptiles (see Storey, 1990, for review). Plants, too, may spend much of the winter in a solid-state condition (Griffith and Antikainen, 1996). 

Chitin is another polysaccharide, but unlike cellulose, its sugars are combined with nitrogen-bearing molecules. Tough and chemically resistant, it makes up the exoskeletons of insects and other arthropods, and the cell walls of many fungi. 

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