Arthropods defenses

While arthropod defensive secretions often rely for their effect on well-known aliphatic acids, aldehydes, phenols, and quinones, there are many cases in which compounds capable of whetting the appetite of any natural products chemist are utilized. For example, steroids play a... 

Weatherston J, Percy JE (1970) Arthropod defensive secretions. In Beroza M (ed) Chemicals controlling insect behavior. Academic Press, New York, p 95... 

Arthropod defensive secretions may also be sequestered from food plants 68). Thus Ferguson and Metcalf 170) found that four species of Diabrotica beetles sequester cucurbitacins as their defense compounds. 

The qualitative and quantitative composition of arthropod defensive secretions may vary according to age, sex, physiological status, instar, caste and season. 

Weatherston, J., and J. Percy Arthropod Defensive Secretions. In M. Beroza ed.. Chemicals Controlling Insect Behavior, p. 95-144. New York Academic Press 1970. 

A widespread and perhaps primitive function of the mandibular gland secretions is defense. Bees typically release these chemicals when they are roughly handled. The secretions include chemicals that are common arthropod defensive compounds. When crickets are treated with the mandibular gland compounds of Ceratina, attack by ants is deterred (Wheeler et al., 1977). 2-Heptanone in Apis worker mandibular glands acts as an alarm pheromone in conjunction with sting gland secretions. 

Component of arthropod defensive secretions isol. from the grasshopper Romalea microptera. Metab. of Streptothrix chromogena. Dienophile, H acceptor for Oppenauer oxidns., mild dehydrogenating agent. 

An excellent review by Roth and Eisner (63) summarized the chemical defense substances found in arthropods up to 1962. These authors listed 31 defense substances of known structure one anhydride, three carboxylic acids, nine aldehydes, one furan, three hydrocarbons, two ketones, one lactone, eight quinones, and three inorganic compounds. Many of these same compounds (unsaturated aldehydes and quinones) have been found in other arthropods since 1962 (38). The compounds are discharged when the animal is disturbed by predators, and there can be no doubt that the action of most of them... 

Meinwald, J., K. Erickson, M. Hartshorn, Y. C. Meinwald, and T. Eisner (1968). Defensive mechanisms of arthropods. XXIII. Anallenic sesquiterpenoid from the grasshopper Romalea microptera. Tetrahedron Lett. 25 2959-2962. 

Defensive Measures Immunizations, good personal hygiene, physical conditioning, use of repellents for arthropods, wearing protective mask, and practicing good sanitation. Spores can be killed by pressure-cooking food to be canned. 

Blum, M. (1981) Chemical Defenses of Arthropods (Academic, New York). 

Perhaps the most interesting arthropodan defensive compounds from the point of view of structural diversity are the alkaloids. While alkaloids had long been believed to arise only as a consequence of plant secondary metabolism, it has become apparent over the last few decades that arthropods are both prolific and innovative alkaloid chemists. The millipede Polyzonium rosalbum, once thought to secrete camphor (20), in fact gives off a camphoraceous/earthy aroma produced by the spirocyclic isoprenoid imine polyzonimine (21). 

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. 

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