Bombardier beetles defense

Figure 11.17 below shows the unbalanced chemical reaction that results in the bombardier beetles defensive spray. 

Peschke, K., Schmitt, K., and Zinner, K. (1986). Occurrence of electronically excited products during the defensive reaction of bombardier beetles. Pbotobiochem. Photobiophys. 12 275-282. 

Animals use chemical weapons for both defense and attack. Considering defensive tactics first, bombardier beetles (Brachinus spp.) can fire a hot solution of irritant... 

Jeffrey Dean, et al., Defensive Spray of the Bombardier Beetle A Biological Pulse Jet. Science 248 (1990) 1219. 

DEFENSIVE APPARATUS OF A BOMBARDIER BEETLE B, COLLECTING VESICLE E, EXPLOSION CHAMBER G, ECTODERMAL GLANDS SECRETING CATALASE L, SECRETORY LOBES M, SPHINCTER MUSCLE 0, OUTLET DUCT. B CONTAINS A MIXTURE OF HYDROQUINONE AND HYDROGEN PEROXIDE, EXPLODED BY CATALASE WHEN IT PASSES INTO E. 

In The Blind Watchmaker Dawkins turns his attention briefly to the bombardier beetle. First he cites a passage from The Neck of the Giraffe, a book by science writer Francis Hitching, that describes the bombardier beetle s defensive system, as part of an argument against Darwinism ... 

Dawkins didn t give us any details of how the bombardier beetle s defensive system might have evolved. To point out the problem with his argument, however, let s use what we know of the beetle s anatomy to build the best possible case for the evolution of the bombardier bee-tie. First, we should note that the function ofthe bombardier beetle s defensive apparatus is to repel attackers. The components of the system are (1) hydrogen peroxide and hydroquinone, which are produced by the secretory lobes (2) the enzyme catalysts, which are made by the ectodermal glands (3) the collecting vesicle (4) the sphincter... 

Thus, to go back to the bombardier beetle and the human eye, the question is whether the numerous anatomical changes can be accounted for by many small mutations. The frustrating answer is that we can t tell. Both the bombardier beetle s defensive apparatus and the vertebrate eye contain so many molecular components (on the order of tens of thousands of different types of molecules) that listing them— and speculating on the mutations that might have produced them—is currently impossible. Too many of the nuts and bolts (and screws, motor parts, handlebars, and so on) are unaccounted for. For us to debate whether Darwinian evolution could produce such large structures is like nineteenth century scientists debating whether cells could arise spontaneously. Such debates are fruitless because not all the components are known. 

Eisner, T Attygalle, A. B., Eisner, M., Aneshansley, D. J., and Meinwald, J. (1991) Chemical Defense of a Primitive Australian Bombardier Beetle (Carabidae) Mystropomus regularise Chemoecology, 2, 29. 

The bombardier beetle uses an explosive discharge as a defensive measure. The chemical reaction involved is the oxidation of hydroquinone by hydrogen peroxide to produce quinone and water ... 

Bombardier beetles can repel predators such as frogs with a chemical defense mechanism powered by the catalytic decomposition of hydrogen peroxide. 

Survival techniques of insects and small animals in a fiercely competitive environment take many forms. For example, chameleons have developed the ability to change color to match their surroundings and the butterfly Limenifis has evolved into a form that mimics the poisonous and unpleasant-tasting monarch butterfly [Danaus], A less passive defense mechanism is employed by bombardier beetles [Brachinus], which repel predators with a "chemical spray."... 

Chemical Defense Many insects secrete hydrogen peroxide (H2O2) and hydroquinone CsH4(OH)2- Bombardier beetles take this a step further by mixing these chemicals with a catalyst. The result is an exothermic chemical reaction and a spray of hot, irritating chemicals for any would-be predator. Researchers hope to use a similar method to reignite aircraft turbine engines. 

The temporal pattern of odor emission can also show marked periodicity on either a short timescale (milliseconds) or a longer one (hours or days). Scent production may occur on a short timescale such that odor quanta are produced and released discretely. For example, some species of female moths have been reported to produce odor puffs rather than steady odor production. Odors used for defense, such as the spray secretions of skunks or bombardier beetles, may last only a few seconds. On longer timescales, the scent emission of pheromones for some organisms may follow a temporal pattern that correlates with diurnal phases or with specific periods in the reproductive cycles of individuals. Several studies of flowering plants have shown that floral scents are emitted for hours during those... 

Given their ability to discharge these chemical bombs when threatened, bombardier beetles are aptly named. Beetles differ from other insects in that they cannot fly instantly. They store their wings under covers, which they must retract before they can take to the air. Sort of like Clark Kent having to shed his everyday clothes before becoming Superman. Since beetles cannot fly to safety the second they are attacked, they have evolved emergency defenses to deploy while they prepare to flee. 

Scientists have studied the African bombardier beetle extensively in order to understand its remarkable defense system. When attacked by predators, mostly ants, the beetle unleashes bursts of hot chemicals with audible detonations. The spray originates from a turret-like appendage under its abdomen, which the beetle maneuvers to achieve remarkable target accuracy. But the truly amazing thing is the chemistry of the spray. 

Bombardier beetles. Beetles of the genus Brachinus and related species. They possess an abdominal defensive gland with which they can shoot explosion-like a hot secretion at an enemy. For this a 25% HjOj solution and a 10% solution of hydroquinone are injected into a combustion chamber . The catalases and polyphenol oxidases (temperature optimum of the enzymes 70-80 °C) present in the chamber effect an explosive reaction to water and benzoquinone or methyl-1,4-benzoquinone and the up to 70 °C hot mixture is shot speciflcally at the enemy. 

Simple phenols that can be converted readily to quinones by enzymatic oxidation are used by arthropods as defensive secretions. The biosynthetic origin of the phenolic substrates is not known. Probably the most remarkable of these is the defense of bombardier beetles, of the genus Brachynus. A secretion as hot as 100°C is produced by a reaction among hydroquinone, a phenolic substrate, H2O2 and the enzyme catalase. A highly exothermic reaction occurs as hydroquinone is oxidized to benzoquinone, the major product of defense. The beetle, when endangered, discharges a hot explo-... 

Cyanohydrin chemistry plays a central role in the defense system of Aphelo-ria corrugata. This millipede uses a two-chamber gland much like that used by the bombardier beetle (see A Word About... Quinones and the Bombardier Beetle in Chapter 7) to deliver a secretion that contains hydrogen cyanide. Apheloria stores benzaldehyde cyanohydrin and, when threatened, converts it to a mixture of benzal-dehyde and hydrogen cyanide, which is then secreted. The hydrogen cyanide gas that emanates from the secretion is an effective deterrent of predators. 

A wide variety of defense substances occur in insects. They are either accumulated simply in the insect s body, like the cardiac glycoside calotropin in the monarch butterfly, or they are constituents of the hemolymph and are discharged, e.g., by reflex bleeding, when a predator attacks the insect, as with cantharidin from the meloid beetle. In some cases the products may be actively expelled. A characteristic example in this respect is the ejection of quinones from special glands of the bombardier beetles Brachynus sp.) (Fig. 338). 

The bombardier beetle uses a catalyzed decomposition of hydrogen peroxide as a means of defense. An enzyme produced by tbe beetle catalyzes tbe rapid exothermic reaction. The resulting steam, along rrvith other irritating chemical, is then ejected. 

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