Tenebrionid beetles

In Australian tenebrionid beetles, defensive compounds and their patterns seem to be of only low chemotaxonomic value. However, the aforementioned aromatic compounds are restricted to the genus Tribolium. Abdominal defensive compounds were used as chemosystematic characters in order to construct a phylogenetic tree for the genus Tribolium [330]. The defensive secretion of adults of Tenebrio molitor was shown to contain toluquinone 7 and m-cresol 89 [333]. The quantification of benzoquinones in single individuals of Tribolium castaneum at different days after adult eclosion indicates that the amount of toxic quinone only shows a maximum subsequent to cuticle sclerotization. Obviously, there is a need for an adequate cuticular barrier for self-protection from these defensive compounds [334]. 

Larvae of the tenebrionid beetle Hypophloeus versipellis were shown to possess an unpaired defensive gland reservoir with an opening situated at the anterior border of the ninth tergite [ 126]. The secretion contains methyl- 1,4-ben-zoquinone 7, ethyl-1,4-benzoquinone 8, ethylhydroquinone, and acetophenone as well as 6-methyl-1,4-naphthoquinone 177,6-ethyl-1,4-naphthoquinone 178, and 6-propyl-1,4-naphthoquinones 179. Several alkenes (probably 1-alkenes) like 1-tridecene, 1-tetradecene, 1-pentadecene (main constituent), 1-hexa-decene, and 1-heptadecene may function as solvents for the solid biologically active compounds. 

The //-alkanes usually range in chain length from 21 to 31 or 33 carbons. Hydrocarbons with fewer than 20 carbons commonly occur as pheromones, defensive compounds and intermediates to pheromones and defensive compounds, but their volatility makes them unsuited to function as cuticular components, n-Alkanes have been found on almost every insect species analyzed, and can range from less than one percent of the total hydrocarbons, as in tsetse flies (Nelson and Carlson, 1986 Nelson et al., 1988) to almost all of the hydrocarbon fraction, as in the adult tenebrionid beetle, Eurychora sp. (Lockey, 1985). Depending upon the species, they can consist of essentially only one major component, such as n-pentacosane in the American cockroach, Periplaneta americana (Jackson, 1972) to a series of //-alkanes, such as the series from C23 to C33 in the housefly, Musca domes-tica (Nelson et al., 1981), with trace amounts to C37 (Mpuru et al., 2001). In all cases, the odd-numbered alkanes predominate, due to their formation from mostly two carbon units followed by a decarboxylation (Blomquist, Chapter 3, this book). Small amounts of even-numbered carbon chain //-alkanes often occur, and presumably arise from chain initiation with a propionyl-CoA rather than an acetyl-CoA. Occasionally, gas chromatographic analyses reveal similar amounts of even-numbered chain //-alkanes and odd-numbered chain components. This is a red flag that the samples must be checked for contamination. 

The composition of cuticular lipids varies at all levels of organization in insects, from among species to within individuals. The amount of cuticular lipid can also vary substantially. For example, wax blooms of desert tenebrionid beetles are associated with reduced water-loss (Hadley, 1994). High densities of wax may also serve to reduce heat load by reflecting solar radiation (Hadley, 1994) or to deter predators (Eigenbrode and Espelie, 1995) thus, it cannot be assumed that water conservation is the primary function of wax... 

Hadley, N.F. (1977). Epicuticular lipids of the desert tenebrionid beetle, Eleodes armatus seasonal and acclimatory effects on chemical composition. Insect Biochem., 7,277-283. 

Geiselhardt, S., Ockenfels, P. and Peschke, K. (2008). 1-Tridecene male-produced sex pheromone of the tenebrionid beetle Parastizopus transgariepinus. 

T10 bark beetles,500 termites,501 ants,501 tenebrionid beetles 502... 

Estimate how fast a Tenebrionid Beetle can push a ball of dung at 41.5°C, (Solution included.)... 

Oil from flower stalk of Petasites japonicus. Defensive secretion of tenebrionid beetles. Fp -49.1°. Bp 192.7°, Bp,o73°. 

Quinone, hydroquinone, methyl-, methoxy- dimethyl-, and ethylqui-nones have all been identified in beetles, and some of them in cockroaches and grasshoppers. The tenebrionid beetle Argoporus alutacea... 

J. Weatherstone and J. E. Percy, Venoms of Coleoptera, in S. Bettini, editor. Arthropod Venoms, Springer, Berlin, 1978, pp. 97 (for a lengthy list of Tenebrionid beetle quinones up to that time). 

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