Water-beetles

Since the predatory water beetles cannot biosynthesise the steroid skeleton de novo, steroidal precursors must be obtained from exogenous sources. Bacillus-strains, isolated from the foregut of the water beetle Agabus affinis, were tested for their ability to transform steroids [101]. After incubation with androst-4-en-3,17-dione two Bacillus strains produced 13 different transformation products. Hydroxylation took place at C6, C7, Cll and C14 resulting in the formation of 6fi-, 7a-, 1 la-, and 14a-hydroxyandrost-4-en-3,17-diones. After incubation with pregnenolone the two Bacillus strains produced a variety of steroids among which 7a-hydroxypregnenolone was the major product [102]. 

Norsesquiterpenes of defensive secretions of a water beetle were isolated and identified on silica and by RPC. Subsequently the method was used to obtain the horsesquiterpene titer of two species (5/9). 

The prothoracic defensive secretion in one of water beetles, llybius fer-nestratus, contains as a main component methyl 8-hydroxyquinoline-2-carboxy-late (51) (Table V), which is not toxic to amphibians and fishes but produces clonic spasms in small mammals like mice (96,100,101). 

A predominant toxin (51) from water beetles of the genus llybius (Table V) shows a UV absorption corresponding to hydroxyquinoline or hydroxyiso-quinoline. The H-NMR spectrum exhibits, beside signals of methyl ester and phenol, signals of five aromatic protons as both ABC and AB systems, the latter indicating two protons at C-3 and C-4 in quinoline. Since electron pyrolysis of 51 gives radioactive 8-hydroxyquinoline, its structure is identified as methyl 8-hydroxyquinoline-2-carboxylate (51) and confirmed by synthesis from xanthurenic acid (52) (Scheme 48) (101). The precursor of this alkaloid was shown to be tryptophan (444). 

A water beetle finds the surface of a pool a matter of life and death, a perilous entanglement or an indispensable support. ... 

T85 Corcyra cephalonica, T86, T87 Gyrinus, Dineutes, water beetles 601 603... 

Water beetle (Dytiscus) defence bombardier beetle (Bradynus) peroxidase substrate for ultimate benzoquinone discharge... 

The secretion of large amounts of cortexone (36) by the water beetle (Dytiscus maaginalis) as a defensive substance has been reported ... 

Schaaf O, Dettner K. (2000) Polyunsaturated monoglycerides and a pregnadiene in defensive glands of the water beetle Agabus affinis. Lipids 35 543-550. 

Gyrinidal. C,4)1,303, Mr 234.30. Defence substance of water beetles (Carabidae) of the genera Gyrinus and Dineutes produced in the so-called pygidial glands... 

CisH,o04, Mr 254.24, yellow cryst., mp. 245.5 -247 C, occurs in the defence secretion of the water beetle Dytiscus marginalis. 

Syn. For- Brilliant Green) see Polyacrylonitrile (Brilliant Green + Water) Beetle 227-8... 

Repeated rDNA has also been shown in the cricket, Acheta (Lima-de-Faria et al., 1969), the water beetles, Dytiscus and Colymbetes (Gall, et al., 1969), and the fungus... 

Several arthropods are rich sources of steroidal defensive compounds. These progestagens are particularly common in water beetles of the subfamilies Colymbetinae and Dytisci-nae. Beetles of these families accumulate steroidal toxins as... 

As early as 1901, Ciardina described the presence of a specially stainable chromatin body in oogonia and oocytes of the water beetle Dytiscus, later on to become known as the Giardinas body. About 30 years later, Bauer (1933) proved by the use of the Feulgen reaction that the Giardina s body contains a large amount of DNA. The occurrence of the extrachromosornal DNA is now well established for many insect species (see Table II). 

Cortexone and 12-hydroxy-4,6-pregnadien-3,20-dione are feeding deterrents of certain water beetles (E 5.1). They act as hormones in vertebrate predators. 

In mammals, birds, insects, and some plants, compounds of the kynurenic acid group are end products of tryptophan metabolism. They are either excreted with the urine (E 1) or are accumulated in the organism. 8-Hydroxyquinaldic acid methyl ester is a feeding deterrent and aseptic of certain water beetles (E 5.1). 

Gentisic acid glycosides act as leaf movement factors in Mimosa species (E 2.2). Gallic acid is an inhibitor of flowering in Kalanchoe blossfeldiana (E 2.2). Benzoic acid, p-hydroxybenzoic acid as well as protocatechuic acid methyl and ethyl esters are secreted from the pygidial glands of water beetles as antiseptics and feeding deterrents (E 5.1). 

Synthesized in the pro thoracic glands of the water beetle Cyhister limhatus and Cyhister tripunctatus feeding deterrents... 

Quinoline derivatives 8-Hydroxyquinaldic acid methyl ester (D 21.5) Synthesized in glands of the water beetle Ilybius fenestratus, feeding deterrent, antiseptic... 

Benzoic acid derivatives Benzoic acid, p-hydroxybenzoic acid, protocatechuic acid methyl and ethyl esters, hydroquinone (D 22.2.5) Hydroquinone (D 22.2.5), H2O2 Secreted from the pygidial glands of the water beetles Dytiscus sp., feeding deterrent, antiseptic Synthesized in glands of the bombardier beetles Brachynus sp. (Fig. 338)... 

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