Stenus

A number of nemertine worms, such as Amphiporus or Nereis, produce alkaloids such as 2,3-bipyridyl, anabaseine, nemertelline, or nereis-toxin, which are toxic to predators such as crayfish 4,17,28,230,226,). Arthropod-made alkaloids include glomerine and homoglomerine in Glom-erus 215), adaline in Adalia 227), coccinelline, euphococcinine, and derivatives in Coccinella, Epilachna, and other coccinellid beetles 28,226,227,235), and stenusine in Stenus 215), which are considered to be antipredatory compounds 4,17,28,494-496). 

The staphylinid beetle Stenus comma secretes the alkaloid stenusine (120) which has water spreading properties and thus allows the insect to move easily over the surface of the water. The absolute stereochemistry of the base has not been established, although the gross structure (120) has been synthesised (H. Schildknecht et al., Angew Chem. Intern.Ed., 1975, 14, 427). Australian mealy bugs Cryptolaemus montrouzieri excrete the dialkyIpiperidine (121), and probably also the trans-isomer as well (W.V. 

Alkaloids are important for butterflies and moths. Beetles of the genus Stenus (e.g., Stenus similis or Stenus bimaculatus) protect themselves... 

Schierling A, Dettner K, Schmidt J, Seifert K. Biosynthesis of the defensive alkaloid cicindeloine in Stenus solutus beetles. Naturwissenschaften 2012 99(8) 665-9. 

Figure 6.11 Putative biosynthetic pathway to stenusine in Stenus bimaculatus.

ScHiLDKNECHT, H., D. Berger, D. Krauss, j. Connert, j. Gehlhaus, and H. Essenbreis Defense chemistry of Stenus comma (Coleoptera Staphylinidae). LXI. J. Chem. Ecol. 2, 1—11 (1976). 

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