Chrysomelids

Fig. 12 Structures of oleanane glycosides from chrysomelid beetles...

Fig. 17 Iridoid derivatives from rove beetles and divergent biosynthesis in chrysomelids and in rove beetles...

Compound 150, one of two isoxazolinones first found in the defensive secretion of chrysomelid beetles, Chrysomela tremulae, shows a UV spectrum... 

Interestingly, Lepidoptera and aphids seem to avoid already infested plants, whereas Coleoptera are in general attracted to volatiles emitted by plants that are under attack by conspecifics. This has been shown for scarabaeid (Domek and Johnson, 1988 Harari etal., 1994 Loughrin etal., 1995b) and chrysomelid beetles (Peng and Weiss, 1992 Bolter et al., 1997 Kalberer et al., 2001). The Colorado... 

Southwell, I. A. and Stiff, I. A. (1989). Presence of long-chain dialkyl ethers in cuticular wax of the Australian chrysomelid beetle Monolepta australis. J. Chem. Ecol., 15, 255-263. 

HARTMANN, T., THEURING, C SCHMIDT, J., RAHIER, M PASTEELS, J.M., Biochemical strategy of sequestration of pyrrolizidine alkaloids by adults and larvae of chrysomelid leaf beetles. J. Insect Physiol., 1999,45, 1085-1095. 

HARTMANN, T WITTE, L., EHMKE, A., THEURING, C ROWELL-RAHIER, M., PASTEELS, J.M., Selective sequestration and metabolism of plant derived pyrrolizidine alkaloids by chrysomelid leaf beetles. Phytochemistry, 1997, 45, 489-497. 

Another unusual structure is represented by the male-produced pheromone of the chrysomelid beetles, Galerucella calmariensis and Galerucella pusilla. The compound, 12,13-dimethyl-5,14-dioxabicyclo[9.2.1]tetra-deca-l(13),ll-dien-4-one, (09) is a lactone including a 3,4-dimethylfuran substructure.943 Similar... 

Figure 3. Association of trans-epoxide hydrolase with arthropod herbivory. Trans/cis ratios of epoxide hydrolase in midguts of adult chrysomelid beetles are plotted relative to number of plant families ( ) or genera ( A) found within the host range of each species. See Figure 2 for details.

Obviously, much more research on pheromone communication in this genus and in other chrysomelid species is needed. However, it seems possible that these Dlabrotica species are achieving specificity in their signals through the use of stereoisomers as single component pheromones. 

Monarch butterflies t.g., Danaus plexipus) combine two sets of natural compounds. Larvae feed on plants rich in cardiac glycosides and use them as chemical defense compounds. Adult butterflies visit plants with PAs, where they collect PAs that are converted to pheromones or transferred to their eggs 4,17,31,33,361,515). A similar PA utilization scheme was observed with larvae of the moth Utetheisa ornatrix 367,516), where the compounds were shown to be deterrent for spiders and birds 225, 525). The chrysomelid beetle Oreina feeds on PA-containing plants, such as Adenostyles, and stores the dieUuy PAs in the defense fluid 463,524). 

Rowell-Rahier, M., Witte, L., Ehmke, A. and Hartmann, T. (1991) Sesquestration of plant pyrrolizidine alkaloids by chrysomelid beetles and selective transfer into the defensive secretions. Chemoecology, 2, 41-8. 

Figure 46 3-Nitropropanoic acid esters (193-195) from chrysomelid beetles and pinoresinol (35) from caterpillars of the cabbage butterfly, Pieris rapae.

In summary, the Delphinium diterpene alkaloids cardiopetamine (30) and 15-acetylcardiopetamine (27) are potent insect antifeedants active on two insect species with different feeding adaptations (a polyphagous Lepidopteran and an oligophagous Chrysomelid beetle), suggesting a potential broad range of antifeedant action for this class of compounds [20]. 

None of the PAs tested resulted toxic to the chrysomelid L. decemlineata. Oreina (Chrysomelidae) beetles are able to take up plant alkaloid N-oxides and eliminate tertiary PAs, but are unable to N-oxidize tertiary PAs [55, 67, 68]. Similarly, L. decemlineata adults could eliminate tertiary PAs efficiently enough to avoid poisoning. 

Plant sesquiterpenes and other terpenoids aie major detenninants of insect-plant interactions (2i 16V Many insecticidal and antifeedant terpenoids are epoxides including monoteipene Q2, 18. sesquiteipene QQ, 19-23). diteipene (Jl, 24) and triteipene derivatives (25-27) typified by the potent antifeedant azadirachtin (28-30). Most biolo cal effects have been determined with Lepidoptera and non-chrysomelid Coleoptera. Occasionally, the same compound, while normally inhibitory to herbivores, may for adapted insect species or at low concentrations have a stimulatory effect (13). Insects, in turn, synthesize their own defensive (21, and pheromonal (22) terpenoids. Plants may utilize insect pheromones such as the sesquiterpene alarm pheromone, rranj-B-famesene, in their own defense (34. 35). Inhibitory cyclic sesquiterpenes (Table I) and diterpenes (Table II) for insect herbivores have been identified from at least 28 genera of the terpenoid-rich Compositae. These studies were largely confined to extrafloral tissues. 

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