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Stenusine, an antimicrobial agent in the rove beetle genus Stenus (Coleoptera, Staphylinidae)
No full textStenusine is well known as the alkaloid, discharged by the rove beetle, genus Stenus Latreille (Coleoptera, Staphylinidae). The Stenus beetles employ the alkaloid as an escape mechanism when on water surfaces. In the case of danger, they lower their abdomen and emit stenusine from their pygidial glands. Stenusine shows a low surface tension and therefore a high spreading pressure; these properties propel the beetle quickly over the water. Many Steninae do not live in habitats with open waters, but in detritus, leaf litter, mosses, etc. This raises the possibility that stenusine might also have another function, e.g., as antibiotic or fungicide. Stenus beetles show an intense grooming behaviour. With gas chromatography-mass spectrometry analyses we could prove that they cover themselves with their secretion. To tests its antimicrobial properties we conducted agar diffusion tests with stenusine and norstenusine, another substance that is abundant in most Stenus species. Both compounds have an antimicrobial effect on entomopathogenic bacteria and fungi. Stenusine not only allows for an extraordinary method of locomotion on water surfaces, it also protects the Steninae from being infested with microorganisms
Biosynthesis of stenusine
No full textThe rove beetles of the genus Stenus Latreille synthesize the alkaloid stenusine in their pygidial glands, which are located in the last three segments of their abdomen. It is proposed that stenusine is derived from the two amino acids, L-lysine and L-isoleucine. Feeding S. bimaculatus beetles with deuterium-labeled amino acids and using GC/MS analysis showed that L-lysine forms the piperidine ring of the stenusine molecule. The side chain originates from L-isoleucine and the N-ethyl group from acetate
The lodgepole × jack pine hybrid zone in Alberta, Canada: a stepping stone for the mountain pine beetle on its journey east across the boreal forest?
No full textHistorical data show that outbreaks of the tree killing mountain pine beetle are often preceded by periods of drought. Global climate change impacts drought frequency and severity and is implicated in the range expansion of the mountain pine beetle into formerly unsuitable habitats. Its expanded range has recently reached the lodgepole × jack pine hybrid zone in central Alberta, Canada, which could act as a transition from its historical lodgepole pine host to a jack pine host present in the boreal forest. This field study tested the effects of water limitation on chemical defenses of mature trees against mountain pine beetle-associated microorganisms and on beetle brood success in lodgepole × jack pine hybrid trees. Tree chemical defenses as measured by monoterpene emission from tree boles and monoterpene concentration in needles were greater in trees that experienced water deficit compared to well-watered trees. Myrcene was identified as specific defensive compound, since it significantly increased upon inoculation with dead mountain pine beetles. Beetles reared in bolts from trees that experienced water deficit emerged with a higher fat content, demonstrating for the first time experimentally that drought conditions benefit mountain pine beetles. Further, our study demonstrated that volatile chemical emission from tree boles and phloem chemistry place the hybrid tree chemotype in-between lodgepole pine and jack pine, which might facilitate the host shift from lodgepole pine to jack pine
Cicindeloine from stenus cicindeloides - isolation, structure elucidation, and total synthesis
No full textThe new piperideine alkaloid cicindeloine (3) was isolated from the pygidial glands of the beetles Stenus cicindeloides and Stenus solutus. The structure and absolute configuration of 3 were elucidated by NMR spectroscopy and asymmetric synthesis, respectively. A very efficient gram-scale synthesis of 3 was developed using an intramolecular aza-Wittig reaction as the final step. The synthetic route is comprised of 12 steps and proceeds in 20?% total yield. Nine of the 12 steps were conducted without column chromatograph
Life History Parameters of Aleyrodes proletella (Hemiptera: Aleyrodidae) on Different Host Plants
No full textIntrageneric differences in the four stereoisomers of stenusine in the rove beetle genus, Stenus (Coleoptera, Staphylinidae)
No full textMost species of the rove beetle genus Stenus employ the spreading alkaloid stenusine as an escape mechanism on water surfaces. In the case of danger, they emit stenusine from their pygidial glands, and it propels them over the water very quickly. Stenusine is a chiral molecule with four stereoisomers: (2'R,3R)-, (2'S,3R)-, (2'S,3S)-, and (2'R,3S)-stenusine. The percentile ratio of these four isomers is only known for the most common species of the genus: Stenus comma. With the intention of determining the stereoisomer ratios of five additional species from the two subgenera, Stenus and Hypostenus, we used GC/mass spectrometry measurements with a chiral phase. The results showed that the ratio differs among the genus. These findings can be a basis for chemotaxonomy. It is also possible that the biological function of stenusine, e.g., as antibiotic or fungicide, varies with changing stereoisomer composition
Effect of water stress and fungal inoculation on monoterpene emission from an historical and a new pine host of the mountain pine beetle
No full textThe mountain pine beetle (Dendroctonus ponderosae, MPB) has killed millions of lodgepole pine (Pinus contorta) trees in Western Canada, and recent range expansion has resulted in attack of jack pine (Pinus banksiana) in Alberta. Establishment of MPB in the Boreal forest will require use of jack pine under a suite of environmental conditions different from those it typically encounters in its native range. Lodgepole and jack pine seedlings were grown under controlled environment conditions and subjected to either water deficit or well watered conditions and inoculated with Grosmannia clavigera, a MPB fungal associate. Soil water content, photosynthesis, stomatal conductance, and emission of volatile organic compounds (VOCs) were monitored over the duration of the six-week study. Monoterpene content of bark and needle tissue was measured at the end of the experiment. ?-Phellandrene, the major monoterpene in lodgepole pine, was almost completely lacking in the volatile emission profile of jack pine. The major compound in jack pine was ?-pinene. The emission of both compounds was positively correlated with stomatal conductance. 3-Carene was emitted at a high concentration from jack pine seedlings, which is in contrast to monoterpene profiles of jack pine from more southern and eastern parts of its range. Fungal inoculation caused a significant increase in total monoterpene emission in water deficit lodgepole pine seedlings right after its application. By 4 weeks into the experiment, water deficit seedlings of both species released significantly lower levels of total monoterpenes than well watered seedlings. Needle tissue contained lower total monoterpene content than bark. Generally, monoterpene tissue content increased over time independent from any treatment. The results suggest that monoterpenes that play a role in pine-MPB interactions differ between lodgepole and jack pine, and also that they are affected by water availability. <br/
Variation in carbon availability, defense chemistry and susceptibility to fungal invasion along the stems of mature trees
No full textNew pyridine alkaloids from rove beetles of the genus Stenus (Coleoptera: Staphylinidae)
No full textThree new pyridine alkaloids were detected in the pygidial glands of some Stenus species. The chemotaxonomic significance of the occurrence of these alkaloids and stenusine in different Stenus species is discussed. The antimicrobial properties of (Z)- and (E)-3-(2-methyl-1-butenyl)-pyridine and the deterrent activities of stenusine and norstenusine were investigated
Influence of water deficit on the molecular responses of Pinus contorta?×?Pinus banksiana mature trees to infection by the mountain pine beetle fungal associate, Grosmannia clavigera
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