This species is based on Lonchocarpus negrensis Benth.(1860). It was transferred first to the genus Derris as Derris amazonica Killip because Taubert (1891) had already proposed Deguelia negrensis for a different species[
Derris amazonica Killip
Lonchocarpus negrensis Benth.
Common Name: Timbo Branco
Deguelia amazonica is a climbing shrub with vigorous, woody stems that can be 30 metres or more long and twine high into the surrounding vegetation. The stems can be up to 50mm in diameter[
The roots contain the insecticide rotenone, though probably not in sufficient quantities for commercial exploitation.
The plant contains rotenone and has been used traditionally as a fish poison - the rotenone kills or stuns the fish making them easy to catch, but the fish remain perfectly edible for mammals. Rotenone is classified by the World Health Organization as moderately hazardous. It is mildly toxic to humans and other mammals, but extremely toxic to many insects (hence its use as an insecticide) and aquatic life, including fish. This higher toxicity in fish and insects is because the lipophilic rotenone is easily taken up through the gills or trachea, but not as easily through the skin or the gastrointestinal tract. The lowest lethal dose for a child is 143 mg/kg, but human deaths from rotenone poisoning are rare because its irritating action causes vomiting. Deliberate ingestion of rotenone, however, can be fatal.
The compound decomposes when exposed to sunlight and usually has an activity of six days in the environment.
Northern S. America - Bolivia, Peru, Colombia, Venezuela, northern Brazil, the Guyanas
Undisturbed forests, river banks and 'igarapé', generally preferring 'terra firme' with clay soils, in non-inundated areas, although it can occur in sandy soils and in seasonally inundated lowland[
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Often found in the wild in shallow and sandy soils that are too poor to support high forest[
This species has a symbiotic relationship with certain soil bacteria; these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[
The roots are a source of rotenone, which is widely used as an insecticide[
]. Rotenone is effective against a range of horticultural pests, such as aphids and caterpillars, and also against external body parasites like ticks, lice, fleas and flies. It is reported to be ineffective against bedbugs, cockroaches, scale insects and red spiders.[
]. This species does not produce enough rotenone to make it worthwhile for commercial production[
]. The rotenone can be found in various parts of the plant, but is generally most abundant in the bark, especially of the roots. The bark can be dried and powdered for use as an insecticidal dust[
Seed - best sown as soon as it is ripe in a partially shaded position in a nursery seedbed. A high germination rate can be expected, with the seed sprouting within a few days[
Like many species within the family Fabaceae, once they have been dried for storage the seeds of this species may benefit from scarification before sowing in order to speed up and improve germination. This can usually be done by pouring a small amount of nearly boiling water on the seeds (being careful not to cook them!) and then soaking them for 12 - 24 hours in warm water. By this time they should have imbibed moisture and swollen - if they have not, then carefully make a nick in the seedcoat (being careful not to damage the embryo) and soak for a further 12 hours before sowing[
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