Changes

:Chromosome number: ''x''= 10, 11, 12, 13;''D. acuminata'': 2''n''= 22,''D. elegans'': 2''n''= 22,''D. elliptica'': 2''n''= 20, 22, 24, 36,''D. malaccensis'': 2''n''= 22, 24,''D. robusta'':''n''= 11,''D. scandens'': 2''n''= 26,''D. trifoliata'':''n''= 10, 11, 2''n''= 22, 24

*''Derris elliptica'' (Wallich) Benth., *''D. malaccensis'' (Benth.) Prain, *''D. trifoliata'' Lour.

*Derris, tuba root (En). *Touba (Fr)

The rotenoids from ''Derris'' constitute an effective alternative to regular synthetic insecticide applications in horticulture and agriculture. They can be applied to control a large array of pests on a range of crops. The insecticide is applied as dust, spray, dip or bait. In cabbage it is used to control the lepidopterous ''Plutella xylostella'' (diamondback moth) and ''Pieris rapae'' . It is also used to control the aphid ''Myzus persicae'' , which is a major pest of vegetables and peaches in China. Furthermore, it is applied against borers, thrips and seedling maggots on maize, golden apple snails ( ''Pomacea'' spp.) on rice, against the tenthredinid ''Caliroa cerasi'' on apple and oriental pear ( ''Pyrus pyrifolia'' (N.L. Burman) Nakai), against cotton stainer, black bean aphids, common cutworm, earcutting caterpillar, and against ''Helluta undalis'' on broccoli. The extract is also effective against pests of stored garlic and rice. In poultry farming it can be used to kill ticks, fleas, lice, mites, flies and to control sticktight fleas. It is reported to be ineffective against bedbugs, cockroaches, scale insects and red spiders.

The stems are sometimes used for rough cordage. The wood of ''D. robusta'' trees is sometimes used for tea chests and implements. ''Derris'' can serve as soil improver. Lianas, including ''D. elliptica'' , may occur as weeds in forest plantations of ''Acacia'' , ''Eucalyptus'' and ''Swietenia'' .

The main producing countries in South-East Asia are Malaysia, Indonesia and the Philippines. Imports in the United States of rotenoid-containing roots, mainly from ''Derris'' , exceeded 3000 t annually in the early 1950s, and in 1963 about 1500 t of crude ''Derris'' roots and 500 t of extract were imported. The introduction of synthetic insecticides, including pyrethrin analogues, has markedly reduced the demand for plant-based insecticides over the last 40-50 years.

The addition of soap solution (0.1%) lowers the toxic concentration of an aqueous extract of roots for snails from 2000 ppm to 100 ppm. Ethanolic and chloroform extracts cause 100% mortality at 100 ppm and 20 ppm, respectively. An ethanolic extract is more toxic than an aqueous extract because this solvent can extract more toxic constituents from the roots. However, this is not practical for use by farmers. Besides, the ethanolic extract is very toxic to fish. Rotenone at 20 ppm causes 83% and 100% mortality in snails after 24 hours and 48 hours, respectively. Rotenone-free extracts of ''D. elliptica'' , obtained by chloroform extraction and thermal heating were found to be still toxic to snails, but not to fish.

Nine pure compounds have been isolated from the roots of ''D. robusta'' : 4 isoflavones and 5 3-phenyl-4-hydroxycoumarins. The isoflavones include derrubone, robustone and robustone methyl-ether; the 3-phenyl-4-hydroxycoumarins include robustic acid and robustin. Seven pure compounds have been isolated from the stems of ''D. scandens'' , e.g. the prenylated isoflavones warangalone, 8-γ,γ-dimethylallylwighteone and 3'-γ,γ-dimethylallylwighteone, and the 3-phenyl-4-hydroxycoumarin robustic acid. All the prenylated isoflavones and robustic acid were found to be potent inhibitors of the catalytic subunit of cyclic AMP-dependent protein kinase (cAK, from rat liver, in vitro). None of the compounds, however, was able to inhibit Ca²⁺dependent and phospholipid-dependent protein kinase C (PKC, from rat brain, in vitro). The flavonoid compound dehydrorotenone, lupeol and a straight-chain ketone have been isolated from the roots of ''D. trifoliata'' , but these compounds seem to have no appreciable insecticidal activity. Pentacyclic triterpenoids have also been isolated, whereas the leaves of ''D. trifoliata'' have yielded the flavonoid rhamnetin 3-0-neohesperidoside. Fresh leaves of ''D. trifoliata'' contain 25 mg/g of lipid, 3 mg/g sterol and 3 mg/g triterpene. The sterol fraction consists of 1.5% cholesterol, 7.5% campesterol, 9% stigmasterol, 21.5% sitosterol and 60.5% stigmast-7-en-3β-ol, the triterpene fraction of 10% β-amyrin, 12% α-amyrin and 78% lupeol. The bark contains up to 9.5% tannin. Seeds of ''D. robusta'' contain the pyranoisoflavone derrone, the isoflavones derrugenin, robustigenin and 5-hydroxy-7-methoxyisoflavone, and rubone, a chalcone.

Aqueous extract of fruits of ''D. trifoliata'' with an LC₅₀value of 0.002-0.003 ppt showed toxicity to fish. The LC₅₀value for roots of ''D. elliptica'' for catfish in Bangladesh was 64-115 ppm. The toxicant in the root powder had completely detoxified in 6-7 days. Root powder is effective for eradicating predatory fishes in fish ponds at 5 ppm in fresh water and at 10-30 ppm in brackish water. ''Derris'' extract also has some fungicidal activity. The leaves of ''D. elliptica'' are said to be poisonous enough to kill cattle.

The wood of ''D. robusta'' is pale brown, with heartwood not distinctly demarcated from the sapwood. It is hard and heavy; the density is about 850 kg/m³at 15% moisture content.

Rotenoids are also obtained from the roots of other legumes such as ''Lonchocarpus'' , ''Millettia'' , ''Piscidia'' and ''Tephrosia'' spp. Other insecticides of plant origin used in South-East Asia are present in seeds of ''Croton tiglium'' L., stem and roots of ''Tinospora'' spp., leaves of ''Vitex negundo'' L., ''Nicotiana tabacum'' L. and ''Azadirachta indica'' A.H.L. Juss. They are also found in leaves, fruits and bark of ''Melia azedarach'' L., whole plants of ''Tanacetum cinerariifolium'' (Trev.) Schultz-Bip., ''Tagetes'' spp. and ''Lantana'' spp., and in leaves, roots and seeds of ''Annona squamosa'' L. As a fungicide, star anise ( ''Illicium verum'' Hook.f.) is more effective. Other piscicidal plants include ''Croton tiglium'' , ''Myrica esculenta'' Buch.-Ham. and ''Sapindus saponaria'' L.

*Woody climbers or scandent shrubs, or sometimes trees ( ''D. robusta'' ) or erect shrubs; roots up to more than 2 m long and up to 2 cm in diameter, dark reddish-brown or greyish-brown; stem of lianas up to 20 m long and up to 10 cm in diameter, often ridged and densely lenticellate. *Leaves alternate, imparipinnate with opposite leaflets, stipules small, stipels sometimes present. *Inflorescence terminal or axillary, pseudoracemose or pseudopaniculate, sometimes contracted, with flowers crowded on the short ultimate branchlets or clustered at the nodes. *Flowers bisexual, 5-merous; calyx tube usually cupular, almost toothless or with short teeth, the upper pair variably joined; corolla papilionaceous, much longer than the calyx, white, pink or purplish, standard often green at base, glabrous or hairy, wings adhering to the keel petals; stamens 10, united into a tube with openings at the base on either side of the upper filament; ovary superior, 1-loculate, with few ovules, style curved and tapering to a very small stigma. *Fruit an oval or elliptical to linear-oblong, flattened, indehiscent pod with wings along upper edge or both edges, 1-few-seeded. *Seeds usually reniform, smooth or wrinkled.

''Derris'' is placed in the tribe ''Millettieae'' within the subfamily ''Papilionoideae'' . It seems closely related to ''Millettia'' and ''Lonchocarpus'' , and to ''Aganope'' (or ''Ostryocarpus'' when this originally African genus is considered as congeneric). It is characterized by the winged sutures of the pods. The genus is often subdivided into 3 sections: section ''Derris'' with about 50 species including ''D. elegans'' and ''D. trifoliolata'' , section ''Brachypterum'' (Wight & Arn.) Benth. with 3 species including ''D. robusta'' and ''D. scandens'' , and section ''Paraderris'' Miq. with 6 species including ''D. elliptica'' and ''D. malaccensis'' . The latter two sections have been raised to generic level, differing from the first one particularly in the the inflorescences and in the pods. However, new combinations for the ''Derris'' species involved have often not yet been made. Sometimes, a fourth section ''Dipteroderris'' Benth. is separated from section ''Derris'' . The 4 South American species closely related to ''Derris'' are usually classified in ''Deguelia'' .

''Derris'' grows best in regions with an annual precipitation of 2300-3300 mm and a mean annual temperature of 29°C29 °C. ''D. elliptica'' can survive dry periods of up to 4 months. This species is often confined to low altitudes, but locally (e.g. in Java) it can be found up to 1500 m altitude. ''Derris'' can be grown on a range of soils varying from coarse sand to heavy clay, but swampy and stony soils are unsuitable. ''Derris'' is sensitive to waterlogging. It prefers a rich friable loam and tolerates a pH 4.3-8. It is often found on river banks, in brushwood, forest borders and secondary forest. ''D. trifoliata'' occurs near the coast in or near mangroves.

Some fungal diseases are reported to damage planted ''D. elliptica'' : a rust ( ''Ustilago derrides'' ), a ''Gloeosporium'' sp. that causes the shoot tips to die, and an unidentified fungal disease that attacks cuttings in nursery beds. Pests are not serious and are easily controlled.

After harvesting, the roots are cleaned, preferably in running water, and rapidly dried in the sun or in an oven at approximately 50°C 50 °C to about 10% moisture content. Drying can be speeded up by cutting the roots into pieces up to 5 cm long. The roots can be stored in a cool and dry place. However, drying the roots seems to degrade the active constituent, particularly when stored too wet.

In South-East Asia, several ''Derris'' species are widely distributed as wild plants, but some species (particularly ''D. elliptica'' and, to a lesser extent, ''D. malaccensis'' ) have been cultivated in gardens since antiquity. This has resulted in the present situation where, e.g. in Java, wild plants of ''D. elliptica'' vary widely but have a low rotenone content (about 0.5%), whereas the cultivated plants vary little but have a high rotenone content (12-13%). Collections of both provenances are available. Hybrids between ''D. elliptica'' and ''D. malaccensis'' have shown promising results. Breeding trials have been hampered by the almost total self-incompatibility or cross-incompatibility of most cultivars of ''D. elliptica'' .

*Auzay Hamid