Practical Lifestyle

Noel F. de Jesus

The rotenoids from plants like derris stand out for their potency and effectiveness against many crop pests.

The high cost of synthetic pesticides, the uncanny way that insects have of becoming resistant to these poisons, and the growing concern over environmental contamination by synthetic chemicals, have spurned renewed interest in the production of botanical pesticides. These are nature's pesticides-plants with root, stem, leaf, fruit or flower extracts that some of our farmers have traditionally used to kill destructive crop pests.
Scientists have already extracted "toxic" substances from marigold, black pepper, garlic, tobacco and even weeds. One commercial pesticide, pyrethrin, is made from chrysanthemum flowers.

Among botanical pesticides, however, the rotenoids stand out for their potency and effectiveness against many crop pests. They are as effective as the pyrethrin and 15 times more toxic than the nicotine in tobacco. The development of natural resistance or insect immunity to these botanical pesticides have rarely been reported despite their widespread and continued use since 1848.

Export of Derris roots, the main source of rotenoids for pesticide formulations in the United States, was a fledgling yet thriving industry in Southeast Asia before World War II. The Philippines, Indonesia and Malaysia were the major Derris suppliers before the war devastated the region's plantations. The United States turned to South and Central America for its Derris needs. In 1974, for instance, it imported 1.7 million kilograms of roots.
While these countries remain the major suppliers of Derris roots for the West's pesticide formulations, Southeast Asia has every chance of competing in the growing lucrative market by reestablishing its Derris plantations.

To revitalize the Derris industry in the region, the breeding and widescale planting of Derris with high levels of rotenoids must be supported by the government's agricultural research agencies.

Uses and advantages of Derris root extracts
With an ancient reputation, in Southeast Asia, it is popular as a fish killer. It has been used to eliminate the deadly piranha in Brazilian rivers. Today, it is used to kill predators like mudfish and gourami or trash fish in fish and prawn ponds. It is sold under brand names like Fishtox, Noxfish and Pronoxfish.

The insecticidal properties of Derris roots were first discovered in 1848 and the plant was first used against the nutmeg caterpillar. Derris was patented for use as an insecticide in England during the late 19th century. American farmers started using it in 1911. By 1940, the United States was importing 2,700 metric tons of Derris roots mainly from Southeast Asia to formulate pesticides. In 1975, it imported 1.7 million kilograms of Derris roots from South America and Africa. The market can only expand because of the escalating cost of synthetic pesticides and their ill-effects on the environment.

Today, there are more than 50 Derris-based commercial pesticide formulations. Most of these are used to kill insects and unwanted fish. These include Rotenox 5 WP, Rotenone 5EC and Noxfire 5EC.

Applied as a powder or spray, Derris is toxic to a wide range of insect pests of human beings, domesticated animals, and agricultural crops.
It is very effective against aphids, beetles, borers, the diamondblack moth, fruitflies, thrips, cabbage worms, fleas, fleabeetles, lice, loopers, mites, mosquitoes, paylids, slugs, and others.

It is recommended for bush and vine crops, citrus, deciduous fruits, mushrooms, asparagus, beans, beets, corn, forage crops, peas, potato, radish, strawberry and other vegetables.

Derris is popular as an insecticide because it is safe to human while toxic to target pests. In fact, a farmer can spray Derris root extracts on a salad vegetable like cabbage today and sell the produce tomorrow without endangering the health of consumers.
Derris root extracts easily and rapidly detoxify in our gastric juices and when exposed to the environment. Its control action lasts for a week. Thus, it does not pollute the environment; nor does it accumulate in the food chain like the persistent synthetic insecticides.

Despite its widespread use for 140 years, reports of insect resistance or the development of immunity to Derris is rare. This is in stark contrast to the synthetic pyrethroids to which insects become resistant after only two to three seasons of continued use.
A farmer can use extracts as dust or crude water extract without using costly or complicated extraction procedures.

Corn, tobacco and mango farmers, who keep backyard plantings of Derris, simply dig out some Derris roots in their backyard, crush or grind these in water, and then spray the crude extract against pests. They usually mix or dilute a concentration of 50 to 100 grams of fresh roots in 16 liters of water. The dilution rate at which the pest control material is effective is one part of root extract to 100 parts of water.

The Derris plant
While the lack of recent studies on Derris cultivation may be a handicap, the abundance of Derris species and their relative hardiness as "wild, undomesticated forest plants" are important factors in efforts to revitalize the industry.
In the Philippines, 13 Derris species thrive in thickets along riverbanks and streams or forests at low elevations from Luzon to Mindanao. They are locally called tubli (Derris elliptica), upi (Derris philippinensis), tuglon (Derris polyntha), malasaga (Derris scandens) and tubling tatlong dahon (Derris trifoliata).

The most popular species is Derris elliptica, a plant with high levels of rotenoid. Derris philippinensis is native to the country but is rarely used as a source of rotenoid. Derris polyntha is also a promising species; it appears to be more toxic to mosquito larvae than the first two species.

Derris is a sturdy leafy leguminous vine. It has fast-growing, brown, hairy branches that climb ramblingly on trellises and intertwine profusely on the ground. They can fix nitrogen in symbiosis with native rhizobia, making them covercrops to improve the fertility of newly established tree plantations.

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