#8 from R&D Innovator Volume 1, Number 3          October 1992

From Patio to Pesticide
by Robert O. Larson

Mr. Larson imports rare wood, mainly for musical instrument construction.  He also conducts seminars on using neem extract for insect control in the field and stored grain.

I was skimming the Atlanta Journal, killing time before my next flight, when I spotted an article on a U. S. Department of Agriculture research group that formulated a pesticide from an extract of the neem seed kernel.  A flood of memories rushed over me as I recalled visiting V.R. Sonti in Nagpur, India in 1973.  My host and I were having a night-cap on his veranda when I noticed the bizarre absence of insects.  This is how I reconstruct our conversation:

"Teddy, how come that even with these bright fluorescent bulbs, I see no bugs?"

"I think it has something to do with those two neem trees in the corner."

"What's a neem tree?"

"It's in the mahogany family."

"Okay, but what does it do?"

"They say when the breeze blows through the neem tree, the air takes on an odor that flying insects dislike.  They stay upwind of the smell."

I walked over to a tree; it seemed odorless. But when I chewed a leaf, I spat it out hastily -- it was extremely bitter.   We continued talking.  "What else can you tell me?"

"My wife washes and dries the seeds, then puts them in with our food grains."

"So what happens?"

"No bugs get into our food bins."

"Really? What else?"

"Well, she takes fresh leaves and puts them under our mattresses and then bugs don't crawl up into our beds."

As we continued talking, the wonders of this tree began to take on mythical dimensions.  His wife, it turned out, put leaves in books to keep insects from devouring them and put leaves in woolens to deter moths from laying eggs.

"Anything else?"

"Sure. If you crush the leaves and rub them on your body, mosquitoes won't bite."

He went on to say that neem leaf juice would cure scabies, relieve rashes, and prevent scarring from poxes.  He closed his fascinating lesson by mentioning that neem twig toothbrushes reduce cavities and prevent gum disease.

I was hooked, but I'm a hardwood importer, not a botanical pesticide expert.  What could I do with the information?  Something else was bothering me.  Even though several hundred million Indians were using this tree every day, we in the West hadn't heard much about it.  I asked why not. 

"No money in it, I guess."

In the Atlanta airport, I felt my amazement return after all those years, so I phoned the USDA researcher named in the article.  When I told Martin Jacobson what I knew, he invited me to visit his lab in Beltsville, Maryland.  There, the chemists and entomologists of the "Neem Team" reviewed their remarkable insect control results and asked me to obtain better seeds.  When I proved able to do that, they were apparently impressed; at any rate, they invited me to help them produce a stable pesticide from the neem tree. 

The neem team suspected that the active ingredient in deterring and killing insects was a recently isolated molecule named azadirachin.  I learned that big chemical companies were not interested in working with an unpatentable, natural product.  The molecule was complex and incompletely understood; no one believed such a tetranortriterpenoid molecule could be synthesized at the time.

I was intrigued and flattered by the challenge and the team's request for help.  Despite a smattering of biology and zoology in my background, I'm no chemist.  I decided my best contributions would be my abundant curiosity, resourcefulness, and tenacity.   I drew up an accord with USDA stipulating that I would oversee the development of an effective and stable pesticide and they, together with USDA researchers nationwide, would study its efficacy on insects and plants.

At first, I couldn't find a chemist able and willing to work in this eclectic area, but I reasoned that since azadirachtin was plant-derived, food chemists might be interested.  I located a chemistry lab with a rich background in consulting to agriculture and food companies.  

Early on, we recognized that the chief problem was not making an effective extract, but in stabilizing it.  Because the USDA extract decomposed by 75 percent in just four weeks, it was commercially useless.  We determined that azadirachtin was most stable in acid conditions.  That made eminent good sense, since its home in the seed was acidic as well.  When we held the pH between 3.8 and 4, like in the seed, the product held stable for months at a time.

Refrigeration enhanced stability but brought about oil separation upon prolonged storage, and this made it difficult to dilute the material with water for spraying plants.  It occurred to me that freezing the extract might cause the oil(s) to separate and the problem oil(s) could then be removed, permitting the easily emulsifiable oils which contained the active material.  This worked beautifully on the first trial and the revised formulation was the one submitted for registration by the Environmental Protection Agency.

We named the product Margosan-O after margosa, the Portugese name for neem.  My first seeds came from a pharmacist who'd been raised in the former Portugese colony of Goa and labelled the package "Margosa."  The USDA lab tests showed that Margosan-O diluted with water was death, delay and heartbreak to insects.  Even dilute extracts gave up to 30 days activity before decomposing into benign chemicals. 

Margosan-O was shown to be non-toxic to mammals, and extremely "soft" on good predator insects.  It is harmless, for example, to honeybees, beneficial wasps, butterflies, and ladybugs.  These results indicate that this pesticide has a unique ability to control more than 135 insects such as whiteflies, gypsy moths, leafminers and thrips without harming the environment.   Earthworms, actually increased in number after Margosan-O spray ran off into the soil!  This highly selective pesticide received a U.S. patent and was registered for use on non-food crops in 1986.

Lately, Neem has been receiving quite a bit of attention worldwide as various corporations  and agricultural entitities learn about the many uses of neem—from pesticides derived from a seed extract to hygienic and medicinal products from other parts of the tree.  Truly a tree for the 90's...and beyond!

What do I conclude from this serendipitous history?  The development of Margosan-O was stimulated from just about every imaginable source.  A news article in Atlanta freshened a memory of an evening in India, which led me to visit the USDA in Maryland, where I became obsessed by this natural product.  The use of food chemists on a pesticide problem helped overcome a shortage of the "right" technical expertise.  Many other people read the Atlanta Journal, many others have visited India, and others knew of the USDA research on neem.  My interests in exotic wood and the environment were the catalysts that stimulated me to evolve an idea into a useful product.

I take no great personal pride in the development of Margosan-O; My own contributions were embarrassingly minimal.  I served more as a conduit for the knowledge and efforts of others than as an laboratory-man.  Perhaps that defines the ideal role of the entrepreneur.