Dong Yaw-Jen is perhaps looking for an allelochemical.

Herewith is a note that may help him:

The ecosystem approach to life processes provides an explanation of the different functions of allelochemicals. The mechanism of action involves acquiring resistance to detoxification by biotransformation that can be caused by a single mechanism, for example by splicing a gene as has been observed for many genes in mosquitoes and house flies (Tsukamoto, M.,  Methods of genetic analysis of insecticide resistance. In: Georghiou, G. P. and Saito, T. (Eds) Pest Resistance to Pesticides, Plenum Press, New York, 1983,pp. 71-98 in Pesticides Toxicity Specificity and Politics, Mirza Arshad Ali Beg, Research & Development Publications, Karachi 2004, DOI: 10.13140/RG.2.1.2893.0726).

 Life processes are governed at the cellular level. Cellular functions and cell growth are related to the capability of the cell wall to get hydrated and stretched and to maintain it in the meantime by extending the hydrogen bonding network. In the case of vegetables and plants also a similar promotion of hydration level and hydrogen bonding network is envisioned. The capability of cells to grow through the extension and maintenance of the hydrogen bonding network in a given microenvironment is aided by hydrogen bondable organic substances and inorganic ions like sodium, potassium, or chloride since they, in their hydrated form and higher degree of hydration, exert high osmotic potential that aids the transfer of the ions. Chemicals having similarity to normal nutrients in being hydrogen-bondable are usually hydrophilic and polar in character. Accordingly they are easily absorbed by the living system. Others that are non-hydrogenbondable are non-polar; they are lipophilic in character and tend to accumulate in lipid environments such as in the adipose tissues.

Robert H. Whittaker and Paul P. Feeny have demonstrated that secondary metabolites called allelochemicals are produced by an individual of one species and able to affect the growth, health, population biology and behavior of another species (www.uky.edu/~garose/sa.htm).

Adult P. polyxenes avoid plants of the group Cruciferae (the mustards) which produce such allelochemicals as sinigrin, a compound that contains a toxic constituent namely allylisothiocyanate,. On the other hand, the butterflies forage avidly among the Umbelliferae, which include such plants as celery.

P. polyxenes larvae were reared on a diet of celery leaves that had been induced to take up sinigrin (James M. Erickson and Paul Feeny 1974. Sinigrin: A Chemical Barrier to the Black Swallowtail Butterfly, Papilio Polyxenes. Ecology 55:103–111). The larvae fed with the diet of celery had their growth markedly inhibited. Celery containing a level of sinigrin equivalent to the level found in cruciferous vegetation was lethal to all the tested larvae. These experiments demonstrated that toxic allelochemicals could render an otherwise suitable host plant unacceptable to an insect pest.

Allelochemicals do not have a specific function in the growth and development of the host plant but they do affect the growth of other plants. They are not simple metabolic wastes which plants have to store. Coumarins, for example, are a class of allelochemicals that can block or slow cell division in the affected plant, particularly in root cells. Several kinds of allelochemicals, including flavonoids, phenolics, and tannins, suppress or alter hormone production or activity in competing plants. They can inhibit the growth of competing plants, and prevent seed germination.

Other chemicals, including terpenes and certain antibiotics, alter membrane permeability of host cells, making them either permeable or impermeable. In some cases, membrane uptake can be enhanced, particularly for micronutrients in low concentration in the soil. A large variety of allelochemicals have both positive and negative effects on metabolic activity of the affected plant.

It may be noted that all xenobiotics, including viruses, bacteria, and allelochemicals act as oxidants. They remove free energy or the driving force, de-polymerize the hydrogen-bonding network and induce oxidative dehydration initiated stress, OD-S in an already stressed situation created during the attack, indicated by dehydration, rise in temperature and release of another group of oxidants.

The allelochemical that may work in situations such as in Taiwan may be obtained from dry distillation of the litter in the orchards.

First try to fumigate on a small scale and in case of positive effect go for large scale trial.

You may use aluminum phosphide if the infestation is heavy.

Dr. Mirza Arshad Ali Beg.

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