On every stem, on every leaf…and at the root of everything that grew, was a professional specialist in the shape of a grub, caterpillar, aphid, or other expert, whose business it was to devour that particular part.
-Oliver Wendell Holmes

A Completely Different Perspective:
Mergence of Entomology & Pathology
And the Vector Pathway

This month instead of talking about a specific pest I thought I would write from a little broader outlook. I have not abandoned my favorite topics of bugs and plant diseases but I have combined them to maybe show you a unique view of the two that you may not have imagined previously. Enjoy.

The problem of insects in relation to plant diseases is an extensive and limitless field. Complex associations between vegetation, pathogens, and insects have been constantly evolving during the last two hundred million years. Since the time when humans first appeared on earth they have traveled the globe taking with them, intentionally and unintentionally a cornucopia of various organisms. Even the agricultural practices of humans have strongly influenced the distribution of crop arthropod pests and disease pathogens. These pests lie dormant on propagation material such as seeds and cuttings that are distributed around the world to emerge as exotic pests at their new destination. Insects are notorious for their unwelcome invasions of new lands bringing with them unknown pathogens, and costly quarantine to guard against such pests must be maintained. These quarantine programs have become even more important with the advent of the free trade policy.

The discovery that insects are concerned in the transmission of plant diseases was made at approximately the same time that it was demonstrated that insects could transmit diseases of people and other animals, but study of the subject has progressed somewhat more rapidly in the field of animal pathology than it has in plant pathology. This difference may be explained in part by the greater value placed upon the life and health of man and his domesticated animals as compared with that of plants. It would seem now that it is time for the research of plant pathology to catch up.

There is no aspect of the study of plant pathology more fundamentally important than that dealing with the methods by which diseases are transmitted and the relative significance of each method. The usual course of disease spores and other propagules are two very common occurrences here in the Pacific Northwest; rain and wind. So looking at the role of insects in the spread and development of plant diseases has been especially slow in receiving the attention that it deserves. Plant pathologists have been inclined either to avoid a study of insects associated with diseases or to treat the problem in a very superficial manner. The problem has been neglected to an equal degree by the entomologists. They have been so greatly concerned with the direct injury to plants by insects that they have had very little time for the study of the more obscure injury caused by insects acting as vectors of plant diseases. Workers in both fields are concerned with protecting agricultural crops against those innumerable pests which take such a large annual toll from the farm income. In spite of this common interest in a problem of such vital importance to human welfare, the two sciences have widely divergent viewpoints. This lack of common ground limits knowledge exchange which is one of the major problems faced by this topic. In recent years there has been some cooperation but the present situation still leaves much to be desired. It is one thing to talk of cooperation and another thing to cooperate.

The ability of the insect and pathogen to continually evolve and out grow peoples efforts to obliterate them is another source of great concern in this topic area. Resistance to whole groups of chemicals by certain insect pests as well as the creation of virulent pathogen strains is the result of the naive attempt of humans to control nature. People’s attitudes are slowly changing from crop situations completely devoid of pest organisms to acceptable levels and complexes of both pest and beneficial organisms.

Thus, it appears that yet again I end up at the same conclusion; Integrated Pest Management, is the past, present and future of our world.

Today the network of relationships linking the human race to itself and to the rest of the biosphere is so complex that all aspects affect all others to an extraordinary degree. Someone should be studying the whole system, however crudely that has to be done, because no gluing together of partial studies of a complex nonlinear system can give a good idea of the behavior of the whole.
-Murray Gell-Mann

References
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