PaRT 2 Insects

Part 2, Insects Recognizing Your Friends — Eliminating Your Foes, contains information on managing pest insects and attracting bene-ficials. It also features a photographic "Insect Identification Guide" of more than 100 com-... 

Commercial hee pollen is collected by means of netlike pollen traps, set up next to the beehives that remove some of the pollen from the hind legs of worker bees as they return to their hives. The collected pollen is manually rid of impurities (dirt, floral parts, insect fragments, etc.) and dried. Major bee pollen-producing countries include China and Spain. Bee pollen from China is mostly derived from buckwheat Fagopyrum escu-lentum Moench) and rape Brassica campes-tris L). 

Fibers (see Fibers, survey) used in textile production can have a wide variety of origins plants, ie, ceUulosic fibers (see Fibers, cellulose esters) animals, ie, protein fibers (see Wool) and, in the twentieth century, synthetic polymers. Depending on the part of the plant, the ceUulosic fibers can be classified as seed fibers, eg, cotton (qv), kapok bast fibers, eg, linen from flax, hemp, jute and leaf fibers, eg, agave. Protein fibers include wool and hair fibers from a large variety of mammals, eg, sheep, goats, camels, rabbits, etc, and the cocoon material of insect larvae (sUk). Real sUk is derived from the cocoon of the silkworm, Bombjx mori and for a long time was only produced in China, from which it was traded widely as a highly valuable material. 

Agricultural Uses. Pesticides represent the second largest commercial market for hydrazine. Hundreds of hydrazine derivatives have been patented for a wide range of agricultural appHcations. Table 13 presents a sampling of the 50—60 that are commercially available or developmental products. These compounds are made from hydrazine, MMH, and UDMH and are for the most part heterocycHc nitrogen compounds (see Insect control technology). 

The function of the essential oil in the plant is not fully understood. Microscopic examination of plant parts that contain the oil sacs readily shows their presence. The odors of flowers are said to act as attractants for insects involved in pollination and thus may aid in preservation and natural selection. Essential oils are almost always bacteriostats and often bacteriocides. Many components of essential oils are chemically active and thus could participate readily in metaboHc reactions. They are sources of plant metaboHc energy, although some chemists have referred to them as waste products of plant metaboHsm. Exudates, which contain essential oils, eg, balsams and resins, act as protective seals against disease or parasites, prevent loss of sap, and are formed readily when the tree tmnks are damaged. 

Schild-knorpel, m. thyroid cartilage, -kraut, n. skullcap Scutellaria), -krote, /. turtle, tortoise. -laus, /. cochineal insect, -part, n. tortoise shell. 

Crude papain, obtained as the dried exudate of the fruit and leaves of Caricapapaya L., Cari-caceae, Is usually found to have been contaminated during collection, drying, or storage by insects, rodent hair and excreta, botanical plant parts, sand, etc. and may thereby become further contaminated by harmful bacteria and enteric organisms. 

Shellac [124,125] is a natural resin used in very old times for varnishes and moulding compounds. The resin secreted by the lac insect, Kerriar paca, is collected by scraping the shellac-encrusted trees found in southern parts of Asia. It consists of a complex mixture of cross-linked polyesters derived from hydroxy acids, principally aleuritic acid (9,10,16-trihydroxyhexadecanoic acid). From a structural point of view, it appears that this material can be used as a crosslinking agent and/or as a monomer for developing dentrite-like polymers. The question is whether it is possible to produce this material from shellac by controlled hydrolysis. 

If flour or meal has become contaminated with storage insects after milling, the insect parts or larvae may be removed for identification by sieving or by a flotation procedure, but perhaps only excrement remains in the sample. This is about the same color as the material upon which the insects have fed and has generally the same appearance macroscopically. By means of the fluorescent light, however, pellets may be rendered more readily visible. If such flour is treated with clove oil, the pellets stand out distinctly and may be readily counted. 

For purposes of interpretation it may be desirable to know the relative size and number of insect parts in contaminated flour, meal, or bakery goods. Particles which pass through a No. 140 sieve (150 meshes per inch) can be identified. These may be recovered from flour with gasoline, after acid hydrolysis, using the Wildman trap flask. 

The insect s choice of food may be governed to a considerable extent, as ours is, by attractants and repellents. In many instances, the actual insecticidal action of plant extractives may be due primarily to an artificially high level of application, while, in fact, the parent plants are only repellent in the field. This repellency may appear to be resistance on the part of the plant, and the chemistry of such resistance factors has begun to receive much-needed attention. For example, Smissman and his coworkers have examined the chemical basis for the inherited resistance of some strains of corn to attack by the European corn borer. 6-Methoxybenzoxazolinone (X) was isolated (2, SO) and shown to be one of the principal resistance factors, and a number of synthetic analogs were found to... 

This is not a complete review of the literature of naturally occurring substances that are being or may be used in pest control. Excellent reviews cover well the older literature of natural insect at-tractants (9, 32, 37, 40, 41, 43, 44, 71) and repellents (7, 17, 22, 25, 54, 63, 64). Only the more important recent developments in this field are discussed here. I hope that this report will stimulate the increased interest and investigation on the part of both chemists and entomologists, working together, that is needed to make the concept a reality. 

The edible parts of parsnips contain a chemical of insecticidal and strong synergistic nature. This chemical, present in a concentration of about 200 p.p.m., was isolated and identified as 5-allyl-l-methoxy -2, 3-methylene-dioxybenzene or myristicin. Its toxicity to various insects (fruit flies, etc.) was established and compared with pyrethrum and aldrin. A second chemical, identified as 2-phenylethyl isothiocyanate, was found in the edible parts of turnips and rutabaga, which also have been consumed for centuries by humans without obvious harm. 

The recent explosion in the discovery of new myosin genes has led to the idea that myosins from different classes probably co-exist in cells. This has raised the obvious question as to what functions these myosins subserve within cells. Up to now, only the genes have been cloned for many of the 35 unique myosins. But this is not a question that can be answered solely by cloning rather, it is absolutely imperative to biochemically characterize these proteins if we are to understand their physiological properties. One way to do this is to express the entire protein or parts of the proteins in bacteria, yeast, or insect cells, and to then purify and characterize... 

Since 1945 the use of synthetic pesticides in the United States has grown 33-fold. The amounts of herbicides, insecticides, and fungicides used have changed with time due, in large part, to changes in agricultural practices and cosmetic standards (14, 15). At the same time, the toxicity and biological effectiveness of these pesticides have increased at least 10-fold (15). For example, in 1945 DDT was applied at a rate of about 2 kg/ha. With the more potent insecticides available now, similar effective insect control is achieved with pyrethroids and aldicarb applied at 0.1 kg/ha and 0.05 kg/ha, respectively. 

In addition, naturally growing plants resist plant pathogen and Insect attack because resistance develops over time via natural selection (35). Also, most natural and crop plants have, as a part of their basic physical and chemical makeup, a wide array of mechanisms that help them resist pest attack. These Include chemical toxicants, repellents, altered plant nutrients, hairiness, thorns, and diverse combinations of these (35). 

Cosmetic Standards. Over the last two decades, the U.S. Food and Drug Administration (FDA) has been lowering the tolerance levels for Insects and insect parts allowed in and on fresh and processed foods (14). Concurrently consumers have sought "more perfect," pest-free produce. To achieve this, farmers have Increased the quantities of pesticide they applied to crops. Although the presence of small amounts of insect parts in such products as catsup and apple sauce, or blemishes on oranges pose no health risk, these stringent standards have stood for many years. 

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