Cotton compounds, toxicity

The roles of these compounds are difficult to elucidate because compounds toxic to one insect may not be toxic to another, but glandless cottonseed is significantly more susceptible to insect attack than glanded cottonseed. Gossypol in cotton acts as an inhibitor of insects but the resistance has not been correlated with the total gossypol. Eagle (19) concluded... 

Most of the compounds of arsenic are toxic when in contact with the skin, when inhaled, or when ingested. As with arsenics cousin phosphorus above it in group 15 of the periodic table, care must be taken when using arsenic. The compound arsenic trioxide (As O ), an excellent weed-killer, is also carcinogenic. Copper acetoarsenite, known as Paris green, is used to spray cotton for boll weevils. A poisonous dose of arsenic as small as 60 miUigrams can be detected within the body by using the Marsh test. 

Different lines, each with Insect resistance, may possess different ratios of antibiotic compounds. Thus, It may be possible to Increase resistance by crossing lines where each contributes genes for biosynthesis of different antibiotic compounds. The tobacco budworm was selected for study In preference to the cotton bollworm because It Is easier to rear and use In the laboratory, Is more resistant to Insecticides In the field, and It Is approximately as susceptible to cotton constituents Incorporated In laboratory diets (14). This present study was carried out to Identify and analyze for cotton constituents that were toxic In laboratory feeding tests, and to determine whether there were positive correlations of their content In leaves and/or other tissue with field resistance. From this Information, the generation of lines with multiple factors for resistance could be Initiated. 

For the Mexican boll weevil a specially prepared calcium arsenate containing up to 20 per cent, of arsenic pentoxide is effective. This is prepared by heating together white arsenic and precipitated chalk in the presence of excess air at 650° C. The cotton plant is not injured by this preparation.10 In Peru about 30,000 acres of cotton fields are dusted annually from aeroplanes with calcium arsenate. Acid arsenates of calcium appear to be more toxic to boll weevils and to locusts than the basic arsenates. This is probably because the latter must be partially hydrolysed to compounds giving more soluble arsenic before toxic results are produced.11 The extensive application of such sprays to cotton plants is frequently followed by heavy infestations of the cotton aphis. This appears to be due in the first place to the positive photo-tropism of the winged females to white substances such as the arsenate, chalk or flour. Increase of the aphis population is then aided by the destruction by the spray of the hymenopterous parasites of the aphis.12... 

Cotton fabrics will char immediately on contact with the compound and produce a dense smoke. A specific toxic effect other than the purely cauterizing effect of the compound has not been observed by the submitter during the past 10 years. 

Studies on the scaleless chicken are underway examining its suitability as a model for assessing toxicity of organophosphates. The first compound selected for field trials was the defoliant DEF (S,S,S-tributylphosphorotrithioate) used during the harvesting of cotton in California and Arizona in the fall (October-November) when air movements are frequently restricted by inversions. DEF has been the subject of sufficient complaints to place it on the pre-RPAR list, although there are no reports of acute or delayed neurotoxicity in humans when it and related chemicals are used according to recommendations. It both inhibits cholinesterases and causes delayed neurotoxicity in hens (3,6). 

An example of an extremely toxic carbamate is aldicarb [2-methyl-2-(methylthio) propionaldehyde]. Both oral and dermal routes are the primary portals of entry, and it has an oral LD50 of 1.0 mg/kg (rat)and a dermal LD50 of 20 mg/kg (rabbit). For this reason it is recommended for application to soils on crops such as cotton, citrus, and sweet potatoes. This compound moves readily through soil profiles and has contaminated groundwater supplies. 

Oxidation dyes. These dyes are produced on the substrate by oxidation of colorless compounds such as aromatic amines and phenols. For example, anihne may be oxidized in cotton with sodium bichromate to produce aniline black. The color produced by aniline black is characterized by a full bluish black shade and excellent fastness. However, oxidation dyes are rapidly decreasing in importance because aniline, other aromatic amines, and bichromate that are used for oxidation, are toxic [7]. 

A modern approach to dealing with insect pests that wreck crops is to use specific attractants to lure the pest to its doom while offering no threat to beneficial creatures. Compounds such as grandisol 34 are not themselves toxic but they are irresistible to specific insect pests. Grandisol, marketed as grandlure , an attractant for male cotton boll weevils, is one of a family of unusual monoterpenes containing a four-membered ring. Others are lineatin 35, an attractant for ambrosia beetles that bore into conifers, filifolone 36, and raikovenal 37 (a sesquiterpene). 

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